document resume ed 204 633 institutiondetect and prevent metal corrosion prepare wood, masonry, and...

DOCUMENT RESUME

ED 204 633 CE 029 608

TITLE Military Curricula for Vocational S TechnicalEducation. Painting I, II. 3-6.

INSTITUTION Army Engineer School, Fort Belvoir, Va.: Ohio StateUniv., Columbus. National Center for Research inVocational Education.

SPONS AGENCY Bureau of Occupational and Adult Education (DHEW /OE),Washington, D.C.

PUB DATE [78]NOTE 241p.: Photographs and some diagrams will not

reproduce well.

EDRS PRICE MF01/PC10 Plus Postage.DESCRIPTORS Autoinstructional Aids: Behavioral Objectives:

*Building Trades: *Equipment Utilization;*Individualized Instruction: Learning Activities:*Painting (Industrial Arts!: Postsecondary Education:Safety: Secondary Education: Skilled Occupations: .

Tests: Textbooks: *Trade and 'industrial Education:Workbooks

IDENTIFIERS _Military Curriculum Project

ABSTRACTThese two'student workbooks with texts for.a

secondary-postsecondary level course in painting comprise one of a'number of military-developed curriculum packages selected forAdaptation to vocational instruction-and curriculum development in n.

civilian setting. The two-part self-study course is designed toprovide the Student with basic.information on safety, equipment, and.procedures in painting. Painting I contains four lessons dealing withmaterials and equipmentl Safety,. Protective Coating laterials,Protective Coating Equipment, and Ladders, Scaffold, and MetalCorrosion. Painting II contains four lessons dealing with applicationprocedures: Painting Wood Surfaces, Painting MaSonry Surfaces,Painting Metal- Surfaces, and Inspection of Surfaces. Each lesson isorganized in this format:'text assignment, objective, reviewexercises, and answers keyed to the coded text for self- evaluation.

The text follows the lessons in each. part. Thirty-question finalexaminations are provided for:each unit, but no answers areavailable. (YLB)

********************************************************************* Reproductions supplied by -EDRS are the'best,that can. be Made

:from the original document..****3it**********,*********************Ii************.*****,************,li

Z M

z

This military technical training course has been selected and adapted by

The Center for Vocational Education for "Trial Implementation of a Model System

to Provide Military Curriculum Materials for Use in Vocational and Technical

Education," a project sponsored by the Bureau of Occupational and Adult Education,

U.S. Department of Health, Education, and Welfare.

Military

Curriculum Materials What Materials

Dissemination Is .. Are Available?

an activity to increase the accessibility of

military-developed curriculum materials to

vocational and technical educators.

This project, funded by the U.S. Office of

Education, includes the identification and

acquisition of curriculum materials in print

form from the Coast Guard, Air Force,

Army, Marine Corps and Navy.

Access to military curriculum materials is

provided through a "Joint Memorandum of

Unchtanding" between the U.S. Office of

Education and the Department of Defense.

The acquired materials are reviewed by staff

and subject matter specialists, and courses

deemed applicable to vocational and tech-

nical education are selected for dissemination.

The National Center for Research in

Vocational Education is the U.S. Office of

Education's designated representative to

acquire the materials and conduct the project

activities.

Project Staff:

Wesley E. Budke, Ph.D,, Director

National Center Clearinghouse

Shirley A. Chase, Ph.D.

Project Director

I, ... ..". ....

One hundred twenty courses on microfiche

(thirteen in paper form) and descriptions of

each have been provided to the vocational

Curriculum Coordination Centers and other

instructional materials agencies for dissemi-

nation.

Course materials include programmed

instruction, curriculum outlines, instructor

guides, student workbooks and technical

manuals,

The 120 courses represent the following

sixteen vocational subject areas:

Agriculture

Aviation

Building &

Construction

Trades

Clerical

Occupations

Communications

Drafting

Electronics

Engine Mechanics

Food Service

Health

Heating & Air

Conditioning

Machine Shop

Management &

Supervision

Meteorology &

Navigation

Photography

Public Service

The number of courses and the subject areas

represented will expand as additional mate-

rials with application to vocational and

technical education are identified and selected

for dissemination.

How Can These

Materials Be Obtained?411.4..4.4. 4 ',44444:a ..444:4; .44, ;tn.,' .4 .4.

Contact the Curriculum Coordination Center

in your region for information on obtaining

materials availability and cost). They

will respond to your request directly or refer

you to an instructional materials agency

closer to you.

CURRICULUM COORDINATION CENTERS

EAST CENTRAL

Rebecca S. Douglass

Director

100 North First Street

Springfield, IL 62777

217/782.0759

MIDWEST

Robert Patton

Director

1515 West Sixth Ave.

Stillwater, OK 74704

405/377.2000

NORTHEAST

Joseph F. Kelly, Ph.D.

Director

225 West State Street

Trenton, NJ 08625

609/292.6562

NORTHWEST

William Daniels

Director

Building 17

Airdustrial Park

Olympia, WA 98504

206/753.0879

SOUTHEAST

James F, Shill, Ph.D.

Director

Mississippi State University

Drawer DX

Mississippi State, MS 39762

601/325.2510

WESTERN

Lawrence F. H. Zane, PhD,

Director

1776 University Ave,

Honolulu, HI 96822

808/948.7834

The National Center

Mission Statement

Fr.7777'.

The National Center for Research in

Vocational Education's mission is to increase

the ability of diverse agencies, institutions,

and organizations to solve educational prob-

lems relating to individual career planning,

preparation, and progression. The National

Center fulfills its mission by:

Generating knowledge through research

Developing educational programs and

products

Evaluating individual program needs

and outcomes

Installing educational programs and

products

Operating information systems and

services

Conducting leadership development and

training programs

FOR FURTHER INFORMATION ABOUT'

Military Curriculum Materials

WRITE OR CALL

Program Information Office

The National Center for Research in Vocational

Education

The Ohio State University

1960 Kenny Road, Columbus, Ohio 43210

Telephone: 6141480655 or Toll Free 8001

6848.4815 within the continental U.S.

io (except Ohio)

Military Curriculum

Materials for

Vocational and

Technical Education

Information and Field

Scrvices Division

The Negev] Center for Research

in Vocational Education

MILITARY CURRICULUM MATERIALS

The military-developed curriculum materials in this course

package were selected by the National Center for Research in

Vocational Education Military Curriculum Project fcr dissem-

ination to the six regional. Curriculum Coordination Centers and

other instructional materials agencies. The purpose of

disseminating these courses was to make curriculum materials

developed by the military more accessible to vocational

educators in the civilian setting.

The course materials were acquired, evaluated by project

staff and practitioners in the field, and prepared for

dissemination. Materials which were specific to the nilitary

were deleted, copyrighted materials were either omitted or appro-

val for their use was obtained. These course packages contain

irriculum resource materials which can be adapted to support

vocational instruction and curriculum development.

PAINTING I, II Correspondence Course I3-6

Oeve loped by:

United States Army

Development andROVIRW Dates

Unknown

Occupational Area:

Building and Construction

Cost:

$3.00

Print Pages:

139

Availability:Military Curriculum Project. The Centerfor Vocational Education, 1960 KennyRd., Columbus, 01-1 43210

. Suggested Background:

None

Target Audiences:

Grades 10adult

Organization of Materials:

Text; student workbook with objectives, exercises, solutions, and discussion of exercises; and unit tests

Type of Instruction:

Individualized, self-paced

Type of Materials: No. of Pages: AverageCompletion Time:

Painting I Materials and Equipment 100 Flexible

Student Workbook and Examination 33

Painting II Application 72. Flexible

Student Workbook and Examination 34

Supplementary Materials Required:

None

fo)

COTO TT ketvFeltrr:r jr..r.A..nav Expires July 1, 1978

Course Description.

This two part course is designe, to provide the student with basic information on safety, equipment, and procedures in painting. Some of the

competencies included are:

Recognize hazards associated with paint materials and equipment and take safety measures that prevent accidentsSelect, use and stnre paint and protective coating materials properlyOperate, maintain and store the equipment used in applying protective coatingUse ladders and scaffolds safelyDetect and prevent metal corrosionPrepare wood, masonry, and metal surfaces for protective coatingInspect surfaces, evaluate paints and workmanship, and calculate surface areas

Painting 1 contains four lessons each containing an objective, text, review exercises, and answers, dealing with materials and equipment.

Lesson 1

Lesson 2

Lesson 3

Lesson 4

Safety covers general safety, accident hazards, fire hazards, health hazards, emergencies, and health services.

Protective Coating Materials covers the purpose, function, composition, and types of protective coatings; mixing andpreparing surface preparation materials; selecting exterior and interior protective coatings; and handling, storing anddisposing of protective coatings.

Protective Coating Equipment covers surface preparation equipment, application equipment, traffic markers, and signmaking equipment.

Ladders, Scaffold, and Metal Corrosion covers types of ladders, scaffolds, and hoisting equipment and types of corrosion,causes of corrosion, corrosion control and metal identification.

Painting II contains four lessons dealing with application procedures.

:Lesson 1 Painting Wood Surfaces deals with general characteristics of wood, preparation and application of protective coating

to interior and exterior surfaces, and camouflage painting.

.Lesson 2 Painting Masonry Surfaces deals with characteristics of concrete and masonry surfaces, preparation and application of

protective coatings to interior and exterior masonry surfaces, and the application of traffic markings.

Lesson 3 Painting Metal Surfaces contains information about visible identification of corrosion, preparing and applying protective

coatings to interior and exterior metal surfaces, repairing metal surfaces, metal conditioning and pretreatment, and

application of stencils and markings.

.Lesson 4 Inspection of Surfaces deals with inspection of old and new protective coatings as well as supervisory tasks.

This course is designed for student self-study with objectives, text, and self-graded tests. The text is coded and all questions are keyed to the

text fo; self evaluation. Thirty-question final examinations are provided for each unit, but no answers are available.

10

CCTd CI Kiln 11:11 VXATIA4 tturAppg1..1 ..., , ...AlDN...04,t

.. . . 1

PAINTING I, II

Table of Contents

Course Description Page 1

Painting I (Materials and Equipment) - lessons Page 3

Painting I (Materials and Equipment) Page 29Memorandum 562 text material

Examination - Painting I Page 128

Painting II (Application) - lessons Page 132

Painting II (Application) Page 161Memorandum 563 text material

Examination - Painting II Page 233

11.

ENGINEER q

SUBCOURSE 562

MATERIALS AND EQUIPMENT

CORRESPONDENCE COURSE PROGRAMU. S. ARMY ENGINEER SCHOOL

FORT BELVOIR, VIRGINIA

12 NRI 106

INTRODUCTION

This subcourse is the first of two subcourseson the subject of painting. It begins with areview of those aspects of safety practicethat are of continuous importance to thepainter. This is followed by instruction onthe selection and mixing of paints, the opera-tion and maintenance of paint equipment andthe proper storage of paint supplies. In addi-tion, a chapter is devoted to the identificationof metals and to the methods employed todetect and prevent corrosion.

This subcourse consists of four lessons andan examination as follows:

Lesson 1. Safety.

2. Protective Coating Materials.

3. Protective Coating Equipment.

4. Ladders, Scaffolding, and Met-al Corrosion.

Examination.

Ten credit hours are allowed for this sub-course.

You will not be limited as to the number ofhours that you may spend on the subcourse,any lesson, or the examination. For statisticalpurposes, you are required to enter in theproper space on each answer sheet the num-ber of hours spent in studying the text andsolving the exercises.

Text Furnished: Memorandum 562, Paint-ing I.

To facilitate removal, answer sheets arebound in reverse order at the end of this pub-lication. Make sure that the number on theanswer sheet is the same as the lesson onwhich you are working.

Each exercise has four choices with onlyONE best answer. Select the choice that youbelieve is best. Then turn to the answer sheetand mark an X through the letter repre-senting thv t choice.

The examination will be sent to you whenyou have successfully completed all the les-sons.

LESSON 1

SAFETY

CREDIT HOURS 2

TEXT ASSIGNMENT Memorandum 562, Chapter 1.

LESSON OBJECTIVE To teach you the hazards associated withpaint materials and equipment and to ex-plain the safety measures that preventaccidents.

EXERCISES

Requirement: Solve the following multiple-choice exercises.

1. Which of the following types ofpaint is not flammable?

a.

b.

c.

d.

oil-base

red-lead primer

rubber base

water-thinned

2. Painters who are sensitive totoxic or skin-irritating materials musttake special precautions. Of the follow-ing materials, which is the only one theyshould work with?

a.

b.

c.

d.

water-thinned paints

varnish

oil paints

texture paint

3. Which of the following wouldyou use to protect yourself against paintfumes and solvent vapors?

a. dispersoid respirator

b. supplied-air respirator

c. safety helmet

d. chemical-cartridge respirator

a.

b.

c.

d.

4. Your safety goggles should

have breakable lenses to permitemergency escape of trapped fumes

have only straight-ahead vision toexclude peripheral distractions

fit loosely for quick, emergency re-moval

have unbreakable glass or plasticlenses

5. You wear a safety helmet forprotection against which of the follow-ing?

a. abrasive blasting

b. solvent vapors

c. falling objects

d. acid cleaners

6. Painters should not wear cloth-ing with tears, rips or loose pocketsbecause they are

17

a. distracting

b. causes of accidents

c. unsightly

d. not useful

7. Which of the following do youconsider most important in working ina hazardous area?

a. drop cloth

b. disciplinary action

c. buddy system

d. duplicate equipment

8. The most common and seriousaccidents that occur during painting op-eration are caused by

a. inhalation of fumes

b. improper storage of equipment

c. fire

d. loss of footing

9. How tall may a stepladder be,in feet, for use while painting?

a. 16 c. 12

b. 14 d. 10

10. What minimum percentage ofoverlap do you require for each sectionin an extension ladder?

a. 25

b. 20

c. 15

d. 10

11. You are placing a ladder againstthe wall of a structure. How far out, atleast, would you place the feet of theladder?

a. two feet

b. Y4 working length of ladder

'. 1/2 working length of ladder

d. 1 yard1 5

12. At what height above theground would you insist that a scaffoldhave full length guard, nags?a. at any height

b. 50 feet

c. twice length of scaffold

d. 25 feet

13. Most paint products are flam-mable. What are the chief causes offire and explosions?

a. liquids and vapors

b. high-flash solvents

c. rubber-base paints

d. damar varnishes and lacquers

14. What is the diameter in inchesof the smallest size casters that youwould use on a rolling tower ?.

a. 3 c. 5

b. 4 d. 6

15. It is standard practice to usewire rope of at least 3/4 inch diameterfor platform slings. What is the leastdiameter in inches of manila rope thatyou would select for boatswain chairsand lifelines?

a. 1

b. Y2

16. Every gallon of solvent in spraypaint will create how many gallons ofpotentially dangerous gas or vapor?

a. fewer than 100

b. more than 100

c. 100

d. 50

17. What would you place under dis-pensing pumps and spigots to absorbany spillage or overflow?

a. oiled rags

b. pails of sand

c. box of sawdust

d. pail of water

18. What precaution do you takewith paint rags and waste?

a. burn them

b. soak in oil and leave in place

c. wet down with water and store inclosed metal container

d. wash and dry thoroughly

19. Which is the most common sol-vent that is used in nonflammable paintremovers?

a.

b.

c.

turpentine

xylol

methylene chloride

d. MEK

20. Which of the following solventsis least irritating to the skin?a.

b.

c.

d.

mineral spiritsturpentinemethyl ethyl ketonexylol

1

q

LESSON 2

PROTECTIVE COATING MATERIALS

CREDIT HOURS 2


LESSON OBJECTIVE To teach you selection and use of paints, andto exploiq the methods of safely handlingand storing paint materials.

. EXERCISES


1. Which of these coatings shouldnot be used for exterior finishing?

a.

b.

C.

d.

damar varnish

spar varnish

oil-base paint

rubber-base paint

2. Why do you add driers to pro-tective coatings?

a.

b.

C.

d.

hasten film hardening

protect the pigment

keep pigment in the solution

increase viscosity

3. You are making aluminum paintfrom aluminum powder. You mix thepowder according to formula, with

a. glue c. varnish

b. water d. shellac

4. What would you do with emptypaint containers after their contents of

old and dried out paint have been dumpedinto a sanitary fill?

a. put them into a Dempsey Dumpster

b. dump them into sanitary fill

c. use them for storing filler

d. burn them

a.

b.

c.

d.

5. Oil-based paints are

very expensive

not durable

hard to color

easy to apply

6. You want to waterproof a con-crete block wall. The best base paintfor such waterproofing isa. silicone c. lacquer

b. oil d. varnish

7. What is zinc oxide?a. varnish c. pigment

b. vehicle d. shellac

8. You have been given the job topaint a steel bridge. Which of the fol.:lowing do you apply?

2-1

a.

b.

c.

d.

red lead primer and aluminum

zinc chromate and deck enamel

aluminum paint and water emulsion

red iron oxide and asphalt varnish

9. Which of the following wouldyou select to provide a smooth, evenfinish on open-grain wood?

a. size

b. phenolic-resin primer-sealer

c. texture paint

d. wood filler

10. The label on a paint can statesthe color and type of paint and

a. Viscosity

b. date of manufacture

c. consister cy

d. blending characteristics

11. Tints are lighter than

a. shades

b. tones

c. hues

d. chromas

12. You are painting a previouslypainted wood surface that is in goodcondition. The primer is

a.

b.

C.

d.

added to undercoat

added to sealer

thinned

omitted

13. You are painting a wooden wallthat has an absorbent surface. Whichof the following would you apply beforestarting to paint?

a.

b.

c.

d.

2 2

shellac and alcohol

stain

aluminum pigment

zinc oxide

I0

14. For best results the tempera-ture of paint materials should be be-tween

a.

b.

c.

d.

40° F and 55° F

50° F and 60° F

60° F and 70° F

65° F and 85° F

15. You want to mix 5 gallons ofpaint that contain a highly volatile thin-ner. What method do you use?

a. boxing

b. paddling

c. propeller

d. shaker

16. You must paint walk stripes ina building. These stripes must glow inthe dark. Which of these do you use?

a.

b.

d.

aluminum paint

highway yellow with glass beads

luminous paint

titanium dioxide

17. Zinc oxide is a desirable coatingfor the inside of a water tank becauseita. admits ultraviolet light

b. is nonpoisonous

c. is white

d. is fast drying

18. Which of the following wouldyou use to apply joint cement to a sheet-rock joint?a. floatb. chisel

c. putty knifed. screwdriver

19. In selecting a can of paint fromthe storeroom, you pick the one thata.b.

c.

d.

has lowest temperatureis on top of the stackbears the oldest daterequires no stirring

ct

20. Of the choices below, which a. zinc chromate c. phenolic resin

you use as a primer on a steel bridge? b. epoxy d. hot alkyd varnish

LESSON 3

PROTECTIVE COATING EQUIPMENT

CREDIT HOURS 2


LESSON OBJECTIVE To teach you the operation, maintenance,.andstorage of the equipment used in applyingprotective coating.

'EXERCISES


1. You must paint several largepieces of equipment that are encrustedwith grease and dirt. You first cleanthem with

a. a vacuum cleaner

b. a buffer

c. an abrasive blaster

d. a steam cleaner

2. When you are stenciling signs,you have 2 or 3 sets of brass stencilswith you because

a. paint builds up on brass quickly

b. many signs have duplicate leUers

c. avoids cleaning a stencil after eachuse

d. stencil letters easily bend out ofshape

3. Which of these would you use tosharpen a chisel?

a. grinding wheel

b. file

c. rasp

d. emery

4. You are using a fountain stencilbrush. You control the flow of ink by

a. releasing the snaplock

b. adjusting the thumbscrew

c. using strong pressure on brush

d. using the shutoff valve

5. You are selecting a new abrasivewheel to put on a portable power grinder.The safe operating speed of the newwheel is checked

a.

b.

C.

d.

on the wheel blotter

in the tool crib

in the applicable TO

on the spark plug

6. Which of these would you useto remove paint from a metal stormdoor?

a. flint paper c. aluminum oxide

b. garnet paper d. rottenstone

7. The airless spray gun developsa high pressure that presents the dangerof sparking between the gun and theobject to be sprayed. What precautiondo you take?

a. spray only during low humidity

b. ground both gun and object

c. wear shock-resistant rubber gloves

d. use explosion-proof motor

8. You put a push-broom handleinto the handle of a roller coater. Why?

a.

b.

c.

d.

to provide more leverage

to get coater into corners easily

to apply more paint in one movement

to reach high places without usingscaffolding

9. You must paint a large gym-nasium building. Which of these do youuse for this volume painting?

a.

b.

e.

d.

stencil sprayer

self-contained spray gun

pressure-feed paint: gun

low-pressure spray unit

10. Which of these would you useto clean rust from a protruding bolthead?

a. grinder c. disc sander

b. steam cleaner d. descaler

11. Which of these would you useto sand a drywall joint?

a. edger

b. buffer

c. vibrator sander

d. disc sander 21

12. You are using a compressor witha gasoline engine. You would changethe oil filter

a. when oil is renewed

b. after every job

c, when dipstick shows 1 quart low

d. whenever gas tank is filled

13. To remove excess paint fromyour brush when you are painting, thebrush should be

a. wiped with a cloth

b. tapped against inside of container

c. wiped on rim of paint can

d. rubbed on hidden part of job

14. Why are glass spheres added totraffic-marking paint?

a.

b.

e.

d.

decrease amount of paint work

increase durability of the paint

improve the base coat

reflect the light

15. What should a good qualitybrush have?

a. flagged bristles

b. metal handle

e. two rows of bristles

d. horsehair bristles

16. On which of the following wouldyou use an abrasive belt?

a.

b.

c.

d.

floor edger

drum sander

disc sander

vibrator sander

17. Which of these would you use tospray a small area with quick-dryinglacquer?

a. low-pressure spray unit

b. high-pressure spray unit

c. suction spray -gun

d. vibrator pump

18. In order to smooth the finishbetween coats of paint on fine wood-work, you use

a. grit abrasive

b. pumice stone

c. file

d. a scraper

19. You are running a power-op-erated traffic marking machine. Which

I"of the following could partly control thewidth of the paint spray?

a. type of gun nozzle

b. thumbscrew on paint tank

c. speed of drive pulley

d. distance of gun nozzle from pave-ment

20. What type spray gun would youconnect directly to a small compressor?

a. internal mixing

b. bleeder

c. nonbleeder

d. suction feed

LESSON 4

LADDERS, SCAFFOLDING, AND METAL CORROSION

CREDIT HOURS

TEXT ASSIGNMENT

LESSON OBJECTIVE

2

Memorandum 562, Chapters 4 and 5.

To teach you how to use ladders and scaffoldsand what methods to use for detecting orpreventing metal corrosion.

EXERCISES

Requirement: Solve the following mUltiple-,

choice exercises. `,/

1. Extension ladders are extendedby means of

a.

b.

c.

d.

springs

block and tackle

hoisting machine

couplings with safety devices

2. You use a hoisting machine toraise a swing stage scaffold. What actiondo you take before leaving that ma-chine?

a. raise scaffold higher than needed,then lock

b. tie yourself securely to scaffold

c. remove control handle and lockbrake

d. push yourself slowly away frombuilding

3. When a ladder is not in use, youhang it on brackets by its side rails inorder to prevent

23

a.

b.

c.

d.

penetration of moisture

use by unauthorized persons

warping

splitting

4. When the erected swing stagescaffold is not in use, it must be

a.

b.

c.

d.

lashed to the building

lowered to the ground

kept upright

disassembled

5. You are placing a 24-foot ladderagainst a wall that you will paint. Howmany feet from the wall do you placethe bottom of the ladder?

a.. 6 c. 10

b. 8 d. 12

6. You want to form a loop in theend of a rope that is easily untied butwill not slip. What knot do you use?

a. clove hitch

b. rolling hitch

c. half hitch

d. bowline

4 1

7. Which knot would you use withthe boatswain chair to allow the work-man to lower himself slowly?

a.

b.

c.

d.

clove hitch

half hitch

double bowline

rolling hitch

8. You are erecting a swing stagescaffold on a building. How do youkeep it from swinging outward after ithas been hoisted?

a.

b.

c.

d.

place weights on outside edge

workman keeps hands on buildingduring hoisting

lash swing stage to the building

equip with stirrup rollers

9. You are on a 15-foot ladder andneed help to complete the job. You tellyour helper to

a.

b.

c.

d.

start painting from lower side

get another ladder

get onto your ladder with you

erect a lean-to scaffold

10. You are erecting a rolling towerwhich will be 4 feet square in base di-mension. How high, in feet, do youmake the tower?

a. 12 c. 20

b. 16 d. 24

11. Metals that cannot be identifiedby visual examination or mechanicaltesting might be identified through useof

a.

b.

C.

d..

a magnet

color numbers

a grinder

an acid-spot test

ti

/6 ,

12. Where does corrosion of metalbegin?

a.

b.

c.

d.

on exposed surface

during milling

before coagulation

in the core

13. What method of corrosion pro-tection uses a sacrificial anode to protectthe structure?

a. impressed current

b.

c.

d.

concentration cell

galvanic anode

differential

14. Two years ago a storage tankwas constructed. Cold rivets were usedto join the steel sheets. Your presentinspection shows corrosion in the joinedparts. What type of corrosion is this?

a. stress

b. galvanic

c. intergranular

d. exfoliation

15. The impressed current methodof cathodic protection prevents cor-rosion to a metal structure by

a.

b.

c.

d.

a source of alternating current

a stronger electrolytepreventing corrosiveness of the soil

balancing the electrical potential

16. Which four conditions must bepresent before electro-chemical corro-sion occurs?

a. electrolyte, conductor, cathode, met-al anode

b. cathode, anode, electrolyte, organicfilm

c. metal anode, conductor, organicfilm, cathode

d. organic film, anode, cathode, elec-trolyte

PI

17. Which of the following couldproduce a condition leading to corro-sion?

a.

b.

C.

d.

reducing voltage of rectifier

viscosity of the paint

passivation

misidentifying metal

18. If you cannot positively identifya metal by visual identification, it shouldbe

a. tested for unusual stress

b. given magnet and spark tests

c. treated as steel

d. given ring test

19. Corrosion presents a greaterproblem when it occurs in the vicinity of

a. a school building housing wood-working equipment

b. a manufacturing plant with 100 au-tomotive vehicles

c. electrified coal mines

d. an office bUilding lighted by fluo-rescent lighting

N. In a pipeline laid in cinders, cor-rosion occurs where the current

a.

b.

c.

d.

accumulates on pipe interior

is equalized

leaves the pipe

enters the pipe

CORR ESPONI0ENCE COURZEU. S. ARMY ENGINEER WHO

SU8COURSE 562 Painting L

LESSON 1 Safety.

SOLUTIONS

Each exercise has a weight of 5. All references are to Memorandum 562.

1. d (par 1-2) 11. b (par 2-3a(9))

2. a (par 1-9) 12. a (par 2-3b (5) )

3. d (par 1-11(b)) 13. a (par 3-1)

4. d (par 1-12) 14. d (par 2-3c(3))

5. a (par 1-13) 15. d (par 2-2c (2) )

6. b (par 1-13) 16. b (par 3.2)

7. c (par 1-14) 17. b (par 3-6k)

8. d (par 2-1) 18. c (par 3-6g)

9. d (par 2-3a(8)) 19. c (par 4-3a)rf10. c (par 2-3a(7)) 20. a (par 4-3a)

For further explanation, see Discussion.

All concerned will be careful that neither this solution nor information concerning thesame comes into the possession of students or prospective students who have not completedthe work to which it pertains.

NM 106 1.1

q

DISCUSSIONExercise:

L All paintb, except water-thinned paints (d) are flammable. Most paints are quitesafe, however, if simple precautions are followed.

2. All personnel should be in good health, but painters who are sensitive to toxic or skinirritating materials should work only with nonsensitizing paint, such as the water-thinned paints(a).

3. Chemical - cartridge respirator (d) is used for protection against fumes and solventvapors. This ty i,e contains activated carbon cartridges which absorb the fumes or vapors.

4. Safety goggles must fit well, contain unbreakable glass or plastic lenses (d) and allowadequate peripheral as well as straight-ahead vision.

5. Safety helmets are worn when painters are working with abrasive blasting (a) media.

6. Cuffs, tears, or rips, loose pockets, loose ties and jewelry should be avoided becausethey are potential causes of accidents (b).

7. Personnel should never work alone in a hazardous area. Two men (buddy system) (o)should be assigned to such jobs, and each should be visible to the other at all times during thepainting operations.

8. By far, the most common and serious accidents are falls from a height or on the (-7:

ground because of a loss of footing (d). Falling or moving objects are the next most serioushazard.

9. Do not use a stepladder over 10 feet (d) high. Never use one as a straight ladder.Never stand on the top platform.

10. Extension ladders should have a minimum overlap of 15% (c) for each section.

11. % working length of the ladder (b) is the distance the foot of the ladder should beaway from the wall.

12. Provide guard railings at any height (a), on the full length of the scaffold and alsoon the ends.

13. Flammable liquids and vapors (a), especially the latter, are by far the chief causes offire and explosion.

14. Provide unit locks on all towers, and do not use casters less than 6 Inches In diam-eter (d).

15. Use manila rope of at least % Inch diameter (d) in boatswain chairs and lifelines.When handling materials with manila rope, use proper knots and hitches.

16. Every gallon of solvent in the spray paint will create more than 100 (b) gallons ofpotentially dangerous gas or var,or.

ab

17. Use pails of sand (b), never sawdust, under dispensing pumps and spigots to absorbany spillage or overflow.

18. Wet down paint sweepings, rags and waste with water, and store in closed metalcontainers (c) until disposed of in an approved manner.

19. Methylene chloride (c) is the most common solvent used in nonflammable paint re-movers.

20. The milder solvents such as mineral spirits (a) are not as irritating to the skin asthe stronger solvents listed in the other choices in the exercise.

CORRESPONDENCE COURSE OFU. S. APT FY ENGINEER SCHOOL

SUBCOURSE 562 Painting I.

LESSON 2 Protective Coating Materials.

SOLUTIONS


1. a (par 13-31) 11. c (par 10-6)

2. a (par 8-35) 12. d (par 12-3)

3. c (par 8-19) 13. a (par 11-4)

4. b (par 14-12) 14. d (par 14-8)

5. d (par 9-3) 15. d (par 10-23)

6. a (par 12-50) 16. c (par 13-23)

7. c (par 8-9) 17. b (par 8-9)

8. a (par 12-37) 18. c (par 11-26)

9. b (par 11-10) 19. c (par 14-7)

10. (par 14-2) 20. a (par 11-12)


All concerned will be careful that neither this solution nor Information concerning thesame comes into the possession of students or prospective students who have not completedthe work to which it pertains.

NRI 10629

a.

b.

c.

d.

red lead primer and aluminum

zinc chromate and deck enamel

aluminum paint and water emulsion

red iron oxide and asphalt varnish

9. Which of the following wouldyou select to provide a smooth, evenfinish on open-grain wood?

a.

b.

c.

d.

size

phenolic-resin primer-sealer

texture paint

wood filler

10. The label on a paint can statesthe color and type of paint and

a.

b.

c.

d.

viscosity

date of manufacture

consistency

blending characteristics

11. Tints are lighter than

a. shades c. hues

b. tones d. chromas

12. You are painting a previouslypainted wood surface that is in goodcondition. The primer is

a.

b.

c.

d.

added to undercoat

added to sealer

thinned

omitted

13. You are painting a wooden wallthat has an absorbent surface. Whichof the following would pou apply beforestarting to paint?a.

b.

cd.

2 -2

shellac and alcohol

stain

aluminum pigment

zinc oxide

30

apt

14. For best results the tempera-ture of paint materials should be be-tween

a. 40° F and 55° Fb. 50° F and 60° Fc. 60° F and 70° Fd. 65° F and 85° F

15. You want to mix 5 gallons ofpaint that contain a highly volatile thin-ner. What method do you use?

a. boxing

b. paddling

c. propeller

d. shaker

16. You must paint walk stripes ina building. These stripes must glow inthe dark. Which of these do you use?

a.

b.

c.

d.

aluminum paint

highway yellow with glass beads

luminous paint

titanium dioxide

17. Zinc oxide is a desirable coatingfor the inside of a water tank becauseita. admits ultraviolet light

b. is nonpoisonous

c. is white

d. is fast drying

18. Which of the following wouldyou use to apply joint cement to a sheet-rock joint?a. float c. putty knifeb. chisel d. screwdriver

19. In selecting a can of paint fromthe storeroom, you pick the one thata.

b.

C.

d.

has lowest temperatureis on top of the stackbears the oldest daterequires no stirring

17. Zinc oxide has many desirable characteristics, but the fact that it is nonpoisonous (b)makes it especially acceptable for use on the inside of a water tank.

18. Joint cement is mixed with water until a thick paste is formed. It is normally appliedwith a broad putty knife (e) or a cement trowel.

19. Can that bears the oldest date (c) is used first. If date of manufacture is not shownon the can, the date of receipt is considered the approximate date of manufacture.

20. Zinc chromate (a) primer is generally used for metal surfaces, such as structuralsteel, bridges, tanks, refrigerators, railroad cars, motor vehicles, and aircraft.

ti

CO RESIP NIDENCE C URSEU, S. ARMY ENGINEER SCii


LESSON 3 Protective Coating Equipment.

SOLUTIONS


1. d (par 1541) 11. c (par 15-22)

2. b (par 18-6) 12. a (par 16-53)

3. a (par 15-7) 13. b (par 16-17b)

4. d (par 18-15) 14. d (par 17-15)

5. a (par 15-30) 15. a (par 16-8)

6. c (par 15-9) 16. b (par 15-25)

7. b (par 16-57) 17. c (par 16-35)

8. d (par 16-25) 18. b (par 15-12)

9. c (par 16-38) 19. d (par 17-7)

10. d (par 15-31) 20. b (par 16-32)


All concerned will be careful that neither this solution nor information concerning thesame comes into the possession of students or prospective students who have not completed

the work to which it pertains.

DISCUSSIONExercise:

1. The steam cleaner (d) uses a solution of detergent and water. Under high velocity,the vaporized spray loosens and removes dirt and incrustations.

2. It is good practice to have two or three sets of each size stencils on hand becausemany signs have two or three of the same letters (b) and it will save time if the complete signcan be made at one time.

3. Sharpen the chisel on a grinding wheel (a) by restoring the bevel, which is usually60° to 70°. Sometimes it is necessary to remove the burrs from the head if the chisel hasmushroomed.

4. The fountain stencil brush is equipped with a shutoff valve (d) between the reservoirand the brush to adjust the flow of stencil ink or to shut it off completely.

5. Reinforced abrasive wheels must be used on the portable power grinder and the safeoperating speed that is indicated on the wheel blotter (a) must not be exceeded.

6. Aluminum oxide (e) with production paper backing is used on both wood and lightmetal surfaces. Its tough coating cuts faster and longer than the flints.

7. The sparking can result in explosion or fire. Be sure that you ground both gun andobject (b) being sprayed. This can be done by attaching a static wire to ground.

8. Handles of the roller coaters accommodate a push-broom handle 'to permit paintingfloors without kneeling and to reach high places without using scaffolding (d).

9. The pressure-feed paint gun (c) is considered one of the best general-purpose gunsfor use with regular paints. Because no siphoning effect is necessary for pressure feed applica-tion, it is the tool for volume painting.

10. The descaler (d) is good for cleaning grooves, corners, rivets and protruding boltsand nuts. The needles can be interchanged with a chisel-like unit.

11. The vibrator sander (c) is an excellent tool for removing old paint and varnish andfor sanding drywall joints.

12. If the engine has an oil filter, the filter cartridge is usually changed when the oil isrenewed (a). The air filter is cleaned as recommended by the manufacturer.

13. Do not wipe the bristles on the edge of the container, as this wears them out or breaksthem. Instead, the brush should be tapped against the inside of the container (b) above thepaint level.

14. Glass spheres are embedded in traffic paint that is applied to curbs, lane markings,and runways. They reflect the light (d) at night.

15. A good quality brush has flagged bristles (a) to hold the paint and to spread it.

olb

16. The drum sander (b) uses an abrasive belt, similar to the belt sander.

17. The suction spray gun (c) is ideal for small areas to be sprayed with lacquers, var-nish, and other light materials.

18. Jeweler's rouge, rottenstone, and pumice stone (b) are three powdered abrasives usedon furniture and fine woodwork to smooth the finishes between coats.

19. The width of the spray is governed by the distance the gun nozzle is from the surfacebeing striped (d) and by the spray gun adjustments.

20. The bleeder (b) type spray does not build up excessive pressure in the compressor.If a spray gun is to be connected directly to a small compressor, it should be the bleeder type.

77

CORRESPONDENCE COURSE OFU. S. ARMY ENGINEE?". SCHOOL


LESSON 4 Ladders, Scaffolding and Metal Corrosion.

SOLUTIONS


1. b (par 19-8 and fig 93) 11. d (par 25-18)

2. c (par 21-13) 12. a (par 22-6)

3. c (par 19-14) 13. c (par 2410)

4. b (par 20 -14e) 14. a (par 22-15)

5. a (par 19-5) 15. a (par 24-12)

6. d (par 21-4) 16. a (par 22-4)

7. d (par 21-7) 17. d (par 25-1)

8. c (par 20-14b) 18. b (par 25-12)

9. b (par 19-15) 19. c (par 23-7)

10. b (par AO) 20. c (par 23-4)



DISCUSSIONExercise:

1. Extension ladders can be adjusted to various lengths by pulling on the rope which isthreaded through the pulley (Figure 93) in a block and tackle (b) arrangement.

2. Hoisting machines that are on scaffolds have a lock and brake which are controlledby the painter. Before leaving the machine the painter must remove control handle and lockthe brake (c).

3. Ladders not in use should be hung on brackets by the side rails in order to preventwarping (c).

4. Swing stage scaffolds erected but not in use should be lowered to the ground (b)for safety reasons.

5. As soon as you have the ladder in a perpendicular position, pull the bottom of theladder out from the wall to a distance of 1/4 the length of the ladder 24' x = 6' (a).

6. The bowline (d) is used to form a loop in the end of a rope that will not slip and thatis easily untied. Figure 108 shows how to tie a bowline knot.

7. The rolling hitch (d) is used to lower a load slowly. The workman can lower himselfby releasing the pull on the fall line and rolling the knot. Figure 109 shows how to tie thisknot.

8. A safety rule that must be followed while you use the swing stage scaffold is to lashthe swing stage to the building (c) as soon as possible after hoisting so that it cannot swingoutward.

9. A safety precaution in using ladders is never to allow anyone on the ladder with you.If you need help to do the work, tell your helper to get another ladder (b) for his own use.

10. The height of the tower must not exceed four times the smallest base dimension(4 x 4 = 16) (b).

11. Acid spot tests (d) are based on the formation of characteristic colors produced bythe reaction of the acid on the metal surface. The color reactions for many metals are listed inpars 25-20 and 25-21.

12. Corrosive attacks begin on the surface (a). There will always be evidence on the sur-face when an attack is in progress.

13. The galvanic anode (c) method of cathodic protection uses an electrode, which is re-ferred to as a sacrificial anode, to protect a structure.

14. A good example of stress corrosion (a) is the use of cold-worked rivets to join steelsheets. The rivets carry an internal strain which makes them anodic to the steel.

-15. With the ifrpressed-current method of protection, a source of alternating current (a)is required. In addition, a rectifier is needed to get the required direct-current potential.

4-2

aq

16. The four things that must be present are the electrolyte, conductor, cathode, metalanode (a), defined respectively as a continuous liquid path, a carrier of flowing electrons, acause, and something that corrodes.

17. By misidentifying metal (d) you may waste your efforts, damage material, or cause

corrosion.

18. If a metal cannot be positively identified by visual examination, the next step is tosee if it is attracted by a magnet and to perform a spark test (b).

19. Direct-current circuits that pass in and out of an electrolyte are a direct cause ofcorrosion. This condition poses the greatest problem in the vicinity of electrical transportationsystem, electrified coal mines (c) or manufacturingplants where their direct-current distribu-tion system requires a ground as a complete or partial circuit return.

20. The current leaves the pipe through the soil to the cinders and returns to the pipe.Severe corrosion occurs at the point where the current leaves the pipe (c).

MEM ANDUM 562

(MATERIALS AND EQUIPMENT)

U. S. ARMY ENGINEER SCHOOL


30111111111N0011111117,4401111

NRI 106

31

CONTENTS

Page

Preface I

Chapter

1. Safety 1

2. Protective Coating Materials 25

3. Protective Coating Equipment 48

4. Ladders, Scaffolds, and Hoisting Equipment 70

5. Metal Identification and Corrosion 82

3a.

PREFACE

The Army operates many installations throughout the world. Many ofthese installations are constructed by civilian contractors, but alteration, addi-tions, and maintenance are performed by military personnel.

This first of two subcourses discusses hi four lessons the following subjectmatter: safety, protective coating materials and equipment; ladders, scaffolds,and hoisting equipment; and metal identification and corrosion control.

A good way to study material is to scan each chapter quickly. Scan thechapter headings and make a quick check to see how the entire lesson relates tothese headings. As you scan the material, look at the major headings, boldface,capitalized, or italicized words for content. Then read the text assignmentthrough rapidly the first time. Next, go back and read for review, getting thematerial fixed in your mind; then work the lesson exercises.

You should have favorable study conditions in order to get the greatestadvantage from a study session. Favorable study conditions include a properlyarranged room, proper lighting and ventilation, comfortable seating arrangement,and the absence of distracting influences. Study at a regular time each day andfor short periods of time, rather than for one long study session.

Keep this memorandum for your own use after you complete the course.

40

SAFETY

SECTION 1 GENERAL

1 -f. Hazards. Every painting assign-ment exposes maintenance personnel to con-ditions and situations that represent actualor potential danger to themselves and toothers in the area. The frequent necessityto use toxic and flammable materials, pres-surized equipment, ladders, scaffolding andrigging always presents a potential hazard.

may also be inherent in the very' c. 'the environment, or caused through

a or carelessness of the operator. Itis, therefore, extremely important to beaware of all potential hazards, since con-tinuous and automatic precautionary meas-ures will minimize the problem and improveboth efficiency and morale of the paintingcrew.

1-2. Paint Materials. Most paint ma-terials are hazardous to some degree. All,except water-thinned paints, are flammable ;many are toxic and others can it -state theskin. However, most paints are quite safe ifsimple precautions are followed.

1-3. Surface Preparation Materials.Preparing a surface for painting often re-quires the use of solvent, acid, or alkalicleaners. All of these will harm the skinunless used with care. Paint removers arealso very irritating to the skin. The use ofhigh pressure abrasive or water blastingmethods may be hazardous. Pressures as lowas 10-15 PSI have been known to causeserious injuries. In addition, carelessnessduring abrasive blasting operations may re-sult in lung disease after continued exposure.Steam cleaning procedures employ high heatand pressure, both very hazardous to theoperator and personnel nearby if not proper-ly handled.

1

33

CHAPTE R 1

1-4. Equipment. Ladders, scaffoldingand rigging must be used for areas whichare not readily accessible from the floor orground. Pressure equipment is used to pre-pare surfaces and to apply paint. All of thisequipment can be extremely hazardous ifhandled carelessly. The proper setting upand dismantling of equipment, tha requiredsafety checks and the basic precautions inhandling equipment, may require more timethan their actual use. Nevertheless, precau-tions should not be omitted on the basis thatrisk decreases in proportion to time of use.

I-5. Environment. Painting condi-tions vary from job to job. One obviouslyhazardous location is the interior of a tank.However, painting the interior of a smallroom or closet may be more hazardous, sinceoften no special precautions are taken andventilation may be inadequate. Furthermore,the painter may encounter other hazardsthat exist in the arein which he workingin addition to the hazards inherent in thepainting operation. For example, slipperyfloors or obstacles located on the floor maycause falls. Electrical or mechanical equip-ment may produce shocks or other seriousinjuries. Uninsulated steam lines or hotpipes may cause severe burns or too rapidevaporation of solvent thus creating a toxichazard.

1-6. Painting Crew. Lack of train-ing, experience. or knowledge of hazards onthe part of any painter produces a possiblethreat to the safety of the crew and othersin the painting area. An element of riskpresent even when well trained workers fol-low all prescribed safety procedures. Properprecautions will reduce this risk to a mini-mum, but no safeguard can guarantee pro-tection against ignorance. Carelessness of

311

even a trained painter will also increase haz-ards tremendously. Deviation from estab-lished procedures by taking "short cuts"often produces unsafe working conditionsresulting in accidents with consequent lossof time and materials, and, of greatest con-cern, human suffering.

1-7. Degree of Hazard. The risks in-volved vary from job to job. Painting theinterior of a home with water-thinned paints,for example, is much less of a hazard thanpainting a water tank 100 feet above theground. The foreman must be responsiblefor taking the special precautions, designa-ting the equipment required and advising hiscrew of the specific hazards for each job.However, the painter should never forgetthat hazards exist in every job, though theyvary in degree. To ignore hazards in anyjob is to increase the odds that accidentswill occur. Relaxing of precautions in onejob will inevitably lead to carelessness in alljobs, regardless of the degree of hazard.Thus habits are formed which will even-tually result in an unnecessary increase inthe accident rate.

1-8. Safety Measures. The potential haz-ards present in all painting operations makea continuing and enforced safety programabsolutely essential. Adequate safety pro-cedures will provide protection against thethree major types of hazards, namely, acci-dents, fire and those to health. All personnelmust be thoroughly familiar with safetyrules. Each worker is responsible for ad-hering to all established precautionary pro-grams for his own protection as well as thatof others. Disregarding safety meas'ares willincrease potential dangers and the odds thatan accident will occur. See Corps of Engi-'neers Manual EM 385-1-1 "General SafetyRequirements", Department of the NavyManual NAVSO P-2455 "Safety Precautionsfor Shore Activities" and Air Force Hand-book AFM 127-101 "Accident Prevention".Also see MIL-STD-1212, "Industrial SafetyBelts and Straps".

1-9. General Health. All personnelshould be in good health. Painters who aresensitive to toxic or skin-irritating materials

should only work with non-sensitive paintmaterials such as water - thinned paints. Anyworker sensitive to heights should not workon ladders, scaffolding, or rigging. Person-nel who have an improper attitude towardssafety should not be allowed in paintingcrews..

1-10. Environment. Study the workingenvironment before sending painters intoany work area. Look for hazards such aspoor ventilation and noxious fumes. Beforea painter is allowed to enter such an area, hemust be protected by devices that will allowhim to work in safety. If ventilation is re-quired, then outside air should be providedat a minimum rate of 15 cubic feet of air perminute per person or 11/2 changes per hour,whichever is greater. Otherwise respiratoryprotective equipment should be provided. Ifexhaust systems are used, such as in a tank,for example, the system must take suctionfrom the bottom of the tank or a similar areain which the work is being done. Never workalone in a hazardous area (see. 1-14..) . Thedischarge from exhaust system's must bearranged so that contaminated air will notcreate a health hazard in surrounding areas.Temperatures should be kept at. 65°F to75°F, if possible.

1-11 Respiratory Protection. Person-nel must wear the proper type of face maskin hazardous areas. All must be devices ap-proved by the United States Bureau ofMines. The most important types of respira-tors are as follows :

a. Dispersoid respirators for protec-tion against dusts az are present when sand-ing. These respirators contain filters only.(See Figure 1.)

b. Chemical cartridge respirators forprotection against fumes and solvent vapors.These respirators contain activated carboncartridges which absorb the fumes or vapors.(See Figure 2.)

c. Supplied air respirators for use inclosed areas where ventilation cannot be sup-plied. (See Figure 3.) Fresh air blowers ofthe positive pressure type, Bureau of Minesapproved, shall be provided for each tworespirators and the hoses limited to 150 feet.

d. Abrasive blasting helmets for usewhen blast cleaning surfaces to be painted.(See Figure 4.)See Department of the Army Technical Bul-letin TB MED 223 and Department of theAir Force Pamphlet AFP-161-1 "Respira-tory Protective Devices", also Department ofthe Navy NAVDOCKS P-342 "Fuel StorageTank Cleaning at the Shore Establishment".The life or health of the wearer may dependon the availability and proper functioning ofrespiratory equipment. They must be cleanedimmediately after use and be properly main-tained and stored in clean, dry compartments.Filters, cartridges, and rubber parts shouldbe inspected before each use, and at regularintervals, for any signs of deterioration.Replace any suspect filter or cartridge imme-diately.

1-12. Eye Protection. Safety gogglesmust be worn in areas where there is anypossibility of dust, fumes or solvents touch-ing the eyes as may occur when blasting,

Figure 1. Mechanical Filter Respirator.

3

43

sanding, or spraying. They must be keptclean and readily available. They should fitwell, contain lenses of unbreakable glass orplastic, and allow adequate peripheral as wellas straight ahead vision. (See Figures 5, 6.)

Figure 2. Chemical Cartridge Respirator.

Figure 3. Supplied Air Respirator.

319

1-13. Protective Clothing. Personnelshould wear clean clothing covering them asmuch as possible to avoid skin contact withpainting or cleaning materials. Cuffs, tearsor rips, loose pockets, loose ties and jewelryshould be avoided since they are potentialcauses of accidents. Safety helmets should beworn when using abrasive blasting media.(See Figure 4.) Hard hats and steel toedsafety shoes should be worn wherever thereis any possibility of danger from fallingobjects. Shoes should have non-skid rubbersoles when working in enclosed spaces orwhere flammable vapors may be present.Acid -proof clothing should be worn when han-dling acid cleaners. Use acid-proof air-sup-plied suits when using acid cleaning materialsin enclosed areas. (See Figures 7 thru 10.)

1-14. Buddy System. Personnel shouldnever work alone in hazardous areas. Atleast two men should be assigned to such

Figure 4. Abrasive Blasting Helmet.

44

jobs, and each should be visible to the otherat all times during the painting operations.Then, if one should have an accident, theother can immediately come to his aid.

Figure 5. Safety Goggles.

Figure 6. Safety Goggles.

4

Figure 7. Hard Hat.

1-15. Responsibility of Foremen. The fore-man should lay out the work and manageprojects in such a manner as to produce thesafest possible conditions. Safety of person-nel is one of his prime responsibilities. Asafety check-off list as illustrated in Figure11 should be used by the foreman before ajob gets underway. In addition all foremenshould adhere to the following program:

a. Always be aware of potential haz-ards in the area.

b. Be sure that each painter under-stands and accepts his personal responsibilityfor safety and that he is informed of allsafety rules.

c. Be sure that all safety measureshave been taken each day before any job isstarted.

d. Insist that the men work safely.Use disciplinary action in accordance withexisting personnel directives, if necessary.

e. Be sure that all equipment meetssafety standards. Use non-sparking tools inhazardous areas. Anticipate possible riskswith new types of equipment. Secure expertadvice on potential hazards in advance.

f. Encourage the men to discus's thehazards in their work. No job should pro-

37

ceed if any question about safety remainsunanswered. Be receptive to their ideas andsuggestions ; these may be the best source offield experience that will prevent accidents.

g. Set a good example for the men bydemonstrating safety in personal work andconduct.

NON SPARKING ,

Figure 8. Safety Shoes.

5

1 5

Figure 9. Acid-Proof Clothing.

38

Figure 10. Acid-Proof Air-Supplied Suit.

ED "No Smoking" warningsED ClothingED Eye ProtectionED Respiratory protectionED Safety BeltsED Warning tags and signsED Toxic materialsED Burns to skinED Falling objectsCD Electrical hazardsCD FootingED Moving objects, cranes, traffic, etc.ED Safety showers and eye bathsED Fire alarm stationCD Fire extinguishers; fire blanketsED Nearest telephoneCD BarricadesED Equipment groundedCD Sparkproof toolsCD Safety or fire permitsCD Flammability or flash pointED Condition of ladders and scaffolding

Figure 11. Safety Check List.

SECTION 2 ACCIDENT HAZARDS

2-1. Causes. Accidents during paintingoperations are caused by unsafe workingequipment, unsafe working conditions andcareless personnel. Any or several of thefollowing can cause accidents:

a. Lack of knowledge, experience andtraining in the use of painting materials andequipment.

b. Improper ingdntenance and storageoj: equipment.

c. Failure to pre-check equipment formechanical and structured flaws.

d. Improper use of equipment.e. Failure to consider environmental

conditions and existing hazards in workareas before, during and after paintingoperations.

f. Personal carelessness.Accidents most frequently involve commonlyused equipment. The most common and seri-ous accidents, by far, are falls either from aheight or on the ground because of a loss offooting. Falling or moving objects are thenext most serious hazard.

2-2. Precautions and Prevention. Nothingshould be taken for granted. Proper use ofeqUipment must be taught to all personnel by

qualified operators. Refresher courses on theuse of all equipment must be regularlyscheduled.

2-3. Equipment Check And Use. Thefollowing basic procedures in setting up anduse of equipment are imperative to assuresafety standards and maximum protection ofall personnel.

a. Ladders:(1) Store wood ladders in a warm,

dry area protected from the weather andground.

(2) Protect wood ladders with clearcoatings only, so that cracks, splinters orother defects will be readily visible.

(3) Inspect all ladders frequentlyfor loose or bent parts, cracks, breaks orsplinters.

(4) All straight and extension lad-ders must have safety shoes. These shouldbe of insulating material for metal ladders.(See Figure 12.)

(5) Do not use portable laddersgreater in length than can be readily carriedand placed by two men. Never splice laddersto form a longer ladder.

(6) Pre-test all ladders and scaffold-ing before use by placing horizontally withblocks under ends and "bouncing" in thecenter or walking along ladder or scaffold.

(7) Extension ladders should have aminimum overlap of 15% for each section.(See Figure 13.)

Figure 12. Ladder Safety Shoes.

7

3?(8) Do not use stepladders over 10

feet high. Never use one as a straight ladder.Never stand on the top platform.

(9) Place ladders so that the hori-zontal distance from the top support to footis at least 1/1, of the working length. Besure that the ladder is securely in place.Rope off all doorways in front of the ladderand place warning signs. (See Figure 13.)

(10) Use hand lines to raise or lowertools and materials. Do not overreach whenworking on ladders. Move the ladder instead.

(11) Never use metal ladders inareas where contact with electric power linesis possible.

Note : The use of portable metal lad-ders is not recommended by the Navy until asatisfactory specification is approved by theNavy Department (NAVSO P-2455).

I

gt lengthof ladder

Figure 13. Ladder Stability.

40b. Scaffolding (See Figures 14 thru 21 ject metal parts damaged by corrosion and

For types of scaffolding): wood parts with defects such as checks,(1) Inspect all parts before use. Re- splits, unsound knots and decay.

Figure 14. Double Polo or Independent Scaffolding.

8

(2) Provide adequate sills or under-pinnings when erecting on filled or softground. Be sure that scaffolds are plumb andlevel. Compensate for uneveness of theground by blocking or using adjusting screws.

(3) Anchor scaffolds to the wallabout every 28 feet in length and 18 feet inheight. Do not force braces to fit. Use hori:zontal diagonal bracing at bottom and atevery 30 feet in height.

(4) Lumber should be straightgrained. All nails should be driven full length

(NO VIZM

ii/and not subject to direct pull.

(5) Provide guard railings regard-less of height, on the full length of the scaf-fold and also on the ends.

(6) Erect scaffolding so that laddersare lined up from top to bottom. Always useladders when climbing scaffolding.

(7) Tubular pole scaffolds should bemade of two inch O.D. galvanized steel tub-ing or other corrosion resistant metal ofequal strength. .They should be erected ordismantled by experienced personnel only.

PACK PPM

Figure 15. Diagonal Bracing on Double Pole Scaffolding.

3

Figure 17. Horse Scaffold, Three Tiers (Max. Height 15 Ft.)

11

-,.

Figure 18. Outrigger Scaffold with Guard Rail.

12

52

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Figure 21. Pipe Scaffolding One ManAssembly Type.

(8) Planking should have at least atwo foot o,verlap. Secure well to wood scaf-folding. Platforms should be made of plank-ing of uniform thickness laid close together.They must overlap and be fastened at sup-

. et..

ports. Do not use planking for other pur-7,-V4! poses; paint them only at the ends to identify

them. Nominal sizes of planking should beVW .g.

II -. i -4, determined from Table 1 below. Values are. .*

f atip.'# given in pounds for loads at center and allow...:Af-,.. 414A "a for weight of planking. .

(9) Test scaffolds and extensibleFigure 20. Pipe Scaffolding Roller planking (extended to working length) by

raising them one foot off the ground andOutrigger Type.

Table 1. Safe Center Load4 for Scaffold PlankSpan feet Sze 2x10* Sx 12° 3:c 8* Sz.10* 3 re 12*

6 200 255 310 525 665 8058 160 190 280 390 600 605

10 120 155 185 815 400 48512 100 130 155 265 335 405

14 110 135 225 285 34616 115 195 250 805

Above values are for planks supported at the ends, wide side of plank face up, and with loads concen-trated at the center of the span. For loads uniformly distributed on the wide surface throughout the length,the safe loads may be twice those given in the table. Loads given are net and do not include the weight ofthe plank. If select structural coast region Douglas flr, merchantable structural longleaf southern pine, ordense structural square edge sound southern pine are used, above loads may be increased 25 percent.

Dressed sizes of planks, reading left to right, are : 1% x 7%, 1% x 9%, 1% x 11%, 2% x 7%, 2% x 9%,2% x 11%, respectively.

5414

loading them with weights at least 4 timesthe anticipated working 1Jad.

c. Rolling Towers:(1) Inspect all tower parts before

use. Do not use parts which are damaged bycorrosion, deterioration, or misuse.

(2) Guy or tie off towers withheights more than three times the minimumbase dimension, and Ox towers at every 18feet of elevation. Maintain stability oftowers over 25 feet high with out-riggersor handling lines. Use horizontal diagonalbracing at bottom and at every heightsection.

(3) Provide unit lock arms on alltowers. Do not use casters less than 6 inchesin diameter. Do not extend adjusting screwsmore than 12 inches.

(4) Do not ride towers. Look where

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you are going when moving them. Do notattempt to move a tower without sufficienthelp. Apply all caster brakes when toweris stationary.

d. Swinging Scaffolds, Swing Stages,Bosun. Chairs. (See Figures 22 thru 24):

(1) Always read instructions on theproper use and maintenance of the equip-ment. Follow prescribed load capacities.

(2) Stages should be at least 27inches wide and supplied with guard rails(not rope).

(3) Only experienced personnel areto erect or operate stages. Check ropes andblocks befo:ce use by suspending stages onefoot off the ground and loading at least 4times the anticipated work load. Beforelocating on the job site, check for nearbyelectric power lines.

. .

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A 7',V;.,;:kilEtlari mat

Figure 22. Swinging Scaffold Ladder Platform Type.

1 5co

112

(4) Power stages should have freefall safety devices with hand controls in caseof power failure.

e. Ropes and Cables:(1) Store ropes and cables coiled in

dry empty drums.(2) Use wire rope at least 3/4 inch

diameter for platform slings; use manilarope at least 5/8 inch diameter in bosunchairs and life lines. Use proper clampswith wire rope, and proper knots and hitcheswhen handling materials with manila rope.(See Figure 25.)

(3) Inspect ropes frequently. Dis-card if exposed to acid or excessive heat.Check for dry rat, brittleness or excessivewear. Never use frozen rope.

(4) Inspect all wire ropes and cablesfrequently in accordance with current ser-vice safety criteria.

(5) Do not attempt to salvage ropeor cable by splicing.

Figuro 23. Bosun Chair.

f. Pressurized Equipment: These rulesapply to all types of equipment used bothfor spraying and blasting.

(1) Use only approved equipment.Use remote control deadman valves on highpressure equipment (60 lbs: or higher).These should be activated by the same airused for blasting or spraying. See Air ForceTechnical Oreers T.O. 00-25-232N "High andLow Pressure Terminology" and T.O. 34Y1-1 -171 "Hydrostatic Testing".

(2) Conduct a hydrostatic test atleast once, preferably twice a year. Testsafety relief valves daily.

(3) Use conductive hose. Groundnozzles, tanks and pressure equipment whenin use, also object being sprayed. (SeeFigures 26 and 27.)

(4) Store hose in dry areas. Whenin use, avoid sharp bends, especially whencurved around an object. Secure high pres-sure hose no more than 10 ft. from operator.

(5) Never point gun or nozzle atanyone or any part of the body. Whenhandling or carrying, hola- by the grip andremove the fingers from the trigger.

(6) Release all pressure before dis-connecting any part of the equipment.

SECTION 3 FIRE HAZARDS

3-1. Causes. Most paint products arehighly flammable and extremely dangerouswhen they or their vapors are exposed toopen flames, sparks or excessive tempera-tures. Flammable liquids and vapors, espe-cially the latter, are, by far, the chief causesof fire and explosion.

3-2. Solvents. Most paint productsare flammable because of the solvents theycontain. These solvents are highly volatile,and some flash, in the presence of a flame,at temperatures below normal ambient paint -ing temperatures. Thus, they may be safein cold weather yet be potentially dangerousin midsummer. It is sf.,fer to use paintmaterials which will flash at temperaturessignificantly higher than painting tempera-tures since environmental changes can, quick-ly change a safe condition to a danorous one.

16

For example, mineral spirits, with a flashpoint of 105°F, is considerably safer to usethan V M & P Naphtha (benzine) which hasa flash point of 50°F or less. FurtheliAiore,a paint, varnish or lacquer containing a mix-ture of solvents will flash at a temperatureclose to that of the most volatile solvent

since this solvent vaporizes more quicklythan the others. A low flashing paint mate-' ial cannot be made safe by blending withanother having a higher flash point. Sincelow flashing solvents volatilize or vaporizereadily, they are most likely to bring abouthigh concentrations of vapor in enclosed

"Zrin"

01:tsouct

IL/UST/IMMORigYIN OF RoPC,

Figure 24. Bosun Chair anc! Swinging Scaffold(Construction Details).

spaces. This is especially true when spray-ing, since spray paints usually contain lowflashing solvents to accelerate drying. Aspray gun which applies a pint to a quartof paint per minute will cause a much greater

LNDLAST PO ND THAU LOOP

WHIPPINGSTEP ISOUNDS OPIPPLO TO CLAMPS'

PULL LOOP TO WITWHIPPINOSTEP Z

CUT Or

CU Off TAXI

WHIPPINGconic' mousse

concentration of vapor than a dozen brushpainters. Every gallon of solvent in the paintwill create more than 100 gallons of poten-tially dangerous gas or vapor. This conditionis even more dangerous in confined spaces

SOUARZ KNOT

SHEET BEND

GLOVE HITCH

BOWUNE

RUNNINGBOWLINE

TWO HALFHITCHES

TIMBER HITCHAND

HALF HITCH

S CAFFOLDHITCH

ROLLING HITCH

ROUND TURN ANDTWO HALF HITCHES

Figure 25. Knots and Hitches Used in Painting Operations.

18 53

since it is possible to cause an explosion, ifa critical ratio of solvent vapor to air isreached, in the presence of a flame or spark.This is why spray equipment must begrounded to prevent ignition by a sparkfrom static electricity. Furthermore, solventvapors, which are heavier than air, willmove along the ground for dozens of yardsfrom the area of application. For this rea-son, all flames must be extinguished anywhere near the painting area. Flash pointsand flammable vapor/air limits of commonpaint solvents are given in Appendix C.

3-3. Oil Paints. Many exterior paintsfor wood and steel are based on raw or re-fined linseed oil. These represent a very

definite fire hazard if paint-soaked waste orwiping rags are allowed to remain lyingaround. As the paint dries, the oxidationof the oil can cause the temperature to riseto the point where the rag or waste materialwill ignite spontaneously. The situation isespecially dangerous with rags contaminatedwith pure raw or boiled linseed oil. (SeeFigure 28.)

3-4. Other Paints. The majority ofpaints applied on site contain high flash sol-vents (over 100°F), therefore, are relativelylow in hazard and require only normal pre-cautions. However, some finishes repreSentan abnormal fire and explosion hazard.Among these are spray finishes as described

Conductive-type hose-to-roof operations.

Air hose to compressor

Nozzle

Ground rod

Figure 26. Grounding of Tank and Equipment.

Conductive-type hose

Non-locking plug-type connector

Expansion-type steel braceletfor wrist of operator

c3

Extension cord

Figure 27. Grounding of Blast Nozzle.

529

Magnetized steelcontact roller (Useclip if steel surfaceis covered with paint

or dirt.)

Figure 28. Combustible Waste, SeparateContainers.

in 2-2" because of the low flashing solventsused. Others are nitrocellulose lacquerswhich burn rapidly because of the nitro-cellulose present, and two-component prod-ucts which are subject to spontaneous com-bustion if mixed in large quantities.

3 -5. Precautions and Prevention. Certaingeneral rules regarding fire and explosionhazards apply to all situations. All paintmaterials should have complete label instruc-tions which stipulate the potential fire haz-ards and precautions to be taken. Paintersmust be continuously advised and remindedof the fire hazards that exist under theparticular conditions of each job, so thatthey will be aware of the dangers involvedand assure that the necessary precautions

are taken and maintained. Fire fightingequipment, of the proper type, must alwaysbe readily available in the paint shop, sprayroom and work areas where a potential firehazard exists. Electric wiring and equipmentinstalled or used in the paint shop, includingstorage room and spray room, must conformto the applicable requirements of the Nation-al- Electrical Code for Hazardous Areas.

3-6. Specific Safety Measures.a. Prohibit smoking anywhere that

paint is either stored, prepared for use orapplied.

b. Provide for adequate ventilation inall of these areas.

c. Perform recurrent spray operationson portable items, e.g., signs, in an approvedspray booth equipped with adequate ventila-tion, a water wash system of fume removaland explosion proof electrical equipment.

d. Wet down spray booth surfaces be-fore cleaning them.

e. Use rubber feet on metal ladders,and be certain that personnel working inhazardous areas use rubber soled shoes.

f. Use non-sparking scrapers andbrushes to clean metal surfaces where firehazards are present.

g. Wet down paint sweepings, rags andwaste with water, and store in closed metalcontainers until disposed of in an approvedmanner. Do not burn in heaters or furnaces.(See Figure 29.)

h. Extinguish all pilot lights on waterheaters, furnaces and other open flame equip-ment on all floors of the structure; beingpainted. Be sure to turn the gas valve off.

i. When painting in confined areasnear machinery or electrical equipment, openall switches and tag them to prevent theirbeing turned on inadvertently.

j. Be sure that all mixers, pumps, mo-tors, and lights used in the paint shop, sprayroom or on the job are explosion proof andelectrically grounded.

k. Use pails of sand (never sawdust)near dispensing pumps and spigots to ab-sorb any spillage or overflow.

1. During painting operations keep fireextinguishers nearby. Be sure that they areof the proper type. (See Table 2.)

fie

Choosefrom these

5 basictypes of

extinguishers

CARBON DIOXIDE

Table 2. Use the Proper Fire Extinguisher

Three Classes of Fires

CLASS A FIRES

Paper, wood, cloth, excel-sior, rubbish, etc., wherequenching and coolingeffect of water is re-quired.

Small surface fires only.

DRY CHEMICAL Small surface fires only.

YESExcellent

WATER Water saturates materialand prevents rekin-dling.

YESEAcellont

FOAM Foam has both smother-ing and wetting action.

VAPORIZING LIQUID Small surface fires only.

m. Check ventilation and temperatureregularly when working in confined areas.

n. Consult with electricians beforepainting in areas where high voltage linesand equipment are located.

o. Keep all work areas clear of ob-structions.

p. Clean up before, during and afterpainting operations. Dispose of sweepingsand waste daily.

SECTION 4 HEALTH HAZARDS

4-1 Causes. A variety of ingredientsused in the manufacture of paint materialsare injurious to the human body in varyingdegrees. While the body can withstand nom-

6127

CLASS B FIRESBurning liquids (gasoline

oil, paints, cooking fats,etc.) where smotheringaction is required.

YESExcellent

Carbon dioxide leaves noresidue, does not affectequipment or foodstuffs.

YESExcellent

Chemical absorbs heat andreleases smothering gason fire; chemical shieldsoperator from heat.

NOWater will spread fire, not

put it out.

YESExcellent

Smothering blanket doesnot dissipate, floats ontop of most spilledliquids.

YES

Releases heavy smother-ing gas on fire.

53

CLASS C FIRES

Fires in live electricalequipment (motors,switches, appliances,etc.) where a non-con-ducting extinguishingagent is required.

YESExcellent

Carbon doxide is a non-conductor, leaves no res-idue, will not damageequipment.

YESExcellent

Chemical-is-a non-conduc-tor; fog of dry chemicalshields operator fromheat.

NOWater, a conductor, should

not be used on live elec-trical equipment.

NOFoam is a conductor and

should never be used onlive electrical equip-ment.

YES

Liquid is a non-conductorand will not damageequipment.

inal quantities of most of these poisons forrelatively short periods of time, continuousor over exposure to them may have harmfuleffects. Furthermore, continued exposure tosome may cause the body to become sensi-tized so that subsequent contact, even insmall amounts, may cause an aggravatedreaction. To this extent, these materials area very definite threat to the normally healthyindividual and a serious danger to personswith chronic illnesses or disorders. Thesematerials are divided into two major groups,i.e., toxic materials and skin irritating ma-terials.

4-2. Toxicity. Toxic materials maybe present in the form of vapor, dust, orspray mist and may enter the body either

511

Figure 29. Keep Combustible Materials inMetal Waste Cans Tightly Covered.

by breathing, swallowing or by absorptionthrough the skin. Symptoms of excessiveexposure can be irritation of the nasal mem-branes, headache, dizziness, loss of appetite,nausea and fatigue. Typical examples oftoxic materials are as follows :

a. Pigments : The most common toxicpigments are lead-containing compounds andzinc chromate. Lead may be present in whiteor tinted paints as white lead; in primers aslead chromate, red lead, or basic lead silicochromate, and in paint driers. Refer to thespecification for the analysis, and take properprecautions if the level of toxic pigment isgreater than 1% of the total weight of solidsin the dry paint film.

b. Solvents : The maximum allowableconcentrations (threshold limit values) forthe common paint solvents are listed in Ap-pendix C. Among the most toxic solventsare benzol (benzene) , methyl (wood) alco-hol and chlorinated solvents, e.g., carbontetrachloride. However, these solvents arerarely used in common paint materials.

c. Binders : Some binders or vehiclesare toxic; for example : epoxies, amines,polyurethanes and polyesters. Avoid breath-ing fumes and spray or contact with skin.Wash hands and face thoroughly before eat-ing or smoking.

4-3. Dermatitis. Dermatitic materialsaffect the skin. The skin becomes irritatedand, if left untreated, infection can set inand progress to allergic sensitization andfinally to incapacitation and hospitalization.Typical examples of dermatitic materialsare :

a. Solvents : All solvents tend to re-move natural oils and fats from the skin,leaving it dry, chapped, irritated, andsensi-tive to infection. The milder solvents, suchas mineral spirits, are not as irritating tothe skin as the stronger solvents such as tur-pentine, xylol (xylenel, MEK (methyl ethylketone) or mco-hylene chloride. (Methylenechloride is the ,nost common solvent used in-non-flammable paint removers.)

b. Resins and Resin Hardeners : Epoxyresins '..nine hardeners, and some urethaneand p enter resins irritate the skin andshould be handled with special care.

4-4. Other Hazardous Materials. Thefollowing materials are also dangerous ifhandled carelessly:

a. Corrosive agents in paint removersand pai..t brush cleaners, e.g., phenol (car-bolic acid).

b. Acid and alkaline cleaners ; acidcomponent of wash primer.

4-5. Precautions. and Prevention. Healthhazards can easily be avoided by a commonsense approach of avoiding unnecessary con-tact with hazardous materials and by strictadherence to established safety measures. See

5, 5

PORTABLE FIRE EXTINGUISHERS

Figure 30. Soda acid.

Soda-acid type extinguishers are used only onClass A fires. The use of the soda-acid extin-guisher is also very simple. Simply direct thehose toward the base of the fire and invert theextinguisher. This inversion causes a mixing ofthe solution inside the tank, a reaction occurs,and the solution is supplied to the hose underpressure.

Figure 31. Foam.

The foam type fire extinguisher may be usedeither on Class A or Class B fires. The methodof using this extinguisher is the same as for thesoda-acid type. Invert it and dircct the hose sothat the foam is played over the surface of thefire. This is for a fire involving liquids. For a firein a solid material the stream of foam should bedirected to fall lightly on, or flow over, the burn-ing surface of the material.

23

C3

Figure 32. Dry chemical.

Dry chemical type extinguishers may be usedon Class B and Class C fires. These units containa dry powder, usually sodium bicarbonate, and anactivating agent of CO2 or nitrogen gas. Theseunits should not be used on trash fires. To put theextinguisher into use, remove the locking pin,open the cartridge discharge valve, and squeezethe nozzle handle.

OPERATING VALVESEAL LOCKING PIN

HANDLE

Figure 33. Carbon dioxide.

Carbon dioxide, or CO2, type extinguishers maybe uscd on Class B and on Class C fires. To op-erate the CO2 extinguishers, pull the seal lockingp:n and open the operating valve. The CO., shouldbe &meted toward the base of the fire with asweeping motion.

"lo

Air Force Regulations AFR 161-10 "Precautary Measurcs for Handling Solvents" and AFR161-18 "Use of Potentially Toxic and HazardousMaterials".

4.6. Specific Safety Measures. The followingrules should be strictly observed:

a. Toxic or dermatitic materials must beproperly identified and kept tightly sealed whennot in use.

b. Designate a competent person to checkthe operation of paint spray booths. Check atregular intervals to insure that the equipment isin a safe and proper operating condition.

c. Be sure that ventilation is adequate inall painting areas. Provide artificial ventilationwhere natural ventilation is inadequate. Usesupplied air respirators, if necessary.

d. Spray all portable items within exhaustventilated booths especially designed for thatPurpose.

e.- Wear goggles and the proper type ofrespirator when spraying, blast cleaning or per-forming any operation where any abnormalamount of vapor, mist or dust is formed.

f. When handlini dermatitic materials, useprotective creams or preferably gloves, and wearappropriate clothing. Change and clean workclothing regularly.

g. Avoid touching any part of the body,especially the face, when handling dermatiticmaterials. Wash hands and face thoroughly be-fore eating and at the end of the day.

5ECTiON 5 EMERGENCIES

leirst Aid. First aid kits must be well stockedwith fresh materials and be available and easilyaccessible during any painting operation. Allpersonnel should be able to give emergency aid.However, any illness must be reported to themedical and industrial safety departments, re-gardless of whether or not it appears to be serious.Some toxic materials do not take full effect fordays.

SECTION 6 HEALTH SERVICES

6-1. Medical Department. The foreman mustconsult with the installation medical departmentregarding any questions or problems relating tothe personal health and hygiene of the men as-signed to him. Decisions in this area are to bemade by the installation medical officer and mustbe strictly followed. Recommendations made by

the medical department are to be presented tothe painting crew and enforced by the foreman.

6-2. Medical Examinations and Records. Allpainting personnel are initially required to havethorough medical examinations .with the resultsentered into their permanent record files. Sub-sequent examinations may be required periodical-ly before personnel assigned to the painting crewcan be exposed to any job or paint material con-sidered to be at all hazardous. The foreman Willalso immediately request a medical examinationof any person suspected of having an illness oraffliction which may have been the result ofpainting operations, or which may be aggravatedby intended painting operations.

C4

24

CHAPTER 2

protective Coating atereals

WHY DO WE PAINT? What is the bestprotective coating to use? How can I do a

professional job of painting? How can I mix thecorrect colors? How should I store protectivecoatings? These are questions that you, as aprotective coating specialist, will probably askyourself. By studying this chapter you should beable to answer them.

2. In the early days of America, paint was asymbol of prestige similar to the large car orhuge yacht. the leading citizens always paintedtheir homes white, and that painted home stoodas a symbol of wealth. There's a legend that alowly shoe cobbler painted his home and wassubsequently tarred and feathered and run out oftown. This wrongdoing made others in the col-onies think and reminded them that all menshould have the same privileges regardless ofwealth.

3. Some of the colonists even went one stepfurther in decorating; they discovered that redoxide of iron could be used to paint the trimred, which would brighten up their homes. Afterthe discovery of copper ore, the colonies foundthat they could create green colors from this ore.Painting and development of colors progressedto the present day when almost any desired colorcan be mixed.

7. Purpose and Function of ProtectiveCoatings

7-1. Why do we paint? At one time protec-tive coatings were used primarily for beautifi-cation, then it was found that painting would pre-serve the wood and prevent rotting. The militaryuses paints to camouflage weapons and installa-tions. A recent usage of paints is for identifi-cation purposes. The use and demand for pro-tective coatings have grown until today over 5billion dollars each year are spent on them. Themilitary , along with other Government agenciesand commercial establishments, uses a consider-able quantity of these coatings for protection,sanitation and cleanliness, illumination and visi-

2C5

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bility, safety and efficiency, appearance, camou-flage, and fire control.

7-2. Protection. Protection of the surface isthe most important purpose of painting. If prop-erly chosen and applied, paint will protect woodenbuildings from moisture and sunlight, metal struc-tures from corrosion, and concrete and masonrysurfaces from the weather. Painting, when reg-ularly programmed, offers long-range protection.that extends the useful life of a structure.

7-3. Sanitation and Cleanliness. Paint andproper painting operations promote sanitationand cleanliness. Paint provides smooth, nonab-sorptive surfaces that are easily washed and keptfree of dirt. Such surfaces tend to keep food-stuffs from adhering. Adhering foodstuff har-bors germs and causes disease. The coating ofrough or porous areas seals out dust and greasethat would otherwise be difficult to remove.Paint coatings will reveal buildup of foreign subL,stances, indicating that better housekeeping prac-tices are in order. Painting, therefore, is an es-sential part of general maintenance programs forhospitals, messhalls, offices, warehouses, and liv-ing quarters.

7-4. Illumination and Visibility. White andlight-tinted paints applied to ceilings and wallsreflect both natural and artificial light and helpbrighten rooms and increase visibility. On theother hand, darker colors reduce the amount ofreflected light. Flat paints diffuse, soften andevenly distribute illumination, whereas gloss fin-ishcs reflect more like mirrors and may createglare. Color contrasts improve visibility of thepainted, surface, especially when the paint is ap-plied in distinctive patterns. For example, whiteon black, white on orange, or yellow on blackcan be seen at greater distances than single col-ors or other combinations of colors.

7-5. Safety and Efficiency. A recent innova-tion in the use of paints is the identification ofpipes carrying different material' such as oil,steam, water, and air through a hangar or indus-trial plant. It is also used to indicate hazards

or danger areas by using various colors. Thisarea usage of paints is expanding at a very rapidpace, especially in schools, hospitals, other in-stitutions, and industrial plants.

7-6. Appearance. Painting is primarily usedfor maintenance and to improve safety and ef-ficiency. Decorative painting is sometimes con-sidered to be secondary in importance and istherefore kept at a minimum. However, thefunctional use of color does create comfortableliving and working conditions and more pleas-ant surroundings that result in improved moraleand increased efficiency.

7-7. Camouflage. Paint is used by militaryforces to camouflage weapons and installationsagainst enemy detection. By expert applicationof colors that blend with the surrounding terrain,it is difficult for the enemy to detect the loca-tions of weapolis,' supplies, buildings, or evenships from the air.

7-8. Fire Retardance. Certain paints delay thespread of fire and assist in confining it to itsorigin. This allows more time during which fire-fighting equipment can arrive to extinguish theblaze before it gets out of control. The use offire - retardant paints is restricted to appreciableareas of highly combustible surfaces and for se-lected uses. Their use is furthcr restricted tointerior surfaces except for Arctic areas. Fire-re-tardant paints must not be considered as sub-stitutes for conventional paints as their cost ismuch higher.

8. Composition of Protective Coatings8-1. To select the best protective coating for

a given 'surface, it is important that you under-stand the composition of coatings. The principalingredients of paints are the pigments and thevehicle. The pigment is the part of the paintthat constitutes the solids 'and the vehicle is thefluid. Many types of materials used in the formu-lation of paints are far too numerous to permitthe inclusion of a description of each in this chap-ter; however, in order to acquaint you with themost common paint pigments and vehicles, theyare discussed as a class, and in some instances,the more important materials in a class are de-scribed.

8-2. Pigments. The pigments are fine solidparticles used in the preparation of paint whichare insoluble in the paint vehicle. Pigments areavailable in two forms, powder and paste, thelatter being ground in oil; Japan, or other vehicleto a stiff consistency. There are five main typesof pigments: white pigments, color pigments,metallic pigments, black pigments, and extenderpigments.

CC26

8-3. White pigments. White pigments are ofgreat importance to the paint industry becausewhite is a widely used color and serves as thebase for popular pastel colors. The most com-mon white pigments usc'd are titanium dioxide,white lead, antimony oxide, and zinc oxide.

8-4. Titanium dioxide has been available forpigment since 1932. It has a definite advantagewhere maximum hiding is required. Titaniumdioxide has overshadowed all other white pig-ments because of its "chalking" ability. Thismeans that the surface becomes chalky and canbe rubbed or ,v:zshed off. This is an obvious ad-vantage in wh,:. or light-colored house paints be-cause rain will v.-ash ,.way the chalk, and alongwith it goes the dig t and grime, leaving a clean,bright surface. It iy s disadvantage with darkcolors because it Ives a fading appearance of thecolor.

8-5. White lead. r.white and light-coloredimportant and oldestThere are two kinds:and basic lead sulfate.

8-6. Basic lead carbonate combines readilywith linseed oil and makes a s:nooth and easilybrushed paint. It has a peculiar drying qualitywithin itself which reacts with the linseed oil tofacilitate' drying. It also has the characteristicsof gradual chalking, which causes the paint filmto lose its gloss and wear away in a fine powderyform. Slow chalking is desirable in any paint,since the action provides a good surface for re-painting without too much preparation.

8-7. Basic lead sulfate, sometimes called sub-limated white lead, has approximately the samehiding power as basic lead carbonate, and inmost cases may be substituted. Lead sulfate isusually considered less durable than lead car-bonate and is usually less expensive.

8-8. Antimony oxide is used chiefly in thecoating industry in the manufacture of fire-re-tardant paints, where it is used in combinationwith chlorinated materials and calcium carbonate.The Navy uses paints with this type of pigmenton interior surfaces of its ships.

8-9. Zinc oxide is one of the finest of all whitepigments and actually one of the whitest. It isopaque to ultraviolet light and, when incorporatedin a paint, protects the film from the destructiveaction. of the ultraviolet rays in sunlight. Whilezinc oxide contributes to the hiding power ofpaint, some of its other properties are more im-portant. It is not discolored by the sulphur gasesin the atmosphere. It is nonpoisonous. Zincoxide- is used as a preventive for mildewing oryellowing and also adds hardness to a paint film.

component of almost allpaints, is one of the mostof the white pigments.the basic lead carbonate

It is a valuable pigment for controlling checkingand chalking and dirt retention of exterior paintfilms. It is also used in metal protective paintsfor rust inhibition, and in others for greater re-sistance to scrubbing.

8-10. Color pigments. Color pigments can beobtained from deposits in the earth's crust orthrough chemical processes.

8-11. Earth colors. The most widely knownearthy colors in the painting industry arc: yellowocher, raw and burnt sienna, and raw and burntumber.

8-12. Yellow ocher contains hydrated oxide ofiron as a coloring matter. Various ochers contain10 to 60 percent hydrated oxide, the remainderbeing silicous matter or clay. In color, yellowothers vary from pt.le. to very dark yellow, al-most olive. When of good quality they are excel-lent pigments, permanent in color, and combincwell with all paint vehicles as well as other pig-ments. With white pigments, they produce finecream or buff tints. They are used primarily astinting colors.

8-13. Raw sienna resembles yellow ocher ingeneral composition, since it is colored by hy-drated iron oxide. It is brownish yellow in color.When used with white, it produces cream tintswhich have greater color strengths than ochers.Raw sicnnas are valuable as staining and grain-ing colors. They are undesirable for body colors.

8-14. Burnt sienna is obtained by roasting rawsienna, thereby producing a strong reddish brownpigment. Burnt sicnnas are used to a lesser de-gree than the raw sienna. However, they are veryvaluable pigments whm used for shading andglazing.

8-15. Raw umber is similar in composition tothe sicnnas. It has a greenish brown color, ispermanent, possesses medium opacity, and mixeswell with paint vehicles. Raw umber gives drabtints with white, and a great variety of othershades when mixed with color pigments, forwhich purpose it is extensively used.

8-16. Burnt umber is calcined raw umber. Itpossesses a rich brown color which, while darkerthan raw umber, is free from redness. Burntumber is used in practically all types of paintsand stains.

8-17. Chemical colors. Chemical colors arcvery important today and arc used more thanearth colors because they can be producedcheaper by chemical reaction from basic raw ma-terials. These colors consist of blue, green, ma-roon, orange, red, yellow, brown, and violet pig-

ments.8-18. Metallic pigments. Metallic pigments

are used to form a metallic film in paints. The27

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most common are alurinum, copper, bronze,and zinc.

8-19. Aluminum pigment. Aluminum pigmentis largely pure metallic aluminum and containsappreciable amounts of polishing lubricant, a

mixture of stearic and other fatty acids: It maybe purchased in either paste or powder form.An average mixing formula for the productionof aluminum paint is 2 pounds of aluminumpowder or paste to 1 gallon of mixing varnish.

8-20. Copper pigments. Copper bronze pow-ders arc usually alloys of copper with smallamounts of zinc and iron. Approximately 1 to2 pounds of metal per gallon will give good hid-ing qualities. Copper bronze in combination withsmall amounts of a toxic substance, such as amercury or arsenic compound, is used for mak-ing anti-fouling ship bottom paint. Variousshades from a light brass to a dark antique cop-per are used in nitrocellulose lacquer to makethe popular brass and bronze finishes.

8-21. Zinc pigment. Zinc dust is a metallicgrey powder with about 3 percent zinc oxide onthe surface. This is a recent development andhas gained importance as a pigment for makingmetal protective coatings.

8-22. Black pigments. One of the most im-portant black pigments known to the paint in-dustry is lamp black. It is most commonly usedfor shading paints, since it has exceptionallygreat shading strength and is extremely perma-nent.

8-23. Extender pigments. Extender pigmentsare certain white or colorless natural substanceswhich arc ground into a fine powder and addedto paints:

To provide a solid base for color pigments.o To make the paint film porous so that a

normal amount of moisture may passthrough it without pushing off the paintfilm.To reduce the excessive spreading rate ofpaints, thereby increasing the thickness of apaint film.

8-24. Some of the more important extenderpigments are:

Barytes (barium sulphate).China clay (aluminum silicate).Mica.Silica (glass sand).Talc (magnesium silicate).Whiting (calcium carbonate).

8-25. Vehicles. In a layman's language, thevehicle is defined as the liquid portion of a paint,enamel, lacquer, or similar substance which holdsthe pigment in the solution. The vehicle may be

(00any of such liquids as drying oils, volatiles (thin-ners, solvents), driers, resins, and varnishes. Itis perhaps the most important part of The coating,as it furnishes the desired qualities of adhesion,toughness, flexibility, and resistance to variousenvironments. It gives the paint its strength andlife. The vehicle is usually divided into two parts:the nonvolatile (solid) portion consisting of oils,resins, or plasticizers; and the volatile (liquidthat evaporates) portion consisting of solvents,diluents, and driers. When the volatile portionevaporates, the, nonvolatiles form the actual filmon the surface.

8-26. Drying oils. An oil is classified as adrying oil if it will set or harden under normalexposure conditions when applied as thin film.Some of the most commonly used drying oils arelinseed oil, soybean oil, tung oil, oiticica, perillaoil, fish oil, and castor oil.

8-27. Linseed oil, the most important of dry-ing oils and the principal nonvolatile paint ve-hicle, is obtained from flaxseed. It is used asthe basic vehicle in paint because it has a naturalability to dry in the open air, forming an elastic,durable solid film which resists the attack ofweather and wear.

8-28. Soybean oil, a slower drying oil than lin-seed oil, is generally used with faster dryingoils. Its main use is in varnish vehicles for in-terior paints and enamels; paints made with soy-bean oil resist yellowing. It is used in some ofthe best interior white enamels

8-29. Tung oil is one of the chief oils usedin the manufacture of fast drying, waterproof oilvarnish. Since raw tung oil dries rapidly butnot to a smooth film, it is not used as such inexterior house paints; whereas linseed oil is al-most universally used. Its chief usage is in themanufacture of varnishes.

8-30. Oiticica oil is extracted from the seedsof certain trees growing in northern Brazil. Itis used in the manufacture of paints and var-nishes. It is similar to tung oil.

8-31. Perilla oil is extracted from the seedsof the perilla plant grown in Manchuria. It isextensively used in the manufacture of varnishbecause of its superior drying and film-formingqualities.

8-32. Fish oil is mostly extracted from themenhaden and pilchard; it is satisfactorily usedfor covering hot surfaces such as smoke stackswhere hard drying paints are not suitable.

8-33. Castor oil is produced from the castor-oil plant. Its use has increased industrially lincebeing accepted as a satisfactory replacement fortung oil.

8-34. Volatiles. (thinners, solvents). Volatiles,more commonly called thinners, are organic

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liquids used to reduce the viscosity of a vehicleor paint to a suitable brushing or spraying con-sistency. Volatiles control many other propertiesof the paint, such as ability lo penetrate and/orwet the surface being coated, leveling, lap time,dispersion of pigments, and ease of brushing orspraying. Some of the more common volatilesare: turpentine, mineral spirits, naphtha, xylene,acetone, and various alcOhols, ethers, ketones,and esters. Water, of course, is used as thinnerfor water emulsion paints. In the selection ofvolatiles to reduce a paint in the field, directionsof the paint manufacturer cr of the specificationsshould be followed, since some paint vehicleswill not mix with certain volatiles.

8-35. Driers. A drier is a catalytic agentwhich, when added to a drying oil or a paint orvarnish containing oil, hastens hardening of thefilm. The most common driers used in paintsare oil-soluble naphtenates of cobalt, manganese,and lead. Lead driers promote hard dryingthroughout the thickness of the film and in-fluence the rate of polymerization of the vehiclemore than they do the rate of oxidation. Leaddriers are not as strongly catalytic as others inpromoting drying of paint films. Cobalt driersassist oxidation strongly and, if used alone, maycause wrinkling because of rapid drying of theouter layer of the film (see fig. 34).

8-36. A given paint or vehicle may make useof on, e,--i-ao, or all of the three drier types, de-pending on the nature of the paint product. Toomush drier or improper combination of driersmay adversely affect the durability of the film,or it may not allow the paint film to harden.Finished paint products should be purchased withdriers added whenever practicable, since the ad-dition of driers in the field is readily susceptibleto error.

8-37. Resins. Natural and synthetic resinsavailable to the paint industry are so numerousand varied in properties that they will only bementioned. This same complexity and multiplic-ity make a definition almost impossible. Resins

Drier Characteristic If Used Alone

Lead Hard DryingThroughout

TQugh Film

Manganese IntermediateDrying

Brittle Film

CobaltIOuterRapid Drying

LayerWrinkling of

Film

3

Figure 34. Characteristics of driers.

together with drying oils comprise the bulk offilm forming materials, or binders in the surfacecoating field. Natural resins, such as resin andshellac, arc. in general, exudations from treesand insects. Synthetic resins, such as alkyds,acrylics, vinyls, phenolic, silicones, epoxies, andpolyurethanes, are manufactured from basic or-,ganic material, such as petroleum, alcohol, coaltar, and vegetable oils.

8-38. Alkyds are the backbone of modernpaints in a great many combinations. Thealkyds, characterized by toughness, flexibility,and durability, are used in exterior and interiorcoatings for utility and decorative purposes.Thcy do not have good chemical resistance.

8-39. The acrylics have outstanding light re-sistance and outdoor weather durability, withmoderate chemical resistance. Used with nitro-cellulose as a hardener, they have better dryingproperties and increased hardness.

8-40. Vinyls are used where construction ma-terials, metal and wood, must be protected fromhigh humidity or acid caustic environment.

8-41. Phenolics appear in varnishes and enam-els requiring extra hardness and abrasion re-sistance.

8-42. Silicones appear primarily in heat-re-sistant coatings. They are not particularly hardsurfaced and may craze. They are usuallybaked.

8-43. Epoxies have outstanding adhesion andchemical resistance. In combination with otherresins, they appear as baking enamels. Air-dry-ing types are reacted with converting agents justprior to application to set up films of improvedcharacteristics.

8-44. Polyurethanes are also converted orcatalyzed in coating applications. The polyure-thane coating is characterized by a very highgloss, superior toughness and outdoor durability,and good chemical resistance.

8-45. Varnishes. Varnishes contain oil, resins,thinners, and driers. Drying oils and resins arecombined in definite proportions. Thinncrs anddriers are then added. The various types ofresins, oils, and other available components makeit possible to produce varnishes adaptable tomany uses. Varnishes may be used as such for

clear coatings or as vehicles for pigmentedpaints.

9. Types of Protective Coatings9-1. What is the best type of protective coat-

ing to use? There is a demand by those re-sponsible for the selection of paint for recom-mendations as to the "best" paint for every classof surface. There are many factors, such as the

b1

condition of the surface, the method of applica-tion, curing conditions, service expected by theuser, and the cost against the length of time theappearance must remain satisfactory, that mustbe considered.

9-2. The materials mentioned in, the preced-ing section are used to make many differenttypes of organic finishes for decorative and pro-tective purposes; however, some of the mostcommon types are the oil base paints, enamels,lacquers, water-mixed paints, varnish, shellac,and stains.

9-3. Oil-Base Paints. These paints consistprincipally of a drying oil (usually linseed)mixed with one or more pigments. Oil paintsmay be modified by addition of varnishes. Ex-terior surfaces of houses and metal surfaces inatmospheric exposure are usually coated withpaints of the oil type. The vehicle in thesepaints can be a combination of raw and proc-essed oils or it may be a single oil, depending onthe properties desired in the paint. The pigmentsand quantities used in oil paints are usually se-lected on the basis of cost and their ability toimpart to the paint the properties dcsired, suchas durability, economy, brushability, and color.Oil-base paints are characterized by easy appli-cation, slow drying, and good ability to wet thesurface being coated. They normally chalk insuch a manner as to permit recoating withoutcostly surface preparation.

9-4. Enamels. Enamel is commonly thought ofas a pigmented, varnish vehicle paint which hasgood flow and leveling properties and dries fairlyrapidly (4 to 16 hours) at normal temperature.In general, the ability of enamel paints to wetthe surface and coat surface irregularities is notas good as oil paints, and they generally fail bychipping, cracking, blistering, or similar actionresulting from gradual decrease of elasticity withage. Enamel films are generally harder, tougher,and more resistant to abrasion and moisturepenetration than oil-type paints. They can beapplied by brushing, spraying, or dipping. Whenthe application is by brush, flow the paint on thesurface rather than brushing it out as with oilpaints. Enamels of the baking type are widelyused in industrial finishing.

9-5. Lacquers. Lacquers differ from oil paintsand enamels in that they contain some, type ofresin as a vehicle. Lacquers are normally ap-plied by spray since most types dry too fast forbrushing. Lacquers are usually applied by a se-ries of thin films. A hard, brittle coating, a

tough and elastic coating, a high or low glossfilm, and many other variations can be obtainedby proper choice of lacquer materials. Durabil-ity of lacquer finishes on some makes of auto-

mobiles is proof that good protection is given bylacquers. The new vinyl paints which are tech-nically lacquers have outstanding durability inmany types of exposures.

9-6. Water-Mixed Paints. These paints aredistinctly different from other paints in that thevehicle is an emulsion of binder and water.Water paints have the advantages of easy appli-cation, drying by evaporation of water, easy re-duction of viscosity with water, and easy cleaningof tools used for application with soap and water.This type of paint was originally used as interiorcoating but recent usage has broadened to theuse of water paint to outside surfaces. Waterpaints fall into many categories, but casein, la-tex, and calcimine are the more important.

9-1. Casein. In cas..in paint, casein (proteinof milk) is used as the binder. Casein paintconsists of powdered casein, hydrated lime, inertand hiding powder pigments, preservative, andtinting colors. Small amounts of vegetable oilsare added to improve washability. The principalpigment added to casein paint is titanium.

9-8. Caseia paints usually cover a surface wallin one coat, dry rapidly, and adhere to newplaster without scaling or blister.

9-9. Casein paints are designed for interiordecorative work on plaster, want:card, fibre-board, stucco, cement blocks, etc. Casein paintsare also available for exterior masonry, stucco,brick, and concrete.

9-10. Latex (emulsions). This term was orig-inally used to describe raw latex rubber emulsionpaint (rubber in water). Now the term is usedin connection with all resin and rubter emulsionpaints. These paints thin with water, and thebrushes are cleaned with water. Many types

have been ir ade, but vinyl and acrylic emulsionsar^ the most popular.

9-11. Emulsion paints are very good on in-terior and exterior masonry because they breathe,allowing vapor to slowly pass through the film.Emulsion paints are glossless. and special colorsmust be ground in a suitable vehicle to colorthem.

9-12. Calcimine. This paint is a 'mixture ofpowdered pigments, such as whiting and china.clay, and glue. The paint is compounded bymixing the prepared pigments with water. Thepaint is a.1 inexpensive way of covering wet anddry wall interior surface. A glue and water sizen be used on wet walls. The best results,however, are obtained by using a varnish sealerand primer before the calcimine is put on.

9-13. Varnish. A varnish is usually a trans-parent liquid, though occasionally opaque, which,when spread in a thin film over a surface forprotection and decoration, will dry to a hardand transparent coating. The kinds and types ofvarnishes are numerous. Some manufacturer'scatalogues list from 100 to 200 varieties. Oilvarnishes are the most important and includespar varnish, interior varnish, flat varnish, rub-bing varnish, and color varnish. All of the abovevarnishes are extensively used to finish and re-finish interior and exterior wood surfaces, suchas floors, furniture, woodwork, metal fixtures,etc. They produce a durable, elastic and t,,trghsurface which dries to a high gloss finish anddef s not mar easily. Exterior varnishes arespecially formulated to resist weathering.

9-14. Shellac. tAiellac comes from the secre-tions of the lacca insect. This insect secretes aresinous material on trees which is gathered,

CHERRY 1 1/2 Pint4_

MAHOGANY 1 Part 1/2 PartLIGHT OAK 1 Part 1/4 Part

DARK OAK Touch 1 Part 1 /::: Part

OLD MAPLE 1/' Part 1 /2 Part 1 /2 Part

WALNUT1 1/2 Part 1/4 Part

1/4 PartWALNUT 1 Part

Figure 35. Mixing oil stains.

30

70

washed, and ground, and then melted andpla,ed on a thin sheet. These thin sheets ofshellac are then broken into flakesone of theforms in which shellac is sold on the market.Shellac is now produced by chemicals in mod-ern factc.ies. Shellac is soluble in alcohol and is

used extensive as a finishing material, espe-cially on fcrnitLre as an undercoat and over

aots to prevent "bleeding."9-15. Stains. Stains are used to change the

color of various types of v. )od and to bring outthc beauty of the grain. They are usually ap-plied before the varnish or other finish; however,some oil t2ins are used as a preservative forshingles a:/i other rough exterior wood surfaces.The most commonly used stains are the water,spirit, oil, and varnish.

9-16. Water stain. Water stain is cheap, pene-trates the wood deeply, and is transparent. Itproduces an even penetration and gives the mosteven and clearest tone of all stains. A disad-vantage in its use is that the water raises thegrain of the wood which is being finished, re-quiring extra sanding. Water stains are used forinside woodwork and furniture.

9-17. Spirit stain. Spirit stains are made bymixing aniline colors in alcohol. They are quicka drying and the colors art. brilliant, transpar-

ent, and beautiful. By using a spirit stain, a

surface lay be stained, filled and shellacked, orvarnished the same day. For thi reason, thesestains are u-Aul for rspair and touchup work onfloors, woodwork, anor fur:- 'sure and for all sortsof quick jobs. Spirit stains have the characteristicof penetrating o1.1 varnish surfaces to a greater

Figure 36. Primary colors.

31

63

Figure 37. Secondary colors.

depth than other stains, but they are not per-manent in sunlight or very strong light.

9-18. Oil stains. Oil stains are probably themost convenient to use in finishing woodwork ofvarious kinds, since they are easily obtained,easily applied, and do not raise the grain of thewood. They dry slowly enough to permit brush-ing and rebrushing without showing lap marks.Whenever he color is too dark, after the stain isapplied, some of it may be wipcd off to pro-duce a lighter color. In the hands of an un-skilled workman, the results obtained will bebetter than by using other types of stains. Oilstains are mixed to a base of ti gallon boiledlinseed oil and 1/2 gallon of turpentine or mineralspirits as shown in figure 35.

9-19. Varnish stain. Varnish stair is com-posed a varnish to which a stain has beenadded. When you use a varnish stain, it is pos-sible to stain and varnish in one operation.

9-20. Now that you have a basic knowledgeof the types of protective coatings, you are abouto undertake the most important task of thetrademixing and preparing the protective coat-ings

10. Mixing and Preparing ProtectiveCoatings

10-1. How can I mix thc correct color? Col-oring and tintirr, paint is not Difficult when anew mixture of paint first made; howevermatching paint already applied on a surface isdifficult, because paint chan,,es shades after dry-ing and aging.

10-2. Coloring and tinting paint for mostpainters 1s" a matter of trial and error. To be aprofessional protective coating specialist, it isnecessary that you understand the color com-binations, color mixing, tinting, color harmony,how to mix paint by boxing and by using powerequipment, how to thin paint, and the specialprocedures required for mixing aluminum paint.

10-3. Color Combination. Skillful mixing ofcolors is one of the most important aspects ofpainting and decorating, especially in interiordecorating. There are three primary, colors ofpaintblue, red, and yellow (see fig. 36).

10-4. Secondary colors are made by mixingany two of the primary colors together. For in-stance, yellow and red form orange; red andblue form purple; and blue and yellow formgreen (see fig. 37).

10-5. The remaining six places on the colorwheel are filled by combining adjacent primarycolors and secondary colors. These are calledtertiary colors. This fills the color wheel with 12colors, all full strength, which are known as hues.(See fig. 38.) From these hues, you can attaintints, tones, and shades.

10-6. Tints are lighter than hues. They areformed by adding white to the color on the colorwheel. Shades are darker than hues and areformed by adding black to any of the colors.Tones are made by adding both black and whiteto the colors on the color wheel.

10-7. Color Mixing (Oil Paint). When mixingoil paint on the job, colors in oil are easier tomix into the paint vehicle than powders. Colorsin oil consist of dry pigments (powders) ground

Figure 38. Hues.

32

in a vehicle of approximately 80 percent linseedoil and 20 percent volatile solvent which willmake the paste of a consistency that will satis-factorily flow from the containers. The majorcolors in oil are the blacks, blues, browns,greens, oranges, reds, and yellows.

10-8. Blacks. The blacks used for shadingand for solid colors include pigments such asboneblack, high-colored carbon black, carbonblack, lamp black, and synthetic black iron ox-ide. Carbon black and lampblack are the strong-est in shading strength. Carbon black and bone-black are blacker in color. Lampblack, however,is the one most frequently used. Black ironoxide is used as a pigment in black metal pro-tective paints, and is also used for shading pur-poses. The pastes can be thinned to brushingconsistency by adding three parts linseed oil, onepart spar varnish, and one-half part drier to onepart of the pigment paste.

10-9. Blues. The blue pigments are iron blue(Prussian blue), ultramarine blue, and copper-phthalocyanine blue. The permanency of ironblue is affected by alkalies, while ultramarineblue is susceptible to acids. Copper-phthalo-cyanine blue is more durable in the light bluetints. These pigments have a fair permanencyin tints or solid colors exposed to the weather.

10-10. Browns. Brown pigments include me-tallic brown, burnt sienna, burnt umber, rawumber, and synthetic brown iron oxide. Thebrowns are among the most durable pigmentsused in paints exposed to the weather. Althoughadaptable as a trim color, metallic brown ismore often used as a solid color. It is used to agreat extent it., saint for barns, metal roofs, andfreight cars. 'I ne other browns are often usedfor tinting paints and making stains. Brown ironoxide is also used as a pigment in some paintsand enamels.

10-11. Greens. The green pigments arechrome green and chromium-oxide green.Chrome green, composed of chrome yellow andiron blue, is used to make tints or solid colorpaints, which, by the way, are sensitive to alka-lies. Chromium-oxide grcen, more permanent ofthe two, is used with white for tinting purposes.It does not have the tinting strength of chromegreen, but withstands high temperatures and isnot effected by alkalies or acids.

10-12. Oranges. Orange pigments consist oftwo shades of chrome orange that are used fortinting and making solid color paints. The pig-ments are basic lead chromate that is processedas light and dark. The dark pigment is used inmaking international orange paint. Both light anddark pigments are relatively permanent whenexposed to the weather.

10-13. Reds. The reds include pigments suchas Venetian red, bright red iron oxide, Indianred, toluidine red, and mineral red. All of thesepigments are used for tinting purposes, excepttoluidinc red. Indian red and bright red ironoxide are very permanent and are used exten-sively in all types o: paints, enamels, and stains.Venetian red and mineral red are often used inbarn and roof paints. Toluidinc red, which is abright red, is permanent when exposed to theweather.

10-14. Yellows. The yellows include a num-ber of pigments. They are; lemon chrome yel-low, medium chrome yellow, yellow ocher, prim-rose chrome yellow, yellow iron oxide, rawsienna, and zinc yellow. The chrome yellowsare satisfactory for tinting exterior paints. Yel-low-ivory colored paste is made by adding andmixing 1 pound of medium chrome yellow to 50pounds of white lead paste. Yellow ocher mixedat a ratio of 1 pound to 50 pounds of white leadpaste makes a durable chamois colored paste forexterior paint.

10-15. Raw sienna is used more for tints andstains than for solid color or trim paints. Whenmixed with white lead in different amounts, it

makes durable ivory and buff tints. The yellowoxides are used particularly in solid color paintsand for tinting floor enamels. Zinc yellow is

used mainly as a rust-inhibitive pigment in metalprimers.

10-16. Color Mixing (Wafer-Base). When youare mixing water-base paint on the job, mix colorpigments that are soluble in water into the paintvehicle. COLORS IN OIL CANNOT BEMIXED WITH WATER-BASE PAINTS.

10-17. Tinting or Shading. When you tint orshade paint with paste, mix the paste with asmall amount of the paint vehicle to thoroughlybreak it up; then, strain through a cheesecloth.When you mix paint to match a certain color,add the tint or shade in small amounts, andtest the paint by brushing it on a surface similarto the one to be painted. Allow the paint to dryin order to check for the proper match.

10-18. If the desired match has not been pro-duced, add either more color or more base paint.If you notice streaks of color when you brushout the paint, it is a sign that you have notthoroughly mixed the color into the base paint.If you add too much color to your base paint,you will have to add considerably more basepaint to lighten the color. As a result, you willhave more paint than you need for the job.

10-19. Color Harmony. Below is a list c: omeDo's and Don't to consider when you t.lccL col-

ors.

L5*

DO use light colors in a small room to cre-ate an impression of larger size.

DO have continuing color flow through thebuildingfrom room to roomusing harmoniouscolors in adjoining areas.

DO paint ceilings of a room in a deepercolor than walls, if you want it to appear lowerand in a lighter shade for the opposite effect.

A. POUR OFF SURFACE LIQUID

B. STIR UP THOROUGHLY FROM BOTTOM

C. POUR FROM CAN TO CAN

Figure 39. How to box paint.

DO study color swatches in both daylightand nightlight, because colors often change underartificial lighting.

DO emphasize horizontal lines in a roomthat is too tall, and emphasize vertical lines in aroom with a low ceiling.

DON'T use a bright color in a large area,or the walls will detract from otherwise decora-tive furnishings and accent pieces.

DON'T paint the woodwork and trim of asmall room in a color that is different from thebackground color, or the room will appear clut-tered and even smaller.

DON'T paint unfortunate architectural fea-turessuch as radiators, pipes, and similar pro-jectionsin a color which contrasts with walls,or they will be emphasized.

DON'T choose neutral, negative, or "non-colors," just becaust they are safe, or you mayforfeit attractive decorating.

DON'T use glossy paints on walls or ceil-ings of living areas since such a surface createsglare.

10-20. Mixing Paints. Primers and paints mustbe mixed (stirred) thoroughly. This will insurethat the paint pigment, which usually settles tothe bottom of the container, and the paint ve-hicle will be thoroughly mixed together. Primersand paint may be mixed by boxing or with powerequipment.

10-21. Boxing.. Whenever paint is to be mixedby hand, follow the procedures listed below:

(1) Pry open the paint container.(2) Pour most of the paint vehicle into a

clean and empty container, as shown in figure39, step A.

(3) Stir the paint pigment which has settledto the bottom of the container into the remain-ing paint vehicle, as shown in figure 39, step B.

(4) While stirring, gradually pour the paintinto the paint vehicle originally poured off.

(5) Stir vigorously and pour the paint fromcan to can, as shown :n figure 39, step C.

10-22. Power equipment. Normally, powerequipment used for stirring paints is 'zither theshaker or the propeller type.

10-23. Shaker-type mixers are uscd to stir anytype of primers or paint, but preferably thosecontaining highly volatile thinners. These mixershandle from as little as I/2 pint to as much as a5-gallon can, depending upon the size of the ma-chine. A typical machine of this type is illus-trated in figure 40. These machines, which aregenerally electrically operated, blend paint ma-terials by shaking them. The electric motor mustbe explosion-proof.

'47 434

CLAMP

SHAKER

MOTOR

Figure 40. Shaker-type mixer.

10-24. The propeller-type paint mixer, shownin figure 41, is used to stir large quantities ofprimer and paint in open containers. Paint isagitated by the propellers or paddles attached toan electrically rotated shaft. The electric motorof this mixer also must be explosion-proof.

10-25. Thinning. Thinners and solvents havedefinite functions in the mixing of coating ma-terials, but for economic reasons, packaged prod-ucts generally contain the smallest percentagepossible of volatile material compared to solid.The resulting high consistency makes it neces-sary to thin package materials to varying de-grees to suit the particular material, the appli-cation method, and the surface being coated.Always add thinner to the coating material. Add-ing coating material to thinner may result in anirreversible separation of some of the coatingingredients. It shoilld be added slowly with con-tinual stirring to obtain complete mixing. Forall thinning, use only thinners recommended inthe instructions on the paint can label. The wrongthinner may destroy certain characteristics of acoating material without immediately giving vis-ual evidence in the wet state. Reduced ma-terial which has increased in viscosity due toevaporation will require corrective additions.However, some coating materials which undergochemical processes, such as polymerization, tocreate a film cannot be thinned beyond a certainpoint and remain usable, neither can they bebrought back to the correct viscosity by thinningafter the chemical action has progressed beyonda recommended point.

10-26. Thinning for the particular job must bedetermined by good judgment and actual test.Both excessive thinning and too little thinningare detrimental to the normal flow-out charac-teristics of a coating. It leads to runs and sags

Figure 41. Propeller-type mixer.

on one hand and rough coatings on the other.The amount of thinning for spray applicationalso directly influences the evaporation rate ofthe volatiles on their passage from the gun tothe work (a, major portion of the thinner can belost enroute). The cooling effect of this evapo-ration, plus the cooling due to expansion of theatomizing air, may lower the temperature of thecoating material as much as 20° Fahrenheit be-low that of the surrounding air. The temperatureof the deposited film may fall below the atmos-pheric dewpoint, and atmospheric water vaporwill condense on it. (As an example, when airtemperature is 70r allrmheit and the relativehumidity is 70 percent, the dewpoint is 63°Fahrenheit or, 7° below the ambient tempera-ture.) At this point, the adhesion qualities ofenamels may be reduced. The refrigerating ef-fect will also affect drying and the flow-out ofquick-drying materials.

35

67

10-27. Mixing Aluminum Pigment. To over-come the special difficulties which may arise indispersing aluminum paste or powder pigmentsin the desired vehicles (lacquers and varnishes),follow these steps closely:

(1) Weigh and measure the amounts recom-mended on the container.

(2) Place the weighed pigment in a cleancontainer large enough to contain the whole mixand allow room for stirring. In a separate cleancontainer, measure the volume of vehicle to gowith the pigment.

(3) Pour the vehicle over the pigment insmall quantities. (Never add the pigment to thevehicle.) It is important that the vehicle beadded in small amounts and that each quantityis thoroughly stirred before more vei-i le is ad:ed.Use 10 percent in the first aidition, the same inthe second, twice as much in the third, and thenthe remainder. Stir thoroughly to usure completewetting of the pigment.

(4) Box by pouring from one container to theother several times.

(5) Strain the material through double ortriple thickness cheesecloth to be certain no lumpsremain.

10-28. During application the aluminum fin-ishing material should be stirred occasionally, butthis stirring should be moderate and only enoughto keep the pigment in susi;ension. Too muchagitation may cause darkening and Iqss of leaf-ing power. Since prolonged storage of mixedaluminized ,cr, riaterials also may destroyleafing powe,, tt,e quantity ofmaterial requira, f-Dr `.ne )...b or Le day's work.If, for unavo,:o;fole the quantity pre-,pared is r;:-.1 QsrAi 1.1stirr.!.,, it may be safely mixedwith frel;:. .11niounts up to 10 percent.

11. Surfmn PrepalsPc.on Materials11-1. 1-!...vv ce r. a professional job of

painting? . rae2...' preparation is one keyto this 11:',:17.....ent surfaces such as a nailhole in woc:i the cracks in a plasterrequire d& treatment and materials.different matt. ials available to improve the rface before paLitings, s-th as undercoats,ers, primers, sizes, wood filler, plastic .nod,

mlking compunnd, putty, texture paint, s,!11:,,-ling compour..l, joint cement, and paintvarnish remover, are covered in this section.

11.2. Undercoats. Undercoats are coatingswhich ay applied prior to the finisb,.1g, c: final.coat. On old work, the undercoat is firstcoat applied; on new work, the undercoats arethe coats applied after the primer and fore the

t29final enamel. Undercoats are essential for theirhiding power and for providing a smooth sur-face for the finish coat.

11-3. Sealers. A sealer is a coating used tofill the pores of absorbent surfaces in prepara-tion for painting. By preventing the absorptionof oil from a paint, sealers not only reduce thenumber of coats of paint required but also 'in-sure a stronger film. Some sealers are used toprotect the finish coat from attack by chemicalsthat are present in the surface to be coated.Clear or pigmented sealers are usually applied asthe first coat to surfaces.

11-4. There are many commercial sealers;one type can be easily made of a mixture ofshellac and alcohol. Reduce the shellac with al-cohol 4 to 1 if it is to be used over a filler, and7 to 1 if it is to be used over stain. Then pourthe mixture into an equal amount of lacquer tomake the sealer.

.11-5. Primers. A primer is a film-formingmaterial used as a first coat of paint, which pro-vides adhesion for the following coats and pre-vents undesirable chemical reaction to a surface.It may be a thinned first coat of paint or aspecially prepared product. Different types ofprimers are available for different types of sur-faces. Included here are exterior wood primer,epoxy primers, phenolic resin primer-sealer, washprimer, zinc chromate, and red lead base primer.

11-6. Exterior wood primer. Wood primersare usually a thinned coat of the paint to beused orl a special'; prepared coat. Specially pre-pared Coats consisting of 35 to 40 percent whitelead, 10 to 15 percent titanium, and the balanceextenders make a very good wood primer.

11-7. Epoxy rimer. Epoxy primer is a two-component pigment primer specially made tostick well and reflect heat. It is nonchalking,nongloss, and very resistant to chemicals, lubri-cants, and corrosive atmospheres.

11-8. This primer is rrede primarily for spray-ing; however, it may be brushed on small areas.Mix it by adding equal parts by volume of thepigmented primer with the catalyst just beforeusing. Use within 10 hours after mixing.

11-9. Because it is an epoxy, this primer isdifficult to remove. There are several types efepoxy primers used on different items. For thisreason, you should follow the manufacturer'srecommendatio is when using them.

11-10. Ph:?.2lic-resin primer-sealer. A newtype of finish Nell suited for open grain :roodsis a phenolicresin primer-sealer which pene-trates into the: pores of the wood, dries, andequalizes the ,;tensity of the hard and soft reins.Staining _and painting of wood thus treated elimi-nates alternating light and dark streaks that are

7

frequently . present on untreated wood. Thissealer is light amber in color and almost as thines water. Pigments car, lee, added as well ascolors in oil to produce almost any color desired.

11-11. Wash prirre,'. The term "wash primer"designates a speeKle er.i..2erial which combinesthe properties of an :ah:bitive wash coat or metalconditioner with the properties of the conven-tional anticorrosive primer. The essential com-ponents of wash primers are phosphoric acid,chromate pigrecet. and polyvinyl butyral resin.Wash primers. eau be formulated that areequally effective over iron, steel, aluminum,treated magnetI,Ini, copper, zinc, and a widevariety of other metals. The advantages of washprimers used by the military are listed below:

Easily x;; plied and dry rapidly.Usable ever wide ranges of temperaturesand heo;idity.Can be :repplied to a variety of metals withgocei resets.Provi.ie temporavy protectina until pro-teetive mating is applied.reevenz er retard under-film corrosion.Exhieli!..iligh degree e.f adhesion to metals.1..;p:f;rade performance 7..L subsequent protec-ve coatings.

11 -1 ?. Zinc z.-2seorni.,. primer. Zinc chromateprime' is -Ned 4.. ee:,reendous quantitiei by thearmed forces. The els: inhibitive- qualities ofzinc chromate preee veri- satisfactory. It is notused in a straight linseed oil vehicle but is usedin synthetic resin rehicles of the phenolic resinor alkyd resin types. For priming structuralsteel. the addition of some raw linseed oil isadvaritageeme. Zinc chromate primer is generallytrel at. a primer for metal surfaces, such as:a.ee.tai*, steel, bridges, tanks, refrigerators; rail-roen ears, motor vehicles, aircraft, etc.

11-13. Red lead base primer. There are fourtyl...es of red lead base, ready-mixed paint, typesI, II, HI, and IV. These four types of paintcan be applied by brush, spraying (hot or cold)or dipping after thinning with mineral spirits.

11-14. Type I is.a red lead and linseed oilpaint used on bridges, similar structural steel,end other metal surfaces. You can use this type,but you must allow 36 hours before applyinganother coat. The linseed oil in this paint servesto wet the surface despite the presence of smalla:%eunts of corrosion products impractical to re-rn eve.

11-15. Type II is a red lead, linseed oil, andalkyd varnish used in place of type I when re-coating is necessary within 16 hours.

11-16. Type HI is a red lead-alkyd varnishpaint used for painting thoroughly clean iron

36

and steel surfaces and for tonchup work wheredrying in a 6-hour period is desired. This typedoes not have .the surface wetting propertieswhich characterize paints containing linseed oil,and, consequently, must be applied to excep-tionally clean surfaces. Because structural steel(bridges, tanks, etc.) is rarely cleaned free ofall corrosion products, this type is not generallyintended for such use.

11-17. Type IV is a red lead-phenolic var-nish paint used as a primer on iron and steelsubjected to severe humid conditions or freshwater immersion. In addition to its excellentwater impermeability, the paint film exhibitsgood resistance to acid and alkaline environ-ments and can be used on water storage tanks,structural work on dams, structural metal andequipment in bottling plants, laundries, etc. Ap-ply the paint only to exceptionally clean sur-faces, because this type does not contain linseedoil or other wetting agents.

11-18. Sizes. Size is used to fill the pores ofplaster or wallboard so that paint will stay onthe surface. There are several types of sizeavailable, but the main types are glue-water anda thinned varnish. Varnish size is prepared bythinning 1 gallon .of varnish with 1 quart ofturpentine. Mix glue and water until the mix-ture will spread easily. Primers and scalers havebeen improved to the extent that sizing is seldomneeded for paint preparation today.

11-19. Wood Filler. The purpose of woodflier is to provide a smooth, even finish on woodhaving open grain, such as walnut, mahogany,and oak. Paste wood fillers are usually made ofsiicx or silica ground in linseed oil and Japandrier with various pigments added for color.Fillers come in standard colors such as ma-hrgany, light oak, dark maple, walnut,b'ack, white, and natural.

11-20. Most fillers come in paste form andare too thick to use without thinning. Thin byadding turpenting, naphtha, or special thinncraccording to instructions on the container. About1/2 pint of thinner to 1 pound of filler is re-quired for coarse, open-grained woods. Closergrained woods, such as walnut, rosewood, ma-hogany, and zebra-wood, require a mixture ofabout 10 ounces of thinner to 1 pound of filler.In mixing filler, it is well to add a little thinnerat a time and then by trying it you can get thedesired consistency.

11-21. Plastic Wood. Plastic wood is a productused to fill holes in wood, especially if the finishis to be clear. Plastic wood is available com-mercially and can be purchased in various sizecans and tubes. This filler dries very rapidly andit must be kept in airtight containers.

37

6?11-22. Caulking Compound. Caulking com-

pound, which usually contains asbestos fiber, apigment for opacity, fish oil or soybean oil; anda drier, is used to seal joints around doors andwindows and between the baseboard and wall-board. It is a compound that will remain elasticfor some time. This allows it to expand andcontract with the movement of the building.There are two main types of caulking- com-pound: the gun type, which is forced into cracksand crevices in ribbonlike form, and the knifetype, which is applied with a putty knife. It canalso be used as window sash putty. It is alsoavailable in rolls or strips to be applied bypressing it into the joint.

11-23. Putty. Putty is used to fill hoies in sur-faces and to replace checked or broken puttyaround windows. Commercial putty is made ofwhite lead and whiting combined with linseedoil and a neutral oil to prevent it from dryingtoo rapidly. Sometimes plastic wood is substi-tuted for putty when filling holes in wood.

11-24. Texture Paints. Texture paints are ofheavy consistency designed to be used to pro-duce a textured effect on a surface. Since theyare thick and can be molded to obtain variousdecorative effects, they are particularly suitablefor finishing sheetroek in dry wall construction.Texture paint can be made on the job by mixingjoint cement with a paint to a butter consistency.Color can be mixed before application.

11-25. Spackling Compound. Spackling com-pound is a white powder. When mixed withwater, it sets quickly without swelling or shrink-ing. It is used to apply a texture effect tosmooth interior surfaces such as plaster, sheet-rock, wallboard, gypsum-board, and primed andunprimed wood.

11-26. Joint Cement. Joint cement is used tofill the depressions left by a hammer when nail-ing sheetrock (hammer marks). It is also usedwith perforated tape to fill the recessed edgesof sheetrock joints. Joint cement is mixed withwater until a thick paste is formed. It is nor-mally applied with a broad blade putty knife ora cement trowel.

11-27. Paint and Varnish Removers. Paint andvarnish removers are made of chemical solventswhich arc spread over the old finish to softenit so that it can be removed with a steel scraper,putty knife, or steel wool. It is available inpaste or liquid form; the liquid form is fasteracting.

11-28. We have covered some of the mostfrequently used surface preparation materials,however there are so many types on the markettoday that it would be impractical to list them

10all in this chapter. The importance of the selec-tion of the proper surface preparation materialsfor the protective coating specialist cannot beoveremphasized.

12. Selecting Exterior Protective Coatings12-1. What type of protective coating should

I use on this surface? What types of protectivecoatings are. available? The protective coatingspecialist must consider the type of surface be-fore attempting to select a protective coating fora particular job.

12-2. Type of Surface. The type of surface towhich the coating is to be applied is the firstconsideration whether you're dealing with wood,metal, or masonry.

12-3. Wood surfaces. When you paint ex-terior wood surfaces, you must decide whetherthe two-coat or three-coat system is to be used.Primer is not necessary when you repaint pre-viously painted surfaces that are in good condi-tion. Surfaces that have never hecn paintedshould be given a primer coat, body coat (un-dercoat), and a final (finish) coat.

12-4. Exterior white oil paint (house paint)is most often chosen for the main exterior sur-faces of buildings. When the three-coat systemis used in painting exterior wooden surfaces withready-mixed paint, a self-primer can be made byadding approximately 1 pint each of drying oiland turpentine to 1 gallon of final coat exteriorwhite oil paint. When the two-coat system isused, the addition of 1 pint of drying oil to thepaint is sufficient.

12-5. When the three-coat system is employed,applicable ready-mixed primers may be usedwithout basically changing the paint.

12-6. Metal surfaces. Galvanized iron, tin, orsteel building materials are available in varioustypes, all of which may rust if not protectedagainst moisture. Copper building materials, al-though they will not rust, will give off a cor-rosive wash which will discolor the metal.Aluminum, like copper, will not rust, but willcorrode if not protected. Conventional housepaints or exterior enamels can be applied tothese surfaces, if the proper prime coating is firstapplied. Aluminum paint can be used for paint-ing metal surfaces.

12-7. Masonry surfaces. Masonry surfacesbrick, cement. stucco, cinder block, or asbestos-cementcan be coated with a variety of paintproducts. One of the nc%,est ideas in paintingbrick is a clear coating which withstands weatherand yet allows the natural appearance of thesurface to show through. Cement-base paintsand rubber-base coatings, vinyl and alkyd emul-

753 38

sion paints are also used on many types ofmasonry. Almost all exterior house paints may beapplied to masonry; however, the surface mustbe prepared properly.

12-8. Good results in painting concreteporches and steps can be obtained with a rubber-base coating, or similar product. Roughening thesurface slightly with muriatie acid is recom-mended before painting concrete that is hard andglossy. Surfaces may also be- primed with analkali-resistant primer.

12-9. Kinds of Exterior Coatings. Listed belowarc several of the more commonly used coatingsfor exterior surfaces. Note that some can beused on both exterior and interior surfaces. Noattempt has been made to list all of the paintsavailable to the protective coating specialist.New paints are being developed each year, andit is a wise protective coating specialist whoreads the latest literature and technical publica-tions to keep abreast of these new developments.

12-10. Exterior white oil paint. Exterior whiteoil paint is a glossy paint compounded for use assecond, or body, and final coats on outside wood,metal, and masonry surfaces. If you are to besuccessful with this paint, the primer must besuitable for the particular matercal. A self-prim-ing paint for wood and masonry can be madefrom the paint by adding I pint of linseed oil to 1gallon of the paint.

12-11. One type of this paint is composed ofseveral white pigments (multiple pigment), whichchalk more or less, depending upon the pigmentsand the amount of each that is included. Theother type is a single-pigment paint that chalksvery little. Chalking is a desirable characteristicof paints where the 'surface will decompose intoa fine powder and wash away; thereby, restoringa clean surface.

12-12. One class of multiple-pigment paint(titanium-lead-zinc) is a white paint, for generaluse, compounded so that it will chalk consid-erably. Another class of multiple-pigment (ti-tanium-zinc) is a lead-free white paint designedfor use where sulfide fumes exist. This paint isnot compounded for tinting purposes.

12-13. Still another combination of white pig-ments (titanium-lead-zinc) similar to the firstclass of this paint, compounded for tinting pur-poses, forms a third class of multiple-pigmentexterior gloss white oil paint. The singlc-pigmenttype of this paint is a white lead glossy oil paintthat comes in white or colors.

12-14. When the surfaces of wood, metal, ormasonry are to receive three coats. of this paint,the mixtures used for body and final coats maybe thinned by adding 1 pint of turpentine ormineral spirits to 1 gallon of paint.

12-15. Exterior Masonry white oil paint. Ex-terior masonry paint is intended for exteriorbody or final coats on primed masonry surfaces,except floors. The paint, white or tints, dries toa flat finish; therefore, when a glossy finish isdesired, exterior glossy paints must be used. Be-cause any paint adheres poorly to glazed sur-faces, such surfaces must be roughened by acidwashing, sandblasting, or rubbing the glaze offwith abrasive stones. Old coatings of organic orcement-water paints that are firm need not beremoved. However, any of the oil paint that isloose or flaking must be removed to insure ad-hesion of the new paint.

12-16. A good self-primer for exterior ma-sonry paint can be compounded by mixing 1/2gallon of nonreactive spar varnish and IA gallonof turpentine or mineral spirits with 1 gallon ofexterior masonry paint. Since moisture is detri-mental to exterior masonry paint, the surfacesmust be thoroughly thy before the primer, body,and final coats are applied.

12-17. Zinc oxide oil or resin paint. A zincdust and zinc oxide paint is manufactured foruse as a primer for zinc surfaces.. The paintmay also be used satisfactorily for body andfinal coats. There are several types of this zincprimer. One type is an air-drying paint havinga linseed oil vehicle. Another type, an enamel,has glyceryl phthalate vehicle, which causes itto dry faster. This enamel can be baked dry ifit is so desired. Still another type, also an enamelcontaining phenolic resin, is especially recom-mended for priming the inside surfaces of steelwater tanks.

12-18. Prior to using zinc primer on newsurfaces, the surfaces must be cleaned with tur-pentine, mineral spirits, or with some approvedcleann to insure good adherence of the primercoat.

12-19. Exterior chrome green oil paint. Chromegreen oil paint is an exterior paint of averagequality to be used on wood, metal, and masonryover a gray tinted body coat. Another type ofthis paint contains a vehicle of spar varnish;consequently, it is a glossy enamel of greaterdurability. It is known as trim enamel, and ithas good hiding power and color retention,

12-20. Exterior olive drab oil paint. Ex-terior olive drab paint is suitable on wood, metal,and masonry exposed to the elements. It is

semigloss paint that has good color retention,and it is used for body and final coats.

12-21. International orange oil paint. Inter-national orange paint is of three different typesand two colors, namely, chrome orange (color ofa ripe tomato) and orange red. The most dur-

able type of international orange paint ; :omeorange pigmented linseed oil paint. It i ow-drying paint used for body and final cthe exterior surfaces of large buildings.amount of spar varnish is included in I

to retain color; however, the color stiitendengy to fade from exposure.

12-22. Another type, an international o. tge

enamel, is similar in color to the .paint above,but it is not as durable; however, it holds itscolor much better and dries faster. The vehiclein the enamel is glyceryl phthalate syntheticenamel, is a vivid orange red, and is very dur-able. The color is fast, and the enamel appearsbest when applied over body coats of the samecolor. The enamel dries sufficiently overnight toallow sanding and the application of anothercoat. It is recommended for body and finalcoats on small metal surfaces.

12-23. Exterior chrome yellow oil paint. Ex-terior medium chrome yellow pia is durablebright yellow paint manufactured for applicationas a final coat on wood, metal, and masonry.It is used primarily for painting towers and traf-fic signs. Significant names applied to tints ofthis paint are: Highway Marking Yellow, Army-Navy Aircraft Yellow, and War DepartmentYellow.

12-24. Exterior rust-inhibiting solvent-resist-ant drum enamel. Exterior rust-inhibiting, sol-vent-resistant enamel for coating metal drums isan olive drab semigloss enamel. It is a one-coat system enamel that contains glyceryl phthal-ate resin, and it dries fast.

12-25. Aluminum paint mixing varnish. Mix-ing varnish is contained in aluminum paint usedfor priming exterior wood and for general pur-poses. It is also used for final coats on metal.There are two types of mixing varnish. One typeis Lung -oil varnish, which is used as the vehiclein aluminum paint for general use. If necessary,for spraying, 1 gallon of aluminum paint con-taining mixing varnish may be thinned with 1

pint of turpentine. Mixing varnish of high vis-cosity should be mixed with aluminum paste,and that of low viscosity should be mixed withaluminum powder to bring the paint to theproper consistency.

12-26. Asphalt varnish. Asphalt varnish is ageneral-purpose varnish suitable for covering wa-ter pipes, gas pipes, and the like. It is composedof asphalt mixed with drying oils, solvents, anddriers. When dry, asphalt varnish has a smoothglossy finish similar to glossy black enamel.

12-27. Water-resisting spar varnish. Water-resisting spar varnish is a durable covering suit-able for either interior or exterior use. Dried

39

varnish of this type has a softer film and less lusterthan some of the other oil type varnishes.

12-28. Clear and pigminted spraying lacquer.Clear and pigmented spraying lacquers are usedover suitably primed metal and wood interioror exterior surfaces. Repaint jobs should have asealer or bleeder coat applied before sprayinglacquer is sprayed overt, a color. Ordinarily,spraying lacquer need not be thinned. There aretwo types of lacquer. One type is clear, and theother is pigmented. A typical clear sprayinglacquer consists of a nonvolatile vehicle (15 per-cent by weight or 10.4 percent by volume). Apigmented lacquer has about 61/4 pounds of suit-able pigment added to a clear lacquer.

12-29. Exterior cold-water white paint pow-der and liquid. Exterior cold-water paint pow-der makes an ine7pensive paint that dries to aporous film. It is a breathing type of paint usedon masonry surfaces where permeability anddurability are as important as beautification. Itmay be obtained in white or in colors. Linseedoil and spar varnish are often mixed with thewater to form the vehicle for exterior cold-waterpaint and to make the paint more durable. How-ever, special water-dispersible oils are on themarket which effect better dispersal of the oilthroughout the water than does boiled linseedoil. The paints resulting from either vehicle areequal in quality.

12-30. Cold-water paint is applied to cleanmasonry surfaces such as concrete, brick, wetwalls, etc.. uniformly dampened (not wet) beforethe paint is applied. The paint may also beused on clean primed wooden or metal surfaces.

12-31. Exterior black oil paint. Exterior blackis a glossy slow-drying paint for final coats onsurfaces of exterior wood, masonry, and struc-tural steel. It is a durable paint with excellenthiding qualities when used on structural steelthat has been primed and body-coated with twocoats of rust-resistant paint.

12-32. Exterior graphite oil paint. Exteriorblack graphite paint is used as body and finalcoats to cover the primed surfaces of ferrousmetals. The graphite in the paint has the prop-erty of leafing which accounts for its durability.There are two types of graphite paint. One typeis a steel gray paint having a metallic luster.Lamp-black or carbon black is mixed with nat-ural flake graphite, as well as with other typesof natural and artificial graphites, and is darkerin color.

12-33. The lighter colored graphite paint isintended for body coats, and the darker coloredpaint ;s designed for final coats.

12-34. Red lead oil paint. Red lead linseedoil paint is a tung-f 11 gloss paint that is made

40

for priming ferrous metals. This paint keepswell in storage, and is superior to the red leadpaint ordinarily mixed on the job. Two coats, onepriming coat and one body coat of this paintare preferable for rust resisting purposes.

12-35. Blue lead oil paint. Blue lead linseedoil paint is another good priming and body paintfor ferrous metals. It is dark gray in color; also, ithas good working qualities, and it is durable. Asin the case of red lead paint, the metallic surfacesshould be given two coats of blue lead paint forrust-resisting purposes.

12-36. Exterior iron oxide red or brown oilpaint. Exterior iron oxide paint is manufacturedin different colors of red and brown. It is aneconomical paint and is durable. Spar varnishand zinc oxide in the paint increase color re-tention of the paint and decrease the tendencyof the paint to mildew. Iron oxide paint is in-tended for use on roofs, barns, freight cars, andthe like. It is used for body and final coats onmetal as well as on wood and masonry. Al-though not as satisfactory as a rust-resisting agentfor ferrous metals, it can be used as a primeron structural steel.

12-37. Aluminum. Probably no other paint isused for as many paint jobs as aluminum paint.Aluminum paint is a desirable coating for battle-ships and large bridges, since the dried filmweighs less than half as much as the film ofany other common paint. One of its importantapplications has been in the covering and pro-tection of steel structures and buildings, not onlybecause it is durable but also because it is lightin color, reflects light and heat more than anyother paint, and has a desirable decorative fin-ish. It is commonly used as a second and finishapplication over a red lead pthning coat.

12-38. When aluminum paint is applied in twoor three coats without priming paint to cleanand rust-free surfaces, it gives excellent service.When you paint steel, the importance of cleansurfaces cannot be overemphasized. Aluminumpaint is also used successfully for painting gal-vanized iron. Without a primer the paint willbond satisfactorily with the galvanizing, providedthat the metal has been exposed to the weatherfor at least 6 months. Aluminum paint possessesexcellent durability when used as a priming coatfor wood construction. It will cover soft, pitchyand resinous spots very effectively. It is alsoefficient in the prevention of bleeding of woodstains. Finish coats of light-colored paints maybe applied when the correct aluminum paint isused first as an undercoat.

12-39. Cement-base paint. This paint comesin powder form and is used on porous interiorand exterior masonry surfaces, except gypsum

plaster. There are two types of powder. Onetype has more hydrated lime and less portlandcement than the other. The second type has 80percent portland cement and 10 percent hy-drated lime, The latter type is used for paintinginside surfaces of swimming pools, water tanks,

etc. Both types contain small percentages of ti-tanium dioxide, zinc sulfate, water repellants.and calcium or aluminum stearate.

12-40. Plastic paint. Another type of protec-tive coating that has been introduced on themarket in the past few years is plastic. "Plastic"as applied to paints is an abused term. The.factthat this word or some variation of it appears ina trade name does not necessarily mean that theproduct has extraordinary properties. Any of thesynthetic resin paints might be called plasticpaint because the phenolic, vinyl, and other syn-thetic resins commonly used in paints are varie-ties of plastic, compounded with special gradesof solution type resins.

12-41. True plastic coatings are now avail-able, and we will discuss some of the commonones briefly. These are tough, flexible coatingsthat are highly resistant to the natural elementsand to many chemicals. They appear to be es-pecially suitable on surfaces when most othercoatings have been ineffective. With increaseduse and improved application methods, costs ofplastic coatings are expected to decrease.

12-42. Vinyl resin plastics are being used to aconsiderable extent as protective coatings. Theseinclude plastisols, organosols, and dry, generallypowdered, vinyl resins. Plastisols are vinyl resinsdissolved in liquid plasticizers which remain assuch until heat treated. Organosols are similarto plastisols except that small amounts of volatilesolvents are added to improve application prop-erties. Both are high-solids-content materials, the

plastisols being essentially 100 percent solids.Fusions of the resins and plasticizers to formplastic film is brought about by raising the tem-perature of the film between 300° and 360° F.These plastics are used in the manufacture of

dishwasher racks, dish drainers, plating tanksand racks, piping and vinyl-on-metal laminatesfor luggage, instrument cabinets, and furnitureto name a few.

12-43. Other plastics, including the cellulosics,acrylonitriles, acrylics, etc., are being used asprotective coatings. These are generally appliedby heat prc sses when the dry resin is fuzedonto the surtace to be protected. They are ap-plied as temporary coatings to gears, shafts,

screws, and other machined parts during shipmentand storage.

12-44. Plastic tapes are also being used forprotection on steel pipe. Both self-adhering and

41

81

'73those requiring a primer are available. Poly-ethylene and polyvinyl chloride tapes are themost common ones and are available in 10-,12-, and 20-mil thickness (20 mils is 20 thou-sandths of an inch). Wire brushing is generallyrequired to clean the surface, ind a primer maybe needed before the tape is applied.

12-45. Floor and deck enamel. Paint with avarnish vehicle is in reality an enamel; it is in-tended for body and final coats on primedwooden and concrete surfaces. It is an excellentfast-drying, tough covering that is flexible enoughto withstand wear and weather.

12-46. A self primer for wooden floors is

'lade by adding 1 quart of thinning liquid (one.art turpentine or mineral spirits and two parts

boiled linseed oil) to 1 gallon of floor and deckenamel. Body coats for wooden floors shouldhave 1 pint of boiled linseed oil added to eachgallon of enamel. The final coat. should be ap-plied as furnished in the container.

12-47. A self-primer for concrete floors is

made by adding 1 quart of thinning liquid (onepart turpentine or mineral spirits to two parts ofspar varnish) to each gallon of enamel. Bodyand final coats of the enamel are applied to con-crete floors as furnished.

1248. Bituminous coatings. Coal tar and as-phalt coatings are used extensively as water-proofing, roofing, and for protection of sub-merged and buried metal pipes and devices.They can be applied at reasonable cost andmake a substantial barrier against attack bymoisture and oxygen.

12-49. Asphalt coatings are available as enam-els, cold applied paints and emulsions. They areconsidered more resistant to the elements thancoal tar.

12-50. Waterproofing. Masonry is porous andsoaks up water, causing damp interior walls,cracked plaster, peeling wallpaper and paints.Silicone water repellent will usually prevent thisproblem. A single application (spray or brush)will provide an invisible water repellent surfacethat will preserve the fin'sh for 5 to 10 years.Oil-base and cement-base paints can be appliedover the application. Oil-base paints will destroythe breathing characteristics of the masonry.

12-51. Swit.uning pool. Rubber-base paintsare popular for Tainting swimming pools or otherwater holding structures; however, water-mix ce-ment base and enamel paints with water-resist-ing varnish vehicle of synthetic resin are pop-ular. Recent developments have led to the useof epoxies, polyesters, and urethanes which havebetter resistance to water, chemicals, and abra-

sion than conventional coatir.gs but they .8.e moreexpensive.

12-52. Fungicidal. Fungicidal paints are use-ful in preserving wood and fabrics by preventingrot. These paints are popular for foundationtimbers, sills, fence posts, farm buildings, etc.

12-53. Fire retardant. These paints when ex-posed to flame retard the spread of fire bychemical action of the contents which tends tosmother the fire.

12-54. Camouflage. Camouflage paints havea dull finish, do not fade, are easily appliel, areof low cost, and cover in one coat. Camouflagepaints are available in nine colors: light green,dark green, sand, field drab, earth brown, earthyellow, loam, earth red, and olive drab.

12-55. Traffic paints. Ready-mixed trafficpaint is known as centerline, zone marking, androad marking paint. It is obtainable in white and

yellow colors. Both paints are intended for ap-plication at a wide range of temperatures tobituminous and concrete highways bearing heavytraffic. Another type of traffic paint is one inwhich glass spheres are added when the paintis applied to the road surface. This semipasteform of paint, available in various colors, is calleda pigmented binder. The glass beads serve as areflector at night as automobile lights strike them.

12-56. White wash. Whitewash is lime pastemixed with water. The paint is inexpensive andis used for covering interior or exterior woodenor masonry surfaces. It is used primarily onbrick, concrete, road or roadside obstructions,sheds. telephone poles, and the like.

12-57. Lime paste is made by slaking quick-lime in enough water to make a stiff paste andallowing it to cure for several months. The mix-ing ratios for two good lime pastes arc: 20

CLAPBOARD SIDING . V.

BRICK J. IVCEMENT & CINDER BLOCK .4

ASBESTOS CEMENT V. VSTUCCO

NATURAL WOOD SIDING & TRIM VMETAL SIDING . V. V.

WOOD FRAME WINDOWS V. V. V,

STEEL WINDOWS V. V. V V.

ALUMINUM WINDOWS 1I. V.

SHUTTERS & OTHER TRIM V. . V.

CANVAS AWNINGS

WOOD SHINGLE ROOF

METAL ROOF V. V ,./.

COAL TAR FELT ROOF VWOOD PORCH FLOOR

CEMENT PORCH FLOOR

COPPER SuRFACES

GALVAN17.ED SURFACES V. V. V. V V.

IRON SURFACES 1 V V. V. V,

FiBlack dc: indicates that aprimer, or sealer may benecessary before the finishingcoat (unleuer surface has beenpreviously finished.)

7 4 'P0 09A CI)A1S.

Slo ve,.o.' P .4,

V \r,:o sq t. cs

.TEL,, 4) ts 15 . 7 714.. Ip ° s, 4,. .:14.0

0 AO fo5

A

yr

a.

Figure 42. What paint to use (exterior).

82 42

L

pounds of quicklime to 10 gallons of water; and50 pounds of hydrated lime to 6 gallons of wa-ter.

12-58. Two formulas for compounding white-

wash are as follows:

Materials Formula No. 1 Formula No. 2

CaseinTrisodium phosphateLime PasteWaterCommon saltPowdered alumMolasses

5 lbs3 lbs8 gal6 gal

8 gal4 gal

12 lbs6 oz1 qt

12-59. Figure 42 is a guide showing the typeof coating recommended for various exterior sur-faces. This chart is designed for general appli-cations, and many times variations must bemade.

12-60. The color that is selected for the ex-terior surfaces should blend with the other struc-tures that are in the area. Often, color selection

at an installation is made by personnel otherthan protective coating specialists.

13. Selecting Interior Protective Coatings13-1. There are many types of interior coat-

ings available to the protective coater today.These coatings, in addition to being decorative,are designed to use on certain types of surfaces.

13-2. Type of Surface. When you select aninterior protective coating, you must first considerwhether the f,Jrfa,..: is wood, metal, or masonry.

13-3. Wood surfaces. The two-coat and three-coat systems are also employed when you applyoil paint to interior wooden surfaces. Under thethree-coat system, approximately 5 gallons of dry-ing oil are added to 100 pounds of white leadpaste to compound a priming paint on the job.When the two-coat system is used, about 4 gal-lons of drying oil are mixed with 100 poundsof white lead paste to compound a priming paint

on the job.13-4. Self-priming paints for interior woodwork

may be formulated from the ready-mixed paintsused as final coats by diluting one gallon of the

paint 25 to 50 percent with drying oil. Slightlymore of the drying oil should be added to thepaint when the three-coat system is used. Ap-plicable ready-mixing priming oil paints for in-terior wooden surfaces are obtainable which maybe used without basically changing the paint.

13-5. Interior woodwork that is to have anatural finish should be primed and sealed witha ready-mixed varnish or spraying lacquer thathas been diluted with the recommended thinner.The varnish or lacquer is applied after the drying

43Q

oil and filler have been put on and are dryenough to receive the primer-sealer. When in-terior woodwork is stained, shellac varnish is usedas a primer, and sealer to avoid the bleeding ofanaline stains. Varnish and lacquer may be usedas a primer and sealer on other types of stains.

13-6. Metal surfaces. When you paint in-terior metal surfaces, you should use a primerand at least one body coat and one final coat.If more coats are applied, the additional coatsare called body coats.

13-7. Masonry surfaces. Interior masonry sur-faces may be body-coated and final-coated withoil paints or water paints which are used onwood or metal surfaces. Besides color, final coatsare selected as to the type of finish desired.Both oil and water vehicle paints that will givea flat finish or an eggsl.11 finish are available.When a gloss or semigloss is desired, the painterusually resorts to oil paints and enamels.

13-3. Kinds of Coatings. Listed below are sev-eral of the more commonly used coatings for in-terior surfaces. Note that some can be used onexterior surfaces as well as interior surfaces.

13-9. As with exterior paints, no attempt hasbeen mule to list everything that is available onthe mar .et. New paints are being developed allthe time, and you should make it your businessto read about the new products through currentpublications that deal with protective coatings.

13-10. Interior cold-water white paint. In-terior cold-water paint powder comes in whiteor tints. The paint is intended primarily forcovering primed wet walls and other masonrysurfaces. It is not satisfactory for surfaces whichare continually damp, because of its suscepti-bility to mildew. Surfaces that are to be re-painted must be free of calcimine and must haveloose or powdering oil paint coatings removed.

13-11. Primer-sealer floor lacquer. Lacquersealer and primer for floors is ;mended for seal-ing clean wooden floors that have been sanded.Sealing a newly sanded close-grained or open-grained filled floor helps to fill the wood poresand provides a good foundation (priming coat).The sealer and primer reduce the tendency ofthe finished surface to mar, integrate the fillerand wood, and smooth the surface.

13-12. Fume- and heat-resisting white enamel.Fume- and heat-resisting white enamel is in-tended for use in chemical laboratories, dairies,refrigerator rooms, sewage disposal plants, andareas subjected to temperature or fumes. Toavoid discoloration, the paint must be free fromlead and iron. This enamel consists mostly ofsuch ingredients as lightproof lithopone, titanium,zinc oxide, or a mixture of these pigments. The

velneic must exclude any netallie compounddriers, but should include linseec tung, soya, orother drying oils, along v,/,'h damar, resin, andturpentine or mineral spirits. A softener such aspine oil is used to plasticize the paint.

13-13. Fume- and heat-resisting white enamelwill stand some tinting, particularly light graywithout discoloring under adverse conditions.The enamel is not as flexible as other whiteenamels and is less water-resisting than some ofthe quick-drying enamels.

13-14. Interior flat white oil paint. Interiorwhite or tinted flat to eggshell (slight gloss)finish oil paint forms a washable body, whichcan be used for final coats on primed interiorwoodwork and masonry. The paint works easily,dries opaque, and has good resistance to scrub-bing with soap and water after it has dried for1 month.

13-15. Interior gloss white enamel. Interiorwhite and tinted gloss enamel can be used oninterior wood, metal, and masonry that has beenprimed and body-coated. Such pigments as ti-tanium dioxide, zinc 'ulfide, and zinc oxide areused in these enamels to obtain the strong opaquewhite color.

13-16. Interior one-coat flat white oil paint.Interior one-coat flat white or tinted oil paint maybe applied to the absorptive, porous surfaces ofwet and dry walls and woods. This paint con-tains titanium dioxide or zinc sulfide suspendedin a vehicle containing tung oil varnish. Thepaint comes in a heavy-bodied consistency that.is thinned at the ratio of three pints of turpen-tine or mineral spirits to 1 gallon of paint. It isdesigned to give uniform coverage without anyspecial primer; however, patched places in plas-ter or spots that show more porosity should bespot-painted once and allowed to dry before thepaint is applied over the entire area.

13-17. Interior resin-emulsion white paintbase. Interior resin-emulsion paint base comesin white or tints. It is intended for making paintsto be used on interior wet or dry walls, masonry,and fabric. The paint may be used on suitablyprimed wooden and metal surfaces. The objectto be body- and final-coated with resin-emulsionpaint must ce clean; and in case of a repaintjob, the old paint must be firm or be removedfrom the surface.

13-18. The paint is an oil-in-water emulsionproduct. It is thinned only with water and canbe applied by any convenient painting method.The paint dries sufficiently hard overnight to berecoated. Directions for mixing with water areoften placed on the container and should be fol-lowed. However, in case there are no instruc-

44

tions, the number by parts (by volume) to beadded to 1 gallon of water are: for plaster, 2;for very porous surfaces, 11/2; and for spray-ing, 2'h.

13-19. Interior concreie floor rubber-basepoint. A rubber-base paint is made for use onconcrete floors subjected to dampness and notexposed to sunlight. The paint should have 1pint of mineral spirits and 1 pint of toluol mixedwith i gallon of paint when used as r pr imingcoat. Body and final coats are applied as fur-nished in the container.

13-20. Interior cold-water white. Interior cold-water paint comes in white or tints. The paint isintended primarily for cov.-iing primed wet wr"and other masonry surfaces. It is not satisfactoryfor surfaces which are continually damp becauseof its susceptibility to mildew. Surfaces that areto be repainted must be free of calcimine andmust have loose or powdering oil paint coatingsremoved.

13-21. Heat-resisting black enamel. Heat-re-sisting black enamel is manufactured for use onsteam pipes and boiler fronts where temperaturesof 400° Fahrenheit or higher are common. Theobjects to he painted should be cooled below140° Fahrenheit before paint is applied and theyshould be held at this tempercture for at least48 hours before being subjected to a higher tem-perature. There is danger in using this enamelindoors unless the area is well ventilated andaway from lights or flames.

13-22. There are two types of heat-resistingblack enamel for metal. One type has a bitum-inous base that is otherwise unpigmented. Theother type has a resin base and is pigmented.The pigmented type, besides being heat-resist-ant, is gasoline- and water-resisting.

13-23. Luminous. Luminous paints are usedto provide decoration which will glow with abrilliance. Luminous paint in dangerous areasthroughout a building will act as safety guides,showing the danger areas even after lights areout. It is similar to the dial and hands of a lu-minous watch.

13-24. Waxes. Wax is available in paste,emulsion, and liquid and forms an important partof the finishing process, especially on furnitureand flours. The wax is normally applied overvarnish or shellac to give protection to the coatedsurface. rt is often applied directly over sealerto provide a waterproof coating.

13-25. Linseed oil. Linseed oil, previouslyexplained i i this chapter, may also be used asa finish for wood su,-fIces. It is ordinarily ap-plied by rubbing.

13-26. Spirit varnish. Shellac-replacement spiritvarnish is a substitute for shellac varnish and

may be used on interior wood, metal, paper, andfabric surfaces. It may be substituted for oilvarnishes where rapid drying is more important

than durability. Shellac replacement varnish isalmost equivalent to shellac v,..nish. It can bebrushed or sprayed, but it cannot be satisfac-torily mixed with oil paints, oil varnishes, lac-quers. turpentine, and mineral spirits.

13-27. Shellac varnish. Shellac varnish is pri-marily a sealer and primer for interior woodenand masonry surfaces. Although it is not as dur-able in some ways as the oil varnishes, somepainters use it for body and final coats. It is

used occasionally on exterior wood surfaces thatare not directly exposed to the weather.

13-28. Shellac varnish is either white(bleached) or orange and is available in light,medium, and heavy bodied consistencies. Both

white and orange shellac varnish comes in twogrades. One grade is lighter in color than theother and is practically free of rosin and sus-

pended matter. The other grade is darker incolor and contains some inso:uble matter; there-fore, this varnish shellac is used where darkercolor and some rosin are not objectionable.

13-29. One thinner for varnish shellac con-sists of a mixture of five parts of methyl alcoholto 100 parts of ethyl alcohol. Another thinnerconsists of one part of aviation gasoline and fiveparts of denatured ethyl acetate to 100 parts ofdenatured alcohol.

13-30. Orange shellac. Orange shellac is used

in making shellac varnish. Several grades oforange shellac are processed and placed on theopen market. The highest grades are known assuperfine and by other names. The second high-

est grade is called fine or by other names. Thethird highest grade is called pure T.N. This

grade is rosin-free and darker than the highergrades. The lowest commercial grade is U.S.S.-

ATN and contains some rosin. This grade may

PLASTER WALLS & CEILING ,/, %.t

WALL BOARD V: V:V

WOOD PANELING V. V: V V;

KITCHEN & BATHROOM WALLS 1.

WOOD FLOORSVVV.4V .

CONCRETE FLOORSV. X

VINYL &' RUBBER TILE FLOORS

ASPHALT TILE FLOORS

LINOLEUM

STAIR TREADSV° V

STAIR RISERS

WOOD TRIM tl: vSTEEL WINDOWS V: V.

ALUMINUM WINDOWS

WINDOW SILLS

STEEL CABINETS$./.

HEATING DUCTS V.

RADIATOR"; tc HEATING PIPES V.,

OLD MASONRY

NEW MASONRY V... _ .1 N

Black dot indicates that aprimer or sealer may benecessary before the finishingcoat (unless surface ha., beenpreviously finished.)

Figure 43. What paint to use (interior).

45

'78be darker in color than the two highest grades,but lighter than the grade just above it.

13-31. Interier dainty varnish. Damar varnishis a spirit varnish made for use as a final coaton interior surfaces. It is also used by manu-facturers as a vehicle for some white and tintedenamels used for covering interior metal sur-faces, such as radiators, exposed to high tem-peratures. It is not satisfactory for surfaces thatare exposed to moisture and abrasion.

13-32. Printer-sealer floor varnish. Varnishsealer and primer, used for treating woodenfloors and cork floors and coverings, furnishesa good foundation for other coats of varnish andfor wax. The varnish aids in filling the pores ofclose-grained wood and filled open-grained wood.There are two classes of this varnish scaler. Oneeli,s:. is made for use on the close-grained woods,awl the other is used on open-grained filledwoods. Varnish sealer and primer is actually athinned out spar varnish, because a good sparvarnish may be used as a sealer and primerwhen it is thinned with turpentine or mineralspirits equal to one-half its volume. This mixtureis similar to the class of varnish scaler andprimer made for open-grained wood. When cutwith equal amounts of thinner, the spar varnishis about the same consistency as the varnishsealer and primer made for close-grained wood.

13-33. Interior varnish. Interior varnish is

manufactured for use on inside woodwork andfloors, except where the varnish is required tohave, rubbing qualities.

13-34. Interior cabinet-rubbing varnish. Cabi-net-rubbing varnish is intended for interiorwooden surfaces where a rubbed finish is de-sired. It is not a baking varnish for metal, noris it a suitable varnish for floors.

13-35. Figure .43 is a guide showing the typeof coating recommended for various interior sur-faces. This chart is designed for general appli-cation, and many times variations must be made.It is always wise for the protective coating spe-cialist to read the label on the container to makecertain the coating is compatible with the surfaceand primer being used.

14. Handling, Storing, and Disposing ofProtective Coatings

14-1. The protective coating specialist mustknow how to store, handle, and dispose of pro-tective coatings efficiently and safety. Properknowledge of these duties will prevent overagestocks, opening of wrong containers, and incom-patible paint jobs. Furthermore, you can preventaccidents and injuries by learning safe disposalmethods.

14-2. Handling Protective Coatings. Whenhandling pailt containers, be careful not to dam-age the labels. Paint labels have valuable in-formation on them, such as the date the paintwas manufactured, its color, type, etc. Withoutthis information, large amounts of paint could bewasted or misused. If the labels are damaged,replace them with the correct information.

14-3. Storing Protective Coating Materials.These items should be stored, whenever possible,in dry, fire-resistant, well-drained, and well-ventilated structures, preferably separated fromother buildings, and under automatic sprinklerprotection. You should not use space heatersand other direct fired heaters to heat storageareas. Floors should be concrete and drained toone point. The drain should run to a sump ordetached cistern and have a deep trap. Thestorage structure should be ventilated withscreened inlet air vents 6 inches above the floorand screened outlet vents through the roof. Thiswill allow paint fumes to escape. You shouldprovide protection for paint containers againstwetting by rain, snow, steam leaks, or othersources of water.

14-4. To avoid direct heat on the materials,they should not be stored near steam lines orother sources of heat. It is recommended thatsteam heat be used with heating coils above thestock, with the coils screened to prevent themfrom contacting the containers. You should notstore paint on floors below grade (ground level).In any case, you should lay the first tier ofcontainers at least 2 inches above the floor levelto allow suitable ventilation and drainage.

14-5. Paints and paint thinner packaged in 55-gallon steel drums may be stored outdoors pro-vided the containers are protected against rust-ing. This is done by painting the bare metalareas and setting the drums on dunnage (scraplumber) so as to provide approximately 2 inchesclearance above the ground. Drums stored outof doors should be laid on their sides to preventthe loss of the markings stenciled on the headscaused by weather-action of rain, snow, and sun.

14-6. Paints and paint thinners must be storedseparately from other materials such as grease,oil, and spare parts. Rags, wood, and other simi-lar combustible material must not be stored inthe same building with paint.

14-7. Containers of paint materials should bereadily accessible at all times. Other materialsmust not be stacked on top of paint materials.Containers should be stored and issued in orderof the dates of manufacture shown in the re-spective labels. Material bearing the oldest dtheis used first. If date of manufacture is not shownon the container, the date of receipt may be

considered as the approximate date of manu-facture for purposes of storage and issue.

14-8. For best results the temperature of paintmaterials should be between 65° and 85° F.(room temperature range) at the time of use.If storage conditions result in paint tempera-tures being below 55° F. or above 95° F., thecontainer should be stored at room temperaturefor approximately 24 hours prior to use.

14-9. Containers of paint may develop inter-nal pressure from high temperatures. This con-dition is apparent as c. bulging of the light gage"tin" containers but is not evident in the heaviergage steel drums. Therefore, containers must beopened with care to allow the pressure to dissi-pate slowly before the seal is completely removed.Failure to observe this precaution may result inyour being spattered by paint exploding be-cause of a sudden release of pressure.

14-10. Containers sealed with bungs areopened by turning out the bung slowly until ahissing sound is heard. When the hissing ceases,indicating equalization of pressure with the

O.1ui 47

atmosphere, the bung can be completely re-moved.

14-11. Containers that are bulged or mis-shapen from internal pressure should have asmall hole punctured in the top to release thepressure. Use a fine, nonspark producing tool,such as aluminum or copper. Signs should beposted on the storage building to read

-FLAMMABLEKEEP FIRE AWAY."

:4-!2. Disposing of Protective Coating Ma-terials. When paints and chemicals become old,dried out, or contaminated with foreign matter,they must be disposed of. They are not discardedlike other waste material. They should be takento the sanitary fill, opened, and then tossed intothe fill. When acids become contaminated orhave served their purpose, you should bury themabout 2 feet deep in a designated disposal area.Rememl: r, chemicals are dangerous; therefore,follow ail directions and procedures when youuse or dispose of then.

So

Protective Coating Equipmeni:

PROTECTIVE COATING equipment hasbeen developed and improved until today the

technician must know how to use, maintain,and store i variety of equipment ranging frompaint brushes to traffic marking machines.

2. If the protective coater knows how to selectand maintain the large variety of equipment andtools that arc available today, he can do ills jobmore efficiently and save many man-hours.

15. Surface Preparation Equipment15-1. Before you apply any protective coating

it is most important to prepare the surface. Youhave hcard the old adagea chain is only asstrong as its weakest linka protective coat isonly as good as the surface it is applied to. Ifthe surface is scaly, dirty, oily, or dusty, the coat-ing will not adhere satisfactorily.

15-2. Mann .11y Operated Tools. There are agreat many hand-operated tools for the protec-tive coater to use. We will discuss only thosethat you are most likely to use in your work.

15-3. Wire brushes. Wire brushes suet- asthose shown in figure .44 are used to removeloose paint froni wood, masonry or metal sirfaces in close places and where power equipment cannot be operated economically. They aremade of different sizes and shapes. snr.ie havirga large gage we bristle, some !, , dependingon the stiffness required. So: ?.f the bristlesare made of steel to be used on steel, wood,masonry, etc.; some are of .o be used or..brass, stainless to be used on s.:;nless steel. etc.Brushes should be stored by flanging on a wallso that the bristles will not be damaged.

15-4. Painter's dusters. Painter's dusters areusually flat or oval in shape and are fitted witha handle similar to a paint brush. They areused to remove fine dust before painting. Storethem by hanging them on a wall or wrappingpaper around them and laying thcm flat. Neverstand them on the bristles.

48

CHAPTER 3

15-5. Scrapers. One type c iper is usedto remove deteriorated paint froc. the surface(see fig. 45); another is used to re, -*.anemarks and mill marks from wood suc,fig. ' C). Scrapers that are made of flex'hi-.mus. :ept sharp to do good wor!scrap.. . :;E: sharpened as shown in 4A cabs s,,,.1per is shown in figurescraper ;7: figure 49. The cutti,,Tthese scrap. .:- sharpened similarlyscraper. the scraper intowith other t... w:11 nick the slia:rp edgeand make ii ,.slaty to resharpen.

15-6. P;:::). (See fig. 50.) Among themany differv,.i stiles of putty knives that areavailable, tilers are those with short, stiff blades;some with long, flexible blades; some wide; andsome narrow. 'Ike original purpose of the puttyknife was to glaze window panes into windowframes, but it is often used to scrape old paintsurfaces and to apply joint cement to sheetrockwalls. Putty knives seldom need sharpening, butshould be stored in a manner to prevent damageto the blade.

15-7. Cold chisels. Cold chisels such as shownin figure 51 are used to chip paint and scale'tom metal surface,. Cold chisels are availablein klijfcrent widais and lengths. Sharpen the chiselon a grinding wheel by restoring the bevel, whichis usually 6Ct° to 70°. Sometimes it is also nec-essary to remove the burrs from head if it hasmushroomed.

15-8. Files. A file is a steel tool used for ell-ting and smoothing metals and wood. A woodrasp is !: coarse file that differs from the ordinaryfile in t;:eiti shape and size. Th-....re are over 3,000types and kinds of tiles and rasps. The mocommon types are shown in figure _52. Files arcscleaned with a file card (a wooden handle wil:1a brush on one side and fine wire teeth on theother). Preserve the sharpness of ales and raspsby storing them in a rack. If it is necessary tocarry files in a toolbox, wrap ti;e3n individuallyin cloth or paper to protect the ceth. Keep them

4s)3

21

Figure 44. Hand wire brushes.

dry to prevent rusting. Do not use rust preventivecompound. Files are very brittle, so do not ham-mer them or use them as pry bars.

15-9. Abrasives. There are many differenttypes of abrasives and each type has a variety ofgrit size and use. Among the types available areflint, garnet, emery, aluminum oxide, and silicon

carbide.e Flint is used mostly by painters because of

low cost, but it dulls and wears quickly.Garnet is a natural mineral and is the choice

abrasive for hand sanding and finishing wood.Emery is a natural mineral that comes from

Turkey and Greece. It is a good cutting agent,but slow. It is used mostly for metal polishingand rust removing.

ea Aluminum oxide with production paperbacking is used on both wood and metal surfacesbecause. its tough coating cuts faster and longerthan flints.

e Silicon carbide is produced by fusing silicaand coke. Its sharp abrasive is used on lacquers,

Figure 45. Paint scraper.

49

Figure 46. Wood scraper.

plas'ics, co,Ipootion materials, and metals for

both wet and di sanding.

15-10. The abrasives are fastened to I aper,

cloth, fiber a .i available in sheets, hells,and for use on sanders. Paper backingcomes in ft-ur popular weig":,6: A is soft and flex-ible and is used where. flexibility is desired; Cand D re thicke.. and used where fle71.17.1i:ty is

1,ccessary; 7 is heavier and is use ,nostly

for machine saniii:scf Cloth backing comes in twoweights: ,7 !S use: with errtzry for hand sanding,while X : used mostly with power tr'-)1s.

15-11. Until recently manufacturers listedtheir abrasives by nutut.!. rs, but it was a com-plicated syst::,,7, sr :tow they have started labeling

their paper 'Jr:, dium, coarse, etc. Figure 53shows tlc cottesponding numbers and grit com-parisons. Figure 54 is a guide to help you select

the coect type and size of abrasive.

15-12. 771 adt:ition to thes3 abrasives, there arethree powdered abrasives-pumice stone, rotten-stone, and jeweler's ouge that are used mostlyin furniture, cr fine v:oodwork finishing1 lc smooth

the finishes hetwe n coats and to polish metalsurfaces. Pumice store comer. it grades "F,""FF," ."FFF," and ''FFFF." "FI :" is the best

(a) DRAWFILING

STEP 2

(b) WHETTING EDGE

FIRST STROKE

STEP 3

(c) TURNING THE EDGE WITH A BURNISHER

(d) EDGE READY FOR USE

Figure 47. Sharpening a scraper.

Figure 48. Cabinet scraper.

90

50

Figure 49. Scraper plane.

Figure 50. Putty knife.

Figure 51. Cold chisel 44".

FLAT BASTARD FILE

AUGER BIT FILE

izealw014.7,COMBINATION FILE

NOMMOMMOMONTRaHALF -ROUND FILE

HAND FILE

Figure 52.

all around powdered abrasive to use. Rottenstoneand jeweler's rouge are available in one grade

only.15-13. Metallic wool. Metallic wool has a var-

iety of uses and in many areas it is better thanabrasives. There are four major types of metallicwool: aluminum wool for use on aluminum; cop-per wool for use on copper; stainless steel woolfor use on stainless steel; and steel wool, the mostcommon type, is used on steel, iron, tin, andwooden surfaces. Metallic wools come in sixgrades from No. 3, the coarsest to 3/0 the finest.Figure 55 is a guide to help you select the cor-rect grade of steel wool.

SuperfineExtra fine

Garnet andAluminum Oxide

10/0-4009/0--3008/0--2807/0--240

Flint

Very fine 6/0-220 4/05/0-180 3/04/0--150 2/0

Fine 3/0--1202/0--100

Medium 0--80 1 / 2

1/2--60 1'Coarse 1--50 1 1 / 2

1 1/2--40 2

Very Coarse 2--36 2 1 / 2

2 1/2--30 3

3--24

Figure 53. Abrasive grit number comparisons.

51

FILE

FLAT !ILL FILE

0ROUND FILL

'.5'aiMEMige152TRIANGULAR FILE

WOOD RASP

Files.

83

15-14. Blowtorches. A blowtorch as shown infigure 56 can be used to remove paint from in-terior and exterior surfaces. Blowtorches areavailable in many forms and use gasoline, alcohol,acetylene, or petroleum gas for fuel.

15-15. A blowtorch is filled by turning it up-side down and unscrewing the filler plug. Un-leaded gasoline is poured into the base whichserves as a funnel. When the tank becomes full,replace the filler plug and wipe off the excessgasoline. (Leaded gasoline will clog the torch.)Turn the blowtorch upright and operate the airpump to put pressure on the gasoline in the res-ervoir. Pour a small amount of gasoline in thebowl below the vaporizing assembly and ignite it.Gasoline can also be placed into the bowl byopening the valve a small amount and allowinggasoline to dijp into it. When the gasoline inthe bowl is almost burned, open the needle valveand the torch will light.

15-16. A blowtorch can be dangerous if notused correctly.

Never light a blowtorch in an unventilatedroom.Always set a blowtorch on a solid surfacewhile lighting it.Never move a blowtorch while gasoline isburn:ng in the bowl below the vaporizing

o a blowtorch in the wind.Do not t' near draperies or curtains.K' awhy from windows as the heat will

mek the glass.o Av.vayS go back over your work to make

certain that no fir exists.

15-17. In addition to the conventional blow-torch, torches are available that use pressurizedpetroleum. These torches are very convenient,expecially for removing paint from smaller areas.

Abrasive Coarse /viedium Fine Use

Aluminum 2 1/2-1 1/2 1/2-0 2/0-3/0 HardwoodOxide 1 1/2 1/2-0 2/0 Aluminum

1 1/2-1 0-2 1/2 2/0-3/0 Copper3-2 1/2 1/2-0 2/0 Steel Si Sheet Metal

Garnet 2 1/2-1 1/2 1/2-0 2/0-3/0 Hardwood1 1/2-1 0 2/0 Softwood

Flint 3-1 1/2 1/2-0 Removing paintand rough scale

Figure 54. Selecting proper abrasives.

GRADE USE

Very Fine 000 Final Smoothing00 Between Coatings (with oil)

Fine 0 Most Commonly UsedMedium 1 General Purpose

2 Rough WorkCoarse 3 Restoration Work

Figure 55. Selecting steel wool.

Figure 56. Blowtorch.

15-18. Caulking guns. Caulking guns come intwo different styles. One. is cartridge loaded andthe other is loaded by unscrewing the end andfitting with bulk compound. The gun is used to(1) fill cracks between window and door framesand the wall of the building, (2) fill cracks inmasonry surfaces prior to painting, and (3) fillthe crack between baseboards and interior wood-work and wallboard prior to painting. It is alsoused to disperse asbestos or fibrous roofing ce-ment when you stick asphalt roofing shingles.After using either type, make certain the gun isclean, as the compound will harden and ruin thegun.

15-19. Power Tools. In areas where powertools can be used, much time and effort can besaved through their use. Also, in some cases, thesame power unit can be utilized for several op-erations by using special attachments. For exam-ple, one power unit can accommodate a grinder,sander, or a buffer.

15-20. Power wire brushes. If the area is verylarge, power wire brushes should be used to con-serve man-hours. Power wire brushes are usedto remove paint from wood, masonry, or metalsurfaces, and corrosion from metal surfaces.

Figure 57. Power brushes.

U

Figure 58. Orbital vibrator sander.

Brushes of fine spring steel should be used. Fig-ure -57 shows two types of wire brushes that canbe used on an electric or air motor, flexible shaftmachine or in the chuck of an electric drill. They

can also be mounted on a stationary or portablegrinder. No maintenance is necessary but whenthe brush wears down, replace it.

15-21. Power sanders. The power sander isused to remove paint and corrosion from metaland wood surfaces and to smooth the surface forfinishing. There are many types of power sand-ers available, but the sanders that you will usemost are the portable vibrator, belt, disc, and thedrum floor sander and floor edgers. You mustwear safety goggles or a face mask while usingthese machines. All portable sanders should bestarted before placing them on the work.

15-22. A portable vibrator sander (electric)is a small machine into which a sheet of abrasiveis clamped. An orbital vibrator sander as shownin figure 58 is small enough to hold in one handwhile sanding. This tool is excellent for remov-ing old paint and varnish and such work assanding of drywdl joints. No maintenance isnecessary on this machine.

15-23. The portable belt sander (fig. 59) usesand endless abrasive-coated belt which runs overtwo flat pulleys. It requires both hands to op-erate. It is used for production finishing and forfast and efficient sanding of wooden surfaces.

Figure 59. Portable belt sander with dust bag.

53

Figure 60. Portable disc sander.

8i9

Figure 61. Floor sander.

Extreme caution must be taken so that the sanderwill not cut too deeply. Clean the sandcr withcompressed air occasionally.

15-24. The portable disc sander (fig. 60) isused mostly on metal surfaces or to remove badlyflaked paint on wood surfaces. One typc is avail-able that will fit the chuck of an electric drill orpower tool. The abrasive discs come in variousgrits for various tasks and can be replaced easily.

15-25. The drum floor sander (fig. 61) usesan abrasive belt, similar to the belt sander. Thesander is used to sand new and painted woodfloors; however, because of its size, it cannotsand close to the walls and in corners. An edgeris used for this purpose. The only maintenancerequired is to blow compressed air through themotor occasionally and replace the belt when itbecomes worn.

15-26. The floor edger (fig. 62) is very simi-lar to the portable disc sander; in fact, the abra-sive disc is interchangeable. The floor edger isdesigned so that it will sand close to the wallsand in corners, eliminating much hand sanding.Clean by blowing compressed air through themotor occasionally.

15-27. Power buffers. There are two types ofpower buffcrs; one type is used to buff woodfloors and the other type is uscd to put a highpolish on metal surfaces, Thcy are cleaned inthe same manner as other power equipment byremoving dust from the motor with compressedair.

Figure 62. Floor edger.

Figure 63. Portable power grinder.

15-28. The floor buffer weighs approximately30-40 pounds. The polishing pads vary in sizefrom 12" to 22" and are made of nylon or animalhair and hog bristle. The pads can be obtainedin coarse, medium, and fine.

15-29. The metal buffer is a rag wheel thatcan be installed on a power tool or a benchgrinder or it can be used with a flexible shaftmachine or in a portable drill equipped with aspecial chuck. The rag wheel is charged withbuffing compounds (jeweler's rouge, rottenstone,or pumice), and it is essential that you wear aface mask and gloves to protect you from fineparticles that come from the wheel. The fineravelings from the wheel are turning at a highrate of speed and are capable of cutting flesh.

15-30. Portable power grinders. The powergrinder is used to remove scale and encrustationfrom metal surfaces. The tool, as shown in figure63, is driven by an electric motor that uses 110 -volt, 60-cycle alternating current. The electricmotor in the grinder is geared and has a chuckso that you can attach different grit size abrasive

wheels. The action of the grindcr may be clock-wise or counterclockwise. Goggles are a mustwhen you use a grinder, and the safety guardmust be in place. Reinforced abrasive wheelsmust be used and the operating speed indicatedon the wheel blotter must not be exceeded.

15-31. Descaler. A descaler is an electric orpneumatic hammer with a multiple-needle head.The needles can be interchanged with a chisellikeunit. This tool is good for cleaning hard-to-get-atareas on metal surfaces, such as grooves, corners,

54

.94

Figure 64. Descaler.

87

Figure 65. Abrasive blaster.

55

95

crevices, rivets, protruding nuts and bolts, andgratings. (See fig. 64). The &scaler operateswith a reciprocating action, its wear-resistant al-loy needles hammering the surface. 'clean. Thistool weighs approximately 41/2 pounds and is14-20 inches long. When using this tool, weargoggles and a face.shield or a hood.

15-32. Portable abrasive blasters. The port-able abrasive blaster, as shown in figure 65, isused to remove paint from metal or masonrysurfaces and corrosion from metal surfaces. It isa very effective method of removing traffic mark-.ings from concrete paving.

15-33. Abrasive blasting equipment is simpleto operate. In fact, only 8 to 16 hours operatingtime is required by an operator with no previousexperience to acquire a basic knowledge of ab-rasive blasting techniques. However, simplethough the operation may he, each type of equip-ment has its own peculiarities, and the operatinginstructions of that type of equipment should befollowed closely to prevent damage to the equip-ment or to the material being cleaned.

15-34. The abrasive blaster is operated bycompressed air. The air pressure bombards thesurface with the abrasive (sand, grit, splitshot, orglass beads) at high velocity. If the compressedair is furnished by a portable compressor, themanual for operating this particilar type of com-pressor must be followed.

15-35. Before attempting to start the blaster,check the abrasive hopper control to make cer-tain it is in the closed position. It is also veryimportant that you check the attachment of theelectrical ground wire of the abrasive hose, sinceabrasive cleaning produces static electricity,which is a fire hazard, particularly around dustareas.

15-36. You must wear complete head and facecovering at all times and be provided pure, oil-free air for breathing when blasting in confinedareas.

15-37. The operator maintenance on a typicalblaster consists of checks at each 5 hours of op-eration, daily, and each 20 hours of operation.

a. 5 hours operation. Disassemble the blastgun and inspect the nozzle for wear and cracks.Replace the nozzle when inside diameter (ID)exceeds 3,11 inch or when it is cracked.

b. Dzily. Remove and fill the chamber screen.c. 20 hours operation. Depressurize the blast

generator, place the choke relief valve in theabrasive flow position, and remove the mixingvalve. Disassemble the valve and inspect the dia-phragm, valve seating surfaces, and the passage-ways for abrasions and ridgings. Replace wornparts as necessary and reassemble-reinstall the

56

mixing valve. Remove the cover on the swingcheck valves (2 each) and make certain that theflapper scats and operates freely.

15-38. When the unit is not to be used forsometime, discharge leftover abrasive through thegun. Open the drain valve at the bottom of thehopper to remove the small quantity that is be-low the level of the pump inlet.

15-39. Remember that the above instructionsare for a typical unit and that you must checkyour operator's manual on your specific blaster,as each unit hrs its own peculiarities.

15-40. Portable vacuum blaster. The portablevacuum blaster is used for the same purpose asthe abrasive blaster. One big advantage of thevacuum blaster is that the used abrasive, debris,and dust arc removed by vacuum during theblasting process.

15-41. Steam cleaner. The steam cleaner (seefig. 66) consists of a metal cabinet that housessuch components and systems as an electric motor(or gasoline engine), a water system, a soapsystem, and a heating system. The steam cleanerblends the detergent with water and pumps thesolution into a heating unit, where it is partiallyvaporized. The heat plus vaporization generates

OPERATINGCOMPONENTS

CLEANING GUN

REAR

WATER SUPPLY HOSE

Figure 66. Steam cleaner.

EXHAUSTFLUE

WATERTANK

110V POWERCORD

pressure in the system. The solution is then di-rected to the cleaning hose and gun from whichit is sprayed upon the surface to he cleaned. Thedetergent and spray, together with impact (fric-tion) caused by high velocity, loosen and removedirt and encrustations. After the cleaning opera-tion is finished, vaporized spray can be convertedinto a solid, high velocity stream of water to rinse

the material being cleaned.15-42. Vacuum cleaners. You can use an in-

dustrial or domestic vacuum cleaner to removedirt, dust, small loose objects, paper, etc., from

surfaces and areas before applying protectivecoatings. A soft bristle brush on the inlet of thevacuum cleaner will help to loosen caked soils.

15-43. Always remember to check the appli-cable technical order or operator's manual whenyou (1) use any of the above-listed items ofequipment and (2) when you perform mainte-nance on equipment.

16. Application Equipment16-1. As a. military protective coating spe-

cialist, it will be your job to apply protectivecoatings to buildings and other structures. It istherefore necessary that you know how to select

the best methods and equipment to do a satisfac-tory job faster and safer, and the most economical

for the military, It is understandable thatpower equipment should be used whenever it isfeasible. To avoid duplication, equipment which

is used for both surface preparation and applica-tion has been included only once in one or the

other of the categories.

FLAG ENDS

BRISTLES

HEEL OF BRISTLES

METAL FERRULE

HANDLE

Figure 67. The principal parts of a paint brush.

57

HOG BRISTLE

HORSE HAIR

Figure 68. Flag end of hog bristle.

16-2. Hand Paddies. Hand paddles are usedby the painter to keep his paint \veil mixed whilehe is painting. Paddles are usually made of woodso they can be discarded after usingsaving acleaning job; however, more efficient metal pad-dles with holes in the blade are available,. It isnot economical to mix large quantities of paintwith a paddle if a power mixer is available.

16-3. Power Paint Mixers and Shakers. Powerpaint mixers and shakers were covered in Chap-ter 2, paragraphs 10-22 through 10-24.

16-4. Paint Buckets. Several plastic bucketsthat will hold at least 11/2 gallons are very usefulto mix paints and clean brushes after using them.A paint can extender also is a handy item whenyou stir paints in the original paint container.

16-5. Paint Strainers. A paint strainer is nec-essary when you use paint that has set all night.When you mix dry pigments and oils it is neces-sary to strain the mixture before using. A straineris also used to strain any coating that is to beused in a spray gun. Some strainers are made ofpaper and cloth. They are inexpensive and shouldbe disposed of in a fireproof container after use.Others are made of fine wire mesh which mustbe cleaned with the same material that is used

to thin the mixture.16-6. Paint Brushes. It is important for a pro-

tective coating specialist to be able to select agood quality brush of the correct size and shapefor a particular job and it is also important toknow how to care for a brush, how to store itproperly, and how to reclaim a brush after it hasbeen abused.

16-7. Selection of brushes. Besides choosinga good quality paint brush, you should also selecta brush that is the right, size and shape for thejob. For example, using a small brush on largesurfaces not only wastes energy but also preventsthe proper spreading of paint.

16-8. A good quality brush is needed if youare to do a good job of applying paint to a smoothsurface. A good quality brush is well bristled,and the bristles are springy. Figure 67 showsthe principal parts of a paint brush. A poorquality brush will neither hold well nor spread

90the paint evenly. Good quality bristles arc madefrom natural or synthetic bristles, or a mixtureof these materials. The bristles of good qualitybrushes are flagged at the ends to hold paintand help spread it. (See fig. 68.)

16-9. A brush made of hog bristle is suitablefor applying enamels and oil-base paints to pro-duce a smooth finish on either interior or exteriorsurfaces. The hog bristle is a tapering hollowtube that forms natural flag ends. The flag end ofeach bristle is like a little brush. These flag endspick up and carry a large amount of paint. Theyalso help to spread the paint evenly on the sur-face. Hog bristles wear away and continuouslyform the flag ends as the tube splits.

16-10. A brush made of nylon bristle is suit-able for use in applying water-thinned and oil-base paints to both interior and exterior surfaces.This synthetic-type bristle is tapered and pos-sesses the resiliency and toughness required fornainting operations. Nylon bristle is similar to,.og bristle, except that the ends of nylon bristles

.; sanded to make them flag. After they areon ,.. 'lagged, they will continue to flag naturallyas th -istle wears away.

16-11. Do not use nylon bristles to applylacquer, since the solvents will ruin the bristles.In general, cleaners containing strong solutionsof acid, alcohol, or phenolics are injurious tosynthetic bristles.

16-12. A brush made of horsehair is a sub-stitute for a hog bristle brush. It is made fromthe manes and tails of horses and does not havethe elasticity and life found in hog bristle. Horse-hair does not retain its stiffness when immersedin oil and paint. It lacks toughness, strength,and wearing qualities and does not hold paintwell.

16-13. Brushes are available in various sizesand shapes. Some are flat, some are oval, someare angular cut and some are chisel shaped forspecial purposes.

16-14. Brushes for applying paint and stainto large wall surfaces, both interior and exterior,are flat and 3 to 6 inches wide. Wall brushesarc 3/1 to 11/2 inches thick and have bristles from2 to 7 inches in length. They arc usually square-ended and square-edged, with the natural bend

Figure 69. Flat wall brush.

58

ANGULAR CUT SASH BRUSH

BEVELED SASH BRUSH

Figure 70. Sash and trim brushes.

of the bristles bending toward the center of thebristle (see fig. 69).

16-15. Sash and trim brushes (see fig. 70)vary in shape and size but most are narrow width,1 to 3 inches. One type has bristles that arebeveled like a cold chisel to get close to windowpanes. One type has an angular cut used bysome painters (see fig. 70) when painting hard-to-reach spots. Another type preferred by somepainters is almost oval in shape.

16-16. Brushes as shown in figure 71 are usedfor varnish, shellac and lacquer and are usuallychisel shaped which contributes to smoother ap-plication and prevents lap marks. This typebrush usually comes in a 2- to 4-inch width andwith extra fine bristles 4 to 6 inches in length.

16-17. Care of brushes. All brushes containa few short bristles which are not caught in thesetting. These should be removed from the brushbefore it is used by striking the bristles againstthe spread fingers of your hand. It is also a goodidea to dip a brush in the thinner used for thepaint and then shake the thinner out before start-ing to paint. This keeps the paint from harden-ing on the surface of the bristles and makescleaning easier.

a. Never stand brushes, wet or dry, on theirbristles. The bristles will set in a curve, and noamount of effort will restore them to their origi-nal condition.

Figure 71. Varnish brush.

WOODEN COVER

BRUSH

ORDINARYTIN CAN

LINSEED OIL

Figure 72. Brush keeper.

b. Do not rub the bristles over the edge ofthe container to remove excess materials, as this

procedure tends to wear or break them. Instead,tap the brush lightly against the inside of thecontainer above the paint level.

16-18. Cleaning of brushes. To keep brushessoft and pliable, you should clean them immedi-ately after use. Once material has been allowedto harden in a brush it is extremely difficult torestore it to its original pliability. The best brushcleaners are the solvents used to thin coatingmaterials. To clean a brush, you should:

Squeeze out as much of the paint as possi-ble.

If some paint has hardened in the brush,soften and work it out.

Pour some solvent into a container, worksolvent thoroughly into the bristles, make surethat it gets to the base of the bristle.

16-19. 'Storage of brushes. All paint brushesin daily use should be kept overnight in a brushkeeper, as illustrated in figure 72. Immersionof cleaned brush bristles in proper oil solvent orthinner will assure you that the bristles will re-main soft and . pliable.

16-20. Use linseed oil for oil paint and varnishbrushes, lacquer thinner for lacquer brushes, andalcohol for shellac brushes. Use sufficient sol-vent material to cover the bristles of all thebrushes. And remember, brushes in the keepershould not touch the bottom or each other. Whenbrushes are not to be used for a length of time,they may be prepared for storage as follows:

Clean thoroughly and immerse in raw lin-seed oil for a short time.

59

9/Remove and press out most of the oil. Wrap

in oiled paper and store flat with no weight onthe bristles.

16-21. Reclaiming of brushes. To reclaim apaint-hardened brush, soak it in a commercialcleaner or a paint remover. A mixture of equalquantities of alcohol, acetone, and benzol is alsoused to soften paint-hardened brushes (otherthan nylon). Leave the brush in the solutionuntil the bristles are soft and pliable. If thebristles are badly bent, soak the brush in machineoil and lay it on a heated piece of metal untilthe oil in the bristles sizzles. While the brush isstill hot, reshape and bind the bristles with metalstrips of wire. After the brush has cooled, washit in mineral spirits and rinse it with benzol oracetone. Then wrap the brush in paper.

16-22. Paint Roller Coaters. Paint roller coat-ers are available in different types. The types

SHORT liANDLE 9" ROLLER

PUSH BROOMOR DUST MOPHANDLE

3" UTILITY ROLLER

11/4" CORNER PAINTER

LONG HANDLE 9" ROLLER

Figure 73. Roller coatcrs.

.1ga

Figure 74. Roller coater and pan.

most commonly used are lamb's wool, mohair,stippler, and high-pile.

16-23. The lamb's wool cover is used forgeneral-purpose painting. The mohair cover isespecially effective with enamels and rubber-basepaints. The stippler is used to produce a deepstipple finish. The high-pile cover, sometimesreferred to as a long-nap cover, is designed forpainting rough surfaces such as brick, stucco,concrete, concrete blocks, tile, siding, shingles,fences and other uneven surfaces.

16-24. The size of rollers used will depend onwhere you are painting. Small rollers, PA and3 inch, are used to apply next to windows anddoor openings and at corners where it is difficultto use larger rollers.

16-25. Figure 73 shows the most commonsizes and types of roller coaters. Industrial rollersare available in widths up to 18 inches. Thehandles of the roller coaters are designed to ac-commodate a push broom or dust mop handle sothat floors can be painted without kneeling, andceilings and high places can be reached withoutthe use of scaffolding.

16-26. Most roller coaters are constructed sothat the covers can be removed from the holderfor cleaning. The materials used for cleaning thecover depend upon the type paint being used.For water paint, use soap and warm water; forenamel, use mineral spirits or turpentine followedby soap and water; and for shellac, use denaturedalcohol, followed by soap and water. Dry theroller thoroughly before storing. When the coverbecomes worn or unusable, replace it with a newone.

16-27. Paint Roller Coater Pans. Paint rollercoater pans are usually shallow, rectangular con-tainers made of metal. They are used to applypaint to the roller. These pans vary in size, de-pending upon the width of the paint roller. Thepan must be wide enough to place the roller in it,

as shown in figure 74. Note the ridges formedon the bottom of the pan which control theamount of paint that stays on the roller when itis pulled over them. The pan is cleaned withthe same materials as the rollers and is oftenused as the container for the fluid to dean therollers.

16-28. Painter's Dusters. Painter's dusters areusually flat or oval in shape and are fitted with ahandle similar to a paint brush. They are usedto remove fine dust before painting. Store themby hanging them on a wall or wrapping paperaround them and laying them flat. Never standthem on the bristle.

16-29. Paint Spray Guns. There are manyvariations of paint spray guns: the internal mix-ing type and external mixing type, suction feedor pressure feed, bleeder or nonbleeder, and at-tached container or a separate container. Eachspray gun may be a combination of any of thevariations listed.

16-30. Internal mixing type. The internalmixing type spray gun mixes the paint and air in-side the gun and spray cap, as illustrated on theleft side of figure 75. The internal mixing typecap requires less air pressure than the externalmixing type and is popular on small units. Themain fault of the internal mixing feature is thatfast-drying materials atomized inside the cap tendto collect inside and around the outlet. Pressurefeed spray guns are usually of the internal mixingtype.

16-31. External mixing type. The externaltype spray gun mixes the paint and air outsideof the gun spray cap, as illustrated on the rightside of figure 75. Spray guns are also of thebleeder and nonbleeder type.

16-32. Bleeder type. A bleeder type spraygun is constructed in such a way that air passesthrough it at all times. This feature prevents ex-cessive pressure buildups in the compressor. If aspray gun is to be connected directly to a smallcompressor, it should be of the bleeder type.

16-33. Aranbleeder type., This type of gun isused in conjunction with a compressor that willautomatically shut off when the pressure reachesthe desired setting. When the trigger on the gunis released, air through the gun is stopped.

AIR

FLUID

AIR

INTERNAL MIX

AIR

FLUID

AIR

EXTERNAL MIX

Figure 75. Internal and external paint guns.

60

100

NOZZLE

BODY SPRAY WIDTHADJUSTMENT

Figure 76. Attached container type spray gun.

16-34. Suction feed. A suction feed spray gunis one in which pressurized air passes over thetip of a fluid tube, sucks fluid from it, and spraysit into the airstream.

16-35. A suction feed spray gun can be identi-fied by the presence of an air vent hole in thepaint cup cover. The suction spray gun is idealfor small areas to be sprayed with lacquer,varnish, and other light materials. However, thisgun should be avoided when heavy paint is to besprayed, since it will not pull heavy materialsup to the nozzle.

16-36. Pressure feed. A pressure feed gun ismade with an airtight container. Pressurized airdirected into the container places the fluid underpressure and forces it up the fluid tube, and atthe same time sprays the fluid.

BODY

NOZZLE

INLET

FLUID INLET

FLUID NEEDLE

TRIGGER

Figure 77. Separate container type spray gun.

61

101

1316-37. A pressure feed gun will spray heavy

paints and materials when supplicd with a lowvolume of air. It is considered one of the best

.ceral-purpose guns for use with regular paints.16-38. The mechanisms of pressure and suc-h feed guns are the same, and both types can

internal and external mixing of the fluid andSince no siphoning effect is necessary forure feed application, it is the tool for volumeng.39. Attached container type. An attachedner type spray gun is usually referred to astype," since the paint is held in a cup at-

tack.. 1 to the bottom of the gun. Cup type guns,which require only an air hose, are used ex-

mively in military, painting. The gun is illus-,,-,kted in figure 76.

16-40. Separate container type. A separate.stainer type spray gun does not have a paint.vainer or cup attached to the lower portion of

the gun. It is illustrated in figure -7-7. This gunreceives paint materials through a fluid hose froma separate container called a_ material pressurefeed paint tank.

16-41. Pressure feed paint tanks are largemetal containers that provide a constant flow ofpaint material at uniform pressure to the paintspray gun. The spray gun is connected to thetank with two hoses, one for air and the otherfor paint material. These tanks range in size from2- to 60-gallon capacities. (See fig. 78.) Basic-ally, they consist of a container with a clamp-onlid, an air pressure regulator, and connections forfluid and air.

16-42. In actual operation, air pressure froma compressor or some other air supply is forcedinto the paint tank. This air pressure causes thepaint to flow out of the tank through a fluidhose to the spray gun. When the paint reachesthe gun head, it comes in contact with air passingthrough the spray gun which atomizes and spraysthe paint.

Figure 78. Pressure feed paint tank.

cfq

COMPRESSOR ELECTRIC MOTOR

Figure 79. Low-pressure spray unit.

16-43. Paint spray guns and pressure feedpaint tanks must be thoroughly cleaned aftereach use. To clean spray guns and tank units,and hoses, wash and wipe out the tanks or spraygun cups. pour a small amount of solvent or thin-ner into them, reassemble and apply air pressureuntil the thinner has been blown through the hoseand gun. Finish by wiping off the units with acloth moistened with solvent or thinner.

AIR COMPRESSOR

SAFETY VALVE

HOSE

16-44. When paint and air passages becomeclogged with paint, it is necessary to disassemblethe units and soak all metal parts in thinner orpaint remover. After the thinner or paint re-mover has softened the paint in the air and paintpassages, take a soft wire of the appropriate sizeand work it back and forth through the passagesuntil they are open and clean. Do not use lye orany other caustic alkali solution for cleaning paintspray equipment.

16-45. Whenever paint guns and tanks are tobe stored for an indefinite time, the surfaces ofmoving parts should be given a thin film of oil.Lubricate the spray gun air valve daily with lightoil. Keep all spray gun packings, such as thefluid needle packing, soft and pliant by occasionaloiling.

16-46. Mr Hose. Air hoses are usually light-weight, flexible, and kink-free, and will withstandpressures as recommended by the manufacturer.Air hoses should be of the proper size lo furnishthe proper amount of air. For proper operationof spray gun equipment, the gun must receive anadequate supply of compressed air.

16-47. Fluid Hose. Fluid hoses are usuallymade of synthetic rubber and are used with all

GASOLINE ENGINE

AUTOMATIC STOP

Figure 80. High-pressure spray unit.

62102

AIR GAGE

tyres of painting materials, solvents, and oils.Fluid hoses arc cleaned at the same time as thegun when thinner or solvent is forced throughthem by air pressure.

16-48. Mr Compressor Units. An air compres-sor unit is a mechanical unit designed to con-tinuously supply compressed air at a specificpressure and volume. Usually, the Army painterwill be concerned with two types of compressorunits, the low-pressure unit and the high-pressureunit.

16-49. Low-pressure spray units. The electricmotor-driven, low-pressure paint spray unit, il-lustrated in figure 79, weighs approximately 50pounds. The overall weight of this unit includesthe air pressure pump, the air pressure tank, andthe driving unit. The driving unit may be either agasoline engine or an electric motor. Since thelow-pressure spray unit is designed to operate ona pressure from 20 to 40 psi, caution must beexercised not to apply higher pressures. Becauseof the low-pressure operation of this gun, it is notrecommended for spraying quick drying paints,lacquers, or enamels.

16-50. High-pressure spray units. High -pres-sure spray units are used for large jobs whereheavy duty spray equipment is required. Theyare driven. by both gasoline engines and electricmotors. A typical gasoline engine driven unit isshown in figure 80. A unit of this type consists ofthe same basic components as the low-pressurepaint spray unit. Usually, these units are com-pletely automatic and hold a working air pressurebetween certain low and high limits (80 and 100psi). The compressor is large enough to deliverair at a volume of 5 cubic feet per minute at apressure of 80 to 100 psi. The larger air receiveror pressure tank, for the same unit, will satisfac-torily deliver an air volume of 7 to 8 cubic feetper minute at a pressure of 80 to 100 psi.

16-51. The only maintenance services neededon an air compressor are cleaning the air filtersand servicing the crankcase. Some compressorsmay require additional lubrication by means ofoil cups. grease cups, or grease gun fittings.

16-52. If electricity is available, electric mo-tors are more satisfactory than gasoline enginesfor driving compressors as they require very littlemaintenance.

16-53. Where electric power is not available,a gasoline-driven unit must be used. The pre-ventive maintenance services for the gasoline en-gine are similar to those for any gasoline engine.The lubricating oil in the crankcase must be keptat the proper level. If it is low, add enough tobring the level up to the full mark. In addition,the oil in the crankcase must be changed and if

95'the engine has an oil filter, the filter cartridge isusually changed when the oil is renewed. Theair filter should also be cleaned as recommendedby the manufacturer. Be sure to check the manu-facturer's handbook or applicable technical orderfor operating instructions and maintenance of theparticular type of equipment that you have.

16-54. Airless Spray Equipment. In an airlessspray system, as shown in figure 81, the spray iscreated by the forcing of paint through a re-stricted orifice at very high pressure. Atomiza-tion of the paint occurs without the use of airjets, thus the name airless spray. Liquid pres-sures from 1900 to 2600 pounds per square inch(psi) are developed in special air operated high-pressure pumps and delivered to the gun througha single hose line.

16-55. The system provides a very rapidmeans of covering large surfaces with wide anglespray without ovcrspray mist or rebound. Thesingle small diameter hose makes gun handlingeasy. The spray produced has a full wet patternfor quick film buildup, but requires extra care inlapping and stroking to avoid excessive coveragethat would result in runs, sags, and wrinkles.

16-56. The system shown is operated by com-pressed air, but electrically operated models areavailable, which are very convenient if electricpower is available.

63

11 3

lop. Lib

Figure 81. Airless spray equipment.

96

DRAIN

CONNECTION

TRANSFORMER

DRAIN

Figure 82. Stationary compressing unit.

16-57. Because of a static electrical potentialgenerated by the high pressure necessary for air-less spraying, it is possible that sparking mayoccur between gun and object being sprayed.This can result in explosion and/or fire. Be surethat both the object being sprayed and the airlessequipment are grounded. This can be done byattaching a static wire to ground. If the hosedoes not contain a static electrical conductor, astatic wire must be attached from spray gun toground.

16-58. Under no circumstances should paintbe permitted to set up, settle out, or dry withinthe pump. Routine maintenance and cleaningshould be done daily as follows:

(1) The motor section is lubricated lightly attime of manufacture. Moisture condensing onthe cylinder wall during compressing action whenpump is operating is cause for further lubrication.However, if an air line lubricator is installed, itshould cause no trouble as long as the amountof oil used can be controlled.

(2) Wipe the inside of the container with alacquer solvent soaked rag. The container is

coated with clear lacquer to inhibit rust. Anysolvent not compatible with lacquer may causecongealing.

(3) Shut off the air supply to the pump bytuning the adjusting knob on the regulator count-erclockwise until no spring pressure is felt. Re-

64

tUTOMATICWATER DRAIN

move pressure from the system by either pullingthe trigger on the gun or by opening the pressurerelease valve on the fluid strainer assembly byturning clockwise.

(4) Detach the main air supply hose from thestem at the regulator and attach to the stem onthe lift assembly. This lifts the pump assemblyfrom the fluid container.

(5) Remove the fluid container, clean, fillwith approximately 1 gallon of clean solvent andreplace the pump.

(6) Remove the spray cap and strainer as-sembly from the spray gun and clean with solventused during painting operation.

(7) Detach the main air supply hose from thestem on the lift and attach to the stem at theregulator. The pump will lower back into thecontainer.

(8) If the pressure release valve was openedto relieve the system pressure, be sure to close itat this point.

(9) Turn the adjusting knob on the regulatorclockwise just far enough so that the pump willoperate slowly when the gun trigger is pulled.

(10) Aim the nozzle of the gun against wastematerial and hold the triggcr back until fluid inthe pump, hose, and gun has been replaced bysolvent.

(11) Aim the nozzle of the gun back into thesolvent container, pull the trigger and circulate

1u4

the solvent in this manner until the fluid remain-ing in the system is suspended in solvent. Clean-ing action will be better if the system pressure is

increased at this point. Lift the inspection capon the container cover assembly and aim thenozzle into the container.

(12) Repeat step (3).(13) Turn the handle on the filter cartridge

one full turn. Do not turn the handle while filteris pressurized or distortion of the unit cartridgewill result. If the handle turns hard, it shouldnot be forced, but the unit cartridge should beremoved for thorough cleaning.

(14) Repeat steps (4), (5), (7), (8), and(9) respectively, using clean solvent.

(15) Open the pressure release valve and al-low the solvent to circulate for a few seconds.

(16) Repeat steps (3) and (4).(17) Empty the container and clean the ex-

terior of the pump and container with a solventsoaked rag.

(18) Wipe off the entire unit with a dry rag.(19) Detach the hose connection from the

stem on the lift and allow the pump assembly tosettle into the empty container.

(20) Turn off the air supply.

16-59. Stationary Compressor Unit. In a paintshop or aircraft hangar where compressed air is

LINE PRESSURE GAGE

WORKING PRESSURE GAGE

OUTLET'COCK

HOSE CONNECTION

DRAIN

Figure 83. Air transformer.

q7

furnished by a large stationary compressor, theair lines leading to the spray guns should beinclined. This is done to permit the condensedmoisture from the compressed air to flow backinto the air pressure tank. Figure 82 shows theinstallation of a stationary compressing unit with

..the air line sloping toward the air compressor.In this manner, the water is drained by the draincock at the base of the air pressure tank.

16-60. Air Transformer. Since spray guns mustbe supplied with clean, moisture-free, regulatedair, a special device must be installed in the airline to perform this job. The device is called anair transformer, illustrated in figure 83 with allits parts named. The air transformer has threefunctions: (1) it separates oil, dirt, and waterfrom the compressed air before it enters a spraygun; (2) IL reduces main line pressure to anydesired working pressure for a spray gun; and(3) it provides convenient hose connections forone or more spray guns. The transformer isusually provided with gages which indicate theworking pressures at the outlets.

16-61. Whenever an air transformer has onlyone working pressure regulator, all attachedspray guns will have the same working pressure.However, if the transformer has two workingpressure regulators, as shown in figure 83, theattached spray guns may be regulated to differentworking pressures.

16-62. An air transformer should be used inall finishing ur refinishing paint shops where asupply of clean, moisture-free regulated air is re-quired. Your paint shop may use an air con-denser to separate oil and moisture from the air.A condenser is used where a regulated supply ofair is available.

16-63. The conventional spray systems havebasic similarities necessary to their efficient op-eration. There must be an adequate source ofcompressed air, a supply of paint, and a spraygun for controlling the combination of air andpaint in an atomized cloud against the surface tobe coated.

16-64. Spray Booth. A permanent spray paintshop requires a well-ventilated and well-illumi-nated spray booth. Figure 84 illustrates a port-able spray booth that is ventilated by the deflec-tor plate shown in the back. It is illuminated byfloodlights recessed in the walls of the booth.Portable floodlights should also be available forthe spray booth; they provide good illuminationdirectly on the area being painted. All lights usedmust be of the vaporproof type.

16-65. Wiping Rags and Dropcloths. Wipingrags should be carried at all times by the pro-tective coatcr to wipe up spills and splatters on

65

NNN

A-e-..1r..-

DM:M-1'0R PLATECOVERING EXHAUST OPENING

FLOODLAMP

Figure 84. Portable spray booth.

unprotected surfaces before they dry. Dropclothsare available in canvas, rubberized fabrics, plas-tic, and sometimes impregnated paper. They areused to protect furniture and floors. Plastic drop-cloths are the most popular because they are in-expensive and can be discarded when they be-come soiled.

17. Traffic Markers17-1. Traffic markers are used to paint stripes

on roads, parking lots, and landing strips and topaint curbs. Stripes can be painted on roads,etc., by hand with the use of a guide, but it isa slow process. If a power operated marker isavailable, it will save a lot of manpower.

17-2. Construction Features. Power-operatedtraffic marking machines differ in design andconstruction. Each manufacturer builds one ormore machines to certain specifications with theirown power, but some do not have a tractiondrive. Such machines must be pushed by handor pulled by a motorized truck or tractor. A fewof the machines are designed to be mounted onmotorized trucks; others are mounted on eitherthree or four wheels, operate on her own power,and furnish power for traction.

17-3. A typical small, power-operated, self-propelled traffic marker is silown in figure 85.This machine is compact in construction, with allof the units in plain view. The paint tank islocated between the wheels, with the gasolineengine and air compressor mounted over it. Thepaint spray gun is located on the right front side.The bead dispenser hopper is mounted in frontand to the right of the engine and compressor.A flexible hose connects the hopper with a ro-tating bead spreader. The front wheel furnisiesthe traction for the machine. Power is trans-mitted to the wheel from the engine by rollerchains.

17-4. Machines of this type are used to painttraffic stripes and dispense glass spheres into thewet paint in one operation. They may have anynumber of spray guns and sphere dispensers, de-pending upon the make and model.

17-5. The air compressor may be of the singleor twin cylinder type, capable of delivering ampleair pressure. The safety valves are generallyset at 75 to 100 psi.

17-6. The paint tanks vary in capacity withthe type of machine. All paint should be strained

Figure S5. Power-operated traffic marker.

66

before it is placed into any paint tank. Painttank lids or covers are of the clamp-en type.Most of the paint tanks have a manual or power-operated agitator which keeps the paint thor-oughly mixed during operation. This agitator isalso used for cleaning the tank.

17-7. The paint guns mounted on a trafficmarking machine are of the same design as thoseused for ordinary spray painting. The width ofthe spray is governed partly by the distance thespray gun nozzle is positioned from the surfacebeing striped and by the spray gun adjustments.

17-8. Glass sphere dispenser hoppers vary insize, depending upon the size of the machine.The sphere dispensing mechanism is driven byan auxiliary shaft. After the gh.ss spheres aremetered (measured out) by the dispensing mech-anism in the ratio of 6 pounds to every gallon ofbinder, they are blown into the wet stripe ofbinder by air pressure.

17-9. Operating Characteristics. Most trafficmarking machines are designed to handle anystandard traffic marking paint. They will alsospray lacquers and reflectorized synthetic mate-rials equally well. If it is necessary to thin trafficmarking paint, always use the reducing agcntrecommended by the manufacturer; never usegasoline. Glass spheres are metered and appliedby a spccial mechanism on the machine.

17-10. Operator Maintenance. The maintenanceof power - operated traffic marker machines shouldbe performed according to the directions set forthby the manufacturer. However, if such manualsare not available, the suggestions listed in thefollowing paragraphs should be followed.

17-11. The preventive maintenance servicesfor the gasoline engine are similar to those forany gasoline engine. The lubricating oil in thecrankcase should be kept at the proper level.This oil should be changed at intervals of 25 to50 operating hours. The oil filter cartridgesshould be renewed when the oil is changed. Theair filter should be removed from the engine,disassembled, and washed in cleaning solvent.New lubricating oil should be placed in the airfilter when it is installed.

17-12. To clean the paint tank, remove allthe paint from it. After this is done remove thecover and pour about a gallon of thinner into thetank. Replace the cover and let the fluid agitatefor 2 m 3 minutes, and drain. Again remove thecover from the tank and wipe it out with a cleancloth. This proccdure helps to get most of thepaint from the tank. Now replace the cover andpour enough thinner into the tank to cover thefluid outlet leading to the spray guns, and applypressure to the paint tank. Open the controlsand force the thinner through the fluid lines and

67107

9?

spray guns. Then drain out what fluid is lzft inthe paint tank and remove the cover. Wipe outthe tank and clean all external units.

17-13. After each use, the paint guns shouldbe removed, disassembled, and cleaned thor-oughly. Here are a few of the things to check:

o The bead spreader, if it has any movingparts, should be lubricated frequently.

o Driving units, such as belts and chains,should be checked frequently for wear. Drivechains may he lubricated as required.

Wheel bearings should be checked for ad-justment and lubricated when necessary.

o Tires should be inflated to the proper pres-sures.

17-14. Grease fittings and oil cups are pro-vided for greasing and oiling various units. Themachine should be stored in a sheltered placewhen not in use.

17-15. Glass Sphere Dispensing Gun. When-ever glass spheres arc to be embedded in trafficpaint which has been applied with a paint brushor spray gun instead of a traffic marker, a glasssphere dispenser is used. This gun is actuallyan air pump. When it is filled with glass spheresand the handle is moved back and forth, thegun jets a uniform spray of spheres. For a lightdistribution, the gun is held so that the dischargechute is at the top, then as the gun is turnedin a clockwise direction, the distribution of glassspheres increases. These glass spheres reflectlight when applied to curbs, lane markings, andrunways.

17-16. Another item used to mark trafficlanes that may easily be seen at night is lami-nated backed adhesive. This material is flexibleand may be cut to form letters, numbers, etc. Itcomes in various colors.

18. Sign Making Equipment18-1. Making signs is a very important part

of your job. A protective coating specialist iscalled on very frequently to paint signs on

Figure 86. Stencil key set.

100

Figure 87. Stencil spray gun.

ground equipment, parking lots, driveways, build-ings and almost everywhere imaginable.

18-2. There is a varied assortment of equip-ment available to assist you to do a professionaljob when you arc called on to "make a sign."

18-3. Stencil-Cutting Machines. Stencil-cuttingmachines may vary in appearance and size. Re-gardless of the size (range from 1/3- up to 4-inchcutters) the machine will have a handwheel toposition an indicator to the letters, number, ormark to be cut, and a cutting handle to depress.The rotating handwheel portion of the stencilmachine contains the punch, which is positionedunder the cutter handle. Positioning the indica-tor brings the punch in alinement with a "die"in the lower portion of the machine. Depressingthe cutting handle forces the "punch" into the"die," thus cutting the desired letter or numberinto the stencil board.

18-4. Stencil Board. The stencil board comesin two grades; a high wear resistance (grade 1)and a moderate wear resistance (grade 2). Thegrade 1 board is available in sheet size 8" x 24",20" x 32", and 24" x 36". The grade 2 boardcomes only in one sheet size, 20" x 24". Thegrade of stencil board needed for a job is deter-mined by whether the stencil will be used onlyonce or several times.

18-5. Stenciling Ink. While any suitable paintmay be used to stencil, there is a specific stencilink that will mark porous surfaces, wood andcardboard shipping containers, burlap, and can-vas. This ink comes in black, white, and yellowcolors.

18-6. Stencil Set (Brass). When a stencil -cut-ting machine is not available for use, a profes-sional job can be obtained with a brass stencilset. It is good practice to have two or three setsof each size on hand, as many signs containtwo or three of the same letters and it will savetime if the complete sign can be made at onetime.

18-7. The stencil set consists of brass numbersand letters that interle:k to form the dcsircdwords and numbers. The outfit includes a con-tainer and the following stencils: complete alpha-bet; figures 0 to 9 and one ampersand; onecomma; one apostrophe; one period; one spacer;and four end pieces. The letters and numbersarc gothic style and may be obtained in 1-, 11/2 -,2-, 3-, and 4-inch sizes.

18-8. Immediately after use, these letters andnumbers should be disassembled and washedwith the same type of thinner used to thin thestencil paint.

18-9. Stencil Key Set. The stencil key set isused as a guide for layout and for drawing lettersand numbers on stencil boards. A 3-inch stencilkey set is shown in figure 86. To use the stencilkey set, first mark off a horizontal line on thestencil board. Then use the key set to outlinethe dcsircd numbers and letters, using either theinside or outside of the set. After all the letters/numbers have been outlined on the stencil board,simply cut them out with a sharp knife or razorblade.

181.10. Spray Gun. A spray gun, as shown infigure 87, is dcsirablc for stenciling. This gun is

. smaller than the one used for painting, and isknown as a touchup gun. It is not mandatoryto have a small stenciling spray gun in a shop;however, it is dcsirablc to have at least onespray gun that can be used only for this purpose.It is usually convenient to have more than onecup for a spray gun when more than one colorof stencil paint is used. The extra cups facilitatespraying different colors of paint. General careand maintenance for a stenciling spray gun arcthe same as previously described for the regularpaint gun.

18-11. Layout tools. Whether you arc usingthe brass stencil or the board you prepared withthe stencil kcy set, you :nust lay out (aline) thestencil in place. The tools that you need for thislayout consist of a straightedge, yardstick, steel-square, and dividers. Using whatever tools youneed, position the stencil and secure it in placewith masking tape.

18-12. Stencil Brushes. On jobswould be impractical to use a spray

68 103

where itgun, you

can use a stencil brash or roller. The most com-mon brushes arc the artist's stencil brush, stencilbrush, and the fountain stencil brush.

18-13. Artist's staid! brush. This brush is

round with black bristles in a long polished cedarhandle. The bristles arc held in place by a metalferrule. The diameter at the ferrule is 1/2 inchand the bristle length is 1 inch.

18-14. Stencil brush. This brush is made of100 percent hog bristles, with the flag ends cut.It has a long wooden handle and comes in either13/10" x 1 " or I'/ 6" x 1A 6" sizes.

18-15. Fountain stencil brush. This is abrush with a reservoir handle. The leakproofreservoir holds a minimum of 2 ounces of stencil

1 ri 069

ink. The bristles extend 11/2" beyond the metalferrule. A shutoff valve is provided between thereservoir and the brush to adjust the flow ofstencil ink as well as to shut it off completely.

18-16. A roller about 2 inches wide and 11/2inches in diameter is sometimes used to stencil.The roller is rolled over a small amount of paintspread on glass or a metal sheet; then rolled overthe stencil to make the sign.

18 -17. Pressurized Spray Cans. Another itemused for stenciling small signs is the pressurizedspray can. Spray cans are easy to use and comein various colors. The chief advantage of thesecans is that there is no cleanup after you com-plete the job.

/Oa CHAPTER 4

Ladders, Scaffolds, and Hoisting Equipment

IIS IMPORTANT for the protective coatingA specialist to know how to select and erectladders and scaffolding to reach an area thatcannot be reached from the ground. In the erec-tion and use of ladders and scaffolding, safety isof prime importance. In the construction field,the number of serious accidents caused by scaf-folds and ladders that are not erected or usedproperly far exceeds those from other sources.A scaffold or ladder that is not erected or usedproperly not only endangers the workers usingthe scaffold but could be a death trap for work-ers under it.

19. Ladders19-1. Ladders are devices used to gain access

to higher levels where work is to be done. It ispossible to paint the entire exterior surface of aone- or two-story building from a ladder; how-ever, it is often more comfortable and timesaving.if scaffolding is erected.

19-2. Ladders are of several typessingle-rung, extension, step, and trestle ladders. Eachladder is designed for a specific use and shouldnot be used for any other purpose. Ladders aremade of magnesium, aluminum, steel, or wellseasoned wood, free of knots or other defects.

19-3. Single-Rung Ladders. A single-rung lad-der consists of two side rails from 8 to 30 feet inlength with rungs (steps) each 12 inches, capableof supporting weights up to 500 pounds. Thesize of a ladder is determined by its overalllength. Figure 88- shows a typical single-rungwooden ladder. It should be equipped withsafety shoes or spikes as shown in figure 89.These shoes help to keep the bottom of the lad-der from slipping.

19-4. The selection of a ladder depends uponthe height at which the painter must work. Apainter works most efficiently in a space nothighcr than his breast nor lower than his knees;therefore, the length of a ladder is critical be-cause the area that can be reached is limited.

A ladder should be long enough so that a paintercan reach his work without climbing past thethird rung from the top.

19-5. A ladder is raised by placing the baseagainst the foundation of the building, raising thetop end, and walking under the ladder towardthe building. As soon as the ladder is perpen-dicular, the bottom is pulled out from the buildingto a distance of V4 of its length as shown infigure 90. If it is necessary to get on top of abuilding, the ladder must extend above the eaveat least 30 inches.

19-6. Two ladders can be adapted to hold ascaffold board or extension plank by the use oftwo steel ladder jacks as shown in figure 91.These jacks can be used in front of or behind theladder. If they are placed between the ladderand the building, it will allow you to be closerto the wall for painting.

19-7. An extension plank as :ilia\ in in figure92 is made of material that is well seasoned,straight grained, and free of any knots or defects.This board is constructed so that it can be ad-justed in length. It is available in various sizes.A scaffold board of lumber that is straight grain,free of knots or any other defect can be usedin lieu of the extension plank. The size of thelumber depends on the span of the scaffold, forinstance:

Size of Plank(inches) Permissible Span

2x 8 8'2 x 10 10'2 x 12 12'2 x 14 14'2 x 16 16'2 x 20 20'3 x 10 20'

19-8. Extension Ladders. Extension ladders asshown in figure 93 consist of two or more sec-tions which can be adjusted to various lengths bypulling on the rope which is reeved (threaded)through the pulley. Although single straight lad-

70

0

0

0

0

9

A

1=siku.acar..)

Figure 88. A single-single ladder.

ders are available up to 30 feet, it is better toavoid single ladders of over 20 feet because ofthe difficulty of raising them.

19-9. Extension ladders overlap to hold thesections together. The sections will overlap atlease 3 feet for a ladder up to 38 feet, 4 feet upto 45 feet, and 5 feet for any extension over 45feet. A positive locking device is provided sothat one ladder may be locked to the rungs of

the other.19-10. Extension ladders are erected in the

same manner as straight ladders with the sections

Figure 89. Ladder safety shoes.

71

111

/03

1/4 LENGTH OF LADDER

Figure 90. A properly placed ladder.

in a down position. After the ladder is erected,the top can be leaned away from the building andraised to the desired height with the pulley andr:..pe arrangement.

19-11. Stepladders. A stepladder, as shown infigure 94, is used on flat surfaces where a soundfooting can be obtained. Stepladders are avail-able in lengths up to 20 feet. When erecting astepladder, be sure that the brace is extendedand locked.

19-12. Trestle ladders. Trestle ladders consistof two single ladders hinged at the top to forril an"A" shaped device. When two of these laddersare erected with a plank or extension platformextending between the rungs of the two ladders,the combination forms a painter's trestle as shownin figure 95.

Figure 91. Ladder jack.

Figure 92. Extension plank jack.

19-13. Ladders must be kept clean and freefrom dirt and paint. Wood ladders should beshellacked or varnished or given two coats oflinseed oil as a protective coating against theweather. Paint is not used on wooden laddersbecause it would hide any obvious defects. Lock-ing devices on stepladders and extension laddersshould be checked for positive action before eachuse.

0

Figure 93. Extension ladder.

Figure 94. A stepladder.

19-14. When ladders are not in use, theyshould be stored in a sheltered, well-ventilatedplace away from weather elements. They shouldbe hung on brackets by the side rails to preventwarping.

19-15. Additional safety precautionS. that youmust observe when using a ladder are:

Under no circumstances use stepladders assubstitutes for workstands.

When ascending or descending a ladder,face the ladder and hold on to each side rail.

When the security of a ladder is endangeredby other activities, rope off the area around it,fasten it securely, and assign a man to steady thebottom.

When you use a ladder in front of doorswhich open toward it, block off the doors androute personnel to another exit.

Never leave a ladder unattended for anylength of time while it is erectedtake it downand lay it on the ground.

When working on a ladder stand no higherthan the third rung from the top and de, not at-tempt to reach beyond a normal arm's length.

If you need help to do the work, have yourhelper get another ladderdon't allow anyone onthe ladder with you.

Figure.95. A painter's trestle.

If there is any danger of the ladder slip-ping, tie it to something solid with a rope. Equip-ping a ladder with safety shoes does not alwayskeep a ladder from slipping.

Never place a ladder on a movable object.Never climb a ladder while using both hands

to hold material; at least one hand must be usedwhile climbing or descending a ladder.

Never place either the top or the bottom ofa ladder against unstable material.

20. Scaffolds20-1. A scaffold is a temporary elevated plat-

form to support workmen and tools. It mayrange from individual planks placed acrossstructural members of a building to steel mobilework platforms. A well constructed or erectedscaffold is safer to work from than a ladder.Types of scaffolds most commonly used bypainters include the scaffold horse, half horse(lean-to), independent metal scaffold, swingstage, and boatswain chair.

20-2. Scaffold Horse. A scaffold horse asshown in figure 96 is a very convenient item touse if you wish to construct a simple scaffold.These horses are normally used in pairs; how-ever, a stairway, porch, or any other stationaryobject can be used to hold one end of a work plat-form while a scaffold horse holds the other.Check the nailing of the legs and braces beforeeach use.

20-3. Independent Metal Scaffold. Double-pole built-up scaffold (metal or wood) is com-pletely independent of the main structure.Several types of patent independent metal scaf-folding are available for simple and rapid erection.The scaffold uprights are braced with diagonalmembers and the working level is covered with aplatform of planks as shown in figure .97. Allbracing must form triangles, and the base of each

73

1 1 n

/05column requires adequate footing plates, asshown in figure 98, for the bearing area on theground. If the ground is fairly even, the footingplates can be secured to a 2 x 8 placed on theground.

20-4. The patented steel scaffolding is usuallyerected by placing the two uprights on the footingplates and inserting the diagonal braces. Thediagonal braces have end fittings which permitrapid locking in position, as shown in figure 99.A second tier is placed on the first tier, with thebottom of each upright locked to the top of thelower tier. A third and fourth upright can beplaced on the ground level and locked to thefirst set with diagonal bracing. The scaffoldingcan be built as high as desired, but high scaf-folding should be tied in to the main structure, asshown in figure 100.

20-5. Side brackets, as shown in figure 101,are clamped on the scaffold uprights (scaffoldleg) to provide platforms at various height levels.

20-6. If the scaffold is to be used on a solidfloor and frequent moving is necessary, a rollingtower can be constructed of the same scaffoldsections by replacing the footing plates with lock-ing casters. The height of the tower must notexceed four times the smallest base dimensions,and it must have a guardrail above the workingplatform. .

20-7. Swing stage scaffold. A swing stage scaf-fold, as shown in figure 102, is used to reach theupper surfaces of the exterior wall of a buildingby suspending a platform from the roof or cornicewith ropes or steel cables. A swing stage scaffoldconsists of two cornice hooks, two swing stagestirrups, guardrail, scaffold platform, toe board,and two sets of blocks and tackle

20-8. Cornice hooks. Cornice hooks are largemetal hooks which hook securely over the top ofa substantial portion of a roof or cornice. Thetop of each hook is provided with an eye towhich tieback ropes are fastened. The other endof the tieback rope must be fastened to the baseof a chimney, soil pipe, or any other securelyattached projection which would support theweight of the scaffold and load to be placed on it.

Figure 96. Scaffold horse.

Figure 97. Independent metal scaffold.

74

Figure 98. Base plate.

These tieback ropes are for safety. The lowerends of the hooks are also equipped with an eyeinto which the blocks are attached.

20-9. Swing stage stirrup. A swing stage stir-rup is the metal unit which supports the scaffoldplatform. Two stirrups are required for a scaf-fold. A ring is located at the top of each stirrupto attach a set of blocks and tackle. Rollers areprovided so that the scaffold will not hit the wall.

20-10. Guardrail. A guardrail of 2 x 4material is a part of the scaffold. The guardrailhelps protect a worker from falling from the plat-form.

20-11. Scaffold platform. A scaffold platformis the working space on which you move aboutas you work. It should be not less than 20 normore than 24 inches in width, and not more than26 feet in length. Well seasoned 2-inch lumberthat is straight and free of knots or other defectsis used for the platform.

20-12. Toeboards. Toeboards constructed of2- x 4-inch material are located at the front andback of the scaffold to prevent material fromslipping or accidentally being knocked off. Theyrun the full length of the scaffold.

Figure 99. Quick lock.1

75

lo?LAG BOLT AND

EXPANSION SHIELD

CLAMP

SCAFFOLD LEG

Figure 100. Building tie in.

20-13. Blocks and tackle. Blocks and tackleof a special type are used on each end of theswing stage scaffold to raise and lower the unitas required. A hoisting machine may be substi-tuted for the blocks and tackle.

20-14. There are many safety rules that youmust practice while using swing stage scaffolds.

a. After erecting and before using a swingstage scaffold, hoist it 1 foot off the ground andtest it with four times the working load.

b. Lash the swing stage to the building orstructure wall as soon as possible after hoistingto keep it from swinging outward.

c. No more than two painters should work ona swing stage at one time. Each painter shouldbe provided with a safety belt which should be

CROSSMEMBER

SCAFFOLD LEG

Figure 101. Side bracket.

10t6

attached to an individual lifeline. The line shouldbe fastened above, free from the stage.

d. All fiber ropes exposed to acids or acidsolutions should be replaced immediately. When-ever possible, use steel cable for hoisting equip-ment when you work with acid solutions.

e. Swing stage scaffolds not in use should belowered to the ground for safety reasons.

CORNICE HOOK

BLOCK & TACKLE

GUARD RAIL

TIE- BACK ROPE

PLATFORM

TOEBOARDS

O

I

I

ISIDE VIEWICA

111, MINNOW/ am Si,

Figure 102. Swing stage scaffold.

BACK

SUPPORT

Figure 103. Boatswain's chair.

DOUBLE BLOCKS

TWO BOWLINES

ROLLING HITCH

DOUBLE BOWLINE

Figure 104. Boatswain's chair with tackle.

76

1' C

A

B

C

Figure 105. The square knot.

f. When you raise a swing stage scaffold, keepthe weight on the outside of the platform untilthe swing stage is secured to the building.

g. Make it a rule never to touch the wall nextto a swing stage until it is seemed to the building.A light push against the wall may swing the stageout in such a way that you may lose your bal-ance and fall.

h. Check the operation :A the hoisting ma-chine every time it is to be us,x1.

i. Inspect each tackle block assembly everytime it is to be used.

j. Lubricate tackle block pulley wheels as nec-essary.

k. Tackle block ropes must be kept undercover to guard against deterioration by weather.

1. Tackle block ropes deteriorate and becomeunsafe when exposed to acids.

m. Tackle block ropes should not be permittedto scrape against sharp litojections such as scaf-folds, window sills, beams, or the walls of build-ings.

n. Ropes under heavy loads must not bepinched between hard surfaces.

o. Wear on rope increases when it runsthrough sheaves which are too small.

p. Ropes should be lubricated with beef tal-low as required.

/09

Figure 106. The bowline.

q. Ropes must not be allowed to slip overpulley wheels that do not turn.

r. Cornice hooks must be inspected for cracksand bends which result from strains.

s. Inspect all planks that are used as a partof a swing stage scaffold.

t. Inspect all swing stage stirrups prior to eachtime they are to be used.

u. Never walk under a swing stage scaffold.v, Never reeve a set of blocks on the ground

where dirt, dust, or mud will get on the ropes.w. Never use a swing stage scaffold without

a guardrail.

20-15. All the units that form a part of aswing stage or the units that are used in conjunc-tion with it should be inspected each time beforethey are used. The wooden platforms, guardrails,and toeboards, as well as metal stirrups andhooks, should be inspected for worn parts. Thesteel cables should be inspected for broken wires,corrosion, wear, and kinks. Fiber rope inspec-tion should reveal any broken, cut, or weakenedstrands.

20-16. Swing staging should be stored in adry place to prevent the warping and splinteringof wooden sections; the rusting of wire cable,tackle blocks, and hoisting machines; and the rot-ting of fiber ropes.

771 11 41

Figure 107. Two half - hitches.

Ito20-17. Boatswain's Chair. A boatswain chair

as shown in figure 103 is made to support oneman. It is used to paint small areas that cannotbe reached by ladders or where it is impracticalto erect a scaffold. It is made up using a doublebowline knot. If the chair is to support a manfor just a short period of time, the notched boardcan be eliminated and the worker can insert hislegs through the loops.

20-18. The boatswain's chair is supported bysecuring blocks and tackle to the roof, ceilingjoists, or rafters. Make certain that they are se-cure. One man can raise or lower himself or canbe assisted from the ground. When workingalone, the fall (control) line is attached to thesuspending tackle with a rolling hitch, as shownin figure 104. This allows the worker to lowerhimself. When the worker is assisted from theground, the fall line must be tied to a tree orbuilding member that will hold the weight of theworker.

21. Hoisting Equipment21-1. The protective coating specialist must

know how to tie simple knots, use blocks andtackle and hoisting equipment efficiently andsafely.

OVERHANDLOOP

21-2. Knots. Knots are used in many ways totie equipment, materials, scaffolds, and manyother items to blocks and tackle so that they canbe raised or lowered as needed. Some of themost commonly used are the square knot, bow-line, half-hitch, double bowline, and rolling hitch.

21-3. Square knot. The square knot is usedfor tying two ropes of the same size together. Itwill not slip and is easy to untie. To tie this knot,lay the running ends of both ropes together butpointing in opposite directions. Pass the runningend of one rope under the standing part of theother. Bring the two running ends up away fromthe point where they cross, as shown at A infigure 105. Cross them again, as shown at B.Pass one running end under the other so thateach is parallel to its own standing part, shown inC, and pull them tight. You have a square knot.

21-4. Bowline. The bowline is used to form aloop in the end of a rope that will not slip and iseasily untied, To tie the bowline, make a loop inthe standing part of the rope, as shown in A infigure 106. Pass the running end through theloop from underneath, shown at B; up andaround the standing part of the rope, shown atC; and back through the loop from the top down,shown at D. The running end passes down

UP THROUGHAND

AROUND BACK

UNDER ITSELF

AND

HROUGH LOOP

DOUBLE A SHORT SECTION

Figure 108. Double bowline.

78

118

FALL LINE END

A

I I I

B

Figure 109. Rolling hitch.

C

SINGLE BLOCK

Figure 110. Reeving single and double blocks.

80

120

Figure 111. Hoisting machine.

through the loop parallel to the rope coming upthrough the loop. Pull the rope tight and youshould have a bowline as shown at E.

21-5. Two half-hitches. A quick way of tyinga rope to a timber is by the use of two half-hitches, as shown in figure 107. To tie this hitch,pass the running end of thee rope around the tim-ber and take a turn around the standing part andunder the running end. This is one-half hitch.Pass the running end around the standing partof the rope and back under itself again and youwill have two half-hitches.

21-6. Double bowline. The double bowlineis made as shown in figure 108. It forms threenonslipping loops. This knot is used for makingthe boatswain's chair that we discussed in theprevious section of this chapter

21-7. Rolling hitch. The rolling hitch is usedto lower a load slowly. An important use of this

1/3

knot for the protective coating specialist is withthe boatswain's chair. The workman can lowerhimself by releasing the pull on the fall line androlling the knot. How to tie this knot is illustratedin figure 109.

21-8. Repeated tying of knots causes rope towear rapidly. It should be inspected frequentlyto insure safety. Check rope visually for abra-sions, broken fibers, cuts, fraying, and deteriora-tion from acids or corrosive substances. Removefrom service any rope fc,und to be defective.When not in use, store rope in a dry, well-ventilated place.

21-9. Blocks and Tackle. Blocks and tackle,also referred to as falls, are one type of hoistingequipment used to raise and lower the platformof a swing stage scaffold. A set of falls can bemade in various combinations of single and dou-ble blocks or even triple blocks or more. Thenumber of sheaves (pulleys) designates the sizeof the block. As the number' of sheaves is in-creased, the mechanical advantage is increased.

21-10. To reeve a set of blocks, lay the blocksout on a level surface other than the ground toavoid getting dirt into the operating parts of theblocks. To reeve single and double blocks, referto figure 110 and thread the rope through thesheaves as shown.

21-11. When the reeving is completed, theblocks are ready to be fastened. One block isconnected securely to the load, the other is con-nected to a substantial anchor. To move the load,pull on the fall line (loose end of the rope).

21-12. When you use blocks and tackle forswing staging, the rope must be first grade Manilaof at least 3/4-inch diameter.

21-13. Hoisting Machine. Another item thatyou may be using while painting in elevatedplaces is the hoisting machine, shown in figure111. This machine uses steel cable instead ofrope. Hoisting machines of this type possess alock and brake which are controlled by thepainter. Before leaving this machine, you shouldremove the control handle and lock the brake.All rope and cable used in supporting scaffoldsmust be inspected daily.

CHAPTER 5

Metal Identification and Corrosion

CORROSION OF METALS is a constantenemy of the military, causing extensive

damage to towers, pipelines, trucks, aircraft, andalmost any other item that is made of metal.Corrosion quietly eats away the understructureor heart of a system. The problem is never end-ing. In this chapter, we will identify corrosion,find out what causes it, and discuss how to con-trol it on various types of metal.

22. Types of Corrosion22-1. Since corrosion of metals results in such

tremendous loss of materials, time, and money,just what is corrosion? As to definitions, let'sconsider four different ones.

a. An engineer from the Electro-ChemicalSociety of New York stated that: "Corrosion isthe destruction of a metal by chemical or elec-trochemical reaction with its environment."

b. A reservoir engineer says: "Corrosion.is aprocess of nature designed to increase the hori-zontal permeability of the casing."

c. Encyclopedia Britannica offers this defini-tion: "Corrosion may be used to denote a chemi-cal change through which metal passes from ele-mentary to the combined condition."

d. Webster's Third New International Dic-tionary, 1963 edition, states: "Corrosion is aprocess of being worn away, as metals by rust ormorals by decay."

22-2. Though the definitions vary, they all boildown to the fact that corrosion is a natural actof the metal trying to return to its lowest level ofenergy. In the case of a metal structure, theiron and steel try to return to their natural state,iron oxide (iron ore). The so-called noblemetals, such as gold and platinum, do not cor-rode since they are chemically uncombined intheir natural state. You, as a protective coatingspecialist, are concerned with the chemicalchanges that occur when metal is exposed to theelements.

82

22-3 The most common theory of corrosion iscalled electrochemical. The electrochemicaltheory of corrosion is best explained by the actionthat takes place in a battery cell. A galvanicbattery cell is produced by placing two dissimilarmetals in a suitable electrolyte, as shown in fig-ure 112. The resulting electrochemical reactiondevelops a potential difference between thesemetals, causing one metal to be anodic and theother metal to be cathodic. In a dry cell, thezinc can is the anode and the carbon rod thecathode. Now, when an external electrical cir-cuit is completed, current flows from the zinccase into the electrolyte, taking with it particlesof zinc. This is an example of galvanic corrosionof the zinc case.

22-4. Four conditions must exist before elec-trochemical corrosion can take place:

(1) There must be something that corrodes(the metal anode).

(2) There must be a cause (cathode).(3) There must be a continuous liquid path

(electrolyte, usually condensate and salt orother contaminants).

(4). There must be a conductor to carry theflow of electrons from the anode to the cathode.This conductor is usually in the form of metal-to-metal contact, such as rivets, bolts, and welds.

22-5. The four conditions that are requiredbefore electrochemical corrosion can proceed areillustrated in figure .113. The elimination of anyof the four conditions will automatically stop cor-rosion; e.g., an organic film on the surface of themetal will prevent the electrolyte from connectingthe cathode and anode, and the current cannotflow; therefore, no corrosion occurs. This is illus-trated in figure 114.

22-6. Because some metals are more subjectto corrosive action than others, the possibility ofa corrosion problem and the necessary controlmeasures vary accordingly. Corrosive attacks be-gin on the surface of metal exposed to corrosiveenvironment. If allowed to progress, corrosion

1 f)20

ZINCCORROSION

POSITIVE TERMINAL

CURRENT FLOW

ZINCANODE

ELECTROLYTE ZINC CO4ASION

BOTTOM OF CASENEGATIVE TERMINAL

Figure 112. Theory fat torrosiorkbattery cell.

works down into the core of the material, asshown in figure -115. Since corrosion never origi-nates in the core, there will always be evidenceon the surface when an attack is in progress asshown in figure -116.

22-7. Before you can identify corrosion, youmust know what corrosion looks like on a metalsurface. Corrosion takes place in various forms,depending on the type of metal, environment, andmechanical conditions. Among the many types ofcorrosion are uniform, galvanic, pitting, stress,intergranular, exfoliation, and concentration cells.

22-8. Uniform Correelon. This is the mostcommon form of corrosion. It is a general attackon the metallic surface. The surface effect pro-duced by most a:7-ect chemical attacks is a uni-form etching of the metal. On a pollehed surfacethis type of corrosion is first seen as a generaldulling of the surface. If such corrosion is al-lowed to continue, the surface becomes rough andpossibly frosted in appearance.

,tiCONTINUOUS MOM OM

y PATH ( ELECTROLYTE ),))))))))))))))))))) i\

0»».011V122:4("»»»»)»»»)»»»)))»

O ANODIC rdo1/1" AREA

CATHODIC

AREA

ELECTRON CONDUCTOR METAL%

,,ElE.CTRoN fteli

1 44444444

Figure 113. Conditions of electrochemical corrosion.

123

22.9. Galvanic Corrosion. This is a completeclass of corrosion involving electrochemical actionbetween two metals or between different areasof the same metal having different heat treat-ments or other metallurgical differences. Galvaniccorrosion occurs when dissimilar metals are incontact and an external circuit is provided by thepresence of moisture. It is usually recognizableby the presence of a buildup of corrosion at thejoint between the metals. For example, alumi-aura and magnesium skins riveted together in anaircraft wing form a galvanic couple if moistureand contamination are present.

22.10. When aluminum pieces are attachedWith steel fasteners or screws,' galvanic corrosion(see figure 117) can occur between the alumi-4urn and the steel. The metals grouped togetherin figure 118 have no strong tendency to producegalvanic corrosion and are relatively safe to usein contact with each other. The coupling of

UNBROKEN PAINT FILM

3

NO CONTACT BETWEEN ELECTROLYTE

AND ANODE AND CATHODE

T

))).?))) ))PATH (ELECTROLYTEjo

)))))))))))), )))10)))))))))2))242/Z)))?))))));

ANODIC

AREA

/4"ELECTION CONDUCTOR METAL

OWNi.

ViRtife 114. Prevention of corrosion by organic film.

116CORROSION CATHODE BRASS BOLT ALUMINUM

CORROSION NEVER STARTSAT THE CORE OF MATERlAt,

Figure 115. Core corrosion.

metals from different groups and diatkit froineach other in figure 118 will usually ke5ult ingalvanic or accelerated corrosion of metalhigher on the list. The farther apart tilt metalsare in figure 119 the greater will be filo galvanictendency. This can be determined by Oessuringthe electrical potential difference betv/tett anytwo metals.

22-11. Pitting Corrosion. Pitting cortAion frayoccur in most alloys, but it is most coPoilloo inaluminum and magnesium. It is first optieeobleas a white or gray powdery deposit, hnilar todust, which blotches the surface. Whtpt the de-posit is cleaned away, tiny pits or hoieS Can beseen in the surface.. This type of cp0o5loo isa localized form that begins at a brtA In thepassive (protective) film. Once broketli a cell isformed between the exposed metal and the pas-sive metal. Such breakdowns in the protectivecoating can occur at a rough spot, olachioingmark, scratch, or other surface flaw. piktiag cor-rosion can also occur under a small dews* (weldspot or dirt particle) which prevents if accessof oxygen to the metal. Pitting corrOion pto-

SURFACE COIVOICIN

CORROSION

ATTACK MUST BEGIN ATOUTER SURFAC!': BEFORE

PENETRATION TO CORE

Figure 116. Point of entry-core co:rpgion

STEEL NAILS (CATHODE)

CORRODING AREA

ROOF

2

STEEL GUTTER(ANODE)

ALUMINUM(ANODE)

CORRODING AREA

COPPER DOWNSPOUT (CATHODE)

Figure 117. Galvanic corrosion-aluminum to steel.

ceeds at a rapid rate if the products of corrosionare conductive.

22-12. Stress Corrosion. This type of corrosionis caused by the distortion of the granular struc-ture of the metal. Such distortion may be in-duced by the metal's being punched, cold riveted,shrink fitted, or otherwise distorted after hot fin-ishing. The distortion may also be caused by abending or twisting of the metal. This bending ortwisting condition may be a continuous stress orit may be an alternating stressed and unstressedcondition.

2243. Stress corrosion is due primarily to thefracture of the metal's surface film or coating.The fracture or tiny cracks permit the entry ofmoisture which results in an acceleration of thecorrosion process.

22-14, After surface cleaning, stress corrosioncracks are usually visible at the bottom of corro-sion pits. These corrosion pits may be formedprior to any stress condition, or they may formsimultaneously with the stress, in which case thepitting rate is more rapid. In the second stage,the stress crack at the base of the pit developsrapidly and gradually penetrates the section untila fracture occurs.

84 124

Group I

Group II

Group III

Group IV

01.01JPING OF METALS AND ALLOYS

;nesium and its alloys.

Cadmium, Zinc, and Aluminum and their alloys(including the aluminum alloys in Group I).

Iron, Lead, and Tin and their alloys (except stain-1Q%s steel).

Copper, Chromium, Nickel, Silver, Gold, Platinum,Titanium, Cobalt, and Rhodium and their alloys;Ytkiraess Steel and Graphite.

1. Metals classified in the same group are considered similar to one another.

a. Metals classified in different groups are considered dissimilar to one another.

i61.1te 118. Comparative groupings of metals and alloys.

22-15. A good exampiA Of stress corrosion isthe use of cold-worked Wets to join steel sheetsused in storage tank cesstruction. The rivetscarry an internal strain, Aic deformation of therivet shank, which makes vtlern ;Anodic to the steel.The stressed area forms /10 Onode to the adjacentunstressed parts. Since 1yt rivets were also very

in area compared 0,ith the steel, they be-come badly corroded in Oniparison with the ac-tion on the steel.

22-16. Intergranular etorojon. This type ofcorrosion is the reuslt of ipc Metallic grain bound-aries and the grain partiPle creating a cell in acorrosive solution or ateoslohere. Intergranularcorrosion is an attack on Ale basic grain structureof the metal. A highly nAttified cross section ofmetal shows that its coVostion is made up of anumber of tiny crystals nt` grains. Each of thesetiny grains has a clearly defined boundary andeach differs chemically ftOtii the one in the centerof the metal. The adjacent grains of different ele-ments react with each ettAer as anodes and cath-odes when they are in cppitaet with an electrolyte.The early stages of this t,)ve cyf corrosion cannotbe detected by normal Aunl inspections.

22-17. Some of the 4N01e5S steels are proneto intergranular corrosion if they are heated. Thiscould occur during weltlihg The heating causeschromium carbides to ctjlect at the grain bound-aries, and the corrsion

22-18. Exfoliation Cinik-Oloot Exfoliation cor-rosion is the visible evidtAcc of intergranular cor-rosion. This type of edrozion shows itself bythe "lifting up" of the 40\Yr Otz grains of a metalwhich is caused by the force of expanding cor-

85

rosion occurring at the grain boundaries just be-low the metal's surface. This type of corrosion ismost often seen on metal surfaces having a roughfinish. The rougher, more strained, and less uni-form a surface, the sooner corrosion will start,and the more localized the .action will be.

22-19. Concentration Cell (Differential En-vironmental) Corrosion. Concentration cell cor-rosion occurs when several areas of a metal sur-face are in contact with different concentrationsof the same electrolyte. Corrosion results froma difference in composition of the electrolyte andfrom the difference in concentration. Both condi-tions cause the corrosion of metals. An exampleof dissimilar environments is shown in figure 120.

22-20. There are three types of concentrationcell corrosion: (1) metal ion concentration cells,(2) oxygen concentration cells, and (3) active-passive concentration-cells.

22-21. Metal ion concentration cells. Metalion concentration cells corrosion consists of dif-ferent concentrations of metallic ions in variousparts of water. A high concentration of metalions will exist under .the surfaces where the wateris stagnant. A low concentration will exist adja-cent to the crevice which is created by the raisedsurfaces. An electrical potential will exist betweenthe two points. The area that has the high ionconcentration will be anodic and will corrode.

22-22. For example, where a large object, suchas a pipeline, passes through different soil en-vironments, major corrosion cells extending overseveral miles may be established. Several am-peres of current may flow in tin metal of thepipeline as a result of this condition. Corrosion

IlgMagnesium (Anodic, or least noble)

Magnesium Alloys

Zinc

CadmitiPri

Alunlintartl Alloys

S41

Gast Iron

te.iriless Steel (active)

Lead

Tin

Nickel (active)

Inconel (active)

Brass

Copper

Bronze

Copper-Nickel Alloys

Titanium

Monel

Nickel (passive)

Inconel (passive)

Stainless Steel (passive)

Silver

Platinum

(cathodic, or most noble) Gold

Figure 119. Metal compatability.

86

of the pipeline will occur where the current leavesthe pipe surfaces.

22-23. Oxygen concentration cells. Oxygenconcentration cell corrosion occurs when a solu-tion contains varying amounts of dissolved oxy-gen/cell can develop at any point where the oxy-gen in the air is not allowed to diffuse into the

RIVER

WATER-SATURATED SOIL'

solution. Typical locations of oxygen concentra-tion cells are under either metallic or nonmetallicdeposits (dirt) on the metal surface and underfaying surfaces such as riveted lap joints. Oxygencells can also develop under gaskets, wood, rub-ber, plastic tape, and other materials in contactwith the metal surface. Corrosion will occur at

DRY SOILWATER-SATURATED

SOIL

ANODE AREA

PIPE

. -

SOIL LEAN IN - -. SOLUBLE SALTS. .

;01114 -- - -6 :

:.;

.6. 66.. CATHODE AREA

,.., .

CATHODE AREA

HIGH SOIL RESISTIVITYAREA

SOIL RICH INSOLUBLE SALTS

DRY SOIL

ANODE AREA

SOIL LEAN IN 66

SOLUBLE SALTS

ANODE AREA

LOW SOIL RESISTIVITYAREA

CATHODEAREA

SAND

..: CATHODE AREA

. .

ANODEAREA

CLAY

CATHODEAREA

SAND

6.\

MOIST SOIL

Figure 120. Dissimilar environmental corrosion.

87

HIGH OXYGEN CONCENTRATION

WATER LEVEL

LOW OXYGEN CONCENTRATION

Figure .121. Low-oxygen concentration areas.

the area of low oxygen concentration (anode),as illustrated in figure 121.

22-24. Active-passive cell. Active-passive cellcorrosion is usually found on metals which de-pend on a tightly adhering passive film, usuallyan oxide, for corrosion protection.

22-25. The corrosive action usually starts asan oxygen concentration cell, e.g., salt depositson the metal surface in the presence of watercontaining oxygen can create the oxygen cell. Thepassive film will be broken beneath the dirt par -tide by the corrosion action of the oxygen cell.Once the passive film is broken, the active metalbeneath the film is exposed to the corrosive at-tack. An electrical potential develops betweenthe large area of the cathode (passive film) andthe small area of the anode (active metal).Rapid pitting of the active metal will result asshown in figure 122.

23. Causes of Corrosion23-1. The action of corrosion on pipelines,

atrtzctures, and equipment conveying water, pe-troleum, and gases is a problem of vast impor-tance. In our homes, corrosion and its productseat away the metal walls of hot water heatersand pipes. When leakage occurs, /the heater orpipes are replaced. The Army has similar prob-lems, but they are much greater. Instead ofmaintaining a few feet of pipe as we do in ourhomes, the Army maintains thousands of feet.Thus, if the effect of corrosion on Army equip-ment can be decreased, a substantial saving canbe made.

23-2. Corrosion may develop under a num-ber of various conditions, among them are millscale, cinders, dissimilarity of pipe surface, dif-ferent soil conditions, stray currents, deimcifica-non, graphitization, and hydrogen embrittlement.

88

23-3. Mill Scale. Mill scale embedded in thewalls of iron pipe during its manufacture is onecause of pipe corrosion. The mill scale actuallybecomes the cathodic area, the iron pipe becomesthe anodic area and conductor, and the moistsoil becomes the electrolyte. Current leaves theiron pipe wall, passes through the electrolyte soilto the mill scale, and returns to the iron pipe.This electrochemical action causes severe pittingof the pipe metal at the anodic areas. Continuedaction of this type will eventually weaken thepipe and cause it to fail.

23-4. Cinders. Another type of corrosion oc-curs when iron pipe is laid in a cinder-fill indirect contact with the cinders. The cinders andthe iron pipe constitute the dissimilar metals, withthe pipe forming the anodic area; the cinders,the cathodic area, and the highly ionized soilserving as the electrolyte. The current leaves thepipe through the soil to the cinders and returnsto the pipe. Severe corrosion occurs at the pointswhere the current leaVes the pipe. The galvaniccorrosion wears away the pipe at an acceleratedrate because of the nonpolarizing effect of thecinders and highly ionized soil contamination ofthe cinders.

23-5. Dissimilarity of Pipe Surface. This typeof galvanic corrosion occurs when there arebright or polished surfaces on some areas of thepipe walls in -contact with suitable electrolyticsoil. These bright surfaces become anodic to theremaining pipe surface. In a highly ionized soil,the polished surfaces corrode at an acceleratedrate, weakening the pipe at that point. Thesebright surfaces may be made by a pipe wrenchproducing scars and scratches on the pipe whenit was assembled. The threads on both ends ofa coupling may expose shining surfaces whichcorrode easily. Corrosion in the threads will.eventually cause the perforation of the pipe wall.

23-6. Different Soil Conditions. This is a gen-eral corrosion problem especially prevalent inhighly alkaline areas. Corrosion currents leavethe pipe wall into compact soils and enter thepipe wall from light sandy soils. The intensityof the corrosion currents and the resulting rate

POROUS CORROSION PRODUCTSFORMING TUBERCLES

Figure 122.

1 0..,c1

Action of low-oxygen corrosion.

of corrosion at the anodic areas of the pipe aredirectly proportional to the conductivity of thesoil. Earth current meters are used to determinethe location of the anodic and cathodic areasand the extent to which corrosion current exists.This meter determines if the pipe requires pro-tection.

23-7. Stray Currents. Direct-current circuitsthat pass in and out pf an electrolyte' usuallystray currents, many of which are a direct causeof corrosion. This condition poses the greatestproblem in the vicinity of electrical transportationsystems, eleCtrified coal mines, or manufacturingplants where their direct-current distribution sys-tem requires a ground as a complete or partialcircuit return. If a metallic structure, such as atank or pipeline, is laid in such an area, a largegalvanic cell is created, making a perfect setupfor corrosion. Corrosion does not occur at thepoint where the current enters the structure be-cause it is cathodically protected. However, atthe section where the current leaves the struc-ture, severe stray current corrosion occurs. Overa period of a year, this type of corrosion hasbeen known to displace as much as 20 poundsof pipe wall for every ampere of current.

23-8. Bacteria. Biological corrosion is anotherdistinct type of corrosion resulting from electro-lytic or galvanic cell action of minute organisms.It is the deterioration of metals by corrosion proc-esses which occur as either a direct or indirectresult of the activity of certain bacteria, partic-ularly in water or soil environment. These or-ganisms causing bacterial corrosion are bacteria,slime, and fungi.

23-9. Microbiological corrosive action in thesoil is due to physical and chemical changes inthe soil .by the action of these organisms. Somebacteria types are responsible for the productionof active galvanic cells. These cells are producedby the variations of oxygen content in the soil(differential aeration) or the reduction of thehydrogen film over the cathodic areas (depolari-zation).

23-10. Bacteria are mostly found in highlywater-logged, sulfate bearing, blue clay soils.The bacteria concentration as well as the cor-rosion rate varies considerably with the differentseasons of the year. Cast iron and steel pipe arecorroded mostly by the sulfides produced by thebacteria.

23-11. Dezincification. Dezincification is a se-lective corrosion which occurs4n copper and zincalloys. When alloys of this kind (brasses) areexposed to this type of corrosion, the zinc willdissolve out of the alloy leaving only the copper.Since most pipe fittings are made of. brass, de-

1 Avo

89

zincification attacks may weaken these fittingsto the point of failure. In this case, the zincions go into solution, leaving the copper. Thesolution may be impure water or oil that acts asan electrolyte.

23-12. Graphitization. Graphitization, orgraphitic softening, is a peculiar form of disinte-gration which attacks grey cast iron. Cast ironis an alloy made of iron and carbon, the carbonbeing in the form of graphite. When cast ironwith such a composition is subjected to graphiti-zation, the iron dissolves out, leaving behind onlythe graphite. This action leaves cast iron weak-ened mechanically. However, after graphitiza-tion, the graphite pipe may last for many yearsif it is not subjected to any mechanical forces orsudden pressures.

23-13. Hydrogen Embrittlement. Hydrogen em-brittlement is a term applied to metal that be-comes brittle due to the action of hydrogen onits surface. When hydrogen forms on the surfaceof steel, the action of the hydrogen may formblisters or actually embrittle the metal. It hasbeen demonstrated that hydrogen liberated nearthe surface of steel in an electrolyte will diffuseinto the metal quite rapidly. This hydrogenpicked up by the steel in an atomic state causesthe steel to become brittle.

23-14. When the production of atomic hydro-gen at the surface of the metal stops, the hydro-gen leaves the metal in a few days, and the metalagain regains its original ductility.

23-15. It has been found that carbon steelsare affected by hydrogen embrittlement accord-ing to the hardness in the steel. The harder themetal the greater is the susceptibility to hydrogenembrittlement. Hydrogen embrittlement in car-bon steels is also increased by the presence ofstresses.

24. Corrosion Control24-1. HoW can you -control corrosion? Now

that you know what corrosion is and what causesit, you must know how to control it. Basically,the same principle that causes corrosion is usedto counteract corrosion. This is done in severalways, but the most common are known as pas-sivation and cathodic protection.

24-2. Passivation. A passivator is an inhibitorwhich changes the potential of a metal to amore cathodic value. An inhibitor is a chemicalsubstance or mixture which, when added to anenvironment usually in small concentration, ef-fectively decreases corrosion. Figure 123 listsseveral types of mixtures for passivating metalsurfaces. Now, the term "passivity" may be de-fined as the property by which certain metalsbecome inactive in a specific environment. Met-

raaals that do not usually form protective films un-der service conditions may be protected by im-mersion in chemical baths containing inhibitors.Passivity of a metal, such as stainless steel, isgained by the formation of a protective film onthe metal's surface by its absorption of atomsor ions.

24-3. By either of the above definitions, pas-sivation of a metal surface serves to make thesurface more resistant to corrosion by eitherphysical or chemical treatment. One is based onthe corrosion behavior of the metal or alloy, andthe other is based on the electrochemical beha-vior of the metal or alloy.

24-4. The passivity of metals can be attrib-uted, directly or indirectly, to a protective filmwhich changes the galvanic potential of the metalor alloy in a more noble direction. For example,the inhibiting action of the chromate ion in zincchromate priming paint provides protection byboth passivation and mechanical means. Thezinc chromate diffused in the paint provides aconcentration of chromate ions on the metal'ssurface and tends to passivate the base metal.The chromate film shares electrons from surfaceiron atoms to make the metal surface less reac-tive and more noble in the galvanic series. So-dium nitrate is also used as a passivator and willrender iron several tenths of a volt more noble

Type of Coating Metal Solution Application

Zinc Iron, Steel 5 to 10 percent hydrochloricacid/water solution for 5 to15 seconds. (76°F.)

Dip or brush

Cadmium Tin Same as above (except 68°-77°F.) Dip or brushTin Iron, Steel 4 oz. concentrated sulfuric acid

.4 oz. tartaric acid

.4 to 8 oz. animal glue

.13 oz. beta-naphthol for eachgallon of water in tank (68° to77°F.)Apply 10 to 30 amperes per sq.ft. metal

Immerse (untildesired thicknessis obtained)

Chromic-Nitric-Hydrofluoric AcidPickle

Used for pick-ling all types ofcastings topassivate surfacebefore machining

37.5 +.. 2.5 oz. chromic acid3 ± .5 fluid oz. nitric acid1 4" . 2 fluid oz. hydrofluoricacid for each gallon of waterin tank. (70° to 90°F.)

Immerse 30seconds to 2minutes

Electroptate Stainless Steel 1 part sulfuric acid in 4 partswater. Apply 200-amperesper sq. ft.

Immerse

Manganese Ferrous metals.(Used to pickleparts that willgo into longterm storage oras a base forpaint)

55 lbs. liquid manganese33 lbs. liquid zinc phosphate20 lbs. degreased steel woolper 100 gallons of water(205° to 210°F.)

Immerse 45minutes (shakeat intervals)

Nickel Brass/CopperS'eol /Aluminum

44 oz. nickel sulfate5 oz. nickel chloride5 oz. boric acid pergallon of water in tank.Apply 20 to 100 amperesper sq. ft.

Immerse

*NOTE: Never add water to an acid when mixing any acid solution. Slowly add the acid tothe water

Figure 123. Passivation solutions.

901"

than iron in distilled water. The nitrate ion is

oxidizing in nature and, like chromates and otheroxidizing passivators, reduces corrosion.

24-5. The use of metallic coatings and clad-dings is another way of making a metal passiveto its environment. This means of protectingmetal plates its surface with another corrosion-resistant metal. In some cases, plating gives thebase metal a hard wear-resistant surface in ad-dition to protection against corrosion.

24-6. Anodic coating can be applied to mag-nesium and zinc as a protection against corrosion.The protective oxide film provided by anodictreatment is of the same general type as thatafforded by the natural oxide film. However, thenatural film is very thin; thus, anodic coatings,because of their greater thickness, uniformity,and abrasion resistance, offer better protectionagainst corrosion. Look again at figure 123 andstudy the types of passivation applicable to dif-ferent mctals as well 'as the chemicals used for

passivation.24-7. Passivation by the electron theory deals

specifically with metals and alloys that becomemore noble because of their electrochemical be-havior. In application, advantage is taken of theinhibiting action of ions in protective coatingswhich passivate by both electrochemical and me-chanical means. Coatings and claddings are alsoused and in rnzny cases provide the most eco-nomical solution to the corrosion problem.

24-8. Cathodic Protection. Cathodic protectionis a method used to protect metal structures fromthe action of corrosion. As explained before, gal-vanic cell corrosion is the major contributing fac-tor to the deterioration of metal by electrochem-ical reaction. The area of a structure thatcorrodes is the anode or positive side of the cell,Corrosion occurs when the positive electric cur-rent leaves the metal and enters the electrolyte.Galvanic cathodic protection is dcsigned to stopthis positive current flow. When the current isstopped, the corrosive action stops and the anodesdisappear. This type of protection depends uponthe neutralization of the corroding current andthe polarization of the cathode metal areas.

24-9. Galvanic cathodic protection is a meansto reduce or prevnt the corrosion of a metalsurface by the use of sacrificial anodes or im-

pressed-current methods. The sacrificial anodemethod is known as the galvanic anode methodand the latter method merely as the impressed-current method. These two methods can be usedseparately or in conjunction with each other, de-pending upon the corrosive characteristics of theelectrolyte surrounding the structure.

24-10. Galvanic anode method. The galvanicanode method of cathodic protection uses an elec-

91

131

167.3

trode referrcd to as a sacrificial anode that cor-rodes to protect a structure. This sacrificial anode

is electrically connected to and placed in thesame electrolytic area of the structure. The anodeused to protect iron or steel structures should bemade of magnesium or zinc so that it will produce

a sufficient potential difference to cause thestructure to become a cathode. The action ofthis type of galvanic protection causes the electriccurrent to flow from the sacrificial anode throughthe electrolyte to the structure to be protected.The electrical connection between the two metalscompletes the circuit and allows the current toreturn to the corroding metal. The sacrificialanode becomes the anode of the established dis-similar metal galvanic cell, and the structure tobe protected becomes the cathode. The currentfrom the sacrificial anode is intense enough tooppose or prevent all positive current flows fromleaving the anodes in the structure to be pro-tected. The prevention of the positive currentflow from the anodic areas in the structure re-duces the corrosion rate to almost zero.

24-11. Galvanic cathodic protection is used inareas where the corrosion rate is low and electric

COLD WATER INLET is HOT WATER OUTLET

PLASTIC DIP TUBE

DRAIN VALVE

SAUSAGE TYPEMAGNESIUMANODES

GAS FIREDHOT WATER TANK

GAGE PIPINGVENT PIPE (COATED) HOUSE

BURIED OIL TANK (COATED)

FILL PIPE/

CU

Nee,

BASEMENT

MAGNESIUM ANODEIN PREPARED BACKFILL

Figure 124. Galvanic cathodic protection.

RECTIFIER

HIGH SILICONCAST IRONANODESBACKFILL

WELLCASING

Figure 125. Impressed-current cathodic protection.

power is not readily available. Figure 124 showsa typical example of galvanic cathodic protection.

24-12. Impressed-current method. The im-pressed-current method of cathodic protection isdesigned to protect large metal structures locatedin corrosive areas. With this method of protec-tion, a source of alternating current is required.In addition, a rectifier is needed to obtain therequired direct-current potential.

24-13. The basic principal of the impressed-current method is merely the application of thegalvanic cell reaction. The component parts ofthis method are: the cathode which is the metalstructure to be protected, the anode made ofsuitable anodic material, the electrolyte or groundwhich is the ionized corrosive material, and therectifier and various connections which serve tocomplete the electrical circuit. The operation ofthis method depends on the rectifier which forcesdirect current from the anode through the elec-trolyte (ground) to the metal structure to be pro-tected. This method causes the metal structureto be the cathode, suppresses all anodic currentsfrom it, and in turn prevents corrosion of thestructure. Figure .125 shows a setup of an im-pressed-current method of cathodic protection.

25. Metal Identification25-1. Unknowingly, you identify metal every

day; for instance, a penny is made of copper,dimes and quarters are made basically of silver,and nickels are made of nickel. You can identifythem by looking at them. Some metals can beidentified by their use, such as aluminum foraircraft skin, and copper for electrical wire.

However, this general classification is not goodenough for the purpose of corrosion control, be-cause if you misidentify a type of metal, thework you do may damage the metal or createa condition that will increase the possibility ofcorrosion. By misidentifying metal, you maywaste your efforts, damage material, or causecorrosion.

25-2. The first and one of the most importantsteps in fighting corrosion is to identify the mate-rial that has been attacked by corrosion or is tobe protected against corrosion. There are othertests besides visual which will help you determinethe type of metal. These are mechanical tests,chemical tests, and complex tests.

25-3. Visual Examination. Often visual exam-ination will reveal numbers or color codes thatwill identify the metal. The Society of Auto-motive Engineers (SAE) and American Iron andSteel Institute (AISI) have established a meansof identifying steels with numbers and colors.

25-4. Number system. The number systemworks in the following manner: A four- or five-digit number is used to indicate the type of steel.For example, 2330 is a number code identifyinga certain steel. The initial number, 2, indicatesthe main alloying element; i.e., nickel in thiscase. See figure 126. The second digit, 3, indi-cates the percentage of the main alloying elementother than carbon. Thus there is 3 percent nickel.The last two digits in the number indicate theamount of carbon expressed in hundredths ofpercent; our example indicates that thesteel has0.30 percent carbon.

25-5. In the case of a five-digit number, thesecond and third digits are used to express thepercent of the main alloying element when thisfigure requires more than one digit; i.e., 1.50percent, 18.00 percent, etc.

25-6. In the case of plain carbon steel, 1095,the same system of interpreting the number isused except that the digit 1 represents carbonsteel, and, since there is no main alloying ele-ment other than carbon, the second digit is al-ways 0.

25-7. Color code system. A color code sys-tem linked to the numerical system of identifyingthe various alloys is used to mark these alloys.At present there are two color code systems inuse for identifying metals and alloys. One systemis the old SAE-AISI system related primarily tosteel, and the other, a new one, changes the oldsystem and also includes aluminum alloys andcopper alloys.

25-8. This new system of identification has itsown color code breakdown which differs fromthe old SAE-AISI system. As described in Tech-nical Order 421374-3, there are ten colors used

921 r)4.0

in this system to represent the numbers 1, 2, 3,4, 5, 6, 7, 8, 9, and 0. Figure 127 helps toexplain this point. These ten colors are also usedto represent letters F, H, 0, T, W, A, B, C,D, and S.

25-9. A combination of these colors, repre-senting a combination of numbers and letters, isused to mark the material to denote its generalcomposition and condition where applicable. Inthe example in figure 128 you see that the alu-minum alloy tubing is marked green, black,green, orange, space, yellow, and red. By com-paring these colors with the numbers on the chart

asin figure 127, you can identify this 'metal as20-25T6.

25-10. A further test in identifying metals isto check for markings such as manufacturers'part numbers or specification numbers. Whensuch data are visible, they should be checkedagainst part numbers, or group numbers shownin the 00-25-113 series of technical orders oralloy groups and material specifications.

25-11. When the specimen cannot be identi-fied by part number or specification markings,examine its physical appearance and determineits possible common use. Check the color of the

Type of Steel Numerals & Digits

Carbon Steels 1XXXPlain Carbon 10XXFree Cutting (Screw Stock) 11XXManganese Steels 13XXNickel Steels 2XXX

0, 50% Nickel 20XX1.50% Nickel 21XX3. 50% Nickel 23XX5. 00% Nickel 25XX

Nickel-Chromium Steels 3XXX1.25% Nickel, O. 60% Chromium 31XX1. 75% Nickel, 1.00% Chromium 32XX3. 50% Nickel, 1.50% Chromium 33XX3. 00% Nickel, 0.80% Chromium 34XX.Corrosion and Heat Resisting 30XXX

Molybdenum Steels 4XXXChromium-Molybdenuth 41XXChromium-Nickel-Molybdenum 43XXNickel-Molybdenum , 46XX & 48XX

Chromium Steels . . . 5XXXLow Chromium (0.60% to 1. 10%) 51XXMedium Chromium ( 1. 20% to 1.50%) . . 52XKX

Corrosion and Heat Resistant 51XXXChromium-Vanadium Steels 6XXXTungsten Steels 7XXX & 7XXXXChrome-Nickel-Molybdenum Steels 8XXXXSilicon-Manganese Steels 9XXX

* The Sulfur content of these steels is higher thanthat normally found in plain carbon steels. These arefast cutting steels usually used for screw stock.

Figure 126. Numerical index for steel identification.

93

133

alo

COLOR IDENTI-FICATION NUMBER COLUMN 1 COLUMN 2 COLUMN 3

Federal StandardNo. 595

ANA Bulletin166

Color Number Letter

1520 501 Blue 1 F1460 503 . Green 2 H

1405 504 Olive Drab 3 01310 506 Yellow 4 T

1205 508 Orange 5 W

1105 509 Red 6 A

1010 510 Maroon 7, B

1755 511 White 8 C

1645 512 Gray 9 D

1770 *622 Black 0 S

* ANA Bulletin 157

Figure 127. Identification marking code.

GREEN

BLACK

GREEN

ORANGE

BASE METAL COLOR CODES

TEMPER AND STRAINHARDENING COLOR CODES

LNION....RED

YELLOW

Figure 128. Identification markings.

94 1

metal. Is the color silvery, like polished alumi-num or magnesium; yellow, like brass or gold;gray, like zinc or lead? Its color may guide youas to the alloys or elements to test for.

25-12. Mechanical Testing. If a metal cannotbe positively identified by visual examination,the next step is to see if it is attracted by amagnet and to perform a spark test.

25-13. Magnetic testing. Magnetic testing con-sists of determining whether the specimen is at-tracted by a magnet. The magnet must be freeswinging from a chain, ring, or string. Usually,a metal attracted by a magnet is iron, steel, oriron base alloys containing nickel, cobalt, orchromium. However, there are exceptions to thisgeneral rule. This test can serve only as an ini-tial step in identifying a specimen and never asa final test.

25-14. Strongly magnetic metals include pureiron, pure nickel, pure cobalt, iron-nickel-cobaltalloys, and alnico. Lightly magnetic alloys in-clude stainless steels and monel steel. All othermetals and alloys are nonmagnetic.

25-15. Spark testing. Some metals can bereadily identified by characteristic sparks thrownoff when the specimen is held against a high-speed grinding wheel. The spark streams mayvary from a few tiny sparks to a shower ofsparks. Skill in spark-testing takes practice.When possible, compare the sparks thrown off bythe unknown specimen with spark streams fromknown samples. Standard samples of known spe-cifications should be maintained for comparisonpurposes. When testing, hold the specimen witha firm, even pressure against the top of the re-

volving grinding wheel. The surface of the grind-ing wheel should be cleaned frequently to freethe wheel of metal particles retained during prioruse.

25-16. A high-speed bench grinder is recom-mended for spark testing. It should have a 6"to 8" wheel, medium grit composition, 1/2 to 3Ahp, 110 or 220 volt, 3,400 to 4,000 rpm. Alwayswear goggles when spark testing.

25 -17. Metals and alloys that will produce aspark on a grinder include aluminum, brass, cad-mium, copper, gold, lead, zinc, and antimony.Stainless steels and high-temperature alloys withiron and nickel base compositions will producecharacteristic sparks. (See fig. .129). As a gen-eral rule, the more .iron in a specimen, the lighterthe. spark will be. As the percent of iron de-creases and the percent of nickel increases, thespark will darken.

25-18. Chemical Spot (Acid) Test. A spot testmay be made by placing one or more drops ofacid on the metal surface of a specimen to ob-serve the reaction to the acid. Snot tests arebased on the formation of characteristic colorsproduced by the reaction of the acid on the metalsurface. A small surface of the specimen shouldbe cleaned with an emery cloth, file, or grindingwheel before making a spot test.

25-19. Some of the acids needed for testingconsist of:

(1) Nitric acid (concentrated).(2) Hydrochloric acid (concentrated).(3) Potassium ferricyanide (10 percent solu-

tiondissolve 10 grams of potassium ferricya-nide in 100 milliliters of water).

WROUGHTIRON

MACHINESTEEL

CARBONTOOLSTEEL

GRAYCASTIRON

WHITECASTIRON

HIGHSPEEDSTEEL

MANGANESESTEEL

STAINLESSSTEEL

TUNSTENCHROMIUMDIE STEEL

NITRIDEDNITRALLOY

.f')

..

,

.:.,11

(IS

A

,

A

.ANNEALEDMALLEABLE

IRON

CEMENTEDTUNGSTENCARBIDESTELLITE NICKEL

P.,4,

Figure 129. 'Typical spark streams.

95

1`'5

25-20. In nitric acid testing, place one dropof concentrated nitric acid on a clean metal sur-face. The following reaction should result:

Metals

BrassCadmiumCobalt (pure)CopperCopper-nickelMagnesiumMonelNickel (pure)SilverTinZinc

Reaction

Blue-greenYellowRedBlue-greenBlue-greenEffervesccntno colorGreenPale greenGray-whiteWhiteEffervescentblack

(brown fumes)

25-21. In nitric aciddiluted (50 percent acidand 50 percent water) testing, place one dropof diluted nitric acid on a clean metal surface.The following reaction should result:

Metals

IronManganese steelNickel iron alloy

(5 to 80 percentnickelbalanceiron)

Reaction

Brown-blackBrownBrown

25-22. Metals and alloys that will not reactto nitric acid (concentrated or diluted) include:aluminum, antimony, cobalt, gold, high-tempera-ture alloys, tungsten, lead, platinum, stainlesssteels, tantalum; and titanium.

25-23. Aqua regia acid consists of on partnitric acid mixed with three parts of hydrochloricacid. Since this mixture breaks down after 24hours, you may make this test by placing onedrop of nitric acid and three drops of hydro-chloric acid on the spot to be tested. This solu-tion should turn blue-green for cobalt-base al-loys, and green for nickel-base alloys.

25-24. Potassium ferricyanide (10-percent so,.lution) May be used to determine the iron con-tent of nickel-base alloys since there is no simplespot test for determining the percent of nickelcontained. This test may be made by adding adrop of potassium ferricyanide to the spot testedby aqua regia. The color reaction will be verydark blue-black for a high iron content, and alight blue for low iron content.

25-25. Complex tests. Complex tests are quali-tative tests consisting of a spectrographic orchemical analysis and should only be used whena specimen cannot be identified by other testsor when the quantity involved warrants it.

96

1

1-2.3- 32.715 Ft Behicsir

127

EXAMINATION

ARMY CORRESPONDENCE COURSE ENGINEER SUBCOURSE 562

PAINING

CREDIT HOURS 2

TEXT ASSIGNMENT ,/ Review previous assignments.

EXEkt105

1. Which of the following would,,nu use to protect yourself against thelusts from sanding?

dispersoid respirator

b. chemical cartridge respirator

c. supplied air respirator

d. hard hat with goggles

2. A hazardous painting location isthe interior of a tank. Which of thefollowing locations might be more haz-ardous?

a. gymnasium

b. closet

c. roof

d. parking lot

8. Which of the following manualswould you select as a guide in the useof general safety measures?

a. TM 5-311 c. EM 385-1-1

b. TM 5-333 d. TM 6-680

4. You are the foreman of a crewabout to start a painting job. You pre-pare your men bya. avoiding discussion of possible haz-

ardsb. giving a supplied-air ventilator to

each

NRI 1 06 1

c. recording unanswered safety ques-tions for answers immediately uponcompletion of job

d. using safety check list

5. When would you splice laddersto form a longer ladder?

a. when bottom ladder was metal

b. when there were safety shoes foronly one ladder

c. if each ladder was not over 10 feetin length

d. never

O. Most paint products are flam-mable because they contain

a. oil

b. pirnents

e. solvents

d. resin

I. Which of the following lists theprimary uses of painting?

a. beautification, decoration, mina-tion

b. maintenance, safety, efficiency

c. camouflage and visibility

d. sanitation and fire retardanes

1

130

8. Which of the followiAg listsearth colors?

a. yellow ocher, raw and bur* sienna,raw and burnt umber

b. pale blue, deep green, dark maroon

c. bright orange, dull red, light /ma-roon

d. browns, voilet, pink

9. A paint drier is aa. vehicle

b. binder

c. film softener

d. catalytic agent

10. What are paint volattiAef

a. catalysts c. thins tfl

b. plasticizers d. driees

11. Which of the followikA Wouldyou use to clean tools and etif\ipuleatthat you had used in paint tAg wltbwater-naixed paints?

a.

b.

C.

d.

turpentine

paint remover

commercial brush-cleaner

soap and water

12. What are the three 1)1Palzrycolors of paint?a. black, white, redb. blue, red, yellowc. green, purple, oranged. bone black, iron blue, metallf brown

18. What are the three atAoRdsrycolors of paint?a. orange, green, purpleb. red, yellow, bluec. black, white, brownd. white, red, black

21' %3

14. What do you use to fill the pores (-7:

of absorbent surfaces in preparation forpainting?

a. epoxy

b. sealer

c. undercut

d. primer

15. What would you use to removeplane marks and mill marks from awood surface?

a. emery

b. scraper

c. knife

d. chisel

16. No maintenance is necessary onthe

a. descaler

b. power buffer

e. orbital vibrator sander

d. portable belt sander

17. A painter in your crew hes noprevious experience with abrasive blast-ing equipment. How many hours op- --

erating time would you need to give hima basic knowledge of abrasive blastingtechniques?

a. 12 to 24 c. 8 to 16b. 10 to 20 d. 6 to 10

18. The abrasive blaster is operatedby

a. steam

b. foot pedals

e. water pressure

d. compressed air

19. You could use a paint brushhaving nylon bristles when you are ap-plying

a. enamel

b. lacquer

a. acid

4. water-thinned paints

20. What would Voir use to clean abrush that has beet *plying shellac?

a. linseed oil

b. paint remover

c. benzol

d. alcohol

21. Which type paint roller coaterwould you use in pOnting shingles?

a, high pile cover

b. lamb's wool cover

c. mohair cover

d. stippler

22. For proper Aparatios of spraygun equipment, the gWi must receivean adequate supply Af

a. compressed air

b. linseed oil

C. alkali

d. paint thinner

23. The lubrica04 oil in the gaso-line engine of a po*troperated traffic-marker machine AN ld be changed atintervals of

a. one to two we4ts

b. 25 to 50 operathlg bourn

c. 20 to 30 operatlbg boars

d. 2 to 4 days

24. The size of a kidder is deter-mined by its

a.

b.

c.

d.

weight

overall length

knots in wood

rung circumfelOce

25. A ladder fob A painting job isselected according tfJ

131

a.. height of building to be painted

b. height at which painter must work

c. distance it must be carried frompaint shop

d. number of men in paint crew

26. What kind of knot would youuse in making the boatswain's chair?

a.

b.

C.

d.

two half bitches

square

bowline

double bowline

27. What causes galvanic corro-sion?

a.

b.

c.

d.

etching of the metal

pitting

stress

electrochemical action

28. While painting, you notice thata brass shutoff valve is bent out ofshape. What type corrosion could be thecause?

a. dezincilication

b. biological

c. intergranular

d. exfoliation

29. What kind of coating would youput on tin to prevent or retard corro-sion?

a. zinc

b. cadmium

c. nickel

d. manganese

30. You place one drop of concen-trated nitric acid on a clean metal sur-face. The metal turns white at thatspot. What is the metal?

a. brass c. tin

b. copper d. monel

S

/3&ENGINEER

SUBCOURSE 563

iwIwi,111011,,',J;MIWNI)111

PAINTING IIAPPLICATION )

CORRESPONDENCE COURSE PROGRAM

U. $. ARMY ENGINEER SCHOOLFORT BELVOIR, VIRGINIA

140 NRI 108

133

INTRODUCTION

This subcourse is a continuation of the in-struction in Memorandum 562, Painting I. Itexplains the preparation of wood, masonry,and metal surfaces to receive coatings ofvarious kinds of paints. The present instruc-tion also covers the methods used to estimatepaint requirements, discusses the fundamen-tals of work inspection, and cites the stan-dards that are used in evaluating acceptableworkmanship.

The =bourse consists of four lessons andan examination as follows:

Lesson 1. Painting Wood Surfaces.2. Painting Masonry Surfaces.3.. Painting Metal Surfaces.4. Inspection of Surfaces.

Examination.

Twelve credit hours are allowed.You will not be limited as to the number

of hours that you may spend on the subcourse,

any lesson or the examination. For statisticalpurposes, you are required to enter in theproper space on each answer sheet the num-ber of hours spent in studying the text andsolving the exercises.

Text furnished:. Memorandum 563, Paint-ing II.

To facilitate removal, answer sheets arebound in reverse order at the end of thispamphlet. Make sure that the number on theanswer sheet is the same as the lesson onwhich you are working.

Each exercise has four choices with onlyONE best answer. Select the choice that youbelieve is best, then turn to the answer sheetand mark an X through the letter repre-senting that choice.

The examination will be sent to you whenyou have successfully completed all the les-sons.

bY/

LESSON 1

PAINTING WOOD SURFACES

CREDIT HOURS 3

TEXT ASSIGNMENT Chapter 1, Memorandum 563.LESSON OBJECTIVE To teach you how to use the equipment and

the techniques needed to apply variouskinds of paints to wood surfaces.

EXERCISES

Requirement. Solve the following multiple-choice exercises.

1. You are using pattern paintingin camouflaging a building. How is thiscamouflage made effective?a. colors chosen should blend with the

backgroundb. patterns should be as small as pos-

siblec. windows should be painted blackd. many colors should be used

2. Which of the following wouldyou use to tighten a knot that "rattles"in a board that you must use?a. type II calking compoundb. shellacc. turpentined. thin screws

3. Paint deterioration has reachedthe advanced break-up stage whena. checking and crumbling appearb. flaking and scaling appearc. disintegration lays bare enough

wood for the boards to show dis-tress of wood weathering

.1/12

d. coating has reached the fissurestage and causes crumbling andflaking

4. You have just sanded and filleda hardwood floor. You want now togive it the most durable surface. Whichof the following do you apply?

a.

C.

d.

spar varnish

shellac

stain varnish

floor sealer

5. How would you use a liquidpaint remover on a wooden surface?

a. brush it back and forth to preventleafing action

b. allow it more time to loosen the oldcoating than you allow for a pasteremover

c. continue to apply the remover untilold coating loosens and drops off

d. allow softening action to continueuntil one stroke of the scraper willtake off everything down to the barewood

1 -1

135

O. You are preparing a wood sur-face for painting. In using a scrapingtool to remove bare wood as part of thispreparation, you would

a. scrape against the grain

b. sandblast surface before the scrap-ing

c. remove only enough wood to clearthe surface of defects

d. wet the surface to raise nap of thegrain

7. You are about to paint a double-hung window. You pull the top sashdown slightly and also raise the lowersash. You do this in order to

a. paint the top rail, bottom rail, andthe inside of the meeting rails

b. paint all glazing compound as aseal with panes

c. prevent sash from sticking

d. paint the muntin and the mullionrails

8. You can recognize mildewthrough a magnifying glass by the

a. granular mildew particles of irregu-lar size and shape

b. numerous egg-shaped spores whilemildew grows

c. numerous egg-shaped spores whenmildew is dry and dormant

d. threadlike mycelia when mildew isdry and dormant

9. A pine floor may be finishedwith a transparent coating, but you de-cide to paint it because

a. it is easier to sandb. pine is a softwood which dents and

mars easilyc. it would require too many coats of

varnishd. it is too difficult to stain

1i3

10. You are preparing to repaint anexterior wood surface. You will usetwo coats on this surface if

a.

b.

C.

d.

you don't prime the surface

the old coating is less than 3 milsthick

the old coating is chalking

the initial paint is streaked

11. Which of the following is a dis-advantage of using interior fiat-finishPaint?a.

b.

produces eggshell surface that peels

fails to distribute light

C. must not be washed after it hasdried

d. will not stand as many vigorouswashings as a semigloss paint .

a.

b.

e.

d.

12- You would use filler on hard-woods

before applying a transparent finish

with pores larger than those inbirchwhen applying an opaque finish

which are heavy and have smallpores

18. You are using a roller to paintstippled surfaces. How do you makesure that the paint is properly appliedand that coverage is adequate?

a. work very slowly so that the fast-spinning roller flings off no paint

b. paint from one edge of ceiling andtoward the door

e. make crisscross strokes and finishwith long parallel strokes

4. load roller to capacity

14. Calking compound comes in twogrades. Both'grades

a. are suitable for use at temperaturesabove 40° F

b. can be used in a calking gun

c. form hard exterior with soft under-body

. d. can be thinned with butyl alcohol

15. You are about to apply waterstain to finish some furniture. You firstdampen the wood surface with water.Why?

a. gives stain more penetrating action

b. raises the nap in the grain of thewood

c. tones down stain color and facili-tates blending

d. removes any filler from wood

16. What happens to the coating inthe flatting stage of paint deteriora-tion?

a. gradually loses its initial gloss

b. becomes powdery

c. rapidly becomes mildowed

d. develops checking sad cracking fis-sures

17. You haVe just varnished an in-terior wood surface. You allow it todry. You would rub this 'vied surfacelightly with steel wool

1 At 4

/36

a. if turpentine fails to remove anyruns

b. if air bubbles appear

C. if second coat is to be appliedagainst the grain

d. before applying the next coat

18. Blue stain on painted surfaces iscaused by moisture and

a. a soluble dye in the wood

b. growth of certain fungi in sapwood

C. excessive heat

d. failure to use undercoat

18. You are applying a three-coatpaint system to new wood construction.You gage the spreading rate to give atotal coating thickness of how manymils? _

a. 2 to 3 c. 4 to 5b. 3 to 4 d. 5 to 6

20. Crawling occurs in freshly ap-plied paint when the

a. new coating fails to wet the surfaceof the old paint

b. new coating is applied in damp airat 25° F or lower

c. solvents in new coating soften oldcoating

d. paint is applied in unduly thicklayers

1-8

LESSON 2

.PAINTING MASONRY SURFACES

CREDIT HOURS 2

TEXT ASSIGNMENT Chapter 2, Memorandum 563.

LESSON OBJECTIVE To teach you the characteristics of masonryand the methods to use in preparing itssurface to receive special paints.

EXERCISES


1. You have applied traffic, oil-basepaint at a temperature of 700 to 90° F.This should dry to a gloss finish withina. 30 minutes e. 2 hoursb. 1 hour d. 3 hours

2. Mortar to be used for repair ofmasonry joints is made by mixinga. 3 parts fine masonry sand and 2

parts portland cementb. 2 parts fine masonry sand and 1

part portland cementc. 1 part fine masonry sand and 1 part

masonry cementd. 2 parts fine masonry sand and 1

part masonry cement

3. You are about to apply epoxyfloor enamel to a concrete floor. Howdo you first prepare the floor?a. etch it with acid13. scrub the floor with triaoditun phos-

phate and waterc. treat it for alkalinityd. treat it for efilorescence

4. If you were applying a series ofcoats known as scratch, brown, andfinish, you would ba

a. bedding abeetrock

b. applying plaster during construc-tion

c. painting wet plaster

d. removing rough spots from sheet-rock

5. You are preparing an acid-watersolution to remove glaze from a con-crete surface. What is this solution andhow do you use it ?,

a. 10-percent muriatic acid solution;allow it to remain on the surfacefor 5 to 10 minutes, then hose it offwith water

b. 20-percent muriatic acid solution;allow it to remain on the surface for20 to 30 minutes, then sponge it offwith water

e. 10-percent muriatic acid solution;apply the paint without removingresidual powder on the surface

d. 20-percent muriatic acid solution;apply the paint before acid evapo-rates

6. You are taping and beddingsheetrock joints. You use three-coatcoverage because you want to

a.

b.

c.

d.

prevent the joint from bending

prevent tape from showing through

insure a proper buildup of com-pound to conceal the joint

prevent the joint cement fromshrinking

7. You received 6 gallons of pig-mented binder for a traffic marking job.How many pounds of glass spheres doyou need?

a. 5 cs. 30

b. 15 d. 40

8. To properly set a nail in sheet-rock, you would strike the nail withsufficient force to get the nail head

a. 1/2 inch below surface and into gyp-sum core

b. even with surface hammer marks

c. 1/32" above surface

d. below the surface of the sheetrock

9. Which of these paints would youuse on exterior masonry walls to attainsome damp-proofing?

a. rubber-base c. cement-baseb. latex d. oil base

10. A varnish size coat for applica-tion to new plaster can be prepared bythinning each gallon of varnish with

a.

b.

C.

d.

1 quart of turpentine1 quart of boiled linseed oil1 pint of turpentine1 pint of boiled linseed oil

11. You must remove loose and seal-ing deteriorated paint from a masonrysurface. Which of the following do youuse?

2 2

1 AC

a.

b.

C.

d.

a sandblaster

heat

lacquer solvent

a lye-water solution

1.38

12. What type of traffic markingpaint is used in conjunction with glassspheres?

a. traffic oil-base paint

b. plastic traffic-marking paint

c. traffic pigmented binder

d. gloss traffic-marking lacquer

18. You must apply a cement-water-sand paint to seal cinderblocks againstmoisture. Which of these do you usefor this job?a.

b.

C.

d.

calcimine brush

camel's hair brush

stiff-bristle brush

high pile roller

14. What is the composition of port-land cement patching plaster?

a. 1 part Keene's cement and 1 partplastering sand

b. 1 part portland cement, 3 parts plas-tering sand, and 34 part lime putty

c. 1 part portland cement, 1 part plas-tering sand, 1 part dehydrated lime

d. 1 part masonry cement and 1 partplastering sand

15. You have applied exterior latexpaint on a masonry surface. When willthis paint be dry to the touch?

a. 10 minutes

b. 10 to 30 minutes

C. 30 to 40 minutes

d. 1 to 2 hours

139 ,

16. Latex paints can be applied tonew concrete or masonry surfaces aftera minimum aging period of how manyweeks

a. 1 to 2 c. 3 to 4

b. 2 to 3 d. 6 to 8

17. You must remove loose pillsterin order to repair a wall. How do youremove this loose plaster?

a. begin at center and work back intothe surrounding area to a pointwhere plaster is solid

b. use a hammer to remove all the oldplaster together with the lath

c. thoroughly wet the damaged areawith xylol before chipping out plas-ter

d. remove scratch coat first

18. You are repairing a mortar jointand suspect that the building is settling.You pack the joint to within 1/2" of thesurface with

a. number 2 calking compound

b. cement mortar

c. type 2 puttyd. number 1 calking compound

19. You have made a solution ofphenolphthalein in alcohol. You applyit to a concrete surface as a test. Whatare you testing for?

a. hardness

b. moisture

c. aggregate content

d. alkalinity

20. You find an interior concretefloor which shows signs of alkalinity.It is also subject to continual dampness.You decide to paint that floor with

a. porch and deck paint

b. varnish vehicle-floor paint

c. transparent silicone paint

d. rubber-base paint

LESSON 3

PAINTING METAL SURFACES

CREDIT HOURS

TEXT ASSIGNMENT

LESSON OBJECTIVE

/yo

3

Chapter 3, Memorandum 563.

To teach you the preparation of metal sur-faces, how to identify and prevent cor-rosion, and how to use paint in preventivemaintenance.

EXERCISES


1. Structural steel bleaces shouldbe sandblasted and pretreated prior topainting when they are subject co

a. water immersion and abrasion

b. atmospheric exposure

c. underground exposure

d. interior exposure

2. You are steam cleaning metal.How many inches away from the sur-face do you hold the cleaning nozzle?

a. 6

b. 12

e. 18

d. 24

3. To prevent a burnished effectwhen power brushing metal surfaces,what is the minimum number of squarefeet that you should clean per minute?

a. 1 a. 4

b. 2 d. 10

4. A spray gun is in reasonablygood operational condition when it can

ixs

be adjusted to produce a spray 6 to 8inches wide when the gun is held

a.

b.

C.

6 to 10 inches from surface

vertical to the surface

12 to 18 inches from the surface

18 to 24 inches from the surface

5. You are using stainless steelnails with lead covered heads to re-fasten corrugated metal siding to woodsiding. Where do you place the nails?

a. on top of the corrugations

b. angled on side of corrugations

c. in valleys between corrugations

d. under the corrugations

6. You are operating a high-pres-sure spray gun. How many pounds ofair pressure per square inch do you set?

a. 60 to 80

b. 80 to 100

c. 100 to 125

d. 130 to 150

7. Corrosion will not normally at-tack galvanized iron pipe unless

3 I

a. pipe is threaded

b. pipe has black iron fittings

c. pipe is used in hot water system

d. coating has been destroyed or dam-aged

8. When you mix the componentsof the vinyl wash coat, you would

a. add base solution to the acid

b. slowly add the acid component tothe resin component and stir con-stantly

o. add acid very rapidly to resin com-ponent and let it set

d. add base solution to the resin com-ponent and shake

9. For proper operation and ad-justment of a low-pressure spray gun,the pounds per square inch of air pres-sure should be between

a. 20 to 40 c. 60 to 80

b. 40 to 60 d. 80 to 100

10. How many inches should youhold the airless spray gun away fromthe surface that you are painting?

a. 4 to 6 c. 12 to 16

b. 8 to 10 d. 20 to 24

11. You have applied a chemicalconditioner to a metal surface. Youwill know that the acid has reactedproperly and has the proper dilutionwhen

a.

b.

C.

d.

3 2

a dark color appears and surface issticky

a powdery surface, grayish white incolor, develops within a few minutesafter application

insoluble gels form on the surface

application was maintained at acoverage rate of 250 to 300 squarefeet per gallon

12. A blasting job has removedpractically all rust, mill scale, and otherforeign matter from the surface of themetal. The surface is now not neces-sarily uniform in eanliness and ap-pearance. What do you call this type ofblast cleaning?

a. vacuum c. white

b. brush-off d. commercial

13. You have a tungsten carbidenozzle which you use to apply sand asa surface abrasive. What is the lifeexpectancy of this nozzle in hours?

a. 50 0. 100

b. 75 d. 30C

14. What psi pressure would youuse when sandblasting brick and mortarsurfaces?

a. 40 to 60 c. 100 to 130

b. 80 to 100 d. 150 to 180

15. To assure intimate contact ofthe liquid with the metal, the chemicalmetal conditioner should be appliedwith a

a.

b.

whitewash brush

roller coater

low-pressure spray gun

d. high-pressure spray gun

16. You have filled a Zahn cup withlacquer. YOU do this because you wantto

a. use a low-pressure spray gun

b. use an airless spray gun

c. measure viscosity

d. use a high-pressure air atomizedspray gun

17. You are operating a sandblaster.You control the quantity of abrasiveused by

a.

b.

c.

d.

air pressure

nozzle valve

nozzle orifice

hopper-control valve

18. You must remove old, hardpaint and heavy, hard rust scale froma steel surface. You use

a. deacaler tool

b. power brush

c. heat and brushing

d. power grinder

iya

19. A blasting job has removed allcorrosion products, all mill scale, allpaint, and all other foreign matter fromthe surface of the metal. This type ofcleaning is called

a. commercial

b. whitec. vacuumd. brush-off

20. You must paint 500 gutterbrackets. Which is the best method touse?a. air-atomized sprayb. airless sprayc. electrostatic sprayd. dip .

8 3

CREDIT HOURS

' TEXT ASSIGNMENT

LESSON OBJECTIVE

LESSON 4

INSPECTION OF SURFACES

2

Chapter 4, Memorandum 563.To teach yoi how to inspect surfaces, to eval-

uate the quality of paints and workman-ship, and how to calculate surface areas.

EXERCISES


1. You notice that a painted metalsurface shows early signs of scaling andflaking. Which of the following is aprobable cause?

a.

b.

C.

d.

poor surface preps: :anon

use of a conditioner

mill scale

use of washcoat in preparing thesurface

2. Under average exposure condi-tions; a protective coating on e:Tteriorwood surfaces should have a life ex-pectancy of how many years?

a. 10

b. 8

c. 6

d. 4

3. The atmosphere in contact witha surface being painted should be at orabove 50° F. for water-thinwd paints.What minimum temperature is set forusing other coatings?

a. 35° Fb. 45° F

c. 50° F

d. 60° F

4. Which of the following wouldyou measure with a dial indicator?

a. dry-film thickness

b. wet-film thickness

c. corrosion pits

d. base metal thickness

5. Paints which do not deteriorateby checking or cracking will waste awayby

a. crumbling

b. chalking

6. Whatches of a mi ometer? .

c. flaking.

d. scaling

e usual range in in-

a. 1 c. 3

b. 2 d. 4

7. One gallon of enamel covers 500feet of floor surface. How many gallonswould you order to apply two coats toa floor area 60 feet long and 40 feetwide?

a. 4 c. 8

b. 6 d. 10

4 -1

8. Which of the following is a fac-tor in the covering capacity of a paint?

a.

b.

c.

d.

thickness

color

size of brush

number of painters

9. You are inspecting nailhead setsin a wooden surface. You make surethata. type II putty was used to fill the

sets

b. surface had been primed before thesets were filled

c. nail sets were filled prior to primingand painting

d. they had been set at least % inchbelow the surface

10. You would permit the paintingof a wood surface if the moisture con-tent of the wood did not exceed

a. 5%b. 7%

c. 12%

d. 15%

11. Which one of the followingwould you select as a cleaner for a woodsurface that you are about to paint?

a. scrapers c. solvent

b. roughening tool d. primer

12. Which of the following is usedto measure film thickness on a testpanel?

a. wet-film gage c. dial gage

b. dry-film gage d. micrometer

13. One gallon of paint covers 400square feet of surface. How many gal-lons would you order to paint buildingwalls that are 100 feet long, 50 feetwide, and 10 feet high?

152

a. 4 c. 8

b. 6 d. 10

14. You are the inspector on a con-struction job on your post. In your pos-session at all times you would have enup-to-date set of

a.

b.

c.

d.

submittals'

change orders

specifications

daily diaries

15. When would you calibrate thedry-film thickness gage?

a, when the surface is slick or glazed

b. if it reads zero when in direct con-tact with the base metal

c. if it does not read zero when indirect contact with the base metal

d. when the base metal is pitted

16. What is a submittal?a. a written directive

b. a sample of material or a manufac-turer's certificate

c. a contact

d. plan of construction

17. If there is a difference betweenthe specifications and the drawings, howis this resolved?

a.

b.

c.

d.

inspector decides

contractor decides

drawings will govern

specifications will govern

18. You have decided to use an oil-base paint on the exterior of a woodenbuilding. How many square fcet woulda gallon of the paint cover?

a. 350 c. 250

b. 300 d. 200

19. Which of the following is a suit-able method for removing glaze fromcleaned concrete and masonry surfaces?

a. roughening

b. solvent

1 3-4 33.663Ft Betvoir

c. vinyl wash

d. sandpaper

20. The daily diary that is keptduring the contractural period is main-tained by the

a. contractor c. workmen

b. inspector d. contract officer

1:3

CORRESPONDENCE COURSE OF-2- U. S. ARMY ENGINEER SCHOOL

/f6

.,.. ,.

SUBCOURSE,

S63 Painting H. ,,,,,.

LESSON 1 Painting Wood Surfaces.

SOLUTIONS


1. a2. a

1,, 3. c

4. d

. d

. c

a

8.

9. b

b10.

(par 2-7)

(par 3-18)

(par 2-17f)

(par 4-31)

(par 2 -24c)

(par 2-3)

(par 3-21)

(par 2-21a)

(par 4-25)

(par 3-5b)

For further explanation, see Discussion sheet.

11. d (par 4-3a)

12. b (par 1-8)

13. c (par 4-7)

14. a (par 2-9)

15. b (par 4-38)'*\'''' .*

16. a (par 2-17b)

17. d (par 4-18)

18. b (par 2-21b)

19. c (par 3-5c)

20. a (par 3-8b)

'f


NRI 108

1117

DISCUSSIONExercise:

1. The patterns should be as large as practicable, and the colors should be chosen toblend with the background (a) for the camouflage to be effective.

2. If the center of the knot just moves in the board it can be secured with shellac; butif the center is loose enough to "rattle", it may be tightened by using a type II calking com-pound (a) which hardens as it dries.

3. When disintegration lays bare enough wood for boards to show distress of woodweathering (c), the coating has reached the stage of advanced breakup.

4. You should allow the filler to dry for 18 hours before pro. ceeding. Floor sealer (d)provides a more durable surface than do shellac or varnish finishes.

5. With paste or liquid remover, the softening action should be allowed to continue un-til one stroke of the scraper will take off everything down to the bare wood (d)..

..

6. Remove only enough wood to clear the surface of defects (c). If you remove too much,you could weaken the structural strength of the wood.

. 7. Pull top sash down slightly and raise the lower sash. This will allow you to paint thetop rail, bottom rail, and the inside of the meeting rails (a). Reposition the sashes to paintthe stiles, muntin, and mullion rails.

8. Mildew is characterized by threadlike mycelia when it is in the growing stage, andby numerous egg-shaped spores when it is dry and dormant (c). If you suspect mildew, use amagnifying glass to inspect the area.

.

9. Pine floors are usually painted because pine is a softwood which dents and marseasily (b). Hardwood floors are generally finished with transparent coatings.' ..

10. When the old coating is less than 3 mils thick (b), two coatings are usually needed.The first coat should be a primer.

11. The flat finish can be washed occasionally, but it will not stand as many vigorous wash-ings as a semigloss paint (d).

for12. Hardwoods with pores larger than those in birch (b) are unsuitable for ordinary ex-terior painting. They require a filler to fill the pores before the application of paint.

13. Make several crisscross strokes and finish with long parallel strokes (c) in one direc-tion. This sequence distributes the paint and insures coverage on stippled surfaces. (See figure22.)

14. Grade I is soft and suitable for use in a calking gun, but Grade II has the consistencyof glazing putty and is applied with a knife. Both grades are suitable for use at temperaturesabove 40° F (a).

2 ,: '-;;Al

`'fi:.*:1.';';'iiii..4 ..itteit#0;ti447

/Y8

15. Before applying water stain, dampen the surface with a wet cloth. This raises the nap

in the grain of the wood (b). When the surface dries, the nap is removed byhand-sanding with

very fine grit sandpaper. Figure 26 illustrates the process.

16. In the flatting stage of paint deterioration, the coating gradually loses its initial gloss(a). Flatting does not justify repainting.

17. Allow 24 hours for drying between coats. After one coat has dried hard, rub the sur-face lightly with steel wool before applying the next coat (d).

18. Blue stain is caused by moisture and the growth of certain fungi in sapwood (b). Itoccurs on surfaces exposed to condensation.

19. On new wood, the first coat should be primer and the last two coats finish paint. Thespreading rate should be gaged to give a total coating thickness of 4 to 5 mils (c).

20. Crawling occurs when the new coating falls to wet the surface of the old paint (a).The new coating in this situation collects in drops as water does on a greasy surface.

CORRESPONDENCE COURSE OF.U. S. ARMY ENGINEER SCHOOL,

SUBCOURSE 563 Painting

LESSON 2 Painting Masonry Surfaces.

SOLUTIONS


1. b (par 11-5) 11. d (par 7 -12)

2. d (par 7-6) 12. c (par 11-4)

3. b (par 10-4) 13. c (par 7-9).

4. b (par 9-3) 14. b (par 9-15)

5. a (par 7-2) 15. c. (par 8-9)

8. c (par 9-28) (par 8-8)

7. c (par 11-7) 17. a (par 9-11)

8. d (par 9-29) 18. b (par 7-7),

9. b (par 8-7) 19. d (par 7-3)

:10. a (par 9-20) 20. d (par 10-2)

For further explanation, see Discussion sheet

10;ki. '

'

: !:

-,;',

I.1;47,74,1,-

All concerned will be careful that neither this solution nor information concerning thesame comes into the possession of students or prospective students whol!trveaot completed

.. ,,,,,,,, 4. ..'t .1the work to which it pertains.' . -1 ,107t14P.,4444

',I 4., sjI4 144.46:4 fewr; NR I 108 -...

t, ,

_

DISCUSSIONExercise:

1. At 70° to 90° F, the paint should set to touch in 30 minutes, and it should dry to agloss finish within 1 hour (b).

2. To repair a masonry joint, remove old mortar and loose material, cleaning the jointwith water from a hose; then fill with mortar that you have made by mixing 2 parts of finemasonry sand and 1 part of masonry cement (d).

3. Before applying the epoxy floor enamel, you should first scrub the floor with trisodiumphosphate and water (b). The floor must then be allowed to dry before you apply the epoxyenamel.

4. A series of three coats known as scratch, brown, and finish are used when applyingplaster during construction (b).

5. You can use a 10-percent muriatic solution. Allow it to remain on the surface for 5to 10 minutes, and then hose it off with water (a). Wear goggles and rubber gloves when usingthis acid, and be sure to add acid to water, not water to acid.

6. After the taping coat (par 9-26) has dried, you should apply a second and third coatof compound over all joints. The three-coat coverage will insure aproper buildup of compoundto conceal the joint (c).

7. Pigment binder is used in conjunction with glass spheres; so you must check that youhave both. The glass spheres should be applied at the rate of 6 pounds per gallon of pigmentbinder. (5 gal binder x 6 pounds = SO pounds) (c).

8. Do not use a nail set to set the nails; use a hammer. Use su, dent force in the blowto recess the nail head below the surface of the sheetrock (d).

9, Latex (b) paint, particularly that made with polyvi1 acetate emulsions, is verysuitable for use on exterior concrete and masonry. This pal 4 moisture and alkali resistantand has desirable deterioration characteristics.

10. Before applying calcimine paint to new plaster that has aged for the minimum time,you should apply a watered-glue or a varnish-thinned size coat. The varnish can be thinned bymixing 1 quart of turpentine (a) with a gallon of varnish.

11. Loose and scalding paint on masonry usually can be removed by using a lye-watersolution (d). This breaks down and dissolves old paint so that it can be flushed from the sur-face with water.

12. Traffic pigmented binder (c) is the type of paint used in conjunction with glass spheres.This binder should be applied at the rate of not less than 100 sq ft and not more than 110 sqft .per gallon.

13. You apply the paint and scrub it into the surface with a stiff-bristle brush (c). Applythe paint heavily enough to fill the many small voids in the cinderblock.

151

14. Portland cement patching plaster should be mixed on the job shortly before it is tobe used. It is composed of 1 part portland cement, three parts plastering sand, and Y4 part limeputty (b)

.% .15. Although latex paint dries to the touch in 30 to 40 minutes (c), it should not be ap-plied in temperatures below 40° F.

16. Latex paint requires a shorter aging period for concrete and masonry surfaces thandoes .oil-base paint, although an aging period of 3 to 4 weeks (c) is recommended.

17. To make the repair, you must remove all loose plaster. Begin at the center and workback into the surrounding area to a point where the plaster is solid (a). Replace defectivelaths and refasten all loose laths.

18. If you suspect that the building is settling, repair the mortar joints. Remove oldmortar to a depth of about 2 inches, pack that opening with cement mortar (b) to within 14inch of the surface, and then fill the remainder of the joint with number 1 calking compound.

turnpink, red, or purple.

solution19. The application of a few drops of a 1-percent solution of phenolphthalein in alcohol

to concrete is a test for alkalinity (d). If alkaline is present, the drops of sion wi:".

20. A rubber-base paint (d) will resist alkali and should be used where the concrete issubject to dampness. This paint is superior to varnish-base paint in wear resistance, but itwill not last with outdoor exposure. ;;

CORRESPONDENCE COURSE OFU. S. ARMY ENGINEER SCHOOL

SUBCOURSE 563 Painting H.

LESSON 3 Painting Metal Surfaces.

SOLUTIONS


1. a (par 16-36)

2. b (par 13-7)

3. b (par 13-10)

4, a (par 16-12)

5. a (par 14-8)

6. b (par 16.9)

7. cl (par 12-3)

8. b (par 15.6)

9. a (par 16-9)

10. c (par 16-27)

For further explanation, see Discussion sheet.

11. b (par 15-4)

12. d (par 13-19b)

13. d (par 13-16)

14. a (par 13-18)

15. a (par 15-3)

16. c (par 16-7)

17. d (par 13-14)

18. a (par 13-13)

19. b (par 13 -19a)

20. d (par 16-2)

All concerned will be careful that neither this solution nor information concerning thesame comes into the possession of students or prospective students who have not completedthe work to which it pertains. ";

NRI 108

153

DISCUSSIONExercise:

1. Structural steel surfaces which are subject to water immersion and abrasion (a)ahould.be sandblasted to the base metal to obtain satisfactory results.

2. For effective cleaning, hold the nozzle approximately 1 foot (b) from the surface tobe cleaned. Be careful to prevent the splash or overspray from contacting electrical equip-ment

3. A burnished effect does not allow good adhesion of paint coatings and should beavoided. Generally a cleaning rate slower than 2 (b) square feet a minute is of little avail forbetter cleaning.

4. By rotating the spray gun cap or air nozzle, it is possible to produce a spray patternabout 6 to 8 inches wide when the gun is held 6 to 10 inches (a) from the surface.

5. When locating the nail fasteners on corrugated siding, place them on top of the cor-rugation (a) and not in the valley. Do not imbed them to the extent that the shape of the sid-ing will be deformed.

6. For a low-pressure spray gun, the air pressure should be between 20 and 40 psi, butfor a high-pressure gun, the air pressure should be between 80 and 100 psi (b).

7. Galvanized pipe is used in most water systems. Normally, corrosion will not attackthis metal unless the coating has been destroyed or damaged (d).

8. Slowly add acid component to the resin component and stir constantly (b) while doingit. If the acid is added too rapidly, without thorough mixing, or if the base solution is pouredinto the acid, the mixture will gel and be unusable.

9. For a low-pressure spray gun, the air pressure should be between 20 and 40 (a) psi.

..t,', 10. The airless spray gun is held 12 to 16 (o) inches away from the surface beingpainted. This distance is necessary because of the heavier material. ;;;'41!''':

:' 11. After the metal conditioner has been applied to a surface, the acid will react withthe metal. When a powdery surface, grayish-white in color, develops within a few minutes afterapplication (b), the acid has reacted properly and has the proper dilution. ..!'"i!ii.f*.'i:'''

'f... .- .

12. Commercial (d) blast cleaning provides a good but not perfect blasting job, and in-

Used as the abrasive, the life would be 2Y2 times greater. P".e.A15".

eludes the removal of practically all rust, mill scale, and other foreign matter from the sur-face

The life of a tungsten carbide nozzle is 300 hours (d) applying sand.;; is

face of the metal.

14. The customary blasting pressure for structural steel work is bout 80-100 psi, butthe normal pressure used for sandblasting brick and mortar surfaces is 40 to 60 (a) psi.

. -11.,44i,

-- 2,,

`

15. The compound is easily applied with a whitewash brush (a,. It can be also appliedby spray, but the brush method is preferred in order to insure intimate contact of the liquidwith the metal, and to avoid use of excessive amounts.

16. The Zahn cup is designed to measure viscosity (c) of fluids directly from their con-tainers. It consists of a 44-mil cup with a hole and a wire handle, as shown in figure 48.

17. A hopper provides storage for the abrasive material. A hopper control valve (d)limits the quantity of abrasive used.

;:18. Chipping with a descaler tool (a) is occasionally necessary to -.dove old, hard paint

and very heavy, hard rust scale. The descaler hammers its head neeilee against the surface,especially in inaccessible areas, such as grooves, crevices, rivets, and si.Y.ilar places.

19. Whits (b) metal blast cleaning removes all corrosion produnc, all mill scale, allpaint, and all other foreign matter from the surface' of the metal, leaving a surface that pro-vides strong adhesion of the protective coating.

20. The dip (d) or flow-coat method is used for volume-production painting of certainitems that are suitable for this painting method. The number and size of the gutter bracketsmake this dip method suitable.

7

CORRESPONDENCE COURSE OF..U. S. ARMY ENGINEER SCHOOL

SUBCOURSE 563 Painting

LESSON 4 Inspection of Surfaces.

SOLUTIONS .


, .,

1. a (par 18-3)

2. d (par 18-4)

3. b (par 19-9)

4. c (par 18-9)

5. b (par 18-4)

6. a (par 18-14)

7. d (pars 18-19, 18-23)

8. a (par 18-21)

9. b (par 19-2)

10. c (par 19-2)

11. a (par 19-2)

12. d (par 19-20)

13. c (par 18-19)

14. o (par 20-6) i've"

15. c (par 19-15)

16. b (par 20-8)

17. d (par 20-7)

18.;

a (par 18-P3, fig 66)

19. a (par 19.3)

20. 1) (par 2041)

)14.1..ti.ef

For further explanation, see Discussion sheet

All concerned will be careful that neither this solution nor Information -concerning thelame comes into the possession of students or prospective students who haie not completedthe work to which it pertains. .,41:r :=4.

2c...0,,t.c.,;

DISCUSSIONExercise:

1. The early failure of a protective coating is generally the result of poor surface prep-aration (a). This is especially true on metal surfaces which show early signs of scaling andflaking.

2. The protective coating on exterior wood surfaces should normally deteriorate by thechalking process. The coating should have a life expectancy of 4 (d) years under averageexposure conditions.

, ....3. During painting, the temperature of the surface and of the atmosphere in contact

with the surface should be at or above s5° F (b) for other than water-thinned coatings.

4. Corrosion pits (c) can be measured with a dial indicator. The indicator is illustratedin figure 62. . . .

5. Paints that do not deteriorate by checking or cracking will waste away by chalking(b) until they become too thin to hide the wood. ..

6. The range of a micrometer is usually 1 inch (a). The size of a micrometer is thelargest dimension that it will measure.,

7. 60' x 40' = 2400' floor area2400' x 2 = 4800' two coats500' = 1 gallon4800 = 9.6 or 10 gallons (d)

. 500 .

If two or three coats are used, the same amount is figured for each coat.

8. It is quite difficult to determine the covering capacity of paint. Thickness (a) isdefinitely a factor, along with method of application, roughness of surface, and absorption ofsurface. . :1.'..C. -

9. All the surface must be checked to insure that nails have been properly set. Then thesurface is primed before all holes and imperfections are filled with putty (b).

10. You should allow painting to proceed only when the moisture content of the wooddoes not exceed 12 percent (c) when measured by a moisture meter.

.

11. Wood surfaces about to be painted should be cleaned of dirt, oil, and other foreignsubstances with mineral spirits, scrapers (a) or sandpaper.

12. After the paint on the test panel has dried, its thickness is measured with an ordi-

13. 00' x 10' = 1000 sq ft X 2 = 2000 sq ft (twc:;:i1. walls)

nary micrometer (d) having flat contact surfaces. ..;

50' x 10' = 500 sq ft x 2 = 1000 sq ft (two end walls)....A.- 3000 sq ft = total will area

- .... ,-:;;,. .,..., ,q.) .

1:,....;,:.&,:',::::,:,-. ..?:1:77,2: $; ,... , .3000

7.(1 gal = 400') .

= 8 gallons (c).1"

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151

14. You should keep an up-to-date set of specifications (c) in your possession at alltimes, and make sure that the contractor also has an up-to-date set. The specifications explainwhat the contractor has contracted to do.

15. The dial reading should' show the thickness of the nonmagnetic'shim. On a smooth,machined surface, the thickness gage should also read zero with the gage in direct contact withthe base metal (c). It should be calibrated if it does not read zero.

,

16. The specifications will specify the type and gage of materials that are to be used,and may require a submittal. The submittal may be a sample' of material or a manufacturer'scertificate (b).

17. There will always be differences of interpretation. Any misinterpretation can changethe entire concept. If there is a difference between the specifications and the drawings; thespecifications will govern (d).

18. The paint coverage column (line 10) indicates that an oil-base paint would cover 350(a) square feet on the wood surface.

19. The preparation of concrete and masonry surfaces to receive paint should include. roughening (a) to remove glaze. , ,

20. The daily diary is the moat important record maintained by the inspector (b) duringthe contractural period. It is consulted many times by the engineer and the contracting officer.

i57

111111111111111W111111N4101111

MEMORANDUM 563

PAINTING H(APPLICATION)

U. S. ARMY ENGINEER SCHOOL


NRI 108

1'.,,c

PREFACE

Ir Memorandum 562, you learned about protective coating materials andequipment, - -f.ety in the use of ladders, scaffolds, and hoisting equipment, andidentification, ,f metals and corrosion products. This subcourse discusses thepreparation of surfaces and the proper application of protective coatings towood, masonry, and metal. Iu addition, the text covers inspection of surfaces.

Your work in this area is of vital importance to the Army. The success of414.y paint job will depend on you, the painter. Painting work is an importantitem it construction and overall maintenance operations. The life, operatingefficiency, and economy of structures are influenced by the effectiveness of theprotective coating you will apply. It is the purpose of this Memorandum toprovide ycni with information that will aid you in doing your job well.

:deep this Memorandum for your own use after you have completed thesubcourse.

ib0

CONTENTS

Page

Preface

Chapter

1 Painting Wood Surfaces 1

2 Painting Masonry Surfaces 24

3 Painting Metal Surfaces 39

4 Inspection of Surfaces 60

ii

Painting Wood Surfaces

Pir HE PRIMARY purpose of painting exterior1 wood surfaces is protection. A secondary

purpose of painting is to obtain a more pleasingappearance. Without the protection of paint orother protective coatings, wood undergoes weath-ering and deterioration. This roughens its sur-face. darkens its color, allows it to warp and cup,and wears its surface away about Vs inch ofthickness per century.

2. As an Army protective coating specialist,it will be your job to prepare surfaces andapply protective coating materials to buildingsand other structures. How well you learn andprepare yourself for the job depends on yourown personal desire and ambition. You can eitherbecome a protective coating specialist or you canbe a dauber. The dauber is the man who canwork only under close supervision and must betold, step by step, how to do the job. The pro-tective coating specialist is a man with vast tech-nical knowledge who knows what needs to bedone, why it needs to be done, and how to do thejob. Sooner or later, this man will become thedauber's supervisor.

3. This chapter deals with the preparation andpainting of wood surfaces. Protective coatingsfor masonry and metal surfaces will be coveredin later chapters. You must know how to prop-erly prepare wood surfaces before they arepainted. To help you do the best job possible,you should have a knowledge of the differenttypes of wood and the characteristics of each.

1. General Characteristics of Wood1-1. Woods are generally divided into either

hardwoods or softwoods. The hardwoods areused much less than softwoods in building con-struction, especially on exterior surfaces. Allwoods vary greatly in their ability to retainpaint. Among softwoods, paint coatings remainsound longest on lightweight boards with narrotr,growth rings. Edge-grain surfaces on the barkside will retain paint better than the pith side efflat-grain boards. The growth rings in softwood

ti

IblCHAPTER 1

(see fig. 1) consist of a dense, darker coloredpart called the summerwood, and a soft, lightercolored part called the springwood. When paintcoatings begin to fail, they do so first and con-tinue faster on the widest streaks of summerwood.This is the reason woods with narrow growth ringshave the best paintability.

1-2. Lumber may be sawed in either of twoways at the mill. The select and choice grades,used for building construction, are quarter-sawed,while the utility or lesser grades may be plane-sawed. The method of sawing at the mill has alot to do with the grain in the finished lumberand the paint-retaining characteristics of thatlumber. As a coating specialist, you should beable to recognize these grain characteristics at aglance. You have probably already determinedthat quarter-sawed lumber is better than plane-sawed. Now, let's find out why this is generallytrue.

1-3. Quarter-sawed Lumber. The main pur-pose for quartersawing is to produce lumberWhich has narrow growth rings and edge-grainsurfaces. This type of lumber will not warp andcup, and it has good paintability. Figure 2 il-lustrates how a log is quarter-sawed at the milland how boards are sawed from the quarters ofthe log. By examining the end grain of one ofthese boards, you can see how the growth ringsproduce a close edge-grain surface which is idealfor painting.

1-4. Plane-Sawed Lumber. Plane-sawed lum-ber is generally used in the construction of suchthings as fences and shipping crates. It is cheaperand faster to produce at the mill. Figure 3 showsthe method of slicing, or flat-sawing, boards fromthe log. You cars sea how this method of saw-ing produces a Mt-grain board, with wide bandsof summerwood, which is less desirable for paint-ing.

1-5. Warping and Cupping. Fresh -sawed lum-ber at the mill is green and full of moisture. It isstacked and bound in a manner to prevent warp-ing and cupping as it dries out and cures. The

Iba- .

INNER BARK

CAMBIUMLAYER

PITH

SUMMERWOOD

Figure 1. Growth rings in a log.

curing process is speeded by kiln drying, duringwhich time heat is used to lower the moisturecontent in the lumber. This curing process re-duces warping and cupping to some degree. Youhave learned that quarter-sawed lumber willwarp and cup less than plane sawed lumber.Let's find out why.

1-6. The growth rings in a green log are cir-cular in shape by nature. As the log cures anddries out, these circular growth rings try tostraighten out. This, along with shrinkage, causesthe log to split, or crack, from the center to itsouter edge in one or more places. Logs are usu-ally processed at the mill before this splittingtakes place. As the logs are sawed, the growthrings become the grain in the individual boards.The portion of the growth rings in any boardtends to straighten out as that board cures. Fig-ure 4 shows the end view of a plane-sawedboard. You can see how this board will warp, orcup, as the growth rings straighten out duringthe curing of the board.

GROWTHRINGS

Figure 2. Quarter-sawing a lop.

2r)

Figure 3. Plane-sawing a log.

1-7. Groups of Softwoods. Average shipmentsof select grades of properly dried softwoods, maybe classified as follows with reference to theirability to retain paint and resist weathering.These classifications are listed as follows:

Gro:Ip 1Retain paint longest and withstandweathering best.

Western red cedarOther cedars except eastern red cedarSouthern cypressRedwood

Group 2Retain paint well, if primed, andwithstand weathering well.

Northern white pineWestern white pineSugar pine

Group 3Retain paint moderately well andwithstand weathering moderately well to poorly.

White firHemlockPonderosa pineSpruce

Group 4Retain paint poorly and withstandweathering poorly.

Douglas firWestern larchSouthern yellow pineNorway pineTamarack

Figure 4. Warpage caused by plane-sawing.

NAp

Figure 5. Wood grain terminology.

1.8. Hardwoods. Hardwoods are used gen-erally for interior construction. Applications- in-clude interior window and door trim, baseboards,moldings, flooring, and cabinet work. Plywoodwallboard with an exposed veneer of mahogany,walnut, cherry, or birch are in common use;These hardwoods are normally protected with r,transparent or clear finish to enhance their nat-ural color and grain structure. Besides the gen-eral wood properties, the s;ze of pores is animportant factor in painting and finishing of hard-woods. Hardwoods are used much less than soft-woods for exterior building construction becauseof their poor paintability and weathering charac-teristics. Hardwoods with pores larger than thosein birch, such as ash, chestnut, elm, hickory, oak,and walnut. are unsuitable for ordinary exteriorpainting. Their use requires an extra operationto fill the pores. Hardwoods with small pores,such as basswood, cottonwood. and poplar, holdpaints about as well as the softwoods of group 3.Heavier hardwoods with small pores, such asbeach, birch, gum, and maple, hold paint about aswell as softwoods of group 4.

1-9. Description of Wood. As we cantina,: ourstudy of the preparation and coating of woodsurfaces, there will be several terms we will useto describe proper methods of doing a job. Dur-ing such operations as sanding, scraping, fillingpores, and brushing primer or paint, we will usesuch terms as "with the grain," "against thegrain," "across the grain," and "end grain."Very carefully study figure 5. Look at the graindirection and determine ;:s relationship to each ofthe terms.

1-10. Now that you have learned about thegeneral characteristics of wood, and how theyaffect painting in general, Iles find out how toproperly prepare these surfaces fcr applying the

0,/ protect?,.... coating.

143

2. Preparation of Exterior Wood Surfaces2-1. All surfaces to be painted must be dealt,

and dry. They must be free from dirt, oil, ma\grease. In some cases, old paint in good condi-Ation makes an excellent base for repainting andshould not be taken off. If the surface to berefinished is checked, cracked, or flaked, thenthe old paint may need to be removed. Youmust know how to properly prepare all surfacesbefore they are painted. You should know thatthe life and appearance of a good paint job de-pends on the proper preparation of. the surfacesbefore painting. The serviceable life of a paintjob can be reduccd by as much as 50 percentby poor surface preparation. You must also real-ize that the highest quality of e-mting re-Aerialswill not stick to a poorly prepared surface.

2-2. New Construction. Normally, new lum-ber and woodwork used in exterior building willrequire very little preparation for painting. Ifthe surfaces are dirty or contaminated by oil,asphalt, or lumber marking crayon, they shouldbe cleaned with a suitable solvent. Any loosegrain or splinters in low grade or poorly manu-factured lumber should be removed and the sur-face made as smooth as practicable. This canusually be done by the use of a ht nd scraper,scraper plane, or sandpaper.

2-3. Using scraping tools. Before using any ofthe scraping tools to remove bare wood, look atthe surface to be worked and determine the di-rection of the grain. Always scrape or plane inthe direction of. ark-1 .vith the grain, and neveragainst the grain s... omvent the cuttingedge of the too. ?,re, 1 digg in, orpulling out chunks c.f sprwgwood or additionalsplinters. Rerno-f: only cf..: ugh wood to clear

Figure 6. Knots in painted surface.

I bq

the surface of defects. In some cases, removalof excessive wood could weaken the structuralstrength of the wood.

2-4. Sanding exterior surfaces. Probably themost difficult and tiresome job to confront youwhile preparing surfaces is hand-sanding. It isnot customary to sand the entire exterior sur-face before painting. Exterior sanding should belimited to spot-sanding for the removal of surfacedefects. On small jobs, you may sand by hand,using a sanding block. On larger projects, youmay use a portable disc. or belt sander. Which-ever method you choose, always sand in the di-rection of the wood grain. Do not sand acrossthe grain as the abrasive on the paper will cutdeep scratches across the summerwood in thegrain. These scratches across the grain are dif-ficult to remove and they will require additionalsanding.

2-5. Removal of pitch. Any resin or sap spotson the surface should be removed by scraper andsandpaper. When the resin is soft, remove it bycleaning with mineral spirits or turpentine.Pitchy areas may be heated by a blowtorch toencourage bleeding of the resin. Caution shouldbe exercised while using the blowtorch to preventscorching the adjacent surfaces.

2-6. Types of knots. There are two generaltypes of knots found in exterior lumber, and youmust know how to properly treat them. One typeis a small, tight knot which may have a soft orspongy center. This knot is usually smaller than3 nickel. The other type is the larger, hard-cente, loose knot. The center of this knot willcontain open cracks. shrinkage of the center maycause it to be loose in the board opening. The

grain in the lumber will form a swirl patternarcivad both types of knot=... There will be earlydiscoloration of paint over %riots in pine and aloss of gloss over knots ;a :!at grain boards. Theeffect of knots on painf co%?.ings is shown infigure 6.

2-7. Treating kroq,.. ards which containloose knots normally will not be found in newconstruction. The ,:artnter should saw out sec-tions containing kr;-./:: before nailing the boardsin place. When do find loose knots, theywill require addiflo:;:;,'a treatment. If the center ofthe knot is t,..) move in the board,it should be secured by sealing it in place withshellac. If the is loose enough to rattle, itmay be tightencl by using a type II calkingcompound which nardens as it dries. This canbe done prior tr priming pine, as the center andareas surrourling the knot will contain enoughturpentine to allow the calking compound to ad-here to the surl.aces. Tight knot::, .wiich havesoft centem mp.v be filled with aging com-pound. Alta. 0!-,1 compound has dried, the areasurroundil:!,, knot may smoothed by ahand scrp.lc or sandpaper. ;j.nots should besealed with a thin c.oat of k3cc.t cealer conformingto Military Specific:Aon Ma..5-12935A, Sealer,Surface. Krit:: prior priming. Shellac may beused with soral: knot sealer, but asealer which meets Or al)ov..-mentioned specifi-cation is much better a >z shellac.

2-8. Repairing. smile blemishes. Nail holesand other dents shm1d be puttied after the prim-ing coat of p:Alrit has been applied and has dried.All nailhep.ds ritaell be set below the surfacewith s :ail srt.. Th.,,,; nail hole should be filled

RATCHET ROD AND PISTON

COMPOUND"TUBE

HOLDERTRIGGER

MECHANISM

1

Figure 7. Calking gun.

4

with putty to completely cover the nailhead. Thiswill prevent rust stains from forming as rainwa-ter runs down the side of a building. Puttycomes in either type I or type II. Type I is anelastic glazing compound which dries on the sur-face but remains slightly soft and plastic under-neath. It is recommended for use over nailheads,as it will not have a tendency to "pop out"should the nail loosen in the board. Type IIputty hardens as it dries and is used to fill holesand cracks where hard material is desirable. It isused to fill dents, hammer marks, or crackscaused by splintering of the lumber. You canapply putty with a putty knife or by hand. Ineither case, you must be sure the putty is workeddown into the hole or crack. Be sure to removeall excess putty from the surrounding area toleave a clean, smooth surface.

2-9. Use of calking compounds. Calkingcompounds are used to seal cracks and waterproof exposed joints around door and windowframes in wood construction. You should primeall bare wood surfaces before calking. There aretwo grades of commercial calking compounds.Grade I is of soft consistency, suitable for ap-plication with a calking gun. Grade 2 has theconsistency of glazing putty and is applied witha knife. Grade I compound shrinks considerablyand sometimes wrinkles. It has the ability toform a tough exterior skin which resists breakingwhile the underbody remains soft and pliable.Both grades are suitable for use at temperaturesabove 40° F.

2-10. You should use strands of oakum, calk-ing cotton, or other fibrous materials to form asuitable backstop for filling deep open cracks.Pack to within Vs inch of exterior smface. Thiswill prevent the excessive use of calking com-pound. Complete filling the crack with com-pound, using a knife or a calking gun.

2-11. The standard, hand-operated calkinggun (see fig. 7) consists of a compound tubeholder, handle, ratchet rod piston, and triggermechanism. The compound comes in a "throw-away" cardboard tube 10 inches long and 2inches in diameter. The tube is inserted into thecompound tube holder of the gun by rotating theratchet rod and pulling it all the way back. Theratchet is then reengaged by pushing the rod andpiston into the end of the calking tube. Opera-tion of the trigger mechanism exerts force on thepiston rod wich causes the piston to eject com-pound through the nozzle. Place the nozzle tipat or into the joint that is being calked. Cracksoften develop in gun-applied compound as a re-sult of bridging the joint which leaves an airpocket behind the compound. To avoid this, youshould use a tip small enough to reach the bot-

5

165tom of the joint and hold the gun at an anglewhich permits you to see that the compound isfilling the joint.

2-12. Gun application is recommended forgeneral use. It is easy. economical. and takesabout one-third of the time for knife application.Knife application is recommended where a neatfinished appearance for some conspicious loca-tion is desired.

2-13. After filling joints or cracks, compressand firm the compound against the sides andedges. Press a beading tool against freshly filledjoints in order to force the compound into them.Insure that the compound adheres firmly to theback and sides of the crack.

2-14. The final operation of the calking jobconsists of cleaning compound smears from sur-faces adjoining calked areas. Use mineral spirits,or other thinner recommended by the manufac-turer of the compound.

2-15. The degree of preparation for paintingmust depend on several factors. First, considerthe grade of lumber used. Next. consider therequired life of the structure. and the protectivecoating to be applied. Other factors which mustbe considered are cost. time involved, and yourown personal safety. For example. you wouldnot expect to give the same degree of surfacepreparation to a storage shed in a constructionyard as you would to a permanent-type office orbarracks structure. This is not to be interpretedas lessening the importance of providing a clean,well-prepared surface for painting. Determiningthe degree to which a given surface must be pre-pared simply calls for the exercise of good judg-ment.

2-16. Previously Coated.Wood. When paint ismaintained with a well-planned schedule, thepreparation for repainting is easy and inexpen-sive. Haphazard maintenance, poor choice ofpaints, or other conditions may result in surfaceswhich are difficult to prepare for 'repainting. Inextreme cases, it may become necessary to re-move all of the old paint before repainting.

2-17. Stages of paint deterioration. Housepaint, for exterior wood, undergoes a slow changefrom the time it is first applied. You must knowwhat these changes are and be able to recognizethem. This knowledge will prevent you from be-ing misled into hasty and unwise early repainting.It will allow you to recognize conditions whichwarrant repainting to prevent further deteriora-tion. Normal deterioration takes place in six

recognizable stages:a. Soiling. The coating gradually becomes

soiled. Dirty paint may be washed but exteriorsurfaces should never be repainted until de-

1 : 3

166'1:.:14..R."'"'Aesla.. ', ,*4;.n.....:7-.;:-.7:-..z..71-'-'-r4".'.' -'..1:-.:,..,--. :.---:7 ;.--1.-...'`.''),;-.: ,

;., ..... 4:.Z.. ........,,:;,.. , ... ....:,;::,.... 4CF-4 _. p , - . 4......?

. :,-;. _ 7 _ . *-,IA . .' _L ; S ' , , . .. 1 7

littrr., , i,,,..ig

Figure 8. Disintegration by crumbling.

terioration has gone much further than mere soil-ing.

b. Flatting. The coating gradually loses itsinitial gloss. It becomes flat, usually within ayear on sunny areas but less rapidly on shadedareas. Flatting does not justify repainting.

c. Chalking. The pigment at the surface be-comes powdery and may be rubbed off like chalkdust. Dirt will disappear during the chalkingstage. On tinted surfaces, the colors appear tofade as the chalking progresses. Normally, ex-terior paint is in the chalking stage during thegreatcr portion of its useful life. Chalking doesnot offer sufficient grounds for repainting ex-terior surfaces.

d. Fissures. Fissures arc of two kinds: check-ing and cracking. In checking. the fissures ap-pear first on the surface but later penetrate en-tirely through the coating. When checking occurs.it usually begins in 2 years, or well within thefirst half of the normal life of the paint. Incracking, the fissures pass entirely through thecoating. Cracking seldom occurs before the mid-point in paint life, or the beginning of the thirdyear after application. The fissures in crackingare larger and more conspicious than those inchecking. Fissures are directly related to the nextphase of paint deterioration and the degree ofpreparation which is required, prior to repainting.

e. Disintegration. The disintegration of paintdepends on the type of fissures it develops whenpassing through the fissure stage. Disintegrationdevelops through crumbling, flaking, or erosionof paint surfaces. Crumbling is an advancedstate and is the direct result of checking duringthe fissure stage. Tiny fragmeMs of coating falloff when the checking penetrates through thecoating. The size and shape of the loosenedcrumbs of paint correspond to the size of thechecking pattern. Normally, the paint crumblesfrom the bands of summerwood much soonerthan it does from the springwood, so the grain

1 "d "4 6at

pattern of the wood is revealed by the disinte-gration of the paint. Refer to figure 8 and keepin mind the magnified area in the illustration isonly Y8 inch by 1/2 inch square. The secondtype of disintegration (flaking) occurs as anaftermath of cracking during the fissure stage.When cracking occurs and leads to curling, theloosened and curled edges of the coating breakoff. The dimensions of the cracking determinethe size of the flaking. Numerous small crackslead to fine flaking and large cracks to coarseflaking. Fine flaking lays bare summerwoodonly as it follows the grain pattern of the wood.Coarse flaking, which may properly be calledscaling, uncovers both springwood and summer-wood at the same time. Flaking paint needs care-ful preparation for repainting to insure all loosepaint is removed. Scaling paint needs still morecareful preparation ane leaves an uncertain foun-dation for the new paint. Figure 9 illustrates anarea 36 inches by 36 inches square in which de-terioration is by flaking and scaling. Repaintingshould be done soon after the most exposed partsof the building have reached disintegration byflaking or scaling. The third type of disintegra-tion is erosion. Some painted surfaces will notsuffer from checking or cracking but will wasteaway over the years, mainly from chalking. Thecoating finally becomes too thin to hide the woodand patches of wood begin to be laid bare. Thesurface usually requires little preparation forpainting as there are no scales of loose paint toremove. The surface should be repainted whenthe coating becomes thin enough to show thegrain of the wood while the coating is wet withrain or when patches of bare wood appear.

11 -44. ,... .

01=7.47.6jutotar-1411- VMS=Figure 9. Deterioration by flaking.

f. Advanced Breakup. When disintegrationlays bare enough wood for boards to show dis-tress of wood weathering, the coating has reachedthe stage of advanced breakup. Signs of woodweathering are development of gray color and finechecks, or cracks, in the wood approaching de-cay. The boards tend to cup and pull loose attheir fastenings. Such surfaces are difficult toprepare for repainting and will consume morethan normal quantities of paint.

2-18. You have learned the six stages in nor-mal paint deterioration. Now, you must deter-mine how to prepare these surfaces for repainting.As a general rule, the preparation of previouslypainted surfaces will take much more of yourtime than the actual application of the newprotective coating. Let's consider these surfacesin two groups: those where the removal of oldpaint is unnecessary and those when old paintmust be removed.

2-19. When removal of old paint is unneces-sary. If there is no loose, curling, or blisteredpaint, preparation is simple. It consists of seeingthat the surface is clean, dry, and free of con-tamination. Surfaces in the chalking or flattingstage will not be repainted unless a requirementexists to keep them glossy. Should you have needto repaint such surfaces, the preparation con-sists mainly in cleaning. Wiping with a painter'sduster may suffice for most of the area. Youmay wash very dirty areas, particularly if thedirt is of an oily or greasy nature. Contamina-tion such as asphalt spilled in roof repairs orresin which has bled through the old coatingshould be removed with scrapers or solvents.

2-20. If there is loose, curling, or blisteredpaint, you must remove all loose particles with ascraper, wire brush, or sandpaper. The checkingor cracking of paint, if there is no loosening orcurling at the edges of the fissures, is not consid-ered loose paint. Areas of summerwood laid bareby fine crumbling or flaking of the paint andlarger areas of springwood and summerwood laidbare by large pieces blistering or scaling shouldbe hand-sanded. You should sand the area in amanner that will "Natheredge" the secure paintinto the bare wood areas. If only a few boardson a building are conspicuously worse than therest in this respect, it may be wise to replace themwith boards of more representative density andgrain pattern..

2-21. In addition to the normal deteriorationstages of protective coatings, there are some ab-normal conditions you may encounter. Youmust know how to prepare thcse surfaces for re-painting.

1

0,7

a.

Figure 10. Surface mildew.

Mildew. In warm, damp climates, mildewmay appear on exterior painted surfaces. Else-where, it may occur as an abnormality in localareas which remain damp for long periods of time(see fig. 10). Mildew is often difficult to distin-guish from soiling by dirt. You should inspectany area you suspect to be mildew with a mag-nifying glass. Mildew is characterized by thread-like mycelia when it is in the growing stage andby numerous egg-shaped spores when it is dryand dormant. Dirt, in contrast, is usually com-posed of granular particles of irregular size andshape. Since mildew is a fungi growth, mildewedsurfaces must be scrubbed clean before repaint-ing or the infection may come through the newpaint. You should wash the area with strong soapand warm water. If possible,- you should cleanthe area with a solution of IA pound trisodiumphosphate to a gallon of water and then rinse thearea. with clean water. Always wear rubbergloves to protect your hands while using this so-lution. Mildewed surfaces, which have been prop-erly washed and treatcd, normally do not requirescraping or sanding prior to painting.

b. Discolorations. Occasionally, discolorationsappear in painted surfaces. In severe cases theywill reappear upon repainting. These discolora-tions are caused by excessive moisture in thewood. If the conditions which produce the mois-ture can be changed, the discolorations will notreappear. In extreme cases of faulty or damaged

r::t.)

:-..onstruction, repairs to prevent the entrance ofwater or aoisture may require the attention ofa carpenter, roofer, or plumber. Differentkinds of wood will react to continuous moistureto produce different kinds of stains. Reddish-brown to black discoloration of paint on red cedaror redwood occurs when the wood becomes wetunder the paint. These woods contain a naturaldye which is soluble in water. Pine boards con-taining streaks of heartwood may develop yellowto brown discoloration beneath the paint. On ex-terior surfaces the stain usually bleaches outafter a few weeks of strong sunshine. The stainmay reappear after repainting in damp or wetseasons of the year. A blue to black discolorationwhich penetrates berrath the coating is blue stain.Blue stain is caused by growth of certain fungiin sapwood. It occurs on windows subject to con-densation, at the base of wood columns or postsunder which rain seeps, and at joints in railings,stoops, shutters and trim. Since discolorations arecaused by moisture, you should seal, or calk,joints and cracks to prevent moisture from get-,ting into or behind boards. Discolored surfacesusually require no additional preparation beforepainting.

c. Peculiarities of Wood. Economy, or avail-ability, often dictates the use of woods in group4 for structures that must be kept painted. Onsuch woods, paint in a given stage of deteriorationreveals its condition more conspicuously thanwoods of groups 1 and 2. Look at the surfaceshown in figure 11. You can see that replace-ment of the board nearly bare of paint wouldmake the next paint job on this building lastmuch longer with satisfactory appearance.

2-22. You have learned to prepare surfacesof normal deterioration for repainting and howto correct conditions which caust abnormal paintdeterioration. Now, let's find out the conditions

/

Figure 11. Ab deterioration.'- 8

which require removal of old paint prior to re-painting.

2-23. When old paint must be removed. Com-plete removal of old paint is so expensive andtime consuming that it is seldom done. In somecases you must do it to get durable repaintingwith acceptable appearance. Each case must bedecided on its own merit, taking into account theprice that can be paid for first-class appearanceand the estimated future life of the building. Thefollowing conditions may justify removal of theold coating:

a. Normal deterioration. Surfaces which havereached the advanced breakup stage of deteriora-tion may be removed. You will find this to betrue in the case of old, neglected buildings wfiichsuddenly must be refurbished to high standardsin appearance. These surfaces normally requirea great deal of preparation prior to repainting.It may be faster and cheaper to remove the rem-Lants-of the old coating whenever a durable andtop-appearance job is specified.

b. Incompatibility between paints. Serious in-compatibility between paints may cause alligator -ing or wet blistering. The surfaces may remaintacky or be slow drying. The conditions areusually apparent very soon after the protectivecoating has been applied. They may result frompoor painting conditions, practices, or workman-ship. The exact cause of these defects will bediscussed in Section 3.

c. Coating thickness. Excessive thickness, oran accumulation of many coats of paint, maycause dry blistering and excessive scaling. Coat-ings more than 0 mils thick may well be re-moved, and coatings 20 mils or more thick cer-tainly should be removed. You can estimate thethickness of the old coating fairly simply by com-paring the edge of a chip of loose paint with theedge of a dollar bill. A dollar bill is 4 to 5 milsthick.

2-24. Methods of paint removal. When it ispractical to do so, you should remove paint fromexterior wood surfaces by wire-brushing, scrap-ing, and sanding. Usually, the old paint sticks toofirmly to come off readily by these means. Insuch cases you must soften the old paint, usingeither heat or paint remover. You can then scrapethe old paint from the surface. Let's learn howto remove paint by using the different methods:

a. Removal by brushing and scraping. Youmay have success in removing old paint which ischalky or scaling with wire brushes and a handscraper. In most instances power. brushes aremore satisfactory to use than hand brushes be-cause less energy is required to use them. Powerbrushes exert enough circular force on the brush

Figure 12. Removal by heat.

to remove stubborn particles which otherwisewould be hard to loosen with 'a hand brush. Afterbrushing the surface, you should use the handscraper to remove any remaining particles ofpaint. If hand-brushing must be used, you shouldalternate the steps of brushing and scraping, brush-ing and scraping until the surface is clean. Whenpossible, the scraper should be pulled in the di-rection of, and with, the grain, to prevent digginginto the wood. You may complete the job bylight, spot-sanding of any rough areas in the sur-face.

b. Removal by heat and scraping. The use ofheat for paint removal is not generally acceptedfor extremely large wood surfaces. You may useit on small areas where brushing and scrapinghas failed to remove the coating. Heat is usuallyapplied with a blowtorch. Since the blowtorchproduces an open flame and extremely high tem-perature, you must take care to avoid charringthe wood. If charring occurs, the new paint willflatten and deteriorate rapidly. You must alsoconstantly watch to see that the building is notset afire. Badly neglected buildings, on which sid-ing has cupped, may allow the flame from thetorch to get into the sheathing or stud spacewhere fire may make headway before it is no-ticed. You should apply only enough heat tosoften the old paint sufficiently for ono strokeof the scraper to take off everything down to thebare wood. Do no ;point or aim the flame at thesurface as you wo,..ld in heating a piece of metal.You should move the torch in a fanning motion;this causes the flame to brush across the surfaceat an angle. Play the flame on the surface untilthe paint bubbles and softens, then scrape it off.The scraper should follow the flame at a distanceof about 2 inches. You may prefer to use a puttyknife rather than the hand scraper on some sur-faces. The proper method of using a blowtorch

9

167

and putty knife to remove paint from a woodensurface is shown in figure 12.

c. Removal by solvents and scraping. Paintremover is a mixture of solvents which will softenold coatings of paint, varnish, lacquer, and shel-lac. After the old coatings have been softened,you can remove them with a hand scraper or aputty knife (see fig. 13). Paint remover comesin either liquid or paste form. Liquid removerdries rapidly, and for that reason, is used onsmall areas at a time. Paste remover remainsmoil ,.. for a considerable length of time and canbe .J6sA on larger areas. The paste form is gen-era;!.y used on exterior walls because you canapply i easily to the vertical surfaces without itflowing off. You should apply the paste with asoft brush, using a mopping-type stroke. Thepaste should be applied across the boards andgrain first. This will work the remover underthe edges of the old coating along the strips ofsummerwood, and into the crevices between theboards. You should then smooth the paste in thedirection of the boards or grain, redipping thebrush into the paste if necessary to insure a gen-erous, even covering by the remover. Do notbrush more than is necessary as overbrushingcauses evaporation of the liquids in the paste andslows the softening action. When liquid paint re-mover is used for small areas, you should brushit on freely in the direction of the board or grainonly. In this manner a wax forms a leafed coat-

Figure 13. Removal using solvents.1'I

no.

ing over the old surface and slows evaporation.This allows the active ingredients in the removermore time to act. Brushing the remover backand forth destroys this leafing action and reducesthe effectiveness of the remover. With eitherpaste or liquid remover, the softening actionshould be allowed to continue until one stroke ofthe scraper will take off everything down to thebare wood. Ordinarily, a clean, wood surface,tirely free from old paint. should be left. Thebared surface should be washed with paint thin-ner and wiped dry with a cloth to remove anywax left by the remover.

2-25. Be extremely cautious when using paintremovers. Most of them are highly flammableand some are toxic. Do not allow the brush toflick small particles of the remover into your eyes,face, or onto your skin. The strong chemicals inthe remover may cause superficial skin burns.

2-26. When scraping off the old paint, depositthe residue from the scraper in an old bucket orcontainer. Do not clean the scraper after eachstroke by slinging or throwing the residue into thesurrounding grass or shrubbery. The chemicalsin the remover may burn or destroy the foliage.

2-27. Regardless of the method you use to re-move paint, you will probably need to spot-sandsmall areas. You should use a sanding block andsheet paper for this operation. You may havesome success using a rotary disc power sander,but you should avoid cutting deep scratches acrossthe grain, which may show through the new coat-ing. Never attempt to remove an old, thick coat-ing by power-sanding alone. The heat buildupbetween the abrasive and the paint surface willcause old paint to stick and form a glaze on theabrasive paper. Continued use of a belt sanderunder these conditions will cause additional heatbuildup and destroy the belt. A good rule to fol-low is: ZIse heat or solvents to remove paint anduse power sanders to smooth wood.

2-28. You should complete the surface prep-aration by inspecting and repairing any small de-fects. Reset and loose nails and fill ar holes,dents, and cracks. Inspect windows 21d doors forbroken glass and missing or damaged glazingcompound.

2-29. Replacing glazing compound. The re-placement of glass and glazing compound re-quires a great deal of skill as well as knowledge.The skill can only be developed through prac-tice. When any portion of old putty (glazingcompound) is missing or loose. all of the puttyshould be removed. The better job you do inscraping the putty from the sash, the easier youcan apply the new compound. When the puttyruns are clean, you should brush their surfaces

10

with mineral spirits or turpentine. This will causethe new putty to stick to the wood. When glassmust be replaced, the new pane should be sizedto fit into the rabbet with about 1/10 inch clear-ance at each edge. This will provide space forbed putty to form a cushion completely aroundthe pane. Either of two types of glazier pointsmay be used to secure the glass into the rabbets.You can drive the triangular-shaped ones with ahammer and the edge of a screwdriver. You mayneed a special gun to drive the diamond-shapedtype. Each type must be driven so deep that theywill be completely covered after the putty is ap-plied. To properly apply the putty, place a con-tinuous bead along the glass face and putty run.This is illustrated in figure 14. You can preparethe putty roll by rolling putty back and forth be-tween the palms of your hands. You completethe glazing operation by pressing the putty intoplace with a putty knife. Use enough pressureto insure that the putty will adhere to the glassand sash. Finish the surface with a full, smoothstroke of the knife...Form a neat, straight bevelwith clean-cut miters at the corners. Trim anybed putty which pushes out on the reverse sideof the glass.

2-30. New construction should be painted orat least prime-coated, as soon as possible aftererection. Old surfaces which have been -cleanedand prepared should be repainted as soon aspracticable as a precaution against deteriorationof the prepared surfaces. You have learned howto prepare exterior wood surfaces for painting;now, let's discuss the proper methods for applyingprotective coatings.

FACETT/

BED NTT(

PIOT), ROLL

GLAZIER'S POINT

Figure 14. Applying glazing compound.

3. Applying Protective Coating toExterior Wood Surfaces

3-1. To be -a top painter, you must have agreat knowledge about the entire operation. Prac-tice plus experience will develop your skill inusing a brush or spray gun. This skill is impor-tant to the beauty and durability of the job. Inaddition, there arc other factors which you mustconsider.

3-2. Atmospheric Conditions. In northern lati-tudes, exterior painting should be done during thewarm part of the year. In southern latitudes,the local rainy season should be avoided. Therewill be times when exterior painting must be donein weather not ideal for painting. The chief haz-ards are rain, dew, frost striking fresh paint, or asharp drop in temperature' while paint is drying.The defects which may result are slow drying,wrinkling, and uneven gloss.

3-3. Time for Drying Between Coats. In dryair at 70° F. or above, you should allow exteriorpaint to dry at least 48 hours before recoating.Dampness or low temperature. may delay dryingfor an additional day or two. You should applythe next coat as soon as possible after the under-coat is dry. Delay of more than a week betweencoats should be avoided. New construction fin-ished in winter, presents a different problem. Theexterior wood, cannot go unprotected through thewinter because its surface will roughen. You cartapply a priming coat in winter but it will offerlittle protection. By the time spring comes. itmay not be in the best condition for recoating.You should complete the exterior painting aspromptly as the hazards of winter will permit.

3-4. Priming of Exterior Wood. The durabilityof protective coatings depends greatly on theproper priming of the surface. There ire threetypes of priming operations: "spot priming," "fullpriming," or "spot priming followed by full prim-ing." Varying conditions of the surface will de-termine which priming operation you use. Thefollowing information will give you a knowledgeof the different priming operations:

a. Spot priming. Spot priming may be consid-ered as a touchup operation. Small defects suchas knots, resin leakage, or small areas of flakingand scaling may be spot-primed. You shouldspot-prime individual bad boards or any newboards which replace old ones. As a generalrule, you will spot-prime only those buildings onwhich the paint is less than 2 years old.

b. Full priming. Full priming means the en-tire surface must receive a priming coat. Youwill always full-prime new construction or sur-faces from which the old coating has been re-moved. You should full-prime old surfaces where

11

the old paint is checking or cracking over theentire area.

c. Spot priming followed by full priming. Spotpriming followed by full priming is a combina-tion of the two operations. You will normallyuse this method on buildings where the paint ismore than 2 years old. When the old paint isdisintegrating, you should remove the loose paintand spot-prime the areas affected. After the spotpriming has dried, follow with a full priming coatover the entire surface.

3-5. Number of Coats Used. On some jobs thetotal number of coats of paint to be applied willbe specified. On other jobs you must determinethe type and number of coats needed. It is ac-cepted practice in the painting trade to describepainting coverage as one coat, two-coat, or three-coat systems. The number of coats to be applied,including primer, will determine the total thick-ness of the coating. On exterior woodwork, athickness of 4 to 5 mils is desired. Paints, whichmeet Federal specifications. are designed to build4 or 5 mils thickness with two heavy coats, orwith three lighter ones. provided the spreadingrate is gaged correctly. The following informa-tion should help you determine the coverage re-quired for any surface:

a. One-coat. Buildings on which the paint isnot curling or scaling. and which do not needpriming, usually need only one coat of finishpaint. One coat provides ample coverage if thereis at least 3 mils' thickness of old coating left onthe surface. If there are scattered patches of flak-ing or scaling which expose bare wood, you shouldspot-prime. the bare places and then apply onefinish coat of paint over the entire surface.

b. Two-coat. When the old coating is less than3 mils' thick, two coats of new paint are usuallyneeded. When there is enough flaking- and scal-ing to expose some bare wood on all parts ofthe wall. two coats should be used. The first coatgenerally should be primer and the second coatwill be finish paint.

c. Three-coat. For painting new wood sur-faces or those from which all old paint has beenremoved, you should use three coats. On newwood, the first coat should be primer and the lasttwo coats finish paint. The second coat (firstcoat of finish paint) should be thinned moderately.before application. Apply the third or final coatas it comes in the can. On bare surfaces to berepainted. you may use priming paint for the firsttwo coats and finish paint for the last coat. Ineither of the three-coat systems. the spreadingrate should be gaged to give a total coating thick-ness of 4 to 5 mils.

I 1 a3-6. You have learned that the number of

coats to be applied should b. governed by thethickness of the old coating ...nd its condition.When repainting, the addition of new paint shouldnot bring the total thickness too much over 6mils. The thicker the old coating, the less newpaint should be added.

3-7. The initial, appearance of the repaint jobwill be affected when the one coat system is used.The paint may dry with less than its full degree

of gloss. It may vary in gloss according to thetexture of the old paint under it. It may showflat spots over the flaking or cracks in the oldpaint. These are all minor blemishes. They will

disappear as soon as the new paint reaches thechalking stage.

3-8. Poor Painting Technique. Poor paintingtechnique may cause a newly painted surface tobe unsatisfactory and unacceptable. These 'con-ditions must be corrected before further paintingis done. Poor or bad paint, as it comes fromthe factory, is seldom responsible. Paints whichconform to Federal specifications.are high qualityproducts suitable for their intended uses. Poorworkmanship is seldom responsible, but it canadd to the problem. A lack of knowledge onYour part'can cause you much grief when you areapplying pain's. It is always safet to repaintsurfaces with the same type paint used before.You should use only 'recommended combinationsof primers and finish paints. Use of dissimilarpaints may cause the following defects:

a. Lifting. Lifting is a softening of the oldpaint by strong solvents in the new coating. Forexample, some rubber-base paints contain sol-

Figure 15. Alligatoring on surface.

12

Figure 16. Wrinkling on surface.

vents used in paint removers, and are incom-patible to many oil base paints.

b. Crawlin'. Crawling occurs when the newcoating fails to wet the surface of the old paint.The new coating will collect it, drops as waterdoes on a greasy surface.

c. Tackiness. Tackiness may occur if the newcoating is applied in damp air or -old tempera-ture. Failure to use paint remover to removewax left on surfaces is likely to slow or preventdrying of a new coating.

d. Alligatoring. In alligatoring, the newly ap-- plied paint cracks and slips over the old coatingso the old coating can be seen through the fis-sures. Alligatoring is ceased by the applicationof dissimilar paint over the old coating. This con-dition is illustrated in figure 15.

3-9. Typical coating combinations that causealligatoring are:

a. House paint applied over bituminous paintor roofing tar.

b. Painting over deposits of pitch or over shel-lac on knots.

c. Paint or enamel applied over varnish..

d. Light colored house paint applied overheavl coatings of darker color.

3 -10. Wrinkling is a drawing up of the newcoating into ridges while the paint is drying. It

may vary from a bold to a fine pattern whichappears to be loss of gloss (see fig. 16). Wrin-kling can occur at any time if paint is applied inunduly thick coatings/ It occurs most often when

there is a drop in temperature of more than 20°F. within a few hours after the coating has beenapplied.

3-11. You should have learned some of thefactors which affect the durability and appear-ance of an exterior paint job. Now, let's discussthe actual procedures for applying the protectivecoating to the surface.

3-12. Application of Exterior. Coating. Youcan apply protective coatings to exterior woodsurfaces either by brush or spray. Each of themethods has its advantages and disadvantages.You can usually paint more neatly by the brushmethod than with spray guns. Spraying of paintrequires troublesome masking. It produces mistand overspray. You can gage the spreading rateof the paint more easily when brushing, becauseyou are guided by feel, sight, and length anddrag of the brush strokes. When spray-painting,you must rely entirely on sight and timing. Youcan do a better job with a brush in depositingextra paint in the hollows without overloadingthe high spots. On the other hand, you can reachwide, deep cavities with the spray that a brushcannot enter. After you become skilled in theuse of the spray gun, you can paint wood aswell as the best brush hands can do. Most toppainters still agree and recommend that the firstprime coat on wood should be brushed on. Theprimer adheres tighter when it is brushed andcross-brushed into the pores of the wood.

3-13. Spraying exterior wood surfaces. Youmay save labor by spray-painting buildings whichhave large wall areas unbroken by windows anddoors. Buildings with many windows and doorsoffer less chance to save labor, especially if theyare trimmed in another color. Spraying ordinarydwellings offers little economy unless the follow-ing short cuts are a- ceptable:

a. Use only one color and type of paint forwalls and trim.

b. Cover all glass with masking compound andspray over sash and glass.

c. Strip the dried paint and masking compoundfrom the glass.

3-14. Instructions for actual use of the spraygun will be covered in Chapter 3. Since youwill be using the brush method to paint most ex-terior wood surfaces, let's discuss the groper useof the brush in applying paint.. ,

3-15. Brushing exterior wood surfaces. Youwill probably use a 4-inch brush for painting ex-terior walls. Make 'sure the brush is clean andremove all loose bristles. Check your paint forproper mixing and box it if necessary. Dip thebrush about 2 inches into the paint several times.

13

173This will work the paint into and load the brush.Each time you load the brush, tap the tip of thebristles against the inside of the container. Thiswill remove any excess paint from the brush.As you move the brush from the paint containerto the work, keep the bristles pointed down-ward. This will prevent paint from running intothe metal ferrule and down the handle of thebrush. Apply the paint to.the surface in two orthree places, as shown in figure 17,A. Next,feather the paint as shown in B. You then finishby using long strokes, as shown in C.

3-16. Hold the brush lightly but firmly. Thepaint should be brushed to a uniform film ofdesirrd thickness. You should brush oil paintsthoroughly to coat all defects in the surface.Rapid-drying paints should be brushed onlyenough to spread the paint and avoid excessivethickness.

3-17. Do not poke or jab the brush into cor-ners or cracks. This will damage or break thebristles. When applying primer to large knots,you should first move the brush in a series ofsmall circles to completely cover the area. Thefinish paint should be applied .by using long,parallel strokes.

3-18. The second and third coats of paintshould be applied in long strokes. You will getbetter results by painting in a series of 2- to 3-

4

1

Figure 17. Brushing paint.

17,1foot strips along the width or length of the build-ing. You should always start the painting at thetop of the area and work down.

3-19. Painting exterior equipment. You willfind the painting of exterior trim, windows, doors,and other equipment to be time consuming.More patience and skill are demanded whilepainting these objects. You must be able to cutstraight lines and edges with the brush. Sincetrim is generally painted after the body of thebuilding, you must avoid drips, spills, or splatters.Even if the trim is to be painted in a differentcolor, you should prime it at the time the walls areprimed.

3-20. Painting exterior trim. You will probablyselect a 2- or 3-inch flat brush for painting ex-terior gym. Door facings, window facings, cor-ner bards, and trim and mouldings, on oraround caves should be primed to a thicknesswhich will require only one coat of finish paint.You should apply the finish paint in the directionof the grain. When using outside enamel or anyfast-drying paint, brush only enough to smooththe paint and prevent runs. You should avoidrebrushing over the newly painted areas whichhave already become tacky.

3-21. Painting window sash. Window sashshould be painted at the time the facings andjambs are painted unless they are to be a dif-ferent color. Single-pane sashs are simple topaint. Sashs which have many separated panesof-glass require more patience. You may selecteither a 1/2- or 3/4-inch oval sash brush for thejob.. When painting double-hung windows (sec

BOTTOM PAIL

Figure 18. Window terminology.

1 CI r) 14

Figure 19. Spray-painting window screens.

fig. 18), the sash should be positioned for paint-ing. Pull the top sash down slightly and raisethe lower sash. This will allow you to paint thetop rail, bottom rail, and the inside of the meet-ing rails. You can then reposition the sashes topaint the stiles, muntin, and mullion rails. Thepaint should completely cover all glazing com-pound to form a seal between the compound andthe pane. When you have several windows topaint, you may want to use a straightedge guide.You can make a guide from an old metal ve-netian blind slat. Cut it to length and place oneedge on a line where the glazing compound joinsthe glass. You can then paint the rail with onesmooth stroke of the brush. Wipe the paint fromthe guide with 'a rag, being careful not to cutyour fingers on the sharp edge. Repeat the pro-cess until all rails are painted.

3-22. Painting wooden screens. Before paint-ing window and door screens, you should removedirt and rust. You can do this by brushing thescreen cloth with a stiff-bristle scrub brush. Thetype of paint you use will vary with the type ofscreen cloth. Black enamel is used on black ironor galvanized screen cloth. Spar varnish is usedon copper or bronze screen. Screens with alumi-num frames and aluminum screen cloth should notbe painted. You should paint wooden frameswhich have been exposed less than 2 years withonly one coat of finish paint. On screens whichhave been exposed more than 2 years, you shouldapply one coat of primer and one finish coat.When many screens must be painted, you maysave much time by spray-painting them, as

shown in figure 19. Stack the screens on saw-

horses. Spray the top screen and remove it fromthe stack. Spray the next onc and remove it.

Continue this proccss until all screens arc painted.The spray mist from the top screens will filterdown through the stack as you paint. The screensnear the bottom will require less spraying.Enamel uscd for spraying scrccn cloth should bethinned with onc pint of mineral spirits to onegallon of enamel. You should be very careful

not to overspray scrccn cloth. Too much paintwill fill thc openings in thc screen. Whcn sprayequipment is not available, you can paint scrccncloth with a wood block, approximately 2 x 4 x 6inches, covered with floor carpet. Dip the blockinto a pan containing the paint and apply it to

the screen.3-23. Painting exterior floors. Exterior wood

steps, platforms, and floors of open porches muststand heavy traffic. You should use a porch anddeck paint which hardens more rapidly thanhouse paints for these areas. As a rule, thesepaints arc worn out by the pounding of trafficrather than the slower action of weather. Forthis reason, priming coats add little to the life

of the surface. The paint can be used as its ownprimer. After several rcpaintings, perch and deckpaint may reach a condition of breakdownthe less trafficked areas. In this case, jou maycompletely remove the old paint before repaint-ing. Porch and deck paints arc normally appliedwith a brush.

3-24. Painting shingles and rough-sawed him.Pier. The rough surfaces of woe d shingles, orboards with unplaned surfaces, are expensive topaint. They absorb excessive quantities of paintand still dry flat. Such surfaces are t.suallycoated for appearance rather than durability.When you are interested oily in durability, youcan brush or mop the surface wiTh hot linseedoil. If the surface is being coated for appear-ance, yc. a should use an exterior wood stain.You should al mys apply two coats of 51.ain be-cause of the high vehicle content. If only onecoat is used, the vehicle solids are absorbed,leaving littL binder to hold the pigment on thesurface. The pigment will then wash awayeasily. Shingle stains are available in red andgreen colors. Other exterior stains are availablein a redwood color or brown. If yet. need astain to match a color of house or trim paint,you can mix it on the job. Mix two parts ofstaining oil with one part of the house or trimpaint. If the staining oil is not available, paintthinner may be substituted. You will normallyapply stain with a brush. You should overbrushall runs immediately as you apply the stain. Thespreading rate is low, often no more than 100square feet per gallon, depending on the rough-

15.

183

175'ness of the wood. When mixing stains. makesure you have enough stain to complete the job.

3-25. Painting creosoted wood. Creosote leaves

wood with a surface difficult to paint. It maysometimes be desired to paint the upper parts of

creosoted posts set in the ground. Most oil paintsor enamels will soon become discolored by creo-sote from the wood, and the surface may alligator.Two coats f exterior aluminum paint will make abright coati.-.12 that resists discoloring as the creo-

sote bleeds The aluminum paint remains b6ghtbecause 'aminum particles float on top ofthe paint vehicle. You should not apply white oilpaint over the aluminum as it may still result in

discoloration. If the creosote surface is old andweathered, or has rough surfaces, you may paint

it white by using a water-thinned paint. You

may use a casein paint, exterior latex, or evenordinary whitewash. A reasonable degree ofwhiteness may be retained for as much as 2

years before rei.ainting is necessary.3-26. We have discussed many aspects of the

preparation and coating of exterior wood sur-faces. Now, let's see what we can learn aboutthe preparation and coating of interior wood sur-

faces.

4. Preparation and Cc ,ting of InteriorWood Surfaces

4-1. Thera, are two primary reasons why in-terior wood surfaces are painted. The first is

for appearance and the second is for cleanlinessand sanitary reasons. Inter' ,r wood surfaces willremain sound for years without a protective coat-ing, since they are not exposed to weather. Ex-cept:0ns arc shower rooms, utility rooms, and

kitchens where the surface is exposed to ex-cessive moisture. Coated surfaces arc easy toclean and they resist the buildup of odor' andgerm-bearing dirt.

4-2. Interior wood surfaces usually require ahigher degree of preparation than exterior sur-faccs. Somc wood paneling uscd in modern in-teriors has a transparent finish. This finish actsas a magnifying glass to bring out the quality andcolor of the grain. It magnifies thc mill marks,checks, dents, and scratches on the surface. Theuse of opaque paint on wood surfaces may covera large number of imperfections; but even thesesurfaces must be well prepared. You shouldnever use exterior house paint on interior woodensurfaces bccausc exterior paint may dry slowly,may never harden as much as desired, and maygradually turn yellow.

4-3. Preparing and Coating Surfaces with

Opaque Coatings. New interior surfaces installedwith top workmanship by the carpenter will re-

quirc less perparation before application of

opaque coatings. You should remove planingmarks, hammer marks, and raised grain by sand-ing. After application of the priming coat, youshould fill all nail holes, cracks, and other de-fects with white-lead, whiting putty. Afte theputty has dried, spot-sand the surface. The primecoat should approximate the color of the finishcoat to be used. Three standard types of finishpaints are provided for interior use. You shouldselect the right one for the job according to thedegree of gloss and washability desired. The fol-lowing information will aid you in selecting theproperCpaint fora particular job.

a. Flat-finish pint. This is a paint which drieswith little gloss, to give a so-called eggshell sur-face. For large areas, such as plywood panels onwalls and ceilings, flat paint presents the mostpleasing appearance. It provides a comfortabledistribution of light. This paint may be washedoccasionally to keep it clean. It will not standas many or such vigorous washings as the. paintsdescribed below.

b. Semigloss-finish paint. Semigloss paint isan enamel made with a varnish vehicle and a highlevel of pigments. It produces a semigloss ap-pearance and is a coating which stands' wear andwashing well. It is generally used for walls andceilings in service rooms, such as kitchens andbathrooms. Here, good washability is importantand moderate gloss surfaces are customary.Semigloss paint should be used for window anddoor trim and for baseboards even when flatfinish paint is lsed on walls and ceilings.

c. Gloss-finish paint. Gloss paint is an enamelwith good hiding power. It has a modzrate levelof total pigment in a varnish vehicle. It pro-duces a high-gloss surface which washes we". Itis considered to be a high-priced interior finishbecause of the surface preparation needed for itsapplication. The high-gloss coating accentuatesall defects in the surface. The surface prepara-tion should include a second prim:- coathas been sanded smooth.

4-4. Opaque paints may be cpp/i.d to wall,And ceilings by brush, spray gur,, or roller. Themethod of application selected :5 governed bythe particular job. Interior enamels are self-leveling and very suitable for brushing; but brushapplication is slow. Spraying inside small roomspresents a ventilation problem, a great fire haz-ard, and requires masking of areas and protec-tion from overspray on floors. The use of aroller coater is reasonably fast but will usuallyrequire two coats for consistent color coverage;also, additional use of a brush is required to cutin corners and paint around trim.

16

Figure. Remr,ving roller comer covers.

4-5. Paints on interior surfaces do not wearaway appreciably %set ween paintings. They willeventually build up too much thickness of coat-ing. Interior painting should always be done withthe minimum otunber of coats and maximumspreading rate consistent with good appearance.

. 4-6. Painting plasterboard. Dry-wall construc-tion, in which plasterboard instead of wet plasteris used, is very populaz in modern frame con-struction. Joints in the plasterboard are taped.arid bedded with a special joint compound andtit. v ::anded smooth. A stipple finish may beapplied to plasterboard to produce a surfacesimilar hi appearance to plaster. Complete de-tails on tai,ing and bedding pia aerboard will becovered in Chapter 2: Paint plasterboard sur-faces in the same manner as interior wood sur-,faces. When plasterboard is used in damp areas,apply o.,.e coat of primer sealer followed by onecoat of kInallici undercoat or prhoer. Plasterboardis more generaiiy painted with self-ic.:ming, in-terior latex paints. These paints dry rapidly andare applied with a roller coater.

4-7. Applying paint with the roller oatenYou have learned the types and sizes of rollercoaters. You will probably select either a lamb'swool or mohair cover for trainthlg interior sur-faces. The roller unit is constructed so thatthe cover can be removed or changui. Figure

20 shows two :;iies of roller units. Note thecover simply slips cm and off one type, while theother must be disassembled to allow removal ofthe cover. You will also need a roller coater panwide en....:gh to accommodate the roller. Eventhoueh most of the painting will be done with arollcr, you need a 2- or 3-inch flat brush to applya strip of paint along the edges and corners ofthe area to be painted, as shown in figure 21.Cut in one area at a time with the brush, thenfollow immediately with the rollor on the remain-ing surface to avoid lap marks. When both ceil-ing and walls are to be painted, always paint theceiling first. Use the same procedure lot paintingboth ceiling and walls, except a long handleroller should be used for the ceiling. Place theroller pan on the floor, partially fill it with paint,

Figure 21. Edging surfaces with brush.

dip the roller into the pan, and squeeze it againstthe bottom with a rolling motion. Now, apply theroller to the ceiling and make several crisscrossstrokes. This distributes the paint and insurescoverage on stippled surfaces. Work quickly butnot too fast because paint will sling off the rollerif it spins too rapidly. Finish the rolling withlong, parallel strokes in one direction. Start atone edge of the ceiling and work your way acrossthe room. You should paint the walls with ashort handle roller. Place the paint pan on theladder shelf. Use the same procedure for paintingthe walls that you use for painting the ceiling.Figure 22 shows the correct way to apply paintin crisscross strokes. Figure 23 shows how tofinish the rolling by using long, parallel strokes.If the painting is interrupted before completion.

17

1 85

Figur-- 22. Painting crisscross with roller.

stop at a joint in the construction or in a cornerof the room. Avoid applying paint over the edgeof paint already set because this may cause un-lightly lap marks. If you notice thin spots, goover that portior again. These thin spots or anyspots wh;ch have been missed are cailed holidays.Whe» repairing hondays. always finish the roll-ing with long, parallel strokes. If a second coat is

I

Figure 23. Painting parallel strokes with rt 1, r.

required, apply it in the same manner as thefirst, starting with the ceiling.

-8. Repainting old opaque surfaces. The dc-grcc of surface preparation for wood surfaces tobe repainted will vary. Surfaces with no dam-age other than normal deterioration require littlepreparation. You should clean the surface bydusting and removing all dirt. If the surface isbadly soiled with dirt of a greasy nature, such asin kitchens, the surface should be washed thor-oughly before refinishing. You may use a gooddetergent soap and water to clean these areas.Any damaged spots, where coating has beenscratched or has worn through to the wood,should be primed. You should spot-sand theseareas after the primer has dried. Unless colorsare changed, satisfactory coverage can be ob-tained with one coat of finish paint. Door, win-dow, and baseboard trim should be sanded lightlyand have one coat of trim enamel applied.

4-9. Plasterboard walls should be dusted thor-oughly before repainting. Dust adheres readily tostippled surfaces. You can clean these surfaceswith a vacuum cleaner and brush attachment.All cracks in the plasterboard must be rcpaircdbefore repainting. If you paint over these crackswithout repairing them properly, the crack willreappear when the new coating dries. Repairsuch cracks by taping and bedding, using the fol-lowing procedure:

a. Obtain a clean container and mix a suitableamount of plasterboard joint compound. Followmanufacturer's directions for mixing and allowthe mixture to set for 20 to 30 minutes prior touse.

b. Usc a 2 x 4-inch sanding block and mediumgrit paper to remove the stipple and old coatingalong the full length of the crack. Rcmovc ev-erything down to the paper surface for a distanceof 2 inches on each side of the crack. Fcathcr-sand the edge cf the stippled area into the baresurface.

c. Restir the joint compound to an even con-sistency. Usc a 4-inch-wide putty knife to applythe joint compound over the crack. Spread thecompound to a thickness of 1/ 6 inch for a distanceof 11/2 inches on each side of the crack.

d. Tear a strip of perforated, joint tape fromthe roll. The tape should be long enough tocover the crack without splicing. Use a wideblade putty knife to imbed the tape into thecompound. The tape should be aligned so thatthe crack falls near the centerline of the tape.Place the knife across and near one end of thetape. Hold that end of the tape in place withone hand and pull the knife along the tape withthe other hand. Apply enough pressure on the

18

knife to imbed the tape into the compound withno wrinkles in, or bubbles under, the tape. Usethe putty knife to remove a11 excess compoundfrom the arca. The tape should be visible in thecompound at this point. If time permits, allowthe tape and compound to dry several hoursbefore proceeding to the next step.

e. Use the putty knife to apply a layer ofjoint compound over the tape. Compound canbe kept for several days if the container is cov-ered with a wet rag. Spread the compound sothe center and edges of the tape are completelycovered. Feather the compound into the edge ofthe old coating by using the flat side of the puttyknife as a trowell. Usc long, even strokes of theblade along the length of the tape. Do not useshort strokes across the tape, as this tends toraise and curl the edge of the tape. Allow thecompound to dry thoroughly.

f. Hand-sand the compound very lightly. Re-move all trowell marks so the surface is smoothand blends into the old coating. Bc careful not tosand through the compound into the tape. Ap-ply the stipple to the rcpaircd area by using asponge. Dip a wet sponge into the joint com-pound and pat lightly over the repaired area.With a little effort, the pattern in the old coatingcan be duplicated. Allow the stipple to dry andthe repair is complete.

4-10. Repair any other areas where the stip-ple has been damaged. Desks or tables placedagainst walls may rub through the coating andleave the plasterboard exposed. If you fail torepair those areas, the new coating will dry flat.Apply new stipple to these areas with a sponge.

4-11. After all repairs are complete and thesurface has been cleaned, you can apply the newcoating. When enamel is used as the finish coat,prime all repaired areas with an enamel under-coat and allow it to dry. When interior latexpaint is used, spot -prime the rcpaircd areas withthe latex paint first and then proceed immediatelyto apply the finish coat. Repainting of plaster-board surfaces should be done by following thesame procedure as for new work.

4-12. Preparing and Coating Surfaces WithTransparent Coatings. Interior walls and ceilingsthat are to receive transparent finishes, must heconstructed from top-quality materials. Number1 grade, clear, fir plywood, or mahogany -ve-neered plywood, make attractive walls for officesin warehouse or shop areas. Thcsc materials arereasonably cheap and easy to obtain. Cherry,walnut, or birch-veneered plywood,, or plank pan-cling may be used in high-priority executive of-fices. Thcsc materials usually come with a fac-tory- applied finish.

4-13. To prepare new surfaces for transparentfinishes, sand the woodwork to remove all marksand blemishes. Be very careful when sanding aveneer surface on plywood. Do not sand throughthe veneer covering into the center ply of theboard. Use either a sanding block or a small vi-brating sander for this operation. Never use abelt or rotary power sander. All sanding shouldbe done in the general direction of the grain.

4-14. Staining interior surfaces. It is often de-

sirable to stain interior wood surfaces before ap-plying transparent finishes. Fir plywood used forceiling and wall panels is generally stained witheither light- or dark-oak oil stain. This adds bodyand richness to the finish. Even for surfaceswhich have a factory finish, you will probablyhave to stain window, door, and base trim tomatch the color of the panels. This trim may beeither softwood or hardwood. You may mix thesestains on the job, using the formula given inMemorandum 562, figure 35.

4-15. When staining softwood, you apply pig-ment oil stain directly to the bare wood. Fordarker colors, such as walnut, you may first brushon one coat of sealer or one thin coat of shellac.Use steel wool to remove the sealer or shellacuntil the surface has the appearance of bare wood.You then apply the oil stain by brush and wipeit off with rags. The longer you let the stain setbefore wiping, the darker the tone will be. Al-ways wipe off all excess residue before the staindries. If you want darker tones. apply anothercoat.

4-16. To stain hardwoods with pores smallerthan those in birch, use pigment oil stains in thesame manner as on softwoods. It is seldom de-sirable to apply sealer or shellac to hardwoodsbefore staining. Hardwoods with larger pores arefinished in a similar manner, except pores mustbe filled with a wood filler before staining. Apaste filler is generally used for ceiling, wall sur-faces, and trim. You should apply the filler vig-orously across the grain and allow it to set from10 to 30 minutes. Remove the excess filler bywiping with rags, first across the grain, then lightlyalong the grain (see fig. 24). After the surfaceis filled and stained, brush on a thin coat of shel-lac. When the shellac has dried, steel-wool thesurface lightly before proceeding with the finish.

4-17. Applying the transparent finish. Two. types of transparent finishes are used for interiorsurfaces: the varnish finish and the sealer andwax finish.

4-18. Apply varnish with a clean brush, eitherflat or oval in shape. Take a full load of varnishon the brush but not enough to drip off. Brushthe varnish out well, but brush no longer than

179

is necessary. Se 'oral thin coats produce a betterfinish than one thick one. A thick coat may run,sag, or wrinkle and require excessive drying time.Allow at least 24 ho.irs for drying between coats.After one coat lias dried hard, rub the surfacelightly with steel wool ..efore applying the nextcoat. This removes all dust particles and nibs inthe surface. The number of ,.-oats you apply willdepend upon - . absorptive nature of the woodand the desir fullness of the finish. If the pri-ority of the appearance ciclnar.ds it, the final coat

19

1 APPLY FILLER WITH GRAIN

2.THEN BRUSH ACROSS GRAIN

3 CLEAN OFF ACROSS GRAIN

=Nor

4. WIPE LIGHTLY WITH C IMN

Figure 24. Applying filler to hardwoods.

ISO

Figure 25. Rubbing surface with pumice stone.

may be rubbed with pumice stone (sec fig. 25).When the finish is to be rubbed, the final coatshould be varnish which meets Federal Specifi-cation TTV-86b, Varnish, Rubbing, Cahinct.The varnish must be thoroughly dry and hard bc-forc rubbing. Usc a felt pad to rub the surfacewith pumice and oil. A mineral oil, such as kero-sene, should be used with the pumice powder tomake a paste. Rub the surfacc with the pad.saturated with the pumice and oil, along thegrain. Avoid rubbing through the finish at edgesor curvatures in the surfacc. Wipe the surfaceclean occasionally to check for the desired luster.Finish the job by cleaning the surfacc with anoil furniture polish.

4-19. Most interior varnish surfaces will notwarrant the additional work required for rubbing.A dull - luster finish may be obtained by using aflat varnish for the final coat. This varnish isself-leveling and drys with a satin finish.

4-20. Refinishing transparent surfaces. If theold surfacc is in good condition, and no changein color is desired, little preparation is necessaryprior to refinishing. Light sandpapering and re-varnishing, or light sandpapering and resealingarc sufficient.

4-21. If the old surface contains dccp scratchesor areas worn through to bare wood, these dc-fccts must be rcpaircd. On light-colored woods,apply a coat of hot linseed oil to the damagedareas; on dark-colored woods, apply oil stain.Seal the damaged area with shellac and carefullybuild up the thickness to that of the damagedarca. The rcpaircd area will appear darker thanthe old surfacc. This condition will correct itselfin time, as the oil is absorbed into the wood.Avoid dccp sanding of scratches in veneered sur-foces as you may sand through the veneer coat-

20

ing. Deep sanding is permissible on wood plank-ing.

4-22. For complete refinishing of old, stainedwood, remove the existing finish with paint andvarnish remover. Wash the bare surface to re-move wax left by the remover. Sandpaper thesurface lightly and refinish as new wood.

4-23. If a lighter stain is desired when refin-ishing, or if the existing color is dark and uneven,sand the area thoroughly. The color can be light-ened when it is possible to uncover some barewood. It may be necessary to use a bleachingsolution by mixing 8 osicces of oxalic acid intoquarts of hot water. More than one applica-tion is often necessary. After the surface hasdried, rcmovc any raised grain with sandpaperand refinish as new wood.

4-24. Coating Interior Floors. Interior floorsare not subjected to weathering as are exteriorfloors. Their appearance is expected to be betterand the finishes more varied. Either opaquepaints or transparent coatings are used on interiorfloors. Interior floors require much more surfacepreparation before refinishing than do exteriorwood floors. They must be sanded smooth, filled,and sealed, before the finish coat is applied.

4-25. Pine floors may be finished with trans-parent coatings; however, these floors are usuallypainted. Pine is a softwood which dents and marseasily. Hardwood floors of oak, maple, or birchare generally always finished with transparentcoatings.

4-26. Before applying any type finish to a newfloor, remove all surface .imperfections by sand-ing. Special sanding machines are used for sand-ing floors. A special edger is used for sandingalong walls. You should seek advice from an ex-perienced operator before attempting to use thefloor sander. An inexperienced workman cancause heavy damage to a floor if the machine isnot operated correctly. The machine must be keptin movement at all times. If the movement isstopped. the abrasive will cut deep grooves or dc-prcssions into the floor. Thcsc may be impos-sible to remove. You should sand the floor in adirection parallel with the boards. Cross sandingcauses deep scratches across the grain of theboards. These scratches will require additionaldccp sanding (with the grain) to rcmovc. Whenyou complete the sanding operation, be sure youclean the area of all dust. Even though the sand-ing machine has a dust bag, the area should becleaned with a vacuum cleaner.

4-27. If the floor is to be painted, a goodgrade of floor paint should be used. Prepare theprimer by adding 1 quart of spar varnish and1/2 pint of mineral thinner to 1 gallon of the floor

paint. Apply the priming coat with a brush, work-ing it well into all cracks and end joints. and al-low the priming coat to dry for 24 hours beforefilling open joints and cracks with a hard-settingputty. Apply the finish coat of floor paint withoutreduction. Brush the paint along the grain andwork it well into the wood.

4-28. Repainting wood floors. Floors whichneed recoating will have the paint worn away intraffic lanes. The remainder of the surface ma)be in good condition. Spot-prime the worn area;and apply one finish coat of paint over the entirefloor. If there is severe paint failure, such asflaking or alligatoring or excessive thicknessbuildup, strip the old coating from the floor, usingpaint and varnish remover. Be very careful whilescraping not to damage the wood surface. Thismay prevent a need for resanding the floor.Clean the surface to remove any wax from thepaint remover, and then repaint as you would anewly sanded floor.

4-29. Applying transparent floor f inishes.Floors that are to be natural finished must besanded with greater perfection than those whichare to be painted. You should fill all open jointsand cracks with a wood-base putty approximatelythe color of the hare floor. This putty can bemade by mixing sanding dust from the floor witha casino or banana oil-base glue. When the puttyhas hardened, the repaired areas must be spot-sanded. Use a sanding block or vibrating sanderfor this operation.

4-30. Hardwoods with large pores must befilled to produce a righ, mirror finish. The fillingoperation is a hard and physically tiring job whichshould be avoided unless absolute perfection isdesired. A paste wood filler is used on floors.You should thin the filler with turpentine or min-eral spirits to a consistency of thick cream. Usea brush to apply it freely across the grain andwork it into the pores. Work on small sectionsat a time. Allow the filler to set until the surfacebegins to lose its gloss and appears dull. Wipeoff the filler with burlap sacking or use a floorbuffing machine. The wiping operation is impor-tant, and is first done across the grain then lightlywith the grain. The buffing machine is suitablefor this operation as the pad rotates in a circularmotion. You should allow the filler to dry for18 hours before proceeding.

4-31. Various transparent finishes may be ap-plied after the floor is sanded and filled. Floorsealer provides a more durable surface than shel-lac or varnish finishes. Shellac is used only onlow-priority jobs or whenever the floor is requiredfor immediate use. Varnish finishes are used foraverage traffic areas when a rich, luxurious sur-

21

face is desired. The life and appearance of anyof the surfaces can he extended by periodic wax-ing.

4-32. When shellac is used, apply it with abrush. Flow the shellac on with short strokes anddo not overbrush. When two coats are used.steel-wool the surface between coats. This canbe done with a power buffer equipped with steelwool pads. Since shellac dries hurriedly, the floorcan be waxed and placed into service in a mini-mum of time.

4-33. The application of floor sealer requiresno special skill. At one time it was believed thatfloor scalers had to be brushed on to achieve topresults. Modern, labor-saving practices haveproven these coatings can be applied effectivelywith a lamb's wool applicator or mop. Apply asmuch sealer as the floor will absorb. Spread ad-ditional scaler over areas that will absorb it. Wipeoff all excess scaler from the floor before it he-comes tacky. Before the first coat dries, burnishit lightly with steel wool and allow the sealer todry overnight. Apply a second coat of sealer inthe same way. Repeat the burnishing operationwith a power buffer using steel wool pads. Againallow the sealer to dry overnight and completethe job by applying a coat of paste wax.

4-34. Varnish should be applied to the floorwith a brush. You should apply a thin coat forthe first coat. Allow the surface to dry overnightand remove the glaze by sanding or rubbing withsteel wool. Wipe the surface with a dry cloth toremove the dust. Apply the second coat and fol-low the same procedure. Complete the job by ap-plying a coat of paste wax to the surface.

4-35. Refinishing transparent surf ace floors.Deep sanding during the refinishing of transpar-ent floors should he avoided whenever possible.Continuous sanding, especially in traffic lanes.can eventually remove enough wood to exposenailhcads and tongue and groove joints. Thiswould require replacement of the flooring. Deepsanding may also produce low places or hollowsin the floor surface. Scrub the floor with soapand water to remove all grease or floor waxbuildup. Use clean water to rinse and then drythe surface by dry-mopping. When the floor isthoroughly dry, steel-wool the surface, using apower buffer. Refinish the surface with one ortwo coats as required.

4-36. Operation of power buffers. We havediscussed the use of power buffers in the finish-ing, refinishing, and maintenance of floors. Let'slearn how to operate this machine properly. Theunit is simply an electric motor with a handleand attachments ranging from soft pads to bristleor wire brushes. To change the attachment, un-plug the cord, lay the machine on its side, and

SPONGE WITHWATER

STAIN SHOULD BE HOT

STAIN WITHWATER STAIN

Figure 26. Applying water stain.

1,9 22

rotate the attachment opposite the normal operat-ing direction. This unclips the attachment for re-moval. Install the brush or pad you want to useand raise the machine to its operational position.When the machine is turned "on," the clips willlock and hold the attachment in place. Duringoperation, do not try to manhandle the machine.By experimenting, you will find that lifting thehandle will cause the machine to move to theleft, lowering the handle to move to the right,and a neutral position will hold it in one spot.For operational safety, make sure the electricalconnections are good and the electric cord doesnot get caught in the machine.

4-37. Finishing Interior Wood Furniture. Whenfinishing furniture, make use of all the knowledgeand skills you have learned in finishing interiorwoods. If the furniture is to be painted, use onlyinterior paints or enamels. The surface must bewell-prepared and undercoated. The applicationof transparent finishes on fine hardwood furniturewill require the ultimate in surface preparation.

4-38. Water stain may be used instead of oilstain. Water stain does not fade or lighten asmost oil stains do. Before applying water stain,dampen the surface with a wet cloth (see fig.26). This will raise the nap in the grain of thewood. When the surface dries, remove the napby hand-sanding with very fine grit sandpaper.Continue by repeating this operation until the nap,no longer raises on the wood. The water staincan then be applied by brush. Applying the stainhot will cause it to have better penetration of thewood.

4-39. Hardwoods with large pores must befilled. You should use a liquid filler on furniturewoods. Brush the filler across the grain to fill thepores. Allow the filler to stand until the surfacelooses its gloss. The first wiping strokes shimildbe at right angles to the grain and should includea patting, or pounding action. This will pack thefiller into the wood pores. It is very importantfrom the standpoint of appearance that the ex-cess filler be removed from the surface. Youshould apply the filler before an oil stain is used;but, you must always apply water stain prior tofilling. Water stains will not penetrate the filler.

4-40. A good rubbing varnish that meets Fed-eral Specification TTV-86b should be used forfinishing fine furniture. You should apply var-nish with a brush in three thin coats. Allow eachcoat to dry at least 24 hours and steel-wool thesurface by hand prior to applying the next coat.After the final coat is thoroughly dry and hard,it should be rubbed with rottenstone and oil. Rot-tenstone is a very finely powdered abrasive, sim-ilar to pumice stone. It is used in the same man-ner as pumice except that a soft cloth is folded

LIGHTCOLOR

Figure 27. Pattern painting.

into a pad for rubbing. Final cleaning should bedone with a clean, soft cloth moistened in ben-zene. For a brilliant, deep-luster finish, apply apaste furniture wax.

5. Camouflage Painting5-1. Camouflage painting is a method used to

hide or conceal the location of buildings or equip-ment from enemy observation. It is generallyused in forward or combat areas to reduce thesilhouette or shadow of a structure. This lessensthe probability of the area's being a target forenemy ground fire or aerial bombing.

5-2. There are very few instances wherestraight lines or right angles appear in the generalmakeup of nature. When a building is placed inthese natural surroundings, it will "stick out likea sore thumb," because the building is made upof straight edges and corners. The two types ofcamouflage painting used on exterior surfaces areidentified as pattern and tone-down painting.

5-3. Pattern Painting. When pattern-paintinga building, use two or three contrasting colors.The paint is applied in irregular patterns andshapes, as illustrated in figure 27. There is nodefinite rule governing pattern sizes, since theydepend on the size of the structure, the type ofsurroundings, and the range of enemy observa-tion. The patterns should be as large as prac-ticable, since small patterns blend into one colorand do not give reliable concealment. The coin'sshould be chosen to blend with the backgro:..-idfor the camouflage to be effecti-c.

1921

IR-774,,

5-4. Tone-Down Painting. Tone-down paint-ing blends colors to reduce contrast. UndJ idealconditions, tor.e-down painting will cause a struc-ture to almost disappear from view. From theair, the light-colored roof of a building standingagainst a light background is easily located bythe shadow the building casts. Against a darkerbackground, the light-colored roof is detected byits own contrast with the background. The idealis to have a dark-colored roof on a dark back-ground. This will cause the building and its

shadow to disappear from view.5-5. You may apply camouflage paint with a

brush, spray gun, roller, or any convenientmethod at hand. To obtain the best results, fol-low the manufacturer's instructions. Failures arecaused by improper mixing, application duringbad weather, and use of the wrong type of paintfor a surface. Normally, the requirements forcamouflage paints are dull finish, no fade, easyto apply, and cover in one coat. You may applycamouflage paints to steel or masonry structuresas well as wood. Tne methods of painting ma-sonry will be discussed in Chapter 2, and metalin Chapter 3.

5-6. Camouflage paints may be procured invarious colors, such as light or dark green. fielddrab, sand. earth brown, earth red, earth yellow.and olive drab. These colors, together with blackand white, will provide sufficient variety for mostcamouflage painting. The following basic colorschemes are recommended as effective for paint-ing patterns on buildings in various regions:

a. In the temperate zone or jungleolivedrab. field drab, or another light color to matchthe terrain, and black.

b. For desert terrainsand, earth yellow,earth red, or another light color to match theterrain, and black.

c. On snow terrainwhite and olive drab orblack and white are very effective.

5-7. In combat zones, the choice of camou-flage paint is determined by the surrounding area.Normally, issue paints from supply are mail-able. If not, you will have to use your owningenuity to make them. Crankcase oil drainings,asphalt, clay and colored mud may be appliedto change the color of surfaces.

!sqCHAPTER 2

Painting Masonry Surfaces

ASONRY SURFACES, such as brick, con-crete, stucco, stone, and cinder or con-

crete blocks are painted for two reasons: forwaterproofing and to improve their appearance.

2. As you remember from Chapter 1, we dis-cussed the procedures for preparing and coatingwooden surfaces. Many of the same methodsare used to apply paint to concrete and masonrysurfaces. However, different materials and someadditional tools are used to clean the surfaces ofsuch buildings. These buildings will require spe-cial treating before the protective coating i3 ap-plied.

3. As a protective coating specialist, you mustbe able to recognize conditions on masonry sur-faces which will affect the life or appearance ofprotective coatings. You must know how to prop-erly prepare and treat these surfaces prior to ap-plication of the protective coating.

6. Characteristics of Concrete andMasonry Surfaces

6-1. The painting of concrete and other ma-sonry surfaces is complicated by several factors.New surfaces will generally require more prepa-ration than old surfaces to obtain a durable andlasting paint job.

6-2. New concrete structures and the mortarjoints of masonry structures contain a largeamount of moisture. This moisture was intro-duced at the time the cement and aggregateswere mixed during construction. Concrete doesnot dry out as regular dirt and water mud does.It hardens from a chemical action by hydration.Although the free water disappears as the con-crete sets or hardens, the concrete will remaindamp and retain moisture for some time. Thishigh-moisture content adds to the difficulty ofpainting the surfaces.

6-3. New concrete and mortar will also con-tain considerable amounts of alkaline substances.The alkali will be located all through the con-crete and it is soluble in water. Alkaline sub-stances which are on or near the surface will

.1 Liri 4..

24

gradually be neutralized and washed away byrainwater. Those which lie more deeply in themasonry or concrete will be carried to the sur-face over a very extended period of time. This iscaused by a leaching action of the moisture inthe concrete. These deposits, as they reach thesurface, cause rapid deterioration of the protec-tive coating.

6-4. New concrete surfaces are likely to besoiled with oil from forms. The surface may beglazed as the result of having been cast againstsmooth, nonabsorbent forms, such as metal.Either of these conditions will affect the satis -.factory performance of paint coatings.

6-5. Old, unpainted masonry and concrete sur-faces may become badly soiled with dirt. Mois-ture and alkali deposits may have disappearedon old surfaces but there may be hard, crystal-like spots of efflorescence. These surfaces mustbe thoroughly cleaned before applying a protec-tive coating. Old masonry surfaces of buildingblocks. brick, or stone may have heavy mortarstains. These are the result of poor cleaning atthe time of construction. Masonry walls mayhave cracks in the mortar joints. These arecaused by foundation settling. All of these de-fects must be repaired before the application ofa protective coating.

6-6. You have learned the common charac-teristics of concrete and masonry surfaces whichaffect the application and durability of protec-tive coatings. Now, let's learn the methods oftreating, repairing, and preparing these surfacesprior to painting or repainting.

7. Preparation of Exterior Surfaces7-1. Many paints have been developed by

manufacturers who claim them to be unaffectedby conditions of the concrete surface. The factremains that there is no substitute for adequatesurface preparation.

7-2. Removing Glaze. Some concrete surfacesare so dense or glazed that they will not retainpaint well. The ideal situation would be to allow

--i342k177.7"--771

411

141

-

Figure 28. Efflorescence on brick.

these surfaces to expose to the weather for a 6-to 12-month period. If this is impractical, useother means to reduce the surface smoothness.You can usually remove the glaze on relativelynew concrete surfaces with steel brushes, abra-sive stones, or by light sandblasting. Keep inmind that you only want to remove the glazefrom the surface. Excessive roughening or pit-ting is unnecessary and undesirable. Old surfacesmay require more extensive sandblasting. Com-plete information on the use of sandblastingequipment will be covered in Chapter 3. If allmechanical means fail, you may roughen or etchthe surface with an acid solution. You can use a10-percent muriatic acid solution and apply it tothe surface with a bristle brush. Allow the solu-tion to remain on the surface for 5 to 10 minutesand then hose it off with water.CAUTION: You must always wear goggles andrubber gloves when using this acid. When mix-ing the acid solution, always add acid to water toprevent splattering. Never pour water into theacid.

7-3. Testing for Alkali. You will find it im-possible to detect alkali deposits by sight alone.These conditions are generally associated withmoisture movement in the concrete. To detectthe presence of free alkali, dampen the surfacewith water. Apply a few drops of a 1-percentsolution of phenolphthalein in alcohol to severalspots over the surface. If alkali is present, thedrops of solution will turn a pink, red, or purplecolor, depending on the concentration of alkali.

7-4. Neutralizing Alkali. There are severalmethods you may use to treat alkali surfaces

103 25

/Srprior to applying the protective coating. Thetreatment used depends on the age of the surfaceand the concentration of the Deposit. You cantreat new surfaces, when they are approximately3 weeks old, with a phosphoric acid-zinc chloridesolution. You make the solution by adding 3-percent phosphoric acid and 2-percent zinc chlo-ride to water. Apply the solution to the surfacewith a stiff-fiber brush. Allow the surface to dryfor at least 24 hours. The solution forms a coat-ing of insoluble compounds on the surface duringthe neutralizing action. Apply the protectivecoating to the surface without further cleaning,which could remove the compounds. You cantreat surfaces which have aged more than 3months with zinc - sulphate solution. Prepare thesolution by adding 2 pounds of zinc sulphate to1 gallon of water. Apply the solution with astiff-fiber brush. After drying, you should removeall loose particles with a dry scrub brush. Thesurface deposits formed by this solution are watersoluble and should be removed by dry-brushing,prior to application of the protective coating.Older concrete surfaces, which have aged for aconsiderable length of time and show minutetraces of alkalinity, can be neutralized with anacid treatment. Apply a 10-percent solution ofmuriatic acid and water. Rinse the surface withwater to remove the acid and allow the sur-face to dry thoroughly before applying the paint.

7-5. Removing Efflorescence. The white crys-talline deposit which forms on masonry walls,especially those made of brick, is known as ef-florescence. Figure 28 shows severe efflorescenceon a brick wall. You may remove light depositswith a steel wire or fiber brush. If this fails, youmust use an add solution. Wet the surface withwater and apply a 20- to 30-percent solution ofmuriatic acid. Allow the solution to remain onthe surface for 5 minutes. Scour the area with astiff-bristle brush, working on small areas ofabout 2 feet square. After this treatment, washand flood the surface thoroughly with clean water.CAUTION: A 20- to 30-percent solution of muri-atic acid is considered to be a strong solution.Always wear rubber gloves, goggles, and acidprotective clothing when using this aid.

7-6. Repairing Joint Cracks. Masonry wallsbuilt of brick, concrete blocks, or cinder blocksmay develop cracks in mortar joints. These cracksresult from foundation settling or other conditionswhich allow wall movement. These cracks usu-ally appear at corners or below windows. Suchcracks must be repaired, not only for appearancebut to waterproof the surface. Even though greatcare is taken to match the color and texture ofthe old mortar joints, these repairs will alwayshe visible. For this reason, masonry buildings

/84

Figure 29. Removing old mortar.

which have numerous joint repairs arc oftenpainted to enhance the overall appearance of thestructure. Where large. deep cracks appear in themortar joint, you must remove the mortar fromthe joint. You can do this by using a hammerand a small cold chisel, as shown in figure 29.Chip out the mortar, the full width of the joint,to a depth of 2 inches wlien a leak must bestopped or to 1/2 inch for routine repair. Removeall dust and loose material with water from ahose after the cutting has been completed. Youshould then prepare some mortar by mixing 2parts of fine masonry sand and 1 part of masonrycement. Prehydration of mortar will greatly re-duce shrinkage. To prehydrate the mortar, mixthe dry ingredients with just enough water to pro-duce a damp mass of such consistency that it willretain its form when compressed into a ball withthe hands. Allow the mortar to stand at least 1hour and not more than 2 hours. After this hasbeen done, mix in a required amount of water toproduce a stiff but workable consistency. Fillingthe joint is called repointing. This is done with

Figure 30. Repointing a joint.

1 r 26

a pointing trowel, as illustrated in figure 30. Youshould pack the mortar tightly into the joint inthin layers, about 1/4-inch thick. Push the mortarinto the joint with a forward motion in one direc-tion from a starting point. This will reduce thepossibility of forming air pockets. After the jointsare filled, you should tool them, as shown in fig-.ure 31, to match the old mortar joints.

7-7. Repaired mortar joints will recrack andreopen if the condition which caused the originalcrack still exists. If you suspect the building isstill settling or moving, repair the mortar joints,using the following procedure. Remove the mor-tar from the joint to a depth of about 2 inches.Pack the opening with cement mortar to withinV2 inch of the surface. Finish filling the joint withnumber 1 caulking compound. This compoundwill dry with a tough exterior skin and resist

Figure 31. Tooling a joint.

breaking. The underbody will remain soft andpliable. The elasticity of the compound will pre-vent the crack from reappearing as the buildingcontinues to settle.

7-8. Repairing Surface Defects. Before paint-ing concrete surfaces, you should repair all pits,chips, holes and honeycomb areas. These surfacedefects can be filled with grout. Grout is madeby mixing one part masonry cement to one partfine masonry sand. Masonry cement must beused because the lime in masonry cement worksas a binder to cause the grout to adhere to shal-low defects. Only enough water should be usedto make the grout into a heavy paste. You shouldwet the surface and allow all free water to drainoff before applying the grout. Use a stiff brushto scrub the grout into all irregularities of the

Figure 32. Sealing cinderblocks.

r!;,k.'

surface. As the grout begins to set, smooth allareas and level them with the surface, using acement trowel. Grouted areas should be cured byspraying water on them several times a day for2 or 3 days or by covering them with wet burlappads.

7-9. Scaling Building Blocks. Concrete andcinder building blocks arc highly porous. Theblocks are made from a dry, stiff concrete mix-ture which does not consolidate completely dur-ing the manufacturing process. The blocks havepoor ability to resist penetration by wind-drivenrain or water from other sources. Any attempttoward scaling these blocks should be on the sur-face facing the water source rather than the dryside. You may use cement-water-sand paint toseal these surfaces. Mix the paint using I partmasonry cement, I part of fine masonry sand,and enough water to make a Thick consistencypaint. You apply the paint and scrub it into thesurface with a stiff-bristle brush, as shown infigure 32. Apply the paint heavily enough to fillthe many small voids in the block surface. Toseal cinder blocks, you should flood the surfacewith water prior to applying the cement paint.After painting, cure the paint for 72 hours bywetting the surface at least three times each day.

7-10. Removing Oil and Grease. Oil film andgrease spots can be removed from masonry withsteel brushes, abrasive stones, or preferably, bylight sandblasting. You may use solvents to re-move heavy grease deposits. After using solvents,the area should be scrubbed with hot water anddetergent. A solution of 1/4 pound household lyeto I gallon of water can be used to remove smalloil stains. After using the lye solution, you must

Pr?flood the area with water to remove all traces ofthe lye. You should wear rubber gloves and gog-gles when using the lye solution. On deep oilstains, you should use trisodium phosphate. Thischemical can be obtained in powder form andmixed with water to make a paste. Apply thepaste over the stain and allow to stand for 30to 45 minutes. Remove the dried paste by scrap-ing, brushing, or sweeping., then, wash the areawith detergent and water.

7-11. Preparation of Previously Coated Sur-faces. Painted masonry with only normal de-terioration of the paint may be repainted aftercleaning. Surfaces which are damaged or showabnormal deterioration of paint will require addi-tional preparation. You should repair anycracks, damaged mortar joints, or surface defects.If the deterioration of the old paint was causedby alkali deposits, glazing, or efflorescence, youshould treat the surface to prevent recurrence.

7-12. Removing paint from masonry. You canremove paint from masonry surfaces by severalmethods. Acid-resistant paints, plastic paints. andepoxy paints are very difficult lc, remove. Thesepaints can be removed by sandblasting. To re-move oil-base paints from a smooth concrete sur-face, you can use either heat or solvent paintremover. Use the same procedures used to re-move paint from wooden surfaces. The surfacemust he smooth enough to allow scraping of theold paint with a putty knife. Loose and scalingpaint on rough concrete building blocks. or brickcan usually be removed by using a lye-watersolution. This solution will break down and dis-solve old paint so it can be flushed from therough surface with water. You may use solventremover on sound oil base paint prior to washingwith the lye-water solution and Cementwater paint containing lime can be removed orreduced by using a 10- to 20-percent muriaticacid-water solution. You apply the solution witha stiff-bristle fiber brush. Allow it to set for 10minutes and flush the surface with water.CAUTION: Always wear proper protective cloth-ing and goggles when working with remover sol-vents, acid solutions, or lye water. Keep in mindthat it may not be necessary to remove all paintfrom surfaces to be repainted. Remove onlyenough paint to provide a sound and solid basefor the new protective coating. If the surface mustbe completely cleaned, sandblast the surface andyou will find that this method produces betterresults than other types of paint removal.

7-13. Once the conditions, which make con-crete and masonry difficult to paint, have beenremedied several paint rr .'crials can be usedsatisfactorily on these surfaces.

27

/Si8. Application of Exterior Coatings

8-1. Several types of paint used on exteriorwalls include cement-base paint, oil -base paint,latex paint, and rubber-base paint. They allhave a damp-proofing effect, but the oil base isusually more effective in this respect. Latex andcement -base paint produce coatings which permitthe structure to "breathe"; that is. moisture vaportransmitted from the inside to the outside of thestructure will pass through the paint film. Blister-ing caused by severe moisture conditions isthereby reduced or eliminated.

8-2. Applying Cement-Base Paint. Cement-base paint can be obtained commercially in twotypes: class A and class B. You should use classA, which contains more lime, for fine texturedsurfaces. Use class B. which contains siliceousmaterials, for open-textured surfaces. The paintconies in powder form, in white or colors. Mixthe cement powder with sufficient water to givea thick, creamy consistency and allow it to standfor 15 to 30 minutes, Remix prior to use andstir frequently during application. Dampen sur-faces prior to paint application with fine waterspray, and allow water to penetrate a few min-utes. You then apply the paint with a stiff-bristlebrush and scrub it thorough!), into surface voids.Cure the first coat for 24 hours, using a fine waterspray. Start the curing as soon as the paint ishardened sufficiently to resist damage. Allowfree film of curing water to disappear before youapply the second coat of paint. After the secondcoat has set, datnpcurc it by spraying two orthree times a day with water for the next 2 days.

8-3. Applying Oil-Base Paint. When using oil-base paint on concrete and masonry surfaces, hesure the surfaces are dry, Avoid painting indamp weather, early in the morning, or late inthe afternoon because concrete surfaces chill andcollect moisture during the night. Bc sure youhave properly prepared unpainted surfaces. Re-move foreign matter and loose particles, androughen glazed surfaces. New close-textured con-crete surfaces should be pretreated to inhibitalkaline reaction wiih oil-base paint. Brush on asolution of zinc sulphate dissolved in water at aconcentration of 2 to 3 pounds per gallon. Whenthe solution dries, dust the surface lightly to re-move any loose salts. Bc careful not to removethe crust formed on the surface or the advantageof pretreatment will be lost.

8-4. Masonry surfaces of concrete or cinderbuilding blocks should be scaled, as was ex-plained in paragraph 7-9, prior to applying oil-base paint. Filling surface voids with oil- orvarnish-base paint would require abnormallyurge amounts of paint. These paints are not

28

adaptable to the scrubbing action necessary towork the paint into the surface voids.

8-5. You can apply oil-base paints with abrush, roller, or spray equipment. The first, orpriming coat, should be brushed on. The paintfor this coat should be reduced with spar varnishin the proportion of I quart to 1 gallon of basepaint. Apply the paint with an old, worn brush.The rough abrasive surfaces of concrete wearnew brushes in a hurry, so use your old brusheson these surfaces. Allow the paint to dry at least24 hours and then apply a second coat. Usc thereduced paint for the second coat and allow it todry for at least 24 hours. You then apply thethird coat, using the paint as it comes from thecan without thinning. The second and third coatsmay be applied with a roller or spray gun.

8-6. Previously painted surfaces, on which theold coating is sound or has normal deterioration,can usually be repainted with one coat of oil-base paint. When necessary, you should treatand spot-prime areas of the surface prior topainting.

8-7. Applying Latex Paints. Latex paint ismanufactured by emulsifying various chemicalformulas in water rather than disolving them inmineral spirits. These emulsions look like themilky latex of the rubber tree and are sometimesmistakenly referred to as rubber-base paint.Water-thinned latex paint, particularly that madewith polyvinyl acetate emulsions, is very suitablefor use on exterior concrete and masonry sur-faces. This paint is moisture and alkali-resistantand it has desirable deterioration characteristics.It resists blistering, cracking, and flacking, andnormally deteriorates through the chalking proc-ess.

8-8. You can apply exterior, latex paint bybrushing or with a roller coatcr. Because of theexcellent alkali resistance and permeability tomoisture vapor, latex paint requires little or nosurface preparation but cleaning. It requires ashorter aging period for concrete and masonrysurfaces than does oil-base paint; although, aperiod of not less than 3 to 4 weeks is recom-mended.

8-9. Exterior latex paint is adaptable to paint-ing open - textured building blocks without a pre-liminary filling or grouting treatment. You canwork the paint into the surface voids with awhitewash brush by using a light scrubbing ac-tion. Although latex paint dries to the touch in30 to 40 minutes. it should not be applied intemperatures below 40° F. A 1- to 12-hour dry-ing period should be allowed between coats. Thepaint requires no water curing. You can applythe second coat to building blocks with a regularpaint brush.

8-10. Many of the substancesmanufacture of latex paint are alsiplastics. For this reason, latex pail escalled plastic paint. Any of the in

paints might be called plastic p,phenolic, vinyl, and other syntheticmonly used in it arc varieties of plan

8-11. Applying Vinyl Paint. Extet-iopaint contains materials that arc related tocoatings used in upholstery and floor cavern',This paint can be thinned as necessary with wa-ter. It has many of the characteristics of Itexpaint and you can apply it to cxtcrior con 'roteor masonry with a brush or roller. The , .intdries fast, in 10 to 30 minutes, and can h-stand water after that time. It cures corn,in 12 hours by forming a tough, long-lasting tilm.It has a disadvantage; it should not be appliedduring cold weather. Do not apply cxtcrior vinylpaint when the temperature is below 50° F. orwhen the temperature will fall below 50° F. dur-ing the 12-hour curing period.

8-12. Applying Acrylic Paint. Acrylic paint isalso composed of a form of plastic in water. Youcan apply acrylic paint with a brush or rollercoater. This paint retains its color longer anddries faster than other so-called plastic paint. Youcan apply it in all kinds of weatherhot, humid,or coldas long as the temperature is slightlyabove freezing. This paint dries to the touch in10 to 20 minutes and you can apply a secondcoat after 1 hour. During application, you should

;flow the paint over the entire surface with onlya minimum of brushing or rolling.

8-13. Applying Chlorinated-Rubber Paint.True rubber-base paint consists of synthetic ornatural rubber dissolved in a liquid such astoluene or solvent naphtha. Masonry surfaces tobe coated with this paint should be dry and clean.You should apply a minimum of three coats onnew or unpainted masonry surfaces. Under se-vere conditions and for maximum durability, fourcoats should be applied. For best results, youshould apply the paint directly to the concreteor masonry surface. No primer is needed. Youcan apply the paint either by brush or rollercoatcr. If the paint is to be applied over an oldcoat of paint, you should paint only a small testsection to determine whether the solvents usedin the chlorinated rubber paint will soften or re-move the old coating. If the old coating is af-fected, it should be completely removed beforethe surface is repainted. You should thin the firstcoat of rubber-base paint with approximately 1

quart of xylem or toluene per gallon of paint.You should thin intermediate coats with 1 pintof xylene or toluene per gallon of paint. Apply

1D7

the finish coat undiluted just as it comes fromthe container.

8-14. Painting Cement-Asbestos Surfaces. Ce-ment-asbestos is manufactured from Portland ce-ment and asbestos fiber. It is used for exteriorsiding application in the form of shingles orboards. It is very hard and brittle. and is highlyfireproof. The natural color of the hoard is grey,but the shingles are available in white or colors.The shingles are nailed in rows over a wood sub-wall so each row partially overlaps the row im-mediately below it. This overlap prevents theshingles from lying flat and results in frequentbreaking of the shingles. Sometimes. during rou-tine maintenance, the broken shingles arc re-placed with new shingles of a different color. Thisresults in a spotted and unattractive appearanceto the building. These buildings may be paintedto improve their appearance.

8-15. Before painting cement-asbestos sur-faces you should clean them and remove anystains with solvent or by washing. All looseshingles should be rcnailcd. Do not strike thenail with a sharp blow of the hammer, or youmay crack the shingle. If additional nails arc re-quired, do not attempt to drive the nail throughthe siding; use an electric drill motor with a ' /H-

inch twist bit and very carefully drill holesthrough the shingles as required for new nails.

8-16. A two-coat coverage is recommendedfor cement-asbestos shingle surfaces of mixedcolors. You should apply the paint with a brushfor best results. Apply a coat of exterior paintprimer, or wood undercoat, as the first coat. Afterthe priming coat dries, apply a finish coat, usingtitanium-lead-zinc cxtcrior house paint. The prim-ing coat should be tinted the approximate colorof the finish coat. Brush the paint well into thepores of the cement-asbestos and cover all edgesand cracks between the shingles.. When paiut4.cement-asbestos boards, finish the painting.w04",long, parallel strokes of the brush.

8-17. You have learned some of the morecommon problems in the preparation of exteriormasonry surfaces, and the application of protec-tive coatings to these surfaces. Now, let's discussthe methods of preparing and coating interiormasonry surfaces.

9. Preparation and Coating InteriorMasonry Surfaces

9-1. Interior walls and ceilings arc dividedinto two types of construction: wet-wall and dry-wall. Wet-wall construction rcfcrs to the applica-tion of a wet plaster directly to a masonry sur-face, or over. metal lath or furring strips onframe construction. Dry-wall construction rcfcrs

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to the use of wallboard. such as shectrock, inplace of plaster on interior surfaces.

9-2. Preparation and Coating Wet-wall Sur-. faces. To better understand the procedure used

for repair and surface preparation of wet-wallsurfaces, let's learn something about the typesand usage of plaster. The many types of plaster.while similar in composition and method of appli-cation. are each used for different utilization re-quirements. They arc explained as follows:

a. Gypsum Plaster. Gypsum plaster is themost widely used in ordinary construction sinceit can he applied directly to interior masonry.It is also applied to metal lath or furring overframe walls.

b. Lime Plaster. Lime plaster, the type foundin many older buildings is generally used for thesame type work as gypsum plaster.

c. Keene's Cement Plaster. Keene's cementplaster produces a very hard, moisture - resistantsurface. It is used in areas subject to continuedmoisture conditions, such as latrines, bathrooms,and kitchens.

d. Portland Cement Plaster. Portland cementplaster is applied directly to interior masonrywalls. Elsewhere, it should be applied over metallath. It should never be applied over gypsumproducts. It is used in similar ,areas rather thanKeene's cement plaster because of economic rea-sons.

9-3. During construction, plaster is applied ina series of coats known as scratch, brown. andfinish. Applications and mixes vary to meet re-quired uses. The three-coat method of applica-tion for gypsum plaster is explained as follows:

a. Scratch Coat. This coat consists of a mix-ture of sand and light aggregate, and gypsumplaster. The sand or aggregate content is in-creased when the scratch coat is applied directlyto masonry. It must be applied to metal lath withsufficient pressure to form a good bond. Thescratch coat is left with a rough surface so itwill accept the next coat.

b. Brown Coat. This coat is also composedof sand or light aggregate and gypsum plaster.The sand or aggregate content is increased overthat used for the scratch coat. It is applied afterthe scratch coat is hard. It is laid and straight-ened to form a true surface. It is left rough toreceive the finish coat.

c. Finish Coat. A typical white finish coatmay be composed of lime putty and calcinedgypsum. It is applied over a partially dry, browncoat or over a dry coat which has been wetted.This coat is laid thinly and brought to a true,even surface. After being allowed to dry a fewminutes, it is troweled to a smooth finish coat.

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9-4. Minor repair to interior plaster. As aprotective coating specialist, you should knowhow to make minor repairs to interior plasterprior to applying a protective coating. Largeareas on which there is excessive damage, orwhich require the replacement of large areas ofplaster should be left to the masonry specialist.Minor repair should be limited to patchingcracks. holes, and repairing small spots of looseor damaged plaster on interior wall and ceilingsurfaces. The equipment you will need for mak-ing minor repairs consists of a spatula or puttyknife, a small diamond-shaped pointing trowel,a sharp chisel, a linoleum knife, a hammer, anda shallow mixing pan.

9-5. Repair of structural cracks. Structuralcracks arc easily identified. They are usuallylarge and well defined. extending across the sur-face and entirely through the plaster. They gen-erally develop during the first year after con-struction, and in most cases can be successfullyand permanently repaired. To repair a structuralcrack, use a linoleum knife or chisel to cut outand remove loose material. Cut the crack to a"V" shape making the surface opening narrowerthan the bottom of the crack. Widen the crackjust enough to insure a good bond between patch-ing plaster and old plaster and lath. Brush outall loose material and thoroughly wet the edgesof the groove and then press the first coat ofpatching plaster firmly into place, fitting thegroove almost to the surface. Allow it to set untilnearly dry but not hard, then complete the patchby applying a coat of finishing plaster. Strike allrepair plaster off flush with the surface andtrowel smooth. Give special attention to theedges of the patch to insure a firm, solid bondbetween old and new plaster.

9-6. The patching plaster may be job-mixedas follows:

a. The first coat should be composed of onepart fihcred gypsum plaster and two and onehalf parts of plastering sand, by volume, mixedwith clean water to a uniform color and workableconsistency.

b. Materials for the second coat may be eithera gypsum plaster or a mix of one part hydratedlime and one-half part calcined gypsum mixedwith water to a suitable consistency.

9-7. A small amount of casein glue added tothe above mixes insures easier application be-cause it tends to retard the setting time of themix. The addition of glue also prevents shrinkingof the mix and aids in forming a better bondwith the old plaster.

9-8. In lieu of the job mixes described above,you may use a commercial patching plaster. This

material is known as spackling compound. It isa mixture of plaster of Paris and powdered gluemixed with clean water to the consistency of softputty. The quantity of any patching materialmust not exceed that which can be applied within30 minutes after mixing. Never retemper (addwater to) plaster material that has begun to dryand harden. Retempered plaster will dry out softand become crumbly.

9-9. Repairing shrinkage cracks. Shrinkagecracks are fine, hairline cracks which arc muchless noticeable than structural cracks. Thesecracks may form an alligator or spider-web pat-tern over small areas of a ceiling or wall surfaceand arc usually the result of the surface dryingtoo rapidly, insufficient troweling, or no trowelingbefore the surface is too dry. Shrinkage cracksdo not extend entirely through the plaster but arelimited to the surface. You can fill these crackswith a white-lead putty, You can make the puttyby mixing white lead and turpentine to a thinpaste. Scrub the paste into the cracks and wipeoff all excess with a cloth folded into a pad.

9-10. Repairing map cracks. Map cracksform a pattern in the surface similar to shrinkagecracks. They arc more defined than shrinkagecracks but are not nearly so wide as structuralcracks. Map cracks penetrate through the plasterand arc generally caused by an improper bondbetween the plaster and lath. You can usespackling compound to fill these cracks. Work asmuch compound into the crack as possible andsmooth the surface. Use a cloth to remove allexcess compound before it dries.

9-11. Repairing loose plaster. Loose plasteris indicated by bulging and cracking of theplaster surface. The extent of loosened plastercan be determined by lightly tapping the surfacewith a small hammer. The resultant sounds willindicate the extent of the loose arca. Looseplaster is usually the result of excess,ve moisture.In severe cases, the fasteners holding the lath tothe structural frame will corrode and allow boththe lath and plaster to bluge or sag. Prior torepairing the damaged plaster, you should locateand eliminate any source of moisture. To makethe repair, you must remove all loose plaster.Begin at the center and work back into the sur-rounding area to a point where the plaster issolid. Replace defective laths and securely refas-ten all laths which have become loosened.

9-12. A patching plaster that is compatible tothe old plaster should be used. To obtain bestresults, apply the patching plaster in at least twocoats. Use the patching plasters explained inparagraph 9-6 to repair gypsum or lime plastersurfaces. Apply a scratch coat and then a finishcoat.

I?'9-13. To patch portland cement plaster, the

edges of the surface surrounding the defectivearca should be thoroughly and continuouslywetted for at least I hour. Just prior to apply-ing the patch, dust the edge of the exposedplaster with a light coat of portland cement.Press the first coat of portland cement plasterinto the repair and fill it nearly to the surface.Scratch or roughen the surface of the patch witha wire brush, or nail, to make a base for re-ceiving the finish coat. Thoroughly cure the firstcoat by keeping it moist for at least 72 hours.Then allow it to dry thoroughly, not less than 7days, prior to applying the finish coat.

9-14. The finish coat should be of the samecomposition as the first coat. Just prior to appli- -cation of the finish coat, redampen the patcharea with water. Press the plaster firmly into theremaining cavity with a .trowel. Float the plasterto a smooth, even surface, then trowel to thesame texture as the surrounding surface. Keepthe patch moist for at least 3 days.

9-15. Portland cement patching plaster shouldbe mixed on the job shortly before it is to beused. It is composed of one part portlandcement, three parts plastering sand, and one-fourth part lime putty.

9-16. Keene's cement plaster surfaces can herepaired by using the mcthcAls stated in the pre-ceding paragraphs, with one exception: Keene'scement plaster must be used. Since this plasterisT:Thtained commercially, the manufacturer'sspecific instructions for mixing and applicationshould be followed.

9-17. Painting plaster surfaces. New plastershould be aged for a period of 60 days prior topainting with oil-base paint. This is necessaryto allow for moisture removal. In the case oflime plaster, the surface alkalinity will be greatlyreduced. Under excellent drying conditions, theaging period may be safely cut to a minimum of30 days. When latex or other water paint is tobe used, a drying-out period of 2 weeks, or aslong as is practicable, is recommended.

9-18. Once the surface has aged sufficiently,you can apply the protective coating. It is to benoted that considerable similarity exists betweenpainting interior plaster and interior woodwork.The same types of interior paint arc used, andthe methods of application are the same. Flat,semigloss, or gloss, interior, oil paint can be ap-plied to new plaster, over a primer-scaler. Youshould use a pigmented, oil, primer-scaler rec-ommended for masonry, and it should be appliedby brush. The primer coat should he followedby a coat of enamel undercoatcr. The under-coatcr and scaler coats should be tinted to ap-

191proximately the same color as the final coat.If a two-coat paint system is satisfactory froman appearance standpoint, the enamel under-coater may be omitted as an economy measure.The. undercoater and the finish coat may beapplied with either a brush, a roller coater, or asprayer.

9-19. A two-coat system, using interior latexor other water-thinned, plastic paint, may beapplied to new plaster. No special primer isneeded unless the plaster is extremely porous.You can apply these water paints with a rollercoater. You should work the paint well into thesurface, by using crisscross strokes, until allholidays disappear. Finish the area by usinglong, parallel strokes.

9-20. Calcimine paint can be applied to newplaster that has aged for the minimum time.Before applyim the paint, you should applyeither a glue or varnish size coat. The wateredglue, or varnish-thinned with 1 quart of turpen-tine per gallon, should be applied by brush.After the size coat dries, use a special calciminebrush to spread the paint in one, thick coat.Spread it out evenly with the least amount ofbrushing. If the edges dry out before an area iscovered, dampen them with clear water, using aclean brush. This will help eliminate lap marks.After painting, you should open all windows anddoors. If it is winter, heat the room to eliminateexcessive moisture in the air. Slow drying oftencauses a spotted appearance.

9-21. Chlorinated, rubber-base paint, for in-terior use, can be applied to new plaster in areassubject to heavy soiling. Rubber-base paint has

Figure 33. Taping a wall joint.

reasonably good washability. The surface mustbe dry and should be aged for a minimum of30 days. No primer is needed. You shouldbrush on the first coat, which is thinned with1 quart of xylol to 1 gallon of paint. The re-maining coats can be applied with a roller coater.

9-22. Repainting old plaster surfaces. Oldplaster surfaces :should be sound, for repainting.You should repair all damaged areas. Surfacesto be repainted with the same type paint as theoriginal paint require no preparation other thancleaning. You must always remove old calciminepaint before repainting these surfaces. The cal-cimine paint can be washed off with warm waterand detergent. Do not attempt to remove thesize coat. When you use chlorinated rubber-basepaint for repainting, always make a test patchto insure that the rubber-base paint is compatiblewith the old paint. Whenever possible, youshould accomplish all repainting with a one-coatcoverage.

9-23. Preparation and Coating of Dry-WallSurfaces. Generally speaking, dry-wall construc-tion refers to the use of a gypsum plaster board -

commonly called sheetrock. This wallboard iscomposed of a gypsum core, encased in a heavymanila sheet on the face side, and a strong papercardboard liner on the back. It is available in1/4-, 3/s-, or 1/2-inch thickness. Sheets cut to a4 x 8 foot size arc considered standard forceiling and wall construction; however, it is man-ufactured in other sizes. The ends of the sheetsare cut square to make butt joints, while theface side edges are recessed 11/2 inches to allowfor tape and bedding of cement covered joints.

The 1/2-inch board is used, in general, for ceilingsand interior partitions. In some instances, twothicknesses of 3/s-inch board are laminated to-gether on the job to form a strong, highly fire-resistant, wall material.

9-24. On new construction, it is the carpenter'sjob to nail, or otherwise secure, the sheetrock tothe ceiling and wall areas. As a protectivecoating specialist, it will be your job to furtherprepare and apply the protective coating to thesesurfaces.

9-25. To prepare new sheetrock surfaces forpainting, you must tape and bed all joints andcorners; cover all nailheads, and, in most cases,apply a stipple coating to the surface.

9-26. Taping and bedding joints. Perforatedtape must be applied over the joints where twopieces of sheetrock meet. Obtain a clean con-tainer and mix the joint cement to the manufac-turer's instructions. Use a wide-blade putty knifeto apply the cement into the recess along thejoint. Tear a piece of perforated tape from theroll long enough to cover the entire joint. For

Figure 34. Taping an inside corner.

extremely long runs, the tape may be worked in6- to 8-foot lengths. You then use a putty knifeto imbed the tape into the cement. Start at oneend and align the tape to fall over the joint.Place the knife across and near the end of thetape. Hold that end of the tape in place withone hand and pull the knife along the tape withthe other hand. Apply enough pressure on theknife to imbed the tape into the compound. Besure you remove all wrinkles and air bubblesfrom under the tape. Figure 33 illustrates theapplication of the tape to a wall joint. After thetape is in place, cover it with a thin coating ofcompound.

9-27. You can tape inside or outside cornersin much the same manner as flat joints. Applythe joint cement compound along the edges of theshectrock where they meet to form the corner.Tear off a piece of tape and fold and crease italong the center so it will fit into or around thecorner. Use the putty knife to imbed the tapeinto the compound so it forms a square andstraight line corner, as illustrated in figure 34.

9-28. After the taping coat has dried, youshould apply a second and third coat of com-pound over all joints. The joint cement willshrink as it dries, and three-coat coverage willinsure a proper buildup of compound to concealthe joint. You can use a putty knife to applythe cement to the joint and then use a cementtrowel to level and smooth the compound. Thisoperation is illustrated in figure 35. Each coatshould be applied to a slightly wider area thanthe preceding coat. Feather the edges andsmooth the joint by using the trowel. When the

11.3final coat is dry, sandpaper the joint smooth toblend with the balance of the surface.

9-29. Covering nailheads. All nailheads mustbe recessed and covered with joint cement. Donot leave any portion of the nailhcad where itwill be contacted by the protective coating. Nail-heads will eventually rust and stain the protec-tive coating unless they are completely coveredwith compound. Do not use a nail set to set thenails; use a claw hammer. Strike the nail withthe hammer as if you were driving the nail.Use sufficient force in the blow to recess thenailhead below the surface of the sheetrock.This will leave a depression around the nailhcadthe size of the hammer driving face. Be carefulnot to hit the nail with such force that the ham-mer will cut through the manila surface of theshcetrod: and into the gypsum core. This de-stroys the holding power of the nail. With alad,: practice, you will be able to properly setthe nail with one blow of the hammer.

9-30. You may use a putty knife to fill thenailhcad depressions with joint ecment. To gainsome speed, try to develop a skill in using atwo-stroke method. The two strokes should forman "X" pattern over the nailhcad. Pick up somecompound on one side of the putty knife. Makethe first stroke downward and at an angle, in amanner which will drag enough cement fromthe blade to fill the depression. Swing the bladeof the knife over and make a second stroke tocompress the cement into the depression; at thesame time, scrape all excess compound from thesurface. (See fig. 36.) You then apply a secondand a third coat of compound after each pre-

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Figure 35. Feathering a joint.

1q1.1

N

Figure 36. Covering nailheads.

ceding coat is dry. These coats are usually ap-plied at the same time as the taping and beddingcoats. After the final coat is dry, sandpaper thespots lightly to blend them to the surface.

9-31. Applying stipple. Sheetroek surfaceswill generally have a stipple or texture applied;however, they may be painted without it. Thestipple can be applied in any degree from a light,fine texture to a heavy, coarse, decorator pattern.These decorator patterns are usually limited toceilings in club rooms, or study and den areasin family housing. A fine texture, which resem-bles a plaster surface, is used in general workareas and offices.

Figure 37. Applying texture with a roller

.; 34

9-32. You can apply a light texture with aroller coater, using a stipple cover. Mix thestipple compound, using joint cement and water,to the consistanee of thick paint. Pour the mix-ture into a roller coater pan and use the rollerto apply the mixture to the surface. Finish therolling operation with long, parallel strokes, andavoid leaving ridges or lap marks. Figure 37illustrates the use of a roller coater to applya fine texture to the surface.

9-33. Decorator patterns can be created byusing such tools as paint brushes, whisk brooms,or sponges. The stipple compound should be ofa thick, heavy consistancy. You will probablyobtain better results by applying the compoundto the surface with a large paint brush. Theroller can be used but it may become slick, andslide across the surface rather than spread thecompound evenly. Work small areas at a time,by first applying the compound, and then making

Figure 38. Applying a decorator pattern.

the pattern in the compound before it begins todry. Fio,,.re 38 shows the use of a whisk broomto create a decorator pattern on a ceiling surface.When applying these surfaces, make sure thepattern is consistant, and the decorations areuniform in size. All textured surfaces must beallowed to dry thoroughly before you apply theprotective coating.

9-34. Painting of new plasterboard surfaceswas discussed in paragraphs 4-6 and 4-7 ofChapter 1. The methods used in the repair andrepainting of old surfaces was covered in para-graphs 4-9 through 4-11.

9-35. Coating Interior Masonry Surfaces. Sur-faces of brick or stone are used frequently ininterior construction. These may be primarily fordecoration, such as planter or flower boxes.They may be functional, such as fireplaces, roomdividers, or areas surrounding built-in cookingovens. These brick or stone surfaces should be

sealed to prevent dusting, especially around eat-ing and cooking areas. Such surfaces, if leftunsealed or unpainted, will continue to emit finedust or sand during their life. These surfacescan be painted with opaque paint, but they areusually sealed with a transparent coating whichwill enhancetheir natural beauty.

9-36. You should be sure the surface is ab-solutely clean before applying a transparentcoating. These surfaces can be scrubbed withwater and soap to remove grease and dirt films.Always allow the surface to dry thoroughly be-fore applying the coating.

9-37. Use a sealer which is recommended bythe manufacturer for masonry surfaces. Sealersof a varnish-solvent base, silicone-water or sol-vent base, and epoxy are available. You shouldmix or prepare these sealers by very carefully fol-lowing the manufacturers instructions. You canapply the sealers by brushing, rolling or spraying:however, brushing usually is recommended. Seal-ers are generally applied in two or three thin coatsrather than one heavy coat. The manufacturer mayrecommend that solvent -base sealers be heatedslightly for the first coat application. Heatingwill thin the sealer and allow it to better pene-trate the pores of the brick or stone.

10. Preparing and Coating ConcreteFloors

10-1. Painting concrete floors for decorationis usually not very satisfactory because of rapidwear from traffic. Consideration should be givento covering interior concrete floors with a floortile. such as asphalt or vinyl asbestos.

10-2. Several types of paint can be used, withvarying degrees of success, on concrete floors. Avarnish-vehicle floor paint can be used on dry,well-aged, concrete floors. A rubber-base paintwill resist alkali and should be used where theconcrete is subject to dampness. The rubber-base paint is superior to varnish-base paint inwear resistance, but it will not last with outdoorexposure. Epoxy floor enamel will produce ahard and durable surface on interior or exteriorfloors. but it is expensive and often difficult toapply.

10-3. Preparing the Floor. Concrete floors areprepared for painting much in the same man-ner as other concrete surfaces. Floors troweledsmooth or glazed, should be etched with acid.If alkali or efflorescence are present, the surfacemust be treated. Above all, The floor must beclean and all traces of oil or grease must beremoved.

10-4. Before applying epoxy floor enamel,you should scrub the floor with trisodium phos-phate and water. You can sprinkle the dry pow-

der onto a wet floor and use an old straw broomto scour the area. Where heavy oil stains havepenetrated the floor, sprinkle the powder heavilyover the stain and allow it to remair. for 24hours. The powder will absorb oil from the floor.The floor must be dry before application of theepoxy enamel.

10-5. Epoxy floor enamel comes in two sepa-rate containers. You mix it, for use on the job.by mixing equal parts from each container. Mixonly enough paint for one coat, as the mixturehas a pot life of only 8 to 10 hours. After mixingthe paint, it should be allowed to set for 1 hourprior to application. Restir the paint and apply itwith a brush. Apply the paint to small areasand brush it out well. Do not overbrush previ-ously painted areas. Allow the first 'coat to dryfor 24 hours. Be sure to clean the brush with asolvent recommended by the manufacturer. Ep-oxy paint hardens by chemical action and thepaint will harden in the brush, even though thebrush is left submerged in the solvent. Mix thepaint for the second coat as you did for the firstcoat: Apply the second coat with a brush andallow it to dry. Epoxy floor enamel will dry. tosupport foot traffic, in 8 hours. It will dry rock-hard in 24 hours, to support heavy machine orvehicular traffic.

10-6. The application of traffic markings willpresent additional problems to those of paintingfloors. These markings are subject to heavy ve-hicular traffic as well as the weather elements.

11. Application of Traffic Markings

11-1. Traffic markings for vehicles are designedand laid out according to military regulationsand manuals. While full compliance with thestandards is required, post commanders aredelegated the authority to determine the de-gree to which such markings will be used. Asa protective coating specialist, it will be yourjob to apply the traffic markings to runways,taxiways, motor pool parking ramps, streets,curbs, and automobile parking lots. Since theaspect of safety is strongly involved, you willprobably coordinate with, and receive guidancefrom such people as the post safety officer,post law enforcement officer, or post operationsofficer, as well as your utilities engineer officer.You may receive dimension drawings to followin applying traffic markings, or you may haveto lay out and plan the job. You should, followthe current directives carefully whenever theyare applicable.

11-2. In some cases, it may be necessary toremove old traffic markings before new markingsare applied. The methods commonly used for re-

1%moving old markings are sandblasting, .acid, orcaustic washing. Cautious use of heat on con-crete is recommended, as excessive heating willdamage the surface and may cause steam blow-outs from pockets of moisture trapped in theconcrete. You should never use heat on bitumi-nous surfaces.

11-3. It is essential that all foreign materials,such as dust, dirt, oil, scale, and other particles,be removed from the surface before marking ma-terials are applied. Dry brushing, brooming, orthe use of compressed air is effective. Externalmoisture caused by rain or snow will prevent theproper bonding of the marking materials; there-fore you should permit the surfaces to becomethoroughly dry before applying the markings.

11-4. Application of Vehicle Traffic Markings.There are three types of paint in general use fortraffic markings: regular traffic, oil-base paint;plastic, traffic marking paint; and traffic, pig-mented binder. The latter type is used in con-junction with glass spheres.

11-5. Traffic, oil-base paint is obtainable inboth white and yellow colors. Beth paints areintended for application, at a wide range of tem-peratures. to bituminous and concrete surfacesbearing heavy traffic. You can apply the paintsby brush or machine. Certain types of trafficmarking machines may require the paint to bethinned. If thinning is required, be sure you usea thinner recommended by the manufacturer. At70° to 90° F., the paint should set to touch in 30minutes and should dry to a gloss finish within 1hour.

11-6. Plastic, traffic marking paint is availablein white and yellow colors and comes in powderform. You must apply it with a traffic markingmachine, which heats the surface and appliesand cures the powder in a single operation. Traf-fic can be returned to the surface immediatelyafter the paint is applied. Plastic, traffic mark-ing paint has a life expectancy far superior tothat of regular oil-base, traffic paint.

11-7. Pigment binder should be applied at therate of not less than 100 square feet and notmore than 110 square feet per gallon. This rateof application will produce a binder film of 0.015inch thickness. This thickness is necessary tobind the glass spheres and produce maximumreflection and hiding power. You can apply thebinder by hand, with a brush, a spray gun, orwith a traffic marking machine. When the binderis applied by hand, you must apply the glassspheres to the wet binder with a sphere dispens-ing gun. The glass spheres should be applied ata rate of 6 pounds per gallon of pigment binder.

11-8. Lane markings for multilane streets are:narked with white paint. These should be laid

out and painted in a broken line with 15-footdashes and 10-foot blank spaces. The minimumwidili of the lines should be 3 inches with amaximum width of 6 inches. The iines shouldterminate at, and not continue through, intersec-tions. Each of the dashes should be straight anduniform in size. Before you apply the paint, usea string to align the dashes and mark the startingpoint for each dash location along the line. Use aspot of paint to make the marks. large enough tobe seen, when operating the traffic marking ma-chine. When marking the lanes. make sure theyare parallel to each other and to the centerline.The centerline on multilane. two-way-trafficstreets should be painted yellow. The centerlinecan be one continuous line. 6 inches wide. or forheavily traveled streets. two parallel lines. notless than 4 inches wide. The parallel centerlinesshould run not less than 6 inches apart andshould be painted with a reflectorized paint. Ontwo-way streets with only one lane of traffic ineach direction, the centerline may be painted ina white, broken line similar to the lane markingson multilane streets.

11-9. When painting traffic markings by hand,do not attempt to paint by sight. to a string. or bygaging the width of the markings by the width ofa brush or spray pattern. You should obtain ormake a marking guide. You can make the guideby fastening two straight boards. parallel to eachother with space between the desired width ofthe line. This guide will enable you to paintuniform in width and with straight edges. Figure39 illustrates the use of a marking guide whenbrushing on a traffic marking.

. 11-10. Automobile parking spaces will requiresome planning. The act of parking must be sim-ple, trouble-free. and safe. Complicated arrange-ments only serve to confuse the driver. Thedriver should be able to drive around effectively

.fir: .z

24

Figure 39. Hand-painting traffic markings.

Figure 40. Parking lot layout

010

197widths, refer to figure 40. For 90° patterns,some authorities recommend 65 feet for twolanes of cars. The width will be controlled byavailable yardage, but 60 feet should be theabsolute minimum. When lesser yardage is avail-able, 60° or 45° parking may be used.

11-11. Parallel to street-curb parking is con-trolled by painting of the curbs. The location ofparking positions may be indicated by markingson the pavement. Curbs are painted white toindicate parking areas, and painted yellow todesignate no-parking zones. You may applypaint to curbs with a brush or a spray gun.

11-12. Both reflectorized and nonreflectorizedtraffic paints are available as follows:

a. Alkyd Relatively slow-dry, nonbleeding.b. Alkyd-Chlorinated Rubber Fast-dry,

tends to bleed on asphalt.c. Vinyl Toluene-Butadiene' Fast-dry, non-

bleeding.d. Nonreflectorized traffic paints in a moisture-

cure, oil free urethane vehicle for use on indoorfloors such as in warehouses and gymnasiums.

11-13. Be sure that paints and pigmentedbinders are well mixed and uniform before theyare applied. If a line striping machine is to beused, test the paint in the machine. Add a smallamount of appropriate solvent only if necessaryto adjust viscosity for proper application.

11-14. Take care to apply the correct amountiO of traffic paint to assure that the proper film0

without previous knowledge of the area. Theentrance and exit to parking lots should beplainly marked, with pavement directional ar-rows, as well as signs. Perpendicular or 90°parking may be favored because this arrange-ment combines economy of space with ease ofcirculation. It allows for two-way movementwith greater safety. Angle parking may be pre-ferred for ease of maneuvering into, and outof, the parking spaces. It is very well suitedfor movement of traffic in one direction. Theangle used, when laying out the markings, de-pends upon the space available. For recommended

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thickness is obtained. Traffic markings are ap-plied at thicknesses above that of other paintsin order to-increase their life as the surface isabraded under traffic.

11-15. Mechanical equipment is available invarious sizes depending on the area to be covered.The three most common sizes are a small hand-propelled model (fig. 41), a self-propelled model(fig. 42), and a large truck model (fig. 43) tocover large areas such as airfield pavements.

11-16. Reflectorized paint is supplied in twoparts in separate containers. One contains thepigmented binder (paint) and the other a mea-sured amount of reflective media. Before thepaint sets up, drop the reflective media on thesurface of the wet paint so that they are imbeddedin the film. Be sure to apply the media uniformlyand at the prescribed rate. The reflective glassspheres can also be applied by means of linestriping equipment provided with a dispenserwhich accurately deposits the correct amount ofthe reflective spheres as the stripe is made, asdiscussed in paragraph 11-7.

lit

Figure 41. Hand-propelled traffic marker. Figure 42. Self-propelled traffic marker.

Figure 43. Traffic marker truck model.

2 ., T3

CHAPTER 3

Painting Metal Surfaces

ETAL SURFACES, which are to beIVI painted, should be free of scale, rust, cor-

rosion. grease, and other foreign materials. Thebest coating performance will result from com-pletely clean surfaces, and the most thoroughpreparation obtainable.

2. In many cases, it is noteconomical to useextreme meticulous cleaning measures. This canbe illustrated by comparing the degree of surfacepreparation required for atmospheric-exposedsteel and that required for steel which is subjectto immersion in water. Experience has shownthat complete removal down to base metal isgenerally unnecessary on surfaces subject only tonormal atmospheric exposure.

3. As a protective coating specialist, you willhave little occasion to protect metal subject toimmersion in water, such as boat hulls, or metallocks and gates in river dams. You must have ;a thorough knowledge of the preparatic a and

0 coating of structural surfaces subject to at-mospheric exposure. The purpose of protectivecoatings is to prevent the corroding mediumfrom contacting the metal. You must be con-stantly alert to the visible signs of corrosion.You should be able to identify corrosion as itappears on different metals.

12. Visible Identification of Corrosion

12-1. Both ferrous and nonferrous metals aresubject to attack by corrosion. There is nobetter way of counteracting corrosion than toeliminate it as soon as it is found. The identi-fication of 'corrosion as it appears to the eye ondifferent metals is explained in the followingparagraphs.

12-2. Steel (Iron). You may find steel or ironin structures or machinery which has never beentreated. This bare metal will rust over its entiresurface. The rust can be identified as a red-to-black powder or scale, which may flake off whendisturbed. On surfaces which have been primed,the rust condition may be evident only where the

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primer has been damaged. Any areas on whichyou -suspect corrosion. should be wiped lightlywith the tip of your fingers. Rust, if present, willdiscolor your fingers and produce a reddish stain.If you notice a bubble or raised area on a paintedsurface,1You should be suspicious of corrosion.Remove the raised or loose paint to determine ifrust has formed on the metal.

12-3. Galvanized Iron. You will find gal-vanized iron pipe used in most water systems.Normally, corrosion will not attack this metal un-less the coating has been destroyed or damaged.Such damage usually occurs in the threaded areaof fittings. You can identify this type of cor-rosion by a white powdery substance on the sur-face. When wiped off, it will uncover a tarnishedarea. On galvanized iron used for roofing etsiding. rusting will generally be scattered. It willappear as light. white incrustations. When thesesurfaces are damaged. the galvanized coating willcrack. flake, or chip to expose the bare metal tocorrosive elements.

12-4. Nickel or Chrome Plated (Steel). Gener-ally, you will see nickel- and chrome-plated itemsused in exposed areas. Since these items areexposed to frequent cleaning and polishing withharsh cleaning solutions or abrasives, they areprime areas for corrosion attack. You identifycorrosion.:on nickel or chrome by small spots onthe .plped surface. These spots are small pores(opehings) in the plating. The corrosion attack,if allowed to continue, enlarges these spots intopits and eventual ruptures.

12-5. Copper. Copper is widely used in water-lines, water tanks, and heat exchangers, sincefresh water forms a protective coating on it.Copper exposed to the atmosphere slowly de-velops a thin, protective coating, or patina. Thegreen ,patina is basic copper sulphate. which isresistant to atmospheric action. You can identifycorrosion on copper by its greenish-white color.If the corrosion is the result of acid, it will appearto be -more grayish white and quite voluminous.When you observe black spots on painted copper

goosurfaces corrosion has started. From this start.the dark or black area becomes covered by agreen film. Protective paint coatings are notrequired on copper because of its resistance tocorrosion. However. paint may be applied fordecorative purposes.

12-6. Aluminum. Aluminum and alloys 01aluminum arc widely used for windows andscreens. doors and facings. or roofing and siding.Aluminum produces a tightly adhering oxidefilm that is highly resistant to corrosion. Nor-mally, aluminum is bright. It you find dullaluminum. check the area for a whitish powderyresidue. Where the oxide film is broken, cor-rosion will have blackened the area and pits willhave begun to form. As corrosion progresses,white-gray corrosion will appear on the cut edgesor corners. An aluminum surface that has beenprimed or painted is subject to corrosion where-ever there is a scratch or gouge. Moisturetrapped under the coating si.rw as a blister.In the early stages you vvEi .vhite-gray cor-rosion in the damaged area. As the corrosionattack continues, the aluminum will appearetched or mottled around the damaged areas.

12-7. Now that you know how to visuallyidentify corrosion on metals. let's discuss themethods used in cleaning corroded areas. Theremoval of corrosion. as well as grease. oil. dirt.mill scale. or other foreign materials is essentialto proper preparation of metal surfaces, prior toapplication of the protective coating.

13. Preparation of Metal Surfaces13-I. Cleaning may be by either oftwo meth-

ods: mechanical or chemical. Materials that areheavily contaminated with grease. scale, rust, ordirt should be precleaned to remove the largestamount of surface contaminants. This proceduremakes the final cleaning operation more effectiveand reduces contamination of cleaning solutionswith excessive amounts of soil. Mechanicalcleaning methods involve the use of brushes,files, grinders, abrasives, sand blasters, steamcleaners, or heat. Chemical cleaning involves thewashing or immersing of metals in a solution ofacid or alkaline compounds. Mechanical clean-ing is sometimes referred to as rough cleaning.and chemical cleaning is referred to as finishcleaning.

13-2. Wet scrubbing with an abrasive scouringpowder or detergent, is a good method for re-moving dirt, oil, or light grease. You should usehot water and a flat, stiff-bristle brush for thisoperation. If you use wiping cloths, you shouldchange cloths frequently to avoid leaving oilfilms on the metal surface.

2, ,

13-3. To Femme light to medium scale. youmay use a dull chisel. scraper. wire brush...A..e.or steel wool. In sonic cleaning. you 014 us'A'a hammer to break off loose scale and then usea file to smooth out any sharp edges. Handcleaning is a time-consuming operation andshould he limited to small areas hicn cannotbe cleaned by other means. You should use sonicform of mechanical cleaning for large areas.

13-4. Mechanical ('leaning. Mechanical clean-ing is determined by the materiul that requirescleaning. the equipment that is available. theamount of cleaning that is necessary. the spaceavailable for cleaning.. and the site of the job. No-bard-and-fast rules can be laid down: conse-quently. it is necessary for you to study the prob-lem and select the most suitable procedures.

13-5. On small jobs. precleaning may be doneby hand. On large jobs. you may use a steamcleaner to remove oil. grease. or dirt.

13-6. Steam cleaning. A steam cleaner con-sists of such components as an electric motor orsmall gasoline engine. a water system. a soapsystem. and a heating system. To operate asteam cleaner. you should follow the operatinginstructions printed on the data instruction plate.If an operator's handbook is available. read itand become thoroughly familiar with the op-erating principles of the machine. Always servicethe cleaner prior to operation. Follow the start-ing instructions exactly and do not eliminate orskip any of the steps. Once the machine isoperating.. check the pressure gages frequentlyto insure proper and safe operation.

13-7. You should not have any difficulty withthe cleaning operation. For effective cleaning.hold the nozzle approximately 1 foot from thesurface to be cleaned. You should he very care-ful to prevent splash or overspray from con-tacting electrical equipment. Water can damagesuch equipment and it may produce a shockhazard.

13-8. Power removal. The use of power-operated handtools is an easy method of roughcleaning and corrosion removal. However. youmust be careful when you use power equipment.It is easy to use too much pressure on thinmetals. such as exterior siding. or interior parti-tions. Even when you have the specified brush.grinding wheel. or sander disc. too much pressurecan cause damage to the metal by burning orwarping. When you use this equipment. wearthe proper goggles. face mask. and clothing forself-protection. Take care to properly ground theequipment and not to stand in water or lay theequipment on damp ground.

13-9. Sonic paint shops are equipped withindividual portable power tools, such as grinders,

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TOO FLAT

TOO TILTED

CORRECT

Figure 44. Correct grinder position.

brushes, sanders. and buffers. Other shops mayhave a universal-type power tool which can beused for any of these cleaning operations. Ifyou in all an abrasive grinding wheel, the toolbecon7 a grinder; if you install a metal brush,and it becomes a power brush. The same toolmay be used with a sanding disc as a sander, ora buffing pad as a buffer. The procedure forusing the tool is similar for any of these opera-tions.

13-10. Power brushes. Power wire brushingwill normally result in better surface preparationthan hand-brushing. In either case, you will beable to remove only the loose scale and rust.On heavily corroded metal, the bristle cannotreach the bottom of the pits. Hard, tightly ad-hering corrosion products and mill scale will notbe removed. Prolonged application of the wirebrush to an area will add little toward bettercleaning and will tend to polish the surface,This burnished effect does not Produce goodadhesion of paint coatings and should beavoided. Generally, a cleaning rate slower than2 square feet a minute is of little avail towardbetter cleaning.

13-11. Power grinders and sanders. Thepower grinder is used to remove scale and en-crustation. You should use a coarse abrasivewheel to remove heavy deposits by wearingaway the corrosion. You would use fine grit-size sanding discs for final dressing or polishingoperations. To prevent the grinder from digginginto the metal, start the grinder off the metaland lift it from the metal before stopping. Donot lay the unit down while the motor is running.

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You can obtain the best results by applyingmoderate pressure as you hold the grinderagainst the work You should keep the grinderslightly tilted so that only one side of the discis in contact with the work. (See fig. 44.) Ifyou apply the entire disc surface to the work,you will feel a "bucking" effect. Excessive pres-sure will slow down the rotation of the disc andreduce its efficiency. In addition, if the grindermotor works too hard. it draws more electricalcurrent and the motor may overheat. You shouldmove the grinder very slowly over the surfacewith parallel and slightly overlapping strokes andwithout burning the metal.

13-12. Since some areas are hard to reach,you may use a flexible shaft to improve thereach of the grinder. Attach one end of theshaft to the grinder and put a disc on the chuckend of the flexible shaft. This attachment makesthe unit more efficient without creating any prob-lems. During grinding operations, wear gogglesand a face shield because corrosion and grinderparticles may break loose and fly off.

13-13. Chipping tools. Chipping with ham-mer- drills or descaler tools is occasionally nec-essary to remove old, hardpaint coatings, andvery heavy, hard rust scale. The use of theseimpact tools should be controlled so as to notleave sharp, projecting ridges which may becomefocal points for later corrosion. A hammer-drill

Figure 45. Descaler.

goais similar to a regular electric drill motor exceptit is equipped with a special chuck which pro-duces a chipping or back-and-forth action. Youcan use special chipping bits in the tool to dis-lodge heavy scale in bends and corners. A de-scaler may be operated electrically, or pneumati-cally. and uses a multiple needle head instead ofbits. The head is made up of steel needles heldtogether by a collar. The descaler hammersthese needles against the surface to loosen anyscale or rust. The descaler is shown in figure45. You can use this tool to clean inaccessibleareas, such as grooves, corners, crevices, rivets,protruding nuts and bolts, and gratings. Graspthe tool firmly, turn it on away from the work,and turn it off while against the work. Youshould always wear goggles while operating thetool.

13-14. Abrasive blasting. Abrasive blastingconsists of bombarding a surface with anabrasive at high velocity. This method of clean-ing metal surfaces is generally superior to othercleaning processes. Abrasive blasting is a rapidmethod of removing corrosion and scale fromferrous metal surfaces. The abrasive cleaner isa self-contained unit which supplies its ownpower from a gasoline engine. The engine fur-nishes power to drive an air compressor. A hop-per provides storage for the abrasive material.A hopper control valve limits the quantity or.abrasive used.

13-15. Abrasives. Abrasives commonly usedfor blast cleaning prior to painting are sand, ironshot, and crushed iron grit. The use of the lattertwo is fairly well restricted to shop work orvacuum blasting, where the abrasive can be re-claimed. It is far too costly for use on fieldwork where considerable loss of abrasive is in-evitable. Shot is spherical in form and is notconsidered as suitable as crushed steel grit forsurface preparation prior to painting, since therounded shot tends to work the metal and is lesseffective in etching the surface. Sand is quitereadily available in most localities and is anexcellent abrasive for field blast cleaning work.The sand used for blasting surfaces preparatoryto application of paint systems should be free ofclay and dust. It should be composed of hardgrains and of such particle size as to be passedby the 20- and retained on the 50-mesh sieve(U.S. Standard sieves). Although sand gradedbetween these sieve sizes is very efficient inblasting rate and produces a desirable anchorpattern for coatings of average thickness, thegraduation should not be adhered to slavishly ifeconomies can be effected by procuring sandwith a somewhat greater range of particle size.For example, 10 percent larger than the No. 20

242

sieve or the same percentage smaller than theNo. 50 sieve does not reduce the efficiency of ablasting sand sufficiently to preclude its use. Ofcourse, these outsize fractions should be con-trolled sufficiently to prevent unworkably largeparticles at one end of the scale and dust atthe other.

13-16. Blasting nozzles. The abrasive is di-rected to the surface being cleaned, by hose anda blasting nozzle. The nozzle has a control valveto start or stop the air pressure and abrasiveflow. A large variety of nozzles are manufac-tured for sandblasting work. Nozzles are madeof ceramic material, cast iron, various steel al-loys, or tungsten carbide. The number of hoursof blasting obtained from one type varies greatlyfrom that obtained from another. When ref-erence is made to the type of materials, the ref-erence is made to the lining area of the nozzle,or that area which is in contact with the airand sand during use. A quick reference to thelife expectancy of nozzles is as follows:

a. Ceramic nozzles which have a life of from1 to 2 hours.

h. Cast iron nozzles which have a life of from6 to 8 hours.

c. Tungsten carbide nozzles which have a lifeof approximately 300 hours.

d. Norbide nozzles which have a life of ap-proximately 750 to 1000 hours.

The hourly life figures given above are for sand.If steel grit is used as the abrasive, the life wouldbe 21/2 times greater.

13-17. Operating the sandblaster. Most unitshave a battery and starter for easy starting. Youshould check the fuel tank and water radiatorfor an adequate quantity and the engine andcompressor for an adequate supply of oil, asshown by the dipstick. You should check theabrasive hopper supply control to make sure thatit is in the closed position. (It should have beenclosed before the last shutdown or during refillof the hopper.) You start the engine by turningthe switch to the START position. You checkthe oil pressure gage to make sure that the indi-cator is in the safe area and allow the engineto build up air pressure (100 psi), which iscontrolled automatically by a governor. At thispoint, you should put on your protective clothingand helmet. Uncoil the abrasive hose, and whileholding the nozzle, set the hopper supply controlto the half-open position. Now you are ready tobegin the cleaning process. Notice that the air-man in figure 46 is holding the nozzle in thecorrect positionready to clean the part. Hecan start the cleaning operation by opening the

Figure 46. Sandblaster.

nozzle control valve. When you open the nozzlevalve, air is expelled and the abrasive is fed fromthe hopper. The air pressure bombards the sur-face with the abrasive at high velocity. You canstop the cleaning by closing the hopper controlvalve. After all the abrasive has cleared thenozzle, close the nozzle valve. Now, if you havefinished your cleaning, shut off the engine. Afterthe engine has stopped, bleed off the air pressurein the tank by opening the nozzle control valve.

13-18. To effectively use the abrasive cleaner,you should hold the nozzle between 12 and 18inches from the surface to be cleaned and at aslight angle from perpendicular. The greatestabrasive impact is obtained with the nozzle per-pendicular to the surface, but the reboundingparticles interfere with the abrasive coming fromthe nozzle and reduce efficiency. The customaryblasting pressure for structural steel work is inthe neighborhood of 80-100 psi. For steel ofsmall cross section and for lightweight metals,the air pressure should be reduced to avoid ex-cessive deformation. The normal pressure usedfor sandblasting brick and mortar surfaces is 40to 60 psi.

13-19. Any degree of cleanliness of steel sur-faces can be obtained by blast cleaning, de-pending on the time you spend on the work.These grades of blast cleaning have been set upas standard practice, and these are used to de-srribe or control the degree of cleaning desired

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on a particular job. The three grades of blastcleaning are explained as follows:

a. White Metal Blast Cleaning. This classifi-cation covers complete removal of all corrosionproducts, all mill scale, all paint, and all otherforeign matter from the surface of the metal. Theend result is a light gray steel surface of uniformappearance with a good anchor pattern for strongadhesion of a protective coating.

b. Commercial blast cleaning. This classifi-cation demands a good but not perfect blastingjob and includes the removal of practically allrust, mill scale, and other foreign matter from thesurface of the metal. The surface will not neces-sarily be uniform in cleanliness and appearance.This grade of blasting will also produce ananchor pattern suitable for bonding applied coat-ings.

c. Brushoff blast cleaning. This classificationrequires only the removal of all loose rust and allloose mill scale. Tight mill scale and minoramounts of adherent rust and old paint are per-mitted to remain on the surface. The surfacesare sufficiently roughened by the blasting to pro-vide a good anchor for paint coatings.

13-20. Regardless of the type of sandblastingyou use, dirt and grit from the cleaning processshould be removed from the surface before youdo any painting. A vacuum cleaner can be usedfor this clean-up operation. It is also importantthat you paint as soon as practicable after clean-ing. A freshly blasted surface is susceptible torusting, especially in humid atmosphere.

13-21. Flame cleaning. Flame cleaning is

used on steel to loosen scale before wire brushingand to dehydrate the metal surface. To use thismethod of cleaning, you must have oxyacetylenegas, flexible hose, a burner head, and a wirebrush. The oxyacetylene burner head has aseries of small. closely spaced holes that projectthe flame at high velocity. For flat surfaces, usea burner head with a row of small openings thatproduce brush like flames. To clean rivetheads,corners, and areas not easily accessible, youwould use a burner head that produces a circulargroup of flames. The heat of the flame reducesthe metal's surface rust to powdered, black oxideof iron, and pops off loose mill scale through thesudden differential expansion caused by the heat.Immediately after you remove the flame fromthe metal, you should wire-brush the heated sur-face to remove all loose particles and rust.

13-22. Before you operate the flame cleaner,you need a pair of heavy gloves and a pair ofsafety glasses. Then find a fire extinguisher andset it near your work area. Now, holding theburner head, slightly open the oxyacetylene valve

aoqand ignite the gas flowing from the burner head.After the gas has ignited, open the gas valveuntil you get small, brushlike flames about 2 to 3inches long. You should pass the flame over thesurface being cleaned at an angle of 45°. Theheat removes or loosens loose mill scale andcauses any moisture beneath the scale to vapor-ize. The oxyacetylene flame will burn oil, grease,and paint; but because of their slow rate of com-bustion, it is inefficient for the removal of suchmaterials. You should not prolong the heatingbecause it may cause warping of the base metalsurfaces. You will discover that the flame heat-ing loosens and pops off some scale and corro-sion, but the wire-brushing you do after the flameheating does most of the cleaning. To shut offthe flame, simply close the oxyacetylene valve.Be careful not to place the hot burner where itmay cause a fire.

13-23. You have learned the types and meth-ods used in rough, or mechanical cleaning ofmetal surfaces. Now, let's discuss chemical, orfinish, cleaning of metals.

13-24. Chemical Cleaning. There are two tech-niques used in chemical cleaning of metals: thebrush-on technique and the immersion technique.The brush-on technique can be used in the fieldfor certain mild chemical applications. The im-mersion technique is reserved for shop use andonly then when the shop is properly equipped.This includes immersion tanks which can beheated, overhead chain hoists for handling itemsduring cleaning, and wash and drying racks.

13-25. Ferrous metals. The chemical rust re-movers that are used on ferrous metals (iron andsteel) are of the acid and alkaline type. Thepurpose of the acid type is to remove red rustand black oxide formations by either immersionor brush application of the chemical. The alkalitype is intended for removing red rust by im-mersion treatment.

a. Acid-type corrosion removers. Phosphoricacid-type. corrosion remover, Specification MILM-10578, type III, is used to remove corrosionfrom ferrous metal surfaces. The remover notonly gets rid of the rust, it also conditions thesurface prior to painting. Before you use theacid-type corrosion remover, you should provideprotection for the adjacent components and partsand remove any grease or soil that might be onthe area or part. If heavy rust is present, youcan remove most of it by chipping, or brushingthe area with a wire brush. After you properlydilute the remover with one part of the concen-trated remover to one part of water by volume,you can apply it to the corroded area with abrush or swab. The remover should remain onthe corroded area long enough to loosen the rust.

2 44

The time, 2 to 10 minues, will vary accordingto the degree of rusting. You can remove theremover by rinsing, preferably with hot water.After completely rinsing the part, dry it and im-mediately apply the protective paint or corrosionpreventive finish.

b. Alkali-type corrosion removers. You canremove corrosion from small parts by immersingthe parts is a sodium-hydroxide-base, corro-sion-removing compound, Specification MILC-14460, type I. The compound will removegrease, paint, and rust from the parts. The com-pound can also be used to clean brass and cop-per, to strip phosphate coatings, and to removerust from critical or machined surfaces withoutcausing dimensional change of the part. How-ever, do not use the solution to remove corrosionfrom aluminum or a joint where dissimilar metalsmeet. The rust removal time will vary accordingto the extent of the rust. After the part has beencleaned, you should rinse it thoroughly with hotwater, dry it, and apply a final protective finish.

13-26. Stainless steel. You can clean rust andscale from stainless steel with a mixture of 12ounces of sulfuric acid per gallon of water. Thewater should be at least 180° F., and the solutionshould be used very liberally. If this solutiondoes not clean the material, prepare a solution asfollows:

Nitric acid 50% by volumeHydrofluoric acid 5% by volumeWater 45% by volume

This solution should have a temperature of 60°F. to 100° F. If possible, you should submergethe material in the solution. You should continuethis treatment for no more than 45 minutes, be-cause a longer period is not any more effective.Next, you rinse the material being cleaned inclear water and immediately passivate the surfaceby applying a solution of 50-percent nitric acidand 50-percent water, by volume. After youhave passivated the material, you should againthoroughly wash it in clear water.

13-27. Carbon steel. You can clean carbonsteel with a 50-percent hydrochloric acid and 50-percent water solution, by volume. The solutiondoes not have to be heated, but the cleaningshould be continued until the material has beencleaned of corrosion. After cleaning the material,you should thoroughly rinse it in clear water andallow it to drain for not over 5 minutes. At thistime, you must flush the material with a 0.01 -percent nitric acid solution. Following this treat-ment, again thoroughly rinse the material in clearwater and allow it to dry.

13-28. Aluminum and aluminum alloys. Youcan clean aluminum and aluminum alloys byusing the same type solutions and mixtures usedfor stainless steel. If you have used tanks for thesolution and cleaned steel in the tanks, the samesolution mixture cannot be used for aluminum.The chemical reaction of the solution and steelis damaging to aluminum. After you havecleaned the aluminum, rinse it in a solution ofclear water.

13-29. Copper and copper alloys. You canchemically clean copper and copper alloys in 18-percent hydrochloric acid or 10-percent sulfuricacid, by volume. You wash the material with thesolution for 2 to 3 minutes and then scrub with abristle brush. You may repeat the procedure un-til the desired cleaning condition is obtained.After cleaning, water-rinse the material until youhave thoroughly removed all trace of the acids.

13-30. Until you become proficient in han-dling chemicals, your supervisor will delegate aqualified individual to be in charge of any clean-ing operation. The individual in charge will in-sure the proper selection, preparation, and use oftreating equipment and materials required for thecleaning operation. After you have shown thatyou can do the work safely, you may do it alone,or you may be put in charge of another man whois new at the cleaning job.

13-31. Whenever you use chemicals for cor-rosion removal, be extremely cautious before,during, and after the process. Before cleaningmetal with strong solutions, you must have suit-able protective clothing and equipment and youmust properly prepare the solution you are goingto use. Be careful not to splash or spray thesolutions on the surroundings. When a solutionbecomes dirty, the results of the cleaning processare unsatisfactory, or the cleaning time becomeslengthy, prepare new solutions. After you havedrained tanks and drain trays, thoroughly cleanthem by flushing with water and scrubbing with afiber bristle brush. Be prepared to catch or trapall of the chemical discharge solutions, becausethey may damage the sewer system or pollutenearby streams or ribers. If your post has anindustrial waste disposal facility, label the wastecontainers according to their contents and sepa-rate them from trash for proper disposal. If yourpost does not have this type of waste disposal,you should transport the waste containers to thesanitary fill for burial. Overall, your use ofchemicals for corrosion removal will be very lim-ited; but now you know what you can do, how itis done, and the result that can be obtained byusing chemicals.

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14. Repair of Metal Surfaces14-1. As a protective coating spc.ialist, it will

be your job to make minor repairs to metal struc-tures. prior to painting or repainting. The repairsthat you make will be limited in scope, but theymay be the most important repairs ever made tothe building. Whenever the paint is renewed, itprovides an occasion for making minor repairsthat otherwise might be neglected until they be-come major repairs. Since corrosion effects differaccording to the metal usage, we will discuss re-pair in reference to where the damage is found.

14-2. Structural Steel. Heavy steel framingis used in many major military buildings andstructures. Your work in this area is limited tocorrosion prevention by painting. The repair ofstructural failures or damage to heavy steel fram-ing must be done under the supervision of astructural engineer. The work is generally ac-complished by contract.

14-3. You will find steel used for framingaround openings for windows and doors, interiorwall partitions, and other purposes. Generally,the emphasis placed on visible structural steel isappearance and the steel will have been painted.Corrosion may be found wherever the paint hasdeteriorated or shows blistering. You can removesmall areas of corrosion from such surfaces bywire brushing. After you have removed all evi-dence of corrosion, spot-prime the area and ap-ply one or two overall coats of matching paint.

14-4. In interior or unseen areas, such as steelframing that supports dropped ceilings, you maybe concerned with eliminating corrosion causedby roof leaks, water piping leaks, or condensa-tion. You would remove the corrosion by wirebrushing and finish the surfaces with a primercoat. You should also eliminate the source ofmoisture or report it to the utilities shop.

14-5. Metal siding. Metal siding is manufac-tured from aluminum, galvanized iron and steel,or black iron. It may be "V" crimp or it mayhave half-oval or half-square corrugations to giveit rigidity. It may be formed to have the ap-pearance of wood siding. The corrogated sheetsare generally installed with the corrogations run-ning vertically. The types which resemble woodsiding are usually installed horizontally. Somealuminum siding and most black-iron siding willhave a factory-applied protective coating. Thismay be simply a baked-on enamel finish, or itmay be a protective coatin designed to meet themost severe applications. 1. sheet of protectedcorrugated metal siding is illustrated in figure 47.

14-6. Before repairing, touching up, or recoat-ing protected metal siding, you should clean thearea. Remove all loose or torn asbestos felt,

45

lob

Figure 47. Protected metal siding.

flaked coating, and rust with a stiff fiber brush.To remove grease, dirt, or chemical deposits, usesoap or a detergent cleaner. You may use sol-vents to soften or disolve bituminous compounds.To repair small bare metal areas, follow thesesteps:.

a. Clean the area and remove any rust with awire brush. Coat the exposed metal, plus 1 inchof the adjoining asbestos felt and bituminous cov-ered surfaces, with asphalt primer.

b. Allow the primer to dry for at least 24hours and then apply bituminous plaster cementuntil you form the continuous plane with theoriginal adjoining surfaces.

c. Allow the cement to set for 24 hours, andthen apply a brush coating of bituminous com-pound, overlapping the adjoining surfaces about1 inch.

14-7. When only the asbestos felt is exposedat a damaged area, repair it. For this repair,apply a brush coat of bituminous compound.After this coat has dried at least 24 hours, applya final coat of the same compound.

14-8. Before painting or repainting galvanizedor aluminum siding, check all bolts, clips, nails,and other ties and fasteners for being in place

46

and tight. If any panels have physical damage,such as cuts, breaks, or cracks, replace them withmatching material. If the siding section is repair-able, you may remove it, straighten any bends,and replace it. You may discover rusted orloosened bolts and screwheads. When you can-not correct this situation by using new bolts orscrews, drill the necessary new holes in an ad-jointing solid portion of the siding. Use stainlesssteel sheet metal screws for fastening siding sheetsto each other and use stainless steel self-tappingscrews to fasten sheets to structural steel. Tofasten siding to wood framing, use stainless steelnails with lead-covered heads on galvanized iron,and use aluminum nails with neoprene washerson aluminum. When locating fasteners on corru-gated siding, place them on top of the corrueationand not in the valley. Do not tighten them to theextent that the shape of the siding will be de-formed.

14-9. Dissimilar Metals. You have alreadylearned that whenever two or more dissimilarmetals are in contact and moisture is present,corrosion develops rapidly. You may find thiscondition to exist when you are painting metalgutter and flushings, or piping. The treatment ofdissimilar metals consists of three steps:

(1) Determine the type of metals involved.(2) Clean any corrosion damage caused by

the contact of the metals.(3) Seal the surface area of each piece of

metal to exclude moisture and insulateagainst an electrical circuit, when the met-als are rejoined.

14-10. When a fastener is made of differentmaterial from the material to which it is attached,remove the fastener and coat it completely withone heavy coat of zinc chromate or inorganiczinc dust primer. Reinstall the fastener while theprimer is still wet. If available, a fastener of thesame material as the rest of the part should beused when replacement is necessary. Cadmium-plated fasteners are considered satisfactory forjoining to aluminum.

14-11. When a pipe, tube, or some other metalpart is damped tightly to a dissimilar metal,loosen the clamps so that the pipe or tube maybe moved away from the dissimilar metal. Paintthe pipe, tube or other metal part, and the dis-similar metal at all points in which the metalstouch, with zinc-chromate primer. Reassemblethe fittings and piping and finish with two coatsof synthetic enamel.

14-12. Dents, Scratches, and Small Holes. Youshould repair all small surface defects prior topainting or repainting metal surfaces. The timeyou spend in such repairs will not only add to

the retardation of corrosion at the damagedareas, but will add greatly to the appearance ofthe finished surface. In most cases, it will beimportant that you repair holes in metal surfacesto prevent water leaks. There are several typesof metal filler and putty which you can use torepair these small surface defects.

14-13. Body filler. Body filler, of the typecommonly used commercially in auto body repairand paint shops, can be used to repair dents,holes, and leaks in metal surfaces. You shouldclean the metal and then mold or shape the fillerto the surface contour as you apply it. The fillerwill dry rock-hard in 4 to 6 hours. After it dries,smooth and feather it by using files, abrasivegrinders, or by sanding.

14-14. Engraving filler. Engraving filler getsits name because it is used for filling stamped orengraved markings on metal, ceramic, and plasticsurfaces. You can use this type of filler to filldeep scratches where no denting is involved onmetal surfaces. It hardens with very little shrink-ag5v--After it has dried, you can sand off theexcess filler to provide a smooth surface with theoriginal metal. You can use the filler equally aswell on painted metal surfaces which have beenscratched. Do not sand the scratched area priorto applying the filler. After the filler had dried.wet-sand the area lightly to blend into thepainted surface.

14-15. Plastic paste filler. Plastic paste fillershave the advantage of a rapid drying time, butthey are more difficult to apply. You must mixthe ingredients immediately prior to applying thefiller, which comes packaged in two containers.The catalyst powder must be added to the liquidfiller to cause it to harden. Once the ingredientshave been mixed, you must work hurriedly tofill the dents, holes, or cracks as the filler will setand completely harden in 20 minutes. The dam-aged area should be cleaned and ready for appli-cation of the filler prior to mixing the ingredients.After the filler has hardened, you can sand it toconform to the surface and then prime or paintthe area as required.

14-16. You may find holes as large as I to 2inches in diameter in metal siding where pipingor electrical conduit has been removed. If thesurface is flat, you may repair the hole by cuttingand installing a metal patch with sheet metalscrews. On corrugated surfaces, you can apply amuslin cloth, or fiberglass patch. Banana-oil-base glue, aircraft dope, or plastic paste filler canbe used as an adhesive for applying the patch.Completely coat the surface of the patch with theadhesive to give it body and strength. After ithas dried, prime or paint to match the surround-ing surface.

479t t./

207

15. Metal Conditioning and Pretreatment15-1. Metal surfaces, which will be subjected

to severe or extreme exposure conditions, mayrequire a pretreatment prior to application of theprotective coating. This pretreatment should notbe confused with the priming of the metal, norshould it be considered as a cleaning process.The pretreatment is necessary to improve orcause adhesion of the protective coating to themetal. There are two types of pretreatmentwhich you may use in the painting of Air Forcemeta', buildings and structures: a chemical metalcond tioner, and a vinyl wash coat treatment.

1S-2. Chemical Metal Conditioner. This ma-terial is a mixture of phosphoric acid, wettingagents, water-soluble oil solvents, and we_ar. Itis available under Military Specification MILM-10578A, type II, or it may be purchased lo-cally in a concentrated solution. The solution re-quires dilution in the proportion of three parts ofwater, by volume, to one part of conditioner. Thisshould produce an acid concentration of 5 to 7percent by weight.

15-3. The compound is easily applied with awhitewash brush. You should work the condi-tioner into the pits, around fasteners, and bolt-heads, and other irregular surfaces. It can alsobe applied by spray, but the brush method ispreferred to assure intimate contact of the liquidwith the metal, and to avoid the use of excessiveamounts.

15-4. After the conditioner is applied to a sur-face, the acid will react with the metal. When adry powdery surface, grayish-white in color de-velops within a few minutes after application,the acid has reacted properly and has the properdilution. If a dark color develops and the sur-face is somewhat sticky, the acid is too concen-trated. In such cases, you may wipe the surfacewith a water-dampened rag to bring about thedesired appearance. It is sometimes necessary,in order to obtain the proper reaction, to useone concentration on warm surfaces in direct sun-light and a different concentration on shadedareas. Surfaces which generally do not show thegray powdery reaction should be retreated, butthe fact that every square inch of a large areadoes not react, should not cause alarm. Treatedsurfaces usually present a somewhat mottled ap-pearance.

15-5. The conditioner is not recommended foruse on structural steel unless it has been sand-blasted. Poorly cleaned areas, mill scale, andother foreign material will cause the acid to reactdifferently on each area. The conditioner is notrecommended for touchup work because the

plaint surrour cling the area being repaired maybe damaged by the acid in the conditioner.

15-6. Vinyl Wash Coat. This wash coat ma-terial is procured under Military SpecificationMILC-15328A, Coating, Pretreatment for Met-als. It is popularly known as WP-1 or as formulaNo. 117 for metals. It comes packaged as twoseparate components which are a base resin solu-tion and an acid diluent. The components mustbe very carefully mixed just prior to use,, by add-ing one volume of the acid component to fourvolumes of the resin component. Slowly add theacid component to the resin component and stirconstantly while doing it. If the acid is added toorapidly, without thorough mixing, or if the basesolution is poured into the acid, the mixture willgel and be unusable.

15-7. The wash-coat material is suitable forapplication by spraying. You should apply it ata coverage rate of 250 to 300 square feet pergallon. This should produce a thin but continu-ous film of 0.3- to 0.5-mil dry film thickness.You should not apply more than 0.5-mil thick-ness under any circumstances. When dry, thecoating should be thick enough to give a contin-uous film, but should not be so heavy as tocompletely hide the underlying metal. The basemetal should show faintly through the dry film.It is important that the wash-coat solution be ap-plied within 8 hours after mixing, even though itscondition appears satisfactory after the time limithas expired.

15-8. You should not apply the wash coatover visibly wet surfaces, because the wash coatmay dry on top of the water film without absorb-ing it, and poor adhesion to the base metal willbe the result. The applied film may turn whiteand be lacking in strength and distensibility. Ifthe wash coat must be applied to damp surfaces,you should apply it by brush or swab. This willbreak up and incorporate the moisture. Althoughthe wash coat is more adaptable to spraying, itcan be brushed or swabbed on without difficulty.

15-9. If the spray does not deposit a wet, uni-form film during application, you should thin thewash coat solution with either 99 percent iso-propanol or normal butanol. You will find thatmore thinning will be required in very warm,windy weather than under more moderate con-ditions. Spray equipment should be cleaned assoon as practicable after use with butanol, 99-percent isopropanol, or denatured ethyl alcohol.Wash coat materials will form insoluble gels afterthe mixture has stood more than 8 hours. Washcoat material which has gelled in spray lines ispractically impossible to remove.

15-10. Dry films of vinyl wash coat may un-dergo some color change. The end color after a

2,1 C48

24 -hoar drying period may vary with weatherconditions or thickness. The fact that the dryfilm does not always exhibit exactly the sameappearance, should not cause concern. Subse-quent coats of primer or paint may be appliedafter 1 hour of drying of the wash coat. Longerperiods of drying, up to several days, are per-missible as long as damage to the wash coat filmfrom corrosion or other causes has not takenplace.

16. Application of Protective Coatings16-1. Metal surfaces must be painted as soon

as possible after they have been prepared. If thesurfaces are allowed to corrode again, they mustbe recleaned before the paint is applied. Youcan apply paint to metal surfaces by brushing,rolling, spraying, flowing, or dipping.

16-2. Dip or Flow-Coat Method. The dip orflow-coat method is used for volume productionpainting of certain items that are suitable forthese painting methods. When you use the dipmethod, have a tank to hold the paint. Thepaint in the dip tank is ma'ntained at a constanttemperature and agitated frequently to assureuniformity of the paint. Check the viscosity ofthe paint at regular intervals, and add more sol-vent when required to replace the volatile solventthat has evaporated. These precautions are nec-essary to obtain a uniform paint film thicknesson the items dipped. Flow coating differs fromdipping that the paint is flowed over the itemto be painted; as the surplus paint flows off theitem, it is caught in a tank or trough from whichit is recirculated by pumps.

16-3. Roller Coating. Roller coating is a fast,economical, hand method of painting large areas.It works as well on metal as on wood or masonrysurfaces and is applied in the same way on each.The amount of pressure regulates the quantityof paint transferred from the fabric on the rollerto the surface being painted. Metal usually takesless paint because it does not absorb as othersurfaces do. Thick fabric rollers, such as thoseused for rough plaster or cinder block are alsobest used when painting chain link fences, wiregrills, or roughened metal.

16-4. Brush Method. Usually, protective coat-ings are applied to metal surfaces with a brushwhen the volume of work does not justify settingup spray apparatus or when equipment is notavailable or is inaccessible to the job. The task ofmasking out parts to remain unpainted is exten-sive when the mist from the spray gun will dam-age equipment in the surrounding area or createa fire hazard. When the brush method is usedto apply coatings on metal surfaces, it is per-

formed in the same manner as for wooden sur-faces.

16-5. Spray Application. The easiest and fast-est method of applying protective coatings tolarge metal surface areas is to spray them on.The coating material that you are going to useshould be strained to remove all particles thatmight clog the spray gun. This is especially im-portant when the material comes from a previ-ously opened container. Follow thc thinning di-rections on the container to be sure of thc properviscosity for applying the spray. Viscosity maybe defined as a fluid's internal resistance to flow.Fluids of low viscosity are thin and flow freely;fluids of high viscosity are thicker and flowslowly. The viscosity of a paint makes a signifi-cant difference in the ease or difficulty of itsapplication, especially if it is applied as a spray.Normally, the viscosity has little direct effect onfilm properties because it is a ratio of the thinnerversus the paint, and the thinner will evaporatein drying. However, you must be concerned be-

Figure 48. Zahn cup.

2 1 ""

2. 0

cause viscosity control is essential to obtain con-sistent results in application. Tou low a viscosityleads to runs or sags. A primer too low in vis-cosity and too thinly applied leads to blushingand too high viscosity may cause orange-peeleffects, excessive film thickness, or dusting. Forconsistent coating results, the viscosity of eachcoating mixture must be controlled.

16-6. Viscosity measurements. Viscosity ismeasured by various methods and instrumentsand is expressed in various units of measure-ment. The tv,ro methods most frequently cited inthe coating industry use either the Ford or theZahn viscometer cups. The viscosity is expressedin seconds through the cup. The seconds indicatethe length of time it takes at a given temperaturefor a known quantity (cup filled to the top) ofthe coating material to flow through a certainsize orifice in the cup. For example, viscositiesat 77° Fahrenheit of 16 to 22 seconds through aNo. 4 Ford cup, or 19 to 27 seconds through aNo. 2 Zahn cup are generally right for sprayingenamels. Lacquers will require about 4 secondsless in either cup. For comparison, the viscosityof water and some thinners is 10 seconds througha No. 4 Ford cup. The Zahn cup is usually con-sidered the standard and most appropriate forfield use.

16-7. Zahn cup. The Zahn cup is designed tomeasure the viscosity of fluids directly from theircontainers. It consists of all-mil cup with a hole(orifice) and a wire handle, as shown in figure48. Fill the cup by immersing it in the fluid;then time the flow of the paint through the orificefrom the second the cup is withdrawn from thepaint being tested to first interruption in the flow.

16-8. In Memorandum 562, v,e discussed thedifferent types of paint spray equipment, butdid not go into the instructions on how they wereto be operated. Now, let's learn how to use them.Since the air-atomized spray is the most commontype used on buildings and structures, we willdiscuss it first.

16-9. Air-atomized spray. Before starting tospray paint, you should check the adjustment ofthe spay gun. There are adjustments for variouspurposes: for example, to control the air pressureand flow of material and to provide a means ofchanging the direction of a spray pattern. For alow-pressure spray gun, the air pressure shouldbe between 20 and 40 psi, for a high-pressuregun between 80 and 100 psi.

16-10. The proper air pressure is essential toa good spray j,.,b. Too high an atomization pres-sure will thin out the center of a spray pattern.As too little air pressure will fail to atomize thematerial sufficiently; a coarse, spattered effect.that is unacceptable, will be the result. This ad-

49

240

SPRAY

PAINT GUN

AIR CONTROL SCREW

MATERIALCONTROL SCREW

d

FLUID HOSE AIR HOSE

Figure 49. Holding spray gun correctly.

justment can be checked most satisfactorily bystudying the spray pattern made by the gun.Such an adjustment may be made with the aircontrol screw located above the handgrip shownin figure 49.

16-11. The speed of operation at which youmove the gun across the surface being painteddetermines how you adjust the flow of materialfrom the gun nozzle. An experimental period inwhich you use various settings of the adjustmentswill be of value in determining the most efficientoperation. The adjustment should permit a com-fortable, rapid stroke with sufficient coveragewithout runs and sags. The flow of materials iscontrolled by the material control screw also lo-cated above the handgrip in figure 49.

16-12. The direction of a spray pattern maybe changed by rotating the spray gun cap or airnozzle. In this manner, it is possible to producea spray pattern about 6 to 8 inches wide whenthe gun is held 6 to 10 inches from the surface.

16-13. Spray gun stroke. You should hold thespray gun perpendicular to the surface, as illus-trated in figure 49. Tilting the gun up or downgives an uneven spray pattern. The distance ofthe spray cap or nozzle from the surface will de-pend upon the air pressure used and the con-sistency of the paint. Generally, the distancevaries from 6 to 10 inches. Holding the spraygun at a greater distance causes a dry spray andexcessive spray dust. The trigger controls the ac-tion of the gun. The farther the trigger is drawnback, the greater the flow of material.

16-14. Move the spray gun with straight, uni-form strokes backwards and forwards across thesurface in such a way that the spray pattern willoverlap about 50 percent of the previous stroke.Use a free arm motion and feather-cut the endof each stroke. You do this by pulling the triggerafter beginning the stroke and releasing it beforethe stroke is completed. Caution should be takennot to arc the gun, since this causes an uneven

2 1 n 50

deposit of paint and excessive overspray at theend of each stroke. Figure 50 illustrates a properspray gun stroke as well as an incorrect stroke.

16-15. When you feel that you can operate aspray gun properly, practice spraying on old car-tons or on sheets of paper tacked to a wall or box.After practicing for about 15 to 20 minutes, youwill get the feel of the gun and acquire enoughconfidence to do actual spray painting.

16-16. Spraying a panel. Panels may besprayed by using horizontal or vertical spray gunstrokes. To spray a panel with horizontal strokes,follow the procedure illustrated in figure 51.

16-17. The work is started with a dry stroke,that is, with the trigger released, a few inchesto the left of the panel. The trigger is pulledat the instant the gun nozzle is opposite the leftedge of the panel. The gun is aimed at the topedge of the panel as the stroke is being con-tinued across it. The trigger is released the in-stant the gun nozzle is opposite the right edgeof the panel. The dry stroke is continued a fewinches before reversing .for the second stroke.When the gun nozzle is opposite the right edgeof the panel, the trigger is pulled, but this timethe nozzle of the gun is aimed at the bottom ofthe first stroke. In this manner the second strokewill overlap the first stroke about one-half. Thissystem gives a double coverage to a surface andassures a full wet coat without streaks. A half_overlaping stroke is usually used for all work.Continue with right and left strokes until thepanel is completed.

16-18. In some cases, in order to reduceoverspray at the right and left ends of a panel,you may use a banding technique. This procedurecalls for single vertical strokes at each end of thepanel, as shown in figure 52.

16-19. Banding assures complete coverage andsaves the paint which is normally wasted as a re-sult of your trying to spray right up to the verticaledge with horizontal strokes. The top and bottomof the panel are sprayed with horizontal strokes

SURFACE

MOVE GUN IN STRAIGHTLINE

BEGIN STROKETHEN PULLTRIGGER

DO NOT ARCSTROKE

RELEASE TRIGGERBEFORE COMPLETINGSTROKE

Figure 50. Spray gun strokes.

START PULLSTROKE TRIGGER

1 /

DRYSTROKE

AIM GUN ATEDGE OF PANEL

RELEASETRIGGER

AFTER FIRST STROKEAIM GUN AT BOTTOMOF PREVIOUS STROKES

Figure 51. Spraying a panel.

aimed at the edges of the panel. These strokesautomatically become banding strokes. Thepanel is then finished with horizontal strokes.

16-20. Long panels may be sprayed withvertical strokes, as illustrated at the top of figure53. Sometimes this procedure is best, sincestroke-end laps are avoided. However, most ex-perienced sprayers prefer the horizontal stroketo the vertical stroke, since spraying with a hori-zontal stroke is more natural. Such operators, be-cause of their experience, are able to make anexcellent job with invisible overlaps. Painting a

SINGLESPRAYSTROKE

ORBAND

allDRYSTROKE

panel with horizontal strokes is shown at thebottom of figure 53.

16-21. Spraying edges. When the edges, aswell as the face of a panel, are to be sprayed, amodified banding technique is used. A singlestroke along the edges paints the edges and bandsthe face of the panel at the same time.

16-22. Outside corners are sprayed in thesame manner. In such cases, the gun is aimedat the corner and the spray coats both adjoiningsurfaces with one stroke of the gun, as shown infigure 54.

FINISH WITH HORIZONTAL STROKES

Figure 52. Banding a panel.

5121

SINGLESPRAYSTROKE

ORBAND

LONG PANELS MAY BE

PAINTED WITH UP ANDDOWN STROKES

OVERLAPS

FIRST

4111-1--18 TO 36" STROKES

SECOND

THIRD

Figure 53. Spraying long panels.

16-23. Inside corners are more difficult tospray, since more strokes are required. Whenspraying an inside corner, each face of the corneris sprayed separately, as shown in figure 55. First,a vertical stroke is made at the corner from thetop down. Then, horizontal strokes are used tospray the area next to the corner.

16-24. Films applied by air-atomized spraywill tend to be somewhat thinner than those ap-plied by brush. In some cases the sprayed coat-ing gives good protection with a dry film thick-ness of only approximately 1 mil (1/1000 inch)per coat.

16-25. Airless spray. Airless spray applica-tion is somewhat similar to spraying waterthrough a garden hose. The paint is atomized

Figure 54. Spraying outside corners.

52

by the force of hydrostatic pressure through anozzle. The type and size of the surface to becoated determines which one of an assortment ofnozzles to use. Spray tips are available toproduce pattern widths that range from 15° to950.

16-26. Hydrostatic pressure combined withthe size of the spray tip orifice determines theamount of material that will pass through thenozzle in a given period of time (flow rate).

Figure 55. Spraying inside corners.

213

CIRCULATINGVALVE

Figure 56. Electrostatic paint system.

This rate will vary according to the type andviscosity of the coating and the size of the nozzleorifice. Heavy-bodied coarse materials needlarger spray orifices than do materials for finelyground finish coats.

16-27. The handling techniques of the airlessspray gun differ from those of the air-atomizedgun in that the airless spray gun is held from12 to 16 inches from the surface being coatedand is moved at a more rapid rate. This actionis necessary because of the heavier material.

16-28. Some of the basic advantages of air-less spray over the air-atomized spray methodare as follows:

Greater reduction in over spraying.Application of heavier films is possible.Materials may be applied without thinning.Rate of production is considerably faster.Consumption of air is substantially lower.

16-29. Electrostatic spray unit. The electro-static unit is basically an electronic, air-operatedsystem. This system adds an electrostatic chargeto the coating material droplets. An electricpowerpack provides extremely high voltage atlow amperage to create a magnetic force betweenthe work piece and the spray particles. The softforward velocity of the paint and the electrostaticattraction principle help guide the individual coat-ing particles to the workpiece and aid both pene-tration and wraparound of the protective coating.Nonmetallic products may also be coated afteran initial preparation with a conductive material.Figure 56 illustrates the bask system. The air-operated portion of the electrostatic unit consists

53

2`"

of a circulating valve, pump, heater, filter, andelectrostatic hand gun.

16-30. The first requirement for safe electro-static painting, because of the nature of its oper-ation, is that the hand gun must be safe. Thegun should not be capable of giving an objection-able shock to the operator or of producing anelectric spark, even under the most adverse con-ditions. Secondly, all conductive objects in thespray area must be positively grounded. Thisincludes the spray booth, racks. workholders, thearticle being painted, all solvent cans. the floor,and even you, as the operator. You should wearconductive shoes. Wear shoes with ordinaryleather soles, but do not wear rubber or corksoles. If you wear gloves, you must cut the palmout of the gloves to allow contact of your handwith the gun handle.

16-31. Some of the advantages of electro-static painting are the saving of paint, improvedoperator health and working conditions. andfaster painting with better quality. Because moreof the paint is deposited on the article beingpainted, less overspray is wasted on walls, floor,and on the operator. Face masks and protectiveclothing can often be eliminated and less elab-orate paint booths and exhaust systems can beused. Since the paint particles are drawn to thearticle being painted, improved quality with lessoperator effort often results. For example. a cyl-inder or pipe can be painted from the front sideas the magnetic attraction will cause the paint towrap completely around it. As the paint coversone area, it will insulate that area and cause thepaint particles to seek out and cover hare areas.

16-32. The air-atomized spray and the airlessspray, as well as brushing and roller coating ofmetal surfaces, are used extensively in the field.The flow or dip method of painting, as well asthe use of the electrostatic spray unit, are prettywell limited to the paint shop area.

16-33. You have learned about the methodsused in the application of protective coatings tometal surfaces. Now, let's discuss some of thepeculiarities involved in painting certain types ofmetal surfaces.

16-34. Painting Structural Steel. New struc-tural steel for service at atmospheric exposure isgenerally cleaned and shop-primed soon after itsrolling or fabrication at the mill and prior to ship-ment to the construction site. Areas on the steelwhich are damaged during erection and allabraded or corroded spots on such shop-coatedsurfaces should be wire-brushed and spot-primed with material similar to the shop coat.

16-35. New steel, which has no shop coat, canbe cleaned by wire brushing. Experience hasshown that removal of all scale, rust, and otherforeign matter is generally unnecessary to obtainan adequate paint job for normal exposure. Thisis true provided you use primers which containa large portion of free linseed oil. Such oil typeprimers have the ability to effectively wet thesurface and penetrate to base metal beneath theedges of mill scale and tightly adherent rust.

16-36. Structural steel surfaces, which are sub-ject to water immersion and abrasion, should besandblasted to the base metal to obtain satis-factory results. Immediately after blasting, thesurface should be pretreated, prior to priming orpainting. Either the chemical metal conditioneror the vinyl wash coat method may be used.

16-37. Painting Galvanized Surfaces. Ga lvan-nized surfaces are generally left unpainted atleast during their early life, since the purpose ofgalvanizing itself is protection of the base metal.However, for the sake of appearance or addi-tional protection, painting is rather frequentlydone. In any event, painting should be initiatedat the first signs that the galvanizing is not ade-quately protecting the underlying base metal. Thegreatest problem in connection with painting ofnew galvanized surfaces is in obtaining andmaintaining good adhesion, since most paints donot adhere well to this type of surface. However,the vinyl-type wash coat adheres well if oil,grease, and other contaminants are first removedfrom the galvanized surface by washing with sol-vents and wiping dry. For use over the vinylwash coat, zinc dust paint may be used. Zincdust pigmented paint is suggested since it per-forms quite well on galvanized surfaces, evenwithout the vinyl wash coat. However, once ad-

2.54

hesion to the galvanizing is established by meansof the vinyl wash coat, almost any type or colorof paint suitable for the exposure conditions maybe used in place of the zinc dust paint with goodresults. For example, in interior exposure, paint-ing of galvanizing would normally be done onlyfor appearance and in such cases the vinyl washcoat might well be followed by whatever paintis being used on adjacent surfaces.

16-38. Painting Aluminum Surfaces. Alumi-num surfaces will normally be left unpainted.However, where such surfaces are to be exposedfor prolonged periods to moisture, concentratedchemical fumes or industrial gases, painting is

generally advisable. Gutters subject to collectionof debris, flashing in contact with concrete, con-tacting surfaces with other metals and contactingsurfaces with damp wood are also situations inwhich the protection of aluminum is indicated.The surfaces should be cleaned with solvents toremove heavy grease and oil accumulations andthen treated with the vinyl-type wash coat.

16-39. There are other satisfactory methodsof preparing aluminum surfaces,' such as anodiz-ing, hot dip phosphate treatment, and hot dipchromic acid treatments but they are for the mostpart not adaptable to field use.

16-40. The paint system recommended forexterior aluminum surfaces consists of the vinylwash coat, two coats of a phenolic-type zincchromate aluminum primer followed by a pheno-lic-type aluminum finish coat. One of the twocoats of primer may be omitted, if desired, wherethe exposure conditions are not severe. In theabsence of the paints for the suggested system,any high-quality .primer, the pigment content ofwhich consists of 50 percent or more of zincchromate, may be used either over bare metal orover the vinyl wash coat. Follow by one or morefinish coats by high-quality aluminum paint orother finish color as required. In general, paintscontaining lead pigments should not be used forthe first coat on aluminum surfaces. Exteriorlead-free house paints may be used in paintingaluminum siding subject to normal exterior ex-posure with good results. High-quality bituminouspaints may be used to advantage in paintingaluminum flashing which is in contact with con-crete or mortar and in painting the inside ofgutters. Aluminum surfaces in contact with dis-similar metals should be cleaned and protected,as was explained in paragraph 14-9.

16-41. Coating Metal Tanks and Piping. Theproper painting of metal tanks and piping is de-pendent on the type of metals used, the type ofmaterials to be stored, and their size and physicallocation. Tanks may be located overhead, atground level, or underground. They may be lo-

cated outside, or they may be located insidestructures, such as mechanical rooms, or power-houses. You may find piping in ceilings, walls:floors, or underground. Your job, as a protectivecoating specialist is not to repair leaks or replacepiping. Your responsibility is preventive mainte-nance and you should make surface repairs andapply protective coatings which will extend theuseful life of these items.

16-42. Overhead piping. Overhead piping isgenerally coated for appearance. In some cases.it must be painted or color-coded for identifica-tion. If you find evidence of corrosion damage.usually at fittings or on threaded surfaces, youshould clean the area with a wire brush. Applya coat of red lead primer and then finish withthe desired color of finish paint.

16-43. Underground piping. Protective coat-ing on underground piping will provide a littlemore challenge to repair. You will become awareof the necessity for this work only when corrosionhas advanced to the stage of causing a leak.When this happens, you will receive a work orderto provide a protective coating to the repairedarea after the leak has been repaired and beforethe pipe is covered up. In most cases, the under-ground pipe will have been coated when newwith a coal-tar primer, wrapped with bondedasbestos felt or kraft paper, and finished off witha thin coat of coal-tar enamel. To properly cleanthis type of surface for repairing, use a scraper,wire brush, flame torch, and possibly an organicsolvent. After you have cleaned the areait maybe a patch or a section of r.ew piperebuild theprotective coating, overlapping the edges of theoriginal coating. Be extremely careful to preventearth or rock from adhering to any portion ofthe repaired area, and be sure that no holidaysare left in the wrappings. The completed repairshould completely seal the pipe so that it willresist any moisture. Coal-tar enamel protectssteel pipe for long periods of time. Service recordsindicate a service life of 50 years or more.

16-44. Copper pipe. Copper pipe or tubingis being used extensively in building water sup-ply systems. Copper pipe, 3 inches or larger indiameter, may be used for sanitary drainage sys-tems. Portions of this piping may be in exposedlocations in buildings, and you may paint it forappearance. Copper surfaces to be paintedshould be solvent-cleaned and treated with vinyl-type wash coat. When cleaning around solderedfittings, you should remove all wax or residueleft by the solder flux. Any green-colored film,which is a sign of corrosion on copper, should heremoved with steel wool. The vinyl wash coattreatment is recommended, although you mayhave some success in applying interior semigloss

552

21foil-base enamel directly to the copper. This istrue provided the surface has aged sufficiently toproduce a thin oxidation coating, and there areno grease, corrosion, or highly polished areaspresent.

16-45. Underground tanks. Underground tanksare used for storage of inflamable liquids, such asdiesel oil and gasoline. Such tankage is left un-painted on the inside surface but you must pro-vide a protective coating to the exterior surfaces.New tanks are generally received with a shopcoat primer already applied. You should wire-brush any damaged spots and touch up with asimilar primer. You can then brush or swab ona coating of bituminous compound, or spray onone or two coats of coal-tar enamel, before thetank is lowered into the excavation. After thetank is set and all pipe connections have beenmade, you should touch up and repair any dam-age to the protective coating which may havebeen caused by the hoisting equipment.

16-46. Overhead tanks. When we speak ofoverhead tanks, most of us immediately think ofwater towers used for storage of potable water.The painting of such tanks is generally (Rine bycontract; however, you may do maintenancepainting or possibly complete painting of thesetanks at remote or oversea locations.

16-47. The hazards involved in painting over-head tanks are great. Not only will you be work-ing at great heights with the possibility of falling,but there is also the danger of asphyxiation fromdust while sandblasting or from fumes whenpainting tank interiors.

16-48. A four-coat paint system is recom-mended for the interior of potable water tanks.The system requires that you sandblast the tankinterior to a white-blast condition and immedi-ately treat the surface with either a vinyl washcoat, or a chemical metal conditioner. You thenapply four coats of zinc dust-zinc oxide, phenolic-type paint. The zinc dust for this paint is pack-aged separately and must be mixed with the basepaint immediately prior to use. The natural colorof the paint is light grey. The paint dries to avery hard film and the drying time between coatsshould be no longer than is required to produce asemihard film, in order to avoid poor intercoatadhesion. In very warm weather, 4 to 6 hoursof drying time between coats should he sufficient.If more than a 24-hour drying period elapses inwarm weather, the succeeding coat may bethinned with ethylene glycol monobutyl ether toimprove intercoat adhesion.

16-49. The size of, and the physical locationof, water towers and other overhead or ground-level storage tanks, determines the color schemefor painting the exterior of the tanks. Many of

A AND B 15 FTOR MORE

A 5 FT OR MORE

B - LESS THAN 15 FT

Figure 57. Marking water towers and similarobstructions.

these tanks, due to their location in relationshipto the airport reference point, will be classifiedas obstructions to air navigation. All such struc-tures must be painted with obstruction markingsas set up by the Air Coordinating Committee.The National Standard of Obstruction Marking,published by the committee, is included as anattachment to TM 5-330, and you should con-sult the regulation which is current at the timeyou do any painting.

16-50. Obstructions shall be marked by theuse of surface colors. Objects shall be paintedaviation surface orange or a combination of avia-tion surface orange and aviation surface white.A summary of the color requirements is set forthbelow.

a. Solid. An object, the projection of whichon any vertical plane has both dimensions lessthan 5 feet, shall be colored aviation surfaceorange.

b. Bands. An object with essentially unbrokensurfaces, the projection of which on any verticalplane is 5 feet or more in one dimension and isless than 15 feet ;n the other dimension, and anyskeleton or smokestack type of object having bothdimensions 5 feet or more shall be colored toshow alternate bands of aviation surface orange

, 56n., 'A

and white. The widths of the orange and whitebands shall be equal and the width of each bandshall be approximately one-seventh the length ofthe major axis of the object, provided that eachband shall have a width of not more than 40 feetnor less than 11/2 feet. The bands shall be per-pendicular to the major axis of the obstruction.The bands at the extremities of the object shallbe orange. Figures 57, 58, and 59 illustrate theapplication of this requirement.

c. Checkerboard Pattern. Objects with essen-tially unbroken surfaces, the projection of whichon any vertical plane is 15 feet or more in bothdimensions, shall be colored to show a checker-board pattern of alternate rectangles of aviationsurface orange and white. The rectangles shallbe not less than 5 feet and not more than 20feet on a side, the corner rectangles being orange.Figures 57 and 58 illustrate the application ofthis requirement.

d. Marking Spherical Shaped Obstructions. Ifa part, or all of certain objects of spherical shapedoes not permit the exact application of thecheckerboard pattern of coloring, then the shapeof the alternate rectangles of Orange and whitecovering the spherical shape may be modified tofit the particular shape of the structural surface,provided the dimensions of the modified rectan-gles remain within the dimensional limits. Figure59 illustrates the application of this requirement.

A AND B 15 FTOR MORE

1-6-131A 5 FT OR MOREB LESS THAN 15 FT

Figure 58. Marking gas holders and similarobstructions.

A

A & B-15 FT OR MORE

Figure 59. Marking spherical shaped obstructions.

16-51. Overhead or ground level tankage,which is not classified as being obstructive, willgenerally be painted aluminum or white. Thesecolors are reflective in nature and tend to reduceheat buildup from direct rays of the sun.

16-52. Because of the costs involved, and thepersonal danger associated with painting over-head tanks, the best possible paint job should beaccomplished. The most effective cleaning meth-ods should be used along with top quality primersand paints to insure the longest possible lifeof the paint job.

16-53. Coating Machinery and Equipment. Asa protective coating specialist, you will be re-quired to paint various types of machinery andGovernment-furnished equipment located through-out Army buildings and structures. On fabricatedand assembled items, such as motors, pumps,electrical equipment, and other mechanical equip-ment, paint systems conforming to the manu-facturer's standard practice should be used inall practicable cases. You may find instanceswhere there is a need for conformance to auniform color scheme or where exceptional cor-rosion conditions must be combatted.

2 "57

21716-54. The initial cleaning of such equipment

generally consists of the removal of grease, dirt,or other foreign materials. This cleaning may bedone with a solvent rag, or it may include the useof chemicals, or mechanical cleaning equipment.Before you do any painting, you should observethe surface area in general. There may be gas-kets, chrome, gages, lubricating fittings, instruc-tion plates, and similar items which need to beprotected. Masking tape, masking paper, andmasking compounds are used for covering theareas which are to be protected.

16-55. Masking tape. You should cover smallareas on irregularly shaped objects or parts withmasking tape, since it stretches and conforms tocurved surfaces. Large areas require a sheet ofwrapping or any other type of paper slightlysmaller than the part to be masked. The paperis held in place by a strip of masking tape.

16-56. Masking paper. Masking paper is aform of masking material that you can apply tosmooth surfaces. It is a strong, lightweight papercoated on one side with an adhesive. You use itmerely by applying a light pressure with yourfingers and hand, and it requires no heating ormoistening. You can easily remove maskingpaper without leaving any deposit of adhesive onthe surface to which it was applied.

16-57. Masking compounds. There are sev-eral prepared liquid or pastes that will serve asmasking compounds. You can apply these eitherwith a brush or with a spray gun. The compoundproduces an excellent protective film. After themasking compound has served its purpose, youcan wash it off without leaving any discolorationor spotting of the masked surface.

16-58. Another material you can use to masksurface areas is paraffin. Paraffin is very effec-tive and water resistant and can be applied veryeasily. To mask an area with paraffin, you firstoutline it with masking tape. Melt the paraffinover a low flame until it becomes as liquid (ap-proximately 150° F.), and then apply the meltedparaffin over the surface by brushing. After themasking has served its purpose, you can peel itoff in a manncr similar to rcmoving maskingtape.

16-59. Spray application is standard in thepainting of mechanical equipment. All safetyprecatuions regarding personnel health, fire pre-vention, ventilation, and electrical grounding aremandatory. You must always select and use theproper paint for the surface being painted. Hard-drying implement enamels or paints are suitablefor application to most mechanical surfaces.Heat resistant paints should be used on surfaceswhich reach extremely high temperatures during

apgnormal operation of the equipment. You shouldnever paint machined surfaces that move withrespect to each other, such as threads, bearingcontacts, or gear teeth. Do not paint electricalparts, such as contacts, relays, insulators, sockets,plugs, connectors or terminals.

16-60. After painting machinery, equipment,pipes and tanks in shop areas or mechanical sys-tem rooms, you must apply stencils and markings.These markings arc required for safety reasonsand to aid the mechanic in performance of op-erator maintenance on the systems.

17. Application of Stencils and Markings

17-1. In the interest of uniformity, legibility,and neatness, freehand painted signs are not rec-commended for use in military structures. Regu-lations require that no smoking areas be markedwith signs. Electrical outlets must be marked toindicate 110 volts, 220 volts, ac or dc, and pipingsystems must be marked to show the direction offlow as well as the contents of the pipe. Figure60 shows a group of pipes which are marked. One

pipe is marked "DOMESTIC HOT WATER,"one is marked "COLD WATER," and one ismarked "GAS." The arrow on the water lineindicates the direction of flow of the water in theline. These markings were applied by usinglaminated marking decals. This type decal hasan adhesive backing which makes it easy toapply to the surface. Decals, plus other types oflaminated markings, are usually available formarking no smoking, re stro oms, offices, andother common applications. These markings maybe made of metal, wood, or plastic, and you canapply them by using adhesives, nails, or screws.

us

Figure 60. Pipe markings.

2. 58

Figure 61. Stencil key set.

17-2. When laminated markings are not avail-able, you can prepare a stencil for any desiredsign. A stencil is simply a thin piece of cardboardin which the letters of a sign have been cut out.You use the stencil as a guide by placing it

against the surface and painting through the cut-outs in the board. When the paint has set suf-ficiently, remove the stencil and you have a neat,legible sign, remaining on the surface.

. 17-3. Stencil board. Stencil board comes intwo grades, a high-wear resistance (grade 1)and a moderate-wear resistance (grade 2). Thegrade 1 board is available in sheet sizes 8" x24", 20" x 32", and 24" x 36". The grade 2board comes only in one sheet size, 20" x 24".You select the grade of stencil board by thenumber of times the stencil will be used.

17-4. Stencil Key Set. The stencil key set isused as a guide for layout and for drawing let-ters and numbers on stencil boards. A 3-inchstencil key set is shown in figure 61. To use thestencil key set, first mark off a horizontal line onthe stencil board. Then use the key set to outlinethe desired numbers and letters, using either theinside or outside of the set. After all the lettershave been outlined on the stencil board, simply cutthem out with a sharp knife or razor blade.

17-5. Stencil-Cutting Machines. Stencil-cuttingmachines vary in appearance and size. Regard-less of the size (from 1/4- up to 4-inch cutters),the machine will have a handwheel to positionan indicator to the letter, number, or mark. to becut, and a cutting handle to depress. The ro-tating handwheel portion of the stencil machinecontains the punch, which is positioned underthe cutter handle. Positioning the indicatorbrings the punch in alinement with a "die" inthe lower portion of the machine. You depressthe cutting handle which forces the "punch" intothe "die," thus cutting the desired letter or num-ber into the stencil board. To space a word,you rotate the handwheel to a blank spot, de-press the handle, and as it is released, the boardmoves to the left and into position for your nextword.

17-6. You can apply markings by using thestencil and a stencil brush, stencil roller, or byspraying. There are three types of stencilbrushes:

a. Artist's stencil brush. This brush is roundwith black bristles in a long polished cedarhandle. The bristles are held in place by a metalferrule. The diameter at the ferrule is 1/2 inchand the bristle length is 1 inch.

b. Stencil brush. This brush is made of 100 -percent hog bristles, with the flag ends cut. It hasa long wooden handle and comes in either 1:)16"x 194 6 " or 1 1,1 6 " X 1 IA 6 " sizes.

c. Fountain stencil brush. This is a brush witha reservoir handle. The leakproof reservoir holdsa minimum of 2 ounces of stencil ink. Thebristles extend 11/2 inches beyond the metal fer-rule. A shutoff is provided between the reservoirand the brush to adjust the flow of stencil inkas well as to shut it off completely.

17-7. Stencil Ink. While any suitable paint maybe used for stenciling, there is a specific ink tobe used with the above brushes. Stencil ink is anopaque itA that will mark porous surfaces, woodand cardboard shipping containers, burlap, andcanvas. This ink comes in the following colors:black, white, and yellow. To use a brush, apply

2!?the ink with a "dabbing" motion, keeping thebrush perpendicular to the surface. The stencilbrush is never "stroked" in applying the ink. Itis strictly a jabbing or tapping motion of thebrush against the surface.

17-8. Stencil roller. You can use a stencilroller to spread paint. This roller is 2 incheswide and 11/2 inches in diameter. Roll the stencilroller over a small amount of paint spread onglass or a metal sheet; then roll it over the stencilon the sign. As soon as possible after the signis stenciled, cut in the ties (space in letters ornumbers) with a small, flat brush. This is im-portant because the brush work will not blendwith the rolled work and ties will show if thepaint is permitted to dry before the ties arefilled in.

17-9. Pressurized spray cans. The pressurizedspray can may be used for painting small signs.These spray cans are easy to use and come invarious colors. The only requirement beforeusing them is that they must be shaken until theball inside the can rolls freely. Shake the spraycan to thoroughly mix the paint, hold the can6"-8" from, and horizontal to, the surface of thestencil and depress the button. Now move thecan horizontal to the spraying surface until youhave an even coat of paint. Allow the paint todry before removing the stencil.

2a0

Inspection of Surfaces

WE KNOW THAT the proper application ofa correct protective coating will enhance

the appearance and prolong the life of any struc-ture. We also know that paints have the abilityto cover many mistakes and produce false im-pressions to a casual observer. It is necessarythen that the inspector not be a casual observerin his inspection duties but rather a close ob-server of materials, workmanship, safety, andfinished surfaces to assure a quality product.

2. As you progress up the protective coatingcareer ladder, by obtaining more technicalknowledge and becoming more proficient in yourjob, you may have the opportunity to work as aninspector. There are several types, or degrees, ofinspection which you may perform.

3. You may be assigned by your supervisor toinspect a structure or a group of buildings todetermine the condition of their protective coat-ings. In this case, you may be required to inspcctthe condition of the protective coating, determinethe cause of any coating failure, and calculatethe square footage of the surfaces. You canthen determine the type and amount of materialsrequired to apply a new protective coating.

4. Again, you may be assigned by your su-pervisor to represent him, or to inspect thequality of workmanship of other protective coat-ing specialists. In this case, call on your pastexperience and technical knowledge, to insurethat thc job is done properly. Thcre will be nospecifications for the job, and you must makeyour decisions based on standard practice. In-spect the surface preparation, the methods usedduring application, proper film thickness, andoverall quality of the work. You should makerecommendations, based on thc inspection, toyour supervisor as the work progresses.

5. Still another type of inspection to whichyou may be assigned is contract inspection. Inthis case, you would be either detailed or as-signed to work as an inspector or field supervisor.Here, your decisions must be based on writtenspecifications which are a part of the contract.

9 60

CHAPTER 4

The specifications and drawings, along with anywritten changes go together to form the contractbetween the Army and the contractor. Froman inspector's point of view, you will have noright to allow any deviation from the specifica-tions. The specifications are the only documentsthat you have available to arbitrate any dispute.You, as the inspector, are responsible to insurethat the Army receives a full dollar's value foreach dollar spent. '18. Inspection of Old Protective Coatings

18-1. Periodic inspection is an intergal partof any well-organized preventive maintenanceprogram. You must periodically inspect the pro-tective coating on buildings and structures to de-termine the condition of the old coating and toidentify the cause of abnormal coating failure.

18-2. Condition of Old Coating. Chapter 1of this Memorandum gave the stages throughwhich the normal deterioration of paint pro-gresses. You also learned the causes, or condi-tions, which lead to abnormal deterioration ofprotective coatings. All the stages of deteriora-tion are applicable to painted wood, masonry,or metal surfaces. Only a few of these condi-tions will Justify the expense of complete re-moval of the old coating. You must decideeach case based on its own merits. You mustconsider the price that can be paid for first-classappearance, the frequency of repainting thatmight be necessary without the removal of theold coating, and the estimated future life of thebuilding.

18-3. Causes of Coating Failure. It is a well-known fact that the early failure of a protectivecoating is generally the result of poor surfacepreparation. This is especially true on masonryor metal surfaces which show early signs ofscaling and flaking. Equally conspicuous scalingon wood surfaces may be caused by heavy bandsof summerwood in the wood grain or by theentrance of water into sidewalls. You must beable to recognize the cause of the coating failure

on any surface and make recommendations toprevent future occurances.

18-4. Wood surfaces. The protective coatingon exterior wood surfaces should deteriorate nor-mally by the chalking process. The coatingshould have a life expectance of 4 years underaverage exposure conditions. Paints that do notdeteriorate by checking or cracking will wasteaway by chalking, until they become too thin tohide the wood. This will continue until patchesof the wood begin to be laid bare. The surfaceshould be repainted when the coating becomesthin enough to show the grain of the wood orwhen patches of bare wood begin to appear.

18-5. When coatings develop into checkingpatterns, disintegration will occur by crumbling.When the coating develops cracking with curlededges, disintegration will be by flaking or scaling.Repainting should be done soon after the mostexposed parts of the building have reached thestage of disintegration by flaking or scaling.

18-6. When paints deteriorate with unduerapidity or in an abnormal manner" the conditionresponsible should be determined and correctedbefore further painting is done. Dense species oflumber, such as those of group 4 woods, shouldbe replaced when practicable to reduce the pos-sibility of checking and cracking. You shouldinspect surfaces for evidence of discolorations,such as blue stain, which indicates the presenceof moisture in the wood. The source of moisture

STEEL BLOCK

A21should be determined and recommendationsmade for eliminating or preventing it.

18-7. Masonry surfaces. Protective coatingson masonry surfaces will deteriorate by chalkingunless conditions exist which cause flaking andscaling. When you find this condition, youshould inspect the surface for signs of ef-florescence, alkaPnity, or glaze. After you de-termine the cause of the coating failure, youshould make recommendations for treating thesurface, prior to repainting.

18-8. Metal surfaces. Corrosion is the No. 1enemy of metal surfaces, so when inspecting,always be alert for signs of it. Check all dam-aged areas in the protective coating for signs ofrust or scaling. Check aluminum or galvanizedsurfaces for looseness or flaking of paint. Ex-amine all fasteners, hangers, and brackets forcorrosion which may be caused from dissimilarmetals. Scrape off loose paint at blisters andscaling on surfaces and examine the base metalfor corrosion.

18-9. Measuring Corrosion Pitting. Corrosionpits can be measured with a dial indicator. Touse it for measuring the depth of corrosion pits,select a locally made steel bar adapter which isat least 4 inches in length to bridge any wavesor bends in the surface being checked. The dialindicator is mounted in the center of the steelbar, as shown in figure 62.

18-10. Calibrate the dial indicator by posi-tioning it in the bar so that the dial indicator

DIAL INDICATORMEASURES.0001 INCH

TAPEREDCONTACTPOINT

4"

EDGE FINISHED FLATAND SQUARE TO ± 0.001

Figure 62. Dial indicator.

2'. n 61

METAL SURFACE

aa3-

Figure 63. Micrometer.

pointer extends slightly below the bar. Thenplace the steel bar on a flat surface which willcause the pointer of the dial indicator to be de-pressed. Loosen the knurled knob on the sideof the indicator and adjust (rotate) the face sothat the instrument's needle is set to the zeroposition. The instrument is "zeroed in" at thissetting and you secure it by tightening theknurled knob on the side of the indicator. Asyou lift the instrument and bar, the pointershould extend past the flat bar surface movingthe needle away from the zero position.

18-11. You are now ready to measure thedepth of corrosion pits with the dial indicator.You place the straight edge of the bar againstthe uncorroded area of the metal on one side ofthe corroded area. If the gage needle movesfrom the zero mark, record the amount (let'ssay the first reading is 1). You move the gageto the other side of the corroded area and takeanother readingrecording the amount (the sec-ond reading is also 1). Now, move the gage sothat the gage pointer is resting in a pit in thecorroded area. You move the gage until you findthe deepest pit (shown by the highest readingon the gage), which is 6 on the needle dial.Now, let's take a look at our reading:

Reading # 1 0.001Reading 0 2 0.001

1 is the base number instead of 0 (These would beaveraged if they were different)

Pit depth reading 0.006Pit depth 6Minus base reading 1

5 = actual totaldepth of cor-rosion pit

62

18-12. So far, you have only measured thedepth of the corrosion pits. You must now meas-ure the original thickness of the structural ma-terial to determine the damage caused by thecorrosion. If the thickness of the structural ma-terial is not known, you can measure the thick-ness with a micrometer.

18-13. Micrometer. The micrometer is themost accurate of the adjustable measuring in-struments. The tool is capable of measuring towithin 0.001 inch; on one equipped with avernier scale, the measurements can be read towithin 0.0001 inch. Figure 63 is a drawing ofan outside micrometer. The screw has 40 threadsper inch so that when the thimble is turned onecomplete revolution the end of the spindle ismoved 0.025 inch ( 1/40 inch). The sleeve of themicrometer is marked off in 40 equal spaces sothat the number of revolutions may be known.The end of the thimble is marked off in 25 equalspaces so that when the sleeve is turned throughthe distance between two of these marks, thespindle is moved 0.001 inch from, or towardthe anvil. The outside micrometer illustrated isused to measure the outside diameter of shafts,the thickness of materials, and other similardimensions.

18-14. The range of a micrometer is usually 1inch. The size of a micrometer is the largestdimension it will measure. A micrometer thatmeasures 2 to 3 inches is referred to as a 3-inchmicrometer.

18-15. When using the micrometer, applyvery slight tension. Turning the spindle clock-wise will bring it closer to the anvil. You shouldplace the material to be measured between the

BARREL REVOLUTION LINE TH MOLE

CORRECT READING 0.304-

CORRECT READING 0.224-

Figure 64. Micrometer reference lines and graduations.

anvil and the spindle and turn the spindle untilthe material is brought into contact with the anvilunder a slip tension (a side movement or slippingof the micrometer across the surface being meas-ured). Once contact is made, avoid springingthe C-frame through excessive gaging pressure.Always hold the spindle of the micrometer per-pendicular to the material being measured.

18-16. Reading a micrometer is quite simplewhen you understand the principle. In most in-struments the screw has a pitch of 0.025 inch.A reference (revolution) line on the side of thebarrel (see fig. 64) parallel to the screw axis isgraduated over a length of 1 inch into 40 equaldivisions. The thimble end will coincide with the0 graduation at the left end of the barrel scalewhen the spindle to anvil distance is exactly zeroor an exact number of inches, depending on theinstrument's capacity. To read the barrel scale,note that each fourth graduation is numbered,starting at the left end with 0 through 9, with asecond 0 at the right end of the graduated inch.The tapered thimble end is divided into 25 equalspaces with every fifth graduation numbered.These graduations are so arranged that when theend of the thimble is properly aligned with any0.025-inch graduation the zero is exactly alignedwith the barrel reference (revolution) line, asshown in figure 64. Since the micrometer isgraduated in 0.001 inch steps, it is customary toread it to the nearest thousandth of an inch.

18-17. We now have a method of measuringthe depth of corrosion pits and a method formeasuring the thickness of structural material.Once, we have both of these measurements wecan determine the extent of the corrosion dam-age as follows:

- -L

Thickness of structural materialDepth of corrosion pit

0.09375 eit2")0.0059.08875

223

Since structural material may fail by corrosionperforation when the average penetration is onlyone-fifth of the thickness, we are within a safecondition.

18-18. After you have inspected the conditionof the old coating on wood. masonry. or metalsurfaces, and determined the cause of abnormalcoating failures, you should prepare a writtenreport of your findings and recommendations.Any time your report calls for repainting of astructure, you should include an estimate of thematerials needed for the job. To estimate theamount of primer or paint required, you mustfigure the area of the building's surfaces insquare feet.

18-19. Calculating Surface Areas. Let's as-sume you have inspected the building shown infigure 65 and have recommended that it be re-painted. The first step will be to measure theoutside walls of the building. Measuring one side,you find the length to be 40 feet and the height10 feet. Now multiply the length by the height(40 X 10 = 400 sq ft) for one sidea total of800 square feet for both sides. Measuring oneend of the building, you find it is 20 feet wideand 10 feet high up to the cave. (20 X 10 =200 sq ft).

18-20. The two ends have a combined totalof 400 sqbare feet, not counting the gable ends.Because the gable end is a triangle, its area isfound by taking one-half of the product of thebase (20 ft) and height (5 ft). The problemworks out: 1/2 X (20 ft X 5 ft) = 50 squarefeet. Now multiply by 2 for a total of 100 squarefeet for both gable ends. Now you add 800square feet for the sides, 400 square feet for theends, and 100 square feet for the gable ends.This gives you a total of 1300 square feet ofexterior wall surface.

18-21. Generally speaking, the outside casingsand molding of doors and windows require as

63Figure 65. 20- X 40-fool building.

much paint as the same area of solid surface.Therefore, no deductions should be made forthem, if they are to be painted the same color.It is quite difficult to make a statement as to theamount of surface a gallon of paint will cover.The covering capacity of paint will depend uponthe following factors:

Thickness of the paint.Method of application.Roughness of the surface.Absorption of the surface.

18-22. As a guide for you, figure 66 showsthe approximate covering capacity of severalpaints for various surfaces. These estimatesshould be merely suggestions, since any or all ofthe previously mentioned factors alter the cover-age capacities of the coatings.

18-23. If you have decided to use oil-basepaint for the exterior walls, take a look at figure66; notice that oil-base paint covers approxi-mately 350 square feet per gallon. Now divide:1300 square feet by 350 square feet = 3.7 gal-lons. So you figure 4 gallons to cover the ex-terior walls with one coat of paint. If two orthree coats are to be used, you usually figure thesame amount for each coat.

18-24. You should prepare a written reportfor each building. The report should containsuch information as the condition of the old coat-ing and the degree of surface preparations re-quired. You should include the type of primingrequired, either spot or full prime. You shouldrecommend either a one-, two-, or three-coatpaint system and specify the type and amount ofpaint required.

Type ofCoating

Aluminum

Aluminum

Enamel Undercoat

Enamel

Enamel

Enamel

Epoxy

Glusize

Lacquer

Paint, Oil

paint, Oi 1

paint, Oi 1

Point, Oil

Paint, Oi 1

Pa i t, Oi 1

Paint. Oil

P-rit, Resin - Emulsion

Patelz, Rubber Base

Paint, Water

Shellac

Stain, OilVarnish

Type ofSurface

Woe.

Metal

Wood

Plaster

Concrete Floors

Wood Floors

Concrete Floors

Plaster

Metal

Wood Siding

Dry Wall

Metal

Plaster

Concrete

Brick

Stucco

Dry Wall

Dry Wall

Plaster

Wood

Wood

Wood

Per PerGallon Pound

Coverage inSquare Feet

600

700

300

500

500

500

300

650

500

350

500

600

500

350

225

150

500

600

600

400

300

200

Figure 66. Paint coverage.

64

19. Inspection of New Protective Coatings19-1. The inspection of new protective coat-

ings is a full-time job. You Must be on the jobfrom the time the surface preparation begins un-til the painting is completed. You must insurethat each step of the i.:tinting operr.'ion is doneby using the proper tools and materials, and thatall safety practices arc observed at all times.

19-2. Inspection During Surface Preparation.Wood surfaces to be painted shall be cleaned ofdirt, oil, and other foreign substances with min-eral spirits, scrapers, or sandpaper. Glazing rab-bets in exterior sash and doors shall be primedprior to glazing. Edges of doors that have beentrimmed during hanging and fitting shall imme-diately be given two coats of primer. Small, dry,seasoned knots should be surface-scraped andthoroughly cleaned, and should be given a thincoat of knot scaler before application of the prim-ing coat. Pitch on large, open, unseasoned knotsand all other pitch shall be scraped off, or if stillsoft, shall be removed with mineral spirits. Ther" noun area is then coated with knot scaler.

re,. surface ...mist be checked to insure that fin-nails have been properly set. Then all

and surface imperfections shall be primed.After priming, all holes and imperfections in fin-ish surfaces shall be filled with putty, allowed todry, and sandpapered smooth. You should allowpainting to proceed only when the moisture con-tent of the wood does not exceed I2 percent asmeasured by a moisture meter.

19-3. Concrete and masonry surfaces that arcto be painted must be prepared by removing ef-florescence, chalk, dust, dirt, oil, grease, excessivemortar, mortar droppings, and by roughening toremove glaze. Immediately before coating withcement -sand or cement-water paint, surfaces tobe painted should be uniformly and thoroughlydampened. Sufficient time shall be allowed forthe water to be absorbed, with no free surfacewater visible. Glued surfaces shall be etchedwith acid-water, thoroughly rinsed with water,and allowed to dry.

19-4. Ferrous surfaces that have not beenshop-coated should be solvent cleaned to removeoil and grease. Surfaces that contain loose rust,loose mill scale, and other foreign substancesshould be mechanically cleaned by power wirebrushing, or sandblasting. Minor amounts of re-sidual rust that cannot be removed except bythorough blast-cleaning and tight mill scale thatcannot be removed by applying a sharp knife toany edge, may be allowed to remain. Aftercleaning, one coat of ferrous metal primer shouldbe applied to the surface. The semitransparentfilm applied to some pipes and tubing at the

65

9'' j

V2,5°

mill is not to be considered as a shop coat, butshall be overcoated with ferrous metal primer.Abraded or corroded spots on shop-coated sur-faces should be wire-brushed and touched upwith material similar to the shop coat.

19-5. Galvanized surfaces to be painted shallbe solvent-cleaned and treated with vinyl-typewash coat. Galvanized surfaces not to be paintedshall be solvent-cleaned and inspected for condi-tion of the galvanize coating.

19-6. Aluminum surfaces to be painted shallbe solvent-cleaned to remove oil and grease andthen be treated with vinyl-type wash coat. Sur-faces not to he painted shall be solvent-cleaned.Prior to priming, all surfaces should be inspectedfor contact with dissimilar metals.

19-7. Inspection During Coating Application.Surfaces that have been cleaned, pretreated, orotherwise prepared for painting shall be given acoat of first-coat material as soon as prac.tiC6bleafter such preparation has been completed, butin any event, prior to deterioration of the pre-pared surface. At time of application, paintshould show no signs of hard settling. excessiveskinning, or other deterioration. Emulsion paintsshall be protected from cold weather by storingin protected shelters to prevent freezing of thepaint.

19-8. Paint shall be thoroughly stirred, strained,and kept at a uniform consistency during appli-cation. Paints of different manufacturers shouldnot be mixed together. Where necessary to suitconditions of surface, temperature, and methodof application, paint may be thinned in accord-ance with the manufacture's directions, but notin excess of I pint of thinner per gallon of paint.

19-9. Paints other than water-thinned coatingsmust be applied cnly to surfaces that are com-pletely free of surface moisture, as determinedby sight or touch. Do not apply paint to surfaceswhen there is visible frost or ice. While paintingis being done, the temperature of the surfacesand of the atmosphere in contact with the sur-faces, shall be at or above 50° F. for water-thinned coatings, and 45° F. for other coatings.

19-10. Sufficient time shall elapse betweensuccessive coats to permit proper drying. Thisperiod shall be modified as necessary to suit ad-verse weather conditions. Oil-base or solvent-type paints shall be considered dry for recreatingwhen the paint feels firm and does not deformor feel sticky under moderate pressure of thethumb.

19-1 L The finished surfaces must be freefrom runs, drops, ridges, waves, laps, and brushmarks. There shall be no variation in color, tex-ture, and fioish. The hiding should be complete,and each coat should be so applied as to produce

a film of uniform thickness. Give special atten-tion to insure that all surfaces including edges,corners, crevices, welds, and rivets receive a filmthickness equivalent to that of adjacent paintedsurfaces.

19-12. Determining Coating Thickness. Theprocess of paint changing from a wet-film to theprotective dry-film layer is called the mechanicsof coatings. This process may be a physical or achemical change and should be grouped undersolvent evaporation or oxidation. For the pur-pose of measuring the thickness of a protectivecoating, you must remember the drying charac-teristics of that coating. This is necessary becausecoating thickness can be taken by a dry- or wet-film gage.

19-13. Dry-film thickness gage. The dry-filmthickness of paint on ferrous metal can be meas-ured directly by the dry-film thickness gageshown in figure 67. The gage can measure thethickness of a nonmagnetic coating that has beenapplied to a magnetic base metal.

19-14. The dry-film thickness gage is more ac-curate on smooth surfaces than rough and is moreaccurate at ranges above 1 mil (0.001 inch) thanbelow. The accuracy of the dry-film gage is plusor minus 10 percent provided the instrument isproperly calibrated and used according to instruc-tions.

19-15. The dry-film thickness gage is avail-able in a variety of thickness ranges. It is light-weight, easy to use in hard-to-reach areas, andneeds no source of electricity. The gage doesnot injure the coating in any way, and its reliabil-ity is accepted by contractors. The 0-20-mil in-strument is best suited for checking most protec-tive coatings. Before using the gage, calibrate itas follows:

Clean a small area (size of gage) of thebase metal.Set a nonmagnetic shim (of a known thick-ness) on the bare ferrous metal base.Position the gage over the nonmagneticshim.

The dial reading should show the thickness ofthe nonmagnetic shim. If the dial reading is dif-ferent than the known thickness of the shim, ad-just the instrument until it reads the correctthickness. On a smooth, machined surface, the in-strument should also read zero with the gage indirect contact with the surface. Even with coat-ing thicknesses of several mils, the instrumentmay not read accurately if the base metal isroughened by blast coating. However, if the in-strument is calibrated on the blasted or roughsurface of the same base metal, the results should

q 66

ON.

el

ADJUSTMENT

.001"SHIM OFKNOWN

THICKNESS

Figure 67. Dry-film thickness gage.

be reasonably accurate. You should recognizethat on rough surfaces the thickness of the pro-tective coating films varies between the peaksand the valleys. If you calibrate the instrumenton a blast-cleaned surface, the test measurementsyou take on the same surface will generally bethe thickness of the protective coating above theaverage high points of the blast pattern. Theactual thickness of the coating over some of thehighest peaks may be much less than the meas-urement shown on the instrument dial. To op-erate the dry-film thickness gage, place the sens-ing "feet" on the coating, press the release button,and read the thickness on the dial at the topof the instrument.

19-16. When measuring thickness, you shouldhold the sensing element of the gage lightlyagainst the coating in order to avoid indentation.If the coating is indented, the gage readings willbe lower than actual. The dry-film thicknessgage should not be used to check the thickness ofcoatings nearer than 1/2 inch from an edge, onsharp interior angles, or on rough, pitted, orwelded surfaces. You should make enoughmeasurements to determine the general uniform-ity of the thickness of the coating. Since a meas-urement takes only a brief interval once the in-strument is calibrated, there is no reason whyhundreds of measurements on a single area can-not be made. By making numerous measure-ments, you can accurately determine if the mini-mum and maximum thicknesses prescribed havebeen complied with...

19-17. Wet-film thickness gage. Another meansof determining protective coating film thicknessis by use of the wet-film thickness roller gageillustrated in figure 68. This instrument meas-ures the thickness of the freshly applied film.From the reading taken with this gage, theamount of paint per square foot of surface areacan be figured. The wet-film thickness gage isavailable in the ranges of 0 to 4, 2 to 12, and 10

.004

"PICKED UP" PAINT.002

V47

Figure 68. Wet-film thickness gage.

to 30 mils. The gage is an eccentric center wheelsupported by two concentric wheels. The gage isheld between the thumb and forefinger and isrolled across a freshly painted surface in the fol-lowing rrmnner. You place it against a plane sur-face. If you are using the 0- to 4-mil gage, theclearance between the inner eccentric wheel andthe surface upon which the two outer concentricwheels rest ranges from 0 to 4 mils. Place thcgage with the highest reading against the paintfilm and then roll it through about 180°. Obtainthe reading by observing where the paint filmwas first contacted and "picked up" on the centereccentric wheel. Read the thickness of the paintfilm from either side of the two concentricwheels at the point where the paint was first"picked up."

19-18. You can obtain an accurate readingwith the wet-film thickness gage on any uniformsurface hard enough to resist identation by thetwo outside wheels of the gage. If the gage ispressed too hard against a soft wood base oragainst a previously applied paint film which hasnot dried hard enough, you will not obtain anaccurate reading. The gage is ideal for measur-ing the thickness of first coats on metal surfaces,but it has a doubtful accuracy when you measurethe wet-film thickness on very quick-dryingpaints, such as vinyl resin primer, especially inwarm weather when the fast evaporation ofhighly volatile solvents causes a very rapid de-crease in the thickness of the paint film. Usegreat care in measuring the wet-film thickness ofsecond coats of paint, especially if the first coatshave dried only the normal time necessary topermit recoating. You can judge whether thcwet-film gage will cause identation by rolling thcgage over a portion of the surface to be painted.

67

19-19. Dry-film test panel. If paint film thick-ness measuring instruments are not available, usesmall aluminum panels for the measurement ofthe paint thickness after drying. You should ap-ply a sufficient number of panels to the surfaceto be painted to get an average test of the filmthickness. Prepare each panel by masking it withtape for a distance of approximately 2 inches.You attach the panels to the surface to be paintedby the use of a small section of masking tapedoubled upon itself, with the adhesive side con-tacting the panel and the surface to be painted.

19-20. The test panels should be removedfrom the surface after the paint is applied. Theareas left unpainted under the panel should betouched up immediately. After the paint on thetest panel has dried, its thickness is measuredwith an ordinary micrometer having flat contactsurfaces. The protective tape is removed fromthe test panel and this surface is used as the basemeasurement. At least six readings should betaken on both painted and unpainted portions ofeach panel to provide an average paint thicknessmeasurement.

19-21. Cleanup. Cloths and cotton waste thatmight constitute a fire hazard shall bc placed inclosed metal containers, or bc destroyed at theend of each day. Upon completion of the work,all scaffolding, empty containers, and other de-bris shall be removed from the site. Paint spotsor stains on adjacent surfaces must be removedand the entire job left clean and acceptable.

20. Contract Inspection20-1. Should you be assigned as a painting

inspector, the chief inspector will brief you onyour new duties. In all probability, you willgo through a period of transition during whichyou will receive extensive on-the-job training so

223that you learn to work with specifications as theyapply to contract inspection.

20-2. Specifications. A specification is a writ-ten directive. It gives to you a word picture.The specifications are intended to provide a com-mon basis of understanding by all concerned.They represent a clear and accurate descriptionof the technical requirements for a material,process, product, or service, including the proce-dure by which one can determine that the re-quirements are met. A qualified engineer pre-pares a set of specifications for each constructionproject. The inspector must be able to interpretthe specifications and determine when the con-tractor complies or does not comply with them.

20-3. A conference is held before the con-tractor starts the project. The inspector assignedto the project will sit in on this conference. Thecontractor will be advised by the contracting offi-cer, as the conference goes through the provisionsof the contract, that any change in the drawingsor the specifications will be coordinated throughthe inspector and the inspection section andpassed on to him. The contracting officer willmake tl..c decision. and the contractor will beinformed, through the inspector, in writing.

20-4. After the contract is let and the con-struction begins, specifications serve as a check-list to the inspector to insure quality of materialand workmanship. To accomplish this, the spe-cifications will specify the following:

a. Quality and sometimes the quantity of ma-terials used in construction usually referringto Federal specification numbers, grade, andcondition.

b. Procedures for material acceptance.c. Performance of the contractor during con-

struction in:Material conservation.Procedure of installation of equipment.Tests that installed equipment must pass foracceptance.

d. Specifications are usually made up in sec.:tions. Each section will be listed in theindex.Section 1, Painting.Section 2, Plumbing.Section 3, Electrical, etc.

e. Each section will list the requirements forthat phase of the work. Typical require-ments for paint are listed below.Type of paint by specification number.Cleaning and preparation of the surface.Storage and mixing of the paints.

68

o Methods of application.Number of coats or thickness.Safety requirements.

20-5. Only by looking at the specificationscan you, as the inspector, know what is to beconstructed. The specifications are the docu-ments that explain what the contractor has con-tracted to do. It informs you as to just what thecontractor is getting paid for. Since the contrac-tor cannot be required to deliver any more thanwhat is called for in the specifications, you mustrequire compliance to what is in the specifica-tions.

20-6. Since all construction must comply withthe specifications unless otherwise authorized bythe contracting officer, (this being authorized bya change order), you must make these changeorders a part of the specifications and keep anup-to-date set of specifications in your possessionat all times and make sure that the contractoralso has an up-to-date set. When you first get aset of the specifications, read over them; andwhenever you come to something that mightcause differences that are of extreme importanceor that are special items, mark them with a redpencil. This makes them easy to refer to and willhelp you to assure that these matters will betaken care of in due process of the construction.Thus they are less likely to be overlooked.

20-7. Resolving Differences. There will alwaysbe differences of interpreation that arise. Thespecifications are the only guide that the inspec-tor has to go by. Any misinterpretation canchange the entire concept. Therefore, any misin-terpretation will be discussed at the preconstruc-tion conference or when the misinterpretationarises. It may be necessary to discuss these itemswith the engineer. Since missing one word in thestudy of the specifications can change the entireconcept, you may need to check the drawings fora true interpretation. If there is a difference inthe specifications and drawings, the specificationswill govern. Do not be belligerent with the con-tractor, but abide by your interpretation unlessyou arc directed to do differently by the engineer.

20-8. Approving Materials. After the contractis under way, the inspector is responsible for see-ing that only material on the Material ApprovedLists is used. The specifications will specify thetype and grade of materials that are to be used.In many instances, this will reference a guidespecification number or a Federal specificationnumber and then require a submittal. The in-spector will need to research the specifications todetermine the exact materials that are to be used.The submittal may be a sample or material or amanufacturer's certificate. All submittals must be

approved by the contracting ,Ifficer (or his tech-nical representative). The approved submittalsshould be cataloged and filed for reference.

20-9. Rejecting Defective Materials. The au-thority for.rejecting defective materials is the spe-cifications. Whenever the materials do not meetthe requirements that are set forth in the specifi-cations, the materials may be rejected. The spe-cifications will specify the types and grades ofthe materials that are to be used, and it will bethe inspector's responsibility to see that all mate-rials will meet the requirements of all the ap-proved submittals on the contract. The specifica-tions may also specify certain conditions that thematerials must meet. You must remember,though, that the grade of material for one phaseof the construction may differ from the require-ment for the same material at another phase.The specifications and the approved submittalsare the inspector's control documents. It is theresponsibility of the inspector to reject faulty ma-terial. If it is noted that material is being in-stalled which is not included on the MaterialApproved Lists, you will inform the contractorand the engineering section. The base civil engi-neer will make recommendations to the contract-ing officer. The contracting officer will be thefinal authority in the rejection of material. Al-most without exception, the contracting officerwill accept recommendations from the inspectorand the engineering office.

20-10. Inspecting Workmanship. The specifi-cations will state that only skilled craftsmen willbe used in all phases of the construction. Checkthe specifications for the cleaning and preparingof the surfaces. They may specify the methods ofapplication for many of the different materialsthat arc to be used. They may state that thecontractor may use the manufacturer's recom-mendations. Work under a contract will be per-formed in a skillful and workmanlike manner.The contracting officer may require, in writing,the contractor to remove from the work any em-ployee that the contracting officer deems incom-petent, careless, or otherwise objectionable. Theinspector is responsible for bringing to the atten-tion of the contractor any unsafe condition or anyunsafe practices of the workmen during theirdaily tasks. Good housekeeping and safe prac-tices are a part of good workmanship. Properequipment and good quality materials, in thehands of qualified craftsmen, will produce qualityconstruction if properly supervised.

20-11. Daily Diary. The daily diary is themost importantrecord maintained by the inspec-tor. During the contractual period, the diary is

referred to many times for information by thepost engineer and the contracting officer. You,as an inspector, must record any informationwhich may be of any possible assistance tothe Contracting Officer in making decisions at asubsequent date. Examples of information are asfollows:

Weather conditions. Weather conditions areyery important when pouring concrete, paint-ing, or asphalt laying. This data can be receivedfrom the post weather office or the nearest civilweather bureau. The data should be recorded asfollows:

Temperature: The high and low temperaturesrecorded during this 24 -hourperiod.

Wind: The velocity and directions ofthe wind.

Phenomena: General overall weather condi-tions such as cloudy, clear, rainor overcast, etc.

Precipitation: The amount of moisture re-ceived during the 24-hour period.

Contract number. This is the number as-signed to the contract by the base procurementoffice.

Contractor. This is the primary contractorand the name of the superintendent. An exam-ple is: York's Plumbing Company, Mr. M.Hawley, Superintendent.

Contractor's employees on the job. List thenumber of employees by trade who arc presenton the job. Example: 4 painters, 10 electricians,etc.

Description of work. This will include anarrative of the work being accomplished. Build-ing numbers should be included.

Progress. Include an estimate of the per-cent of the total job completed, a percentage ofvarious portions of work completed and a state-ment as to whether or not the progress scheduleis being met. Materials on site should be in-cluded in the progress estimate.

Supplies or materials. Include all Govern-ment-furnished equipment, material or suppliesdelivered to the contractor. List all material de-livered to the job site by the contractor and allsalvageable material turned in by the contractor.Backup documents should be filed in the contractjacket file which is maintained in the inspectionsection. These arc only a few of the items to beincluded in the daily diary. There is no limit tothe amount of information you may enter in thisreport. A good policy to follow is: if in doubtabout anything, record it in the diary. Rememberto always make complete entries.

69

2 ,ri

a30

EXAMINATION

ARMY CORRESPONDENCE COURSE ENGINEER SUBCOURSE 563

PAINTING II

CREDIT HOURS 2

TEXT ASSIGNMENT Review previous assignments.

EXERCISES


1. Paint on softwoods will remainsound longest when it is applied on

a. edge-grain surfaces on the barkside

b. pith side of flat-grain boards

c. the summerwood

d. lightweight boards with narrowgrowth rings

2. Which of the following woodswill best retain paint and resist weather-ing?

a. redwood

b. hemlock

c. spruce

d. Norway pine

3. Disintegration of a wood sur-face reveals boards that show distressof wood weathering. What is this stageof disintegration called?

a. chalking

b. checking

c. wrinkling

d. crawling

4. The application of a dissimilarpaint over an old coating causes

a. tackiness

b. alligatoring

c. wrinkling

d. crawling

5. How do you prevent paint fromrunning into the metal ferrule and downthe handle of the brush?

a. dip brush into the paint only 1/2 inch

b. keep the bristles pointed downward

c. check the paint for proper mixing

d. tap tip of bristles against inside ofcontainer

6. You plan to spray enamel onscreen cloth. Which of the followingwould you use to thin the enamel?

a. mineral spirits

b.

C.

d.

flat finish paint

transparent varnish

hot linseed oil

7. When painting shingles for sur-face durability you would

a. overbrush primer with thinner

b.

c.

d.

mop the surface with hot linseed oil

apply two coats of wood stain

leave as little binder as possible

1

a31

2

8. Which of the following is a dis-advantage in applying opaque paintswith a roller coater to walls and ceil-ings?

a. will usually require two coats forconsistent color coverage

b. self-leveling enamels cannot be ap-plied with a roller

c. roller produces unwanted stipplefinish

d. gloss paints dry flat when appliedwith roller

9. What is the least number ofhours that you allow for drying betweencoats of varnish?

a. 10 c. 24

b. 15 d. 30

10. You must repair a gypsum plas-ter surface, to which you will applythree coats of the patching plaster.Which of the following lists the correctsequence of application?

a.

b.

C.

d.

brc wn, scratch, finish

brown, finish, scratch

scratch, finish, brown

scratch, brown, finish

11. You have applied a first coat ofacrylic paint to a masonry surface. Howmany hours would you wait before ap-plying a second coat?

a. 1

b. 4

c. 8

d. 12

12. You must repair a deep crackin a brick mortar joint where a leakmust be stopped. You should chip outthe old mortar to a depth of how manyinches?

a. 2 c. 31/2

b. 3 d. 4

9

13. You are using portland cementplaster to make a repair. You shouldallow the first coat to

a. cure by keeping it moist for at least72 hours

b. dry thoroughly for not more than24 hours

c. dry thoroughly for 5 days

d. cure by keeping it moist for a maxi-mum of 8 hours

14. Which of the following wouldyou use to remove old calcimine paintfrom a plaster wall?

a. water-base paint and varnish re-mover

b. warm water and detergent

c. turpentine

d. latex paint and varnish

15. A crack in plaster is large andwell defined. It extends across the sur-face and goes entirely through the plas-ter. What do you call this kind ofcrack ?

a. foundation c. shrinkage

b. structural d. map

16. On your post there is an over-head tank which is not obstructive. Howwould you paint this tank?

a. with coal-tar enamel overall

b. with yellow and black in checker-board pattern

c. with aluminum or white paint

d. in alternate bands of green andblack

17. You must fill small dents andcracks in a metal surface, and sand andprime them within an hour. Which ofthe following fillers would allow you tofinish the job within the time set?

a.

b.

c.

d.

body filler

engraving filler

plastic paste filler

spackling compound

18. You must repair the protectivecoating on a wrapped underground pipe.You would

a. make double application of heatedcoal-tar enamel

b. wrap the pipe in four layers of felt

c. use red lead primer as finish coat

d. be sure that no holidays are left inwrappings

19. What is the approximate blast-ing pressure used for cleaning struc-tural steel?

a.

b.

C.

d.

40 to 60 psi

80 to 100 psi

100 to 130 psi

150 to 180

20. How ma' .y Inches away fromthe surface wcu1-i you hold the nozzlewhen you are abrasive-cleaning metal?

a. 2 to 6 c. 12 to 18

b. 6 to 12 d. 14 to 20

21. Which of th3 following wouldyou use to rema 1, grease, or dirt

m large rnet.Q Aulaces?

b.

c.

d.

sandv.

iznpuct Lool

steam cleaner

chemical solution

22. You are using asphalt primer torepair felt and bituminous covered sur-faces. For how many hours would youallow this primer to dry before youapplied bituminous plaster cement?

a. 10 c. 20

b. 15 d. 24

23. Which of the following indicatescorrosion on copper?

a.

b.

c.

d.

greenish-white color

white-blue powder

green patina

reddish scale

24. Coal-tar enamel protects under-ground steel pipe for years. How manyyears?

a. 5 to 10

b. 5 to 15

c. 10 to 15

d. 50 or more

25. A micrometer equipped with avernier scale can be read to within

a. 0.01 inch c. 0.0001 inch

b. 0.001 inch d. 0.00001 inch

26. One gallon of aluminum appliedto a wood surface will cover how manysquare feet?

a. 500 c. 650

b. 600 d. 700

27. What is the maximum amountof thinner that you would use per gallonof paint?

a.. y2 pint c. 1 quart

b. 1 pint d. 3 pints

28. You are about to measure dry-film thickness with a properly calibrateddry-film thickness gage. How many mea-surements do you recommend should bemade on a single area?

a. 25

b. 50

c. 75

d. hundreds

29. The process whereby a paintchanges from a wet-film layer to a pro-tective dry-film layer is called

a. mechanics of coatingsb. nonmagnetic shimc. pigment exchanged. disintegration

30. You are the inspector on aproject that is being done under con-

2.,-L -a.

4

tract. Which of the following would youuse for rejecting defective materials?

a. specifications

b. daily diary

C. contract

d. building plan

1 3-4 -33.665Ft Belvo Ir

document resume ed 204 633 institutiondetect and prevent metal corrosion prepare wood, masonry, and...

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