Understanding and Caring for Architectural Drawings and ReproductionsValinda S. CarrollPreservation ManagerWilliam R. and Norma B. Harvey LibraryHampton University

ARSCOR January 24, 2013

Preservation Factors• Substrate• Media• Process• Environment/ Storage

Handmade Papers

• Rag writing papers in use through early 19th c for all drawing types

• Handmade and mouldmade (cylinder) rag• Hot pressed and gelatin sized wove paper

surface for ink washes and watercolors• Rag fine art papers in use for competition and

presentation drawings through 1940’s

Machine Made Papers

• 1840’s low-quality paper sold on rolls • Rough cartridge paper (originally handmade

cartridge paper in 18th c) available by 1840• Detail and Manila papers lower quality for full-

scale working drawings, often colored paper; not compatible with washes or watercolor

Translucent supports• Prepared tracing paper: paper impregnated by

oil or resin (vegetable parchment or vellum)• Natural tracing paper: heavily beaten pulp• Parchment paper: fibers broken down by acid• Tracing cloth or “linen:” coated cotton (1850-

1970)• Cellulose acetate and polyester films (1940’s-

present) “Mylar”

Grids and Rules

• Pre-printed ruled grid lines; “cross section papers” or “profile” papers first used by Thomas Jefferson, borrowed from French tapestry pattern makers

• Not common prior to 19th c• Used by engineers

Media• Graphite pencil (18th c to

present)• Colored pencils, crayons,

pastels (early 20th c)• Iron gall ink: dark brown,

corrosive; used for notations on drawings executed with other media (18th c to 1940’s)

• Japan ink: oxidized iron gall ink suspended in vegetable gum (mid 19th c)

More Media

• India ink: water-soluble ink based on lampblack and animal hide glue (ink stick, not bottled)

• Bottled ink: mid 19th c, various formulas• Modern “India ink:” “waterproof” bottled ink

containing lampblack suspended in shellac- alcohol solution

• Colored inks: sticks or bottled, pigment or dye

tan recto, white verso

uniform paper tone, Prussian Blue image color

Diazo print

Positive blueprintPractice

identifying processes

Diazo print • Soft lines• Usually purplish-blue line on off-

white background (black, brown, other line colors possible)

• May have “dirty” or hazy appearance

• Verso lighter than recto (residual phenols discolor paper)

Blueprint

• Usually negative image, embedded in paper fibers (white lines on blue ground)

• Blue recto with white verso• Ferric ferrocyanide “Prussian blue”

color (not violet/purple)• Copied from translucent original• Pellet print slightly different from

blueprint positive (image on surface)

evidence of damage to tracing paper support of original (master)

•alcohol-based

•fugitive color

•1880-1920 for architectural use

Hectograph

Aniline Print

• 1860’s -1870’s most popular• Used by engineers and contractors rather than

architects• Blue, black, or purple line with soft edge• Greenish tint (“green print”) background• Coating only on recto• Image fades easily

Silver Halide processes

• Photostat (1909): silver halide usually negative

• CB “Dupro” “wash-off” print on tracing cloth (1920’s): silver halide black line print

• Silver gelatin contact print (1890’s-1940’s): opaque or translucent, high-contrast or continuous tone image

• Autopositive, Kodak Q, Retroflex print (1947) : silver halide black line on acetate or Mylar

Photostat

• Cool black and white image with emulsion• Often negative, but positive image post-1953• Could reproduce a non-transparent original• Silver mirroring• Brown staining or liquid tide lines on verso

from inadequate fixing or inadequate rinsing• Small, standard dimensions

Photomechanical processes

• Direct carbon and powdered carbon (1880’s-1910’s): black pigment in gelatin, line or half-tone positive

• Photolithography (1870’s)

• True to scale print/ lithoprint/ gel litho (1904-1950’s)

• Electrostatic print (1948); large format 1970’s, vellum, paper , or Mylar

Chemical Hazards

• All silver halide processes are sensitive to sulfur

• Most processes are alkali sensitive

• Diazo and sepia prints offgas and damage adjacent documents

• Prints from different processes should be isolated by Melinex folders, Microchamber Silversafe paper, etc.

• Folders and interleaves should pass P.A.T.

• Use pH neutral interleaf

Storage

• Flat files are best option• Powder-coated steel,

not baked enamel (to avoid off-gassing VOC)

• All items stored flat in folders

• Individual folders best option

• Up to ten items in one folder (interleaved)

• Place interleaving paper inside encapsulation or Melinex folder to absorb degradation products

Rolled Storage

• Rolled storage for flexible oversized material

• Roll onto 4” diameter or larger tube

• Isolate acidic tube with Marvelseal (best) or Melinex (short-term)

• Roll with interleaf or Melinex folder (seam or fold parallel to tube)

• Provide support for rolls• Store unsupported rolls

in shallow boxes to prevent distortions or tears (short-term)

Resources• Price, Lois Olcott. Line, shade, and shadow : the fabrication and

preservation of architectural drawings. New Castle, DE : Oak Knoll Press, 2010.

• Price, Lois Olcott. “History and identification of photo-reproductive processes used for architectural drawings prior to 1930.” Topics in Photographic Preservation. Washington: American Institute for Conservation, 1995: 41-49

• Kissel, Eléonore and Erin Vigneau. Architectural photoreproductions : a manual for identification and care. New Castle, DE : Oak Knoll Press, 1999.

• Kissel, Eléonore and Erin Vigneau. Architectural photoreproductions : a manual for identification and care[ 2nd ed.]. New Castle, DE : Oak Knoll Press, 2009.