Architectural Architectural Finishes Finishes AnalysisAnalysis

Architectural Conservation I, University of Vermont Historic Preservation Program, Prof. Thomas Visser

Vehicle Appearance Test Reaction

Oil-based

(paint or varnish)

May be slightly translucent

May be shaved

Paint stripper

Alcohol

Water

Leathery

No reaction

No reaction

Latex emulsion

(paint or varnish)

Plastic-like resilience Paint stripper Alcohol

Water

Gummy

Little/ no reaction

No reaction

Distemper /calcimine May be crumbly Water Dissolves

Shellac

(sealer, varnish or paint)

Translucent amber (if not pigmented)

Alcohol Dissolves

Linseed oil

(sealer)

Translucent reddish amber

May be first coat

Paint stripper

Alcohol

Leathery

No reaction

Asphaltic Tar-like, black or dark brown

Mineral spirits Dissolves brown-black

Finishes analysis testsfor various vehicles

Pigment Test Reaction

Lead white Sodium sulfide* black

Titanium dioxide Sodium sulfide none

Zinc oxide Sodium sulfide none

Whiting (CaCo3) Acetic acid* fizzes

Finishes analysis testsWhite pigments

*Important: Sodium sulfide must not come close to any acids as hydrogen sulfide fumes may be produced.

Architectural finishes analysis using Architectural finishes analysis using ultraviolet fluorescence microscopyultraviolet fluorescence microscopy

Light

Typical spectral emission of UV arc illuminator

Fluorescence excitation spectrum and emission spectrum

UV Fluorescence microscope

A full left

B do not adjust

C ••••

D • or 0

E •

F full left counterclockwise

G do not adjust

H photo lever - left for eyes

I coarse focus

J fine focus

K use 4X or 10X objective

Turn on UV transformer, if it does not buzz and no UV light appears, let it cool for a few minutes and try againAdjust eyepieces to match your pupillary distance

To supplement with reflected light, use small desk lamp or fiber optic illuminator

UV fluorescence colors of vehicles

Medium Fluorescence color

Linseed oil, fresh

Linseed oil, congealed

Weak orange

Dark orange

Tung oil Whitish beige

Japan drier Pale flesh color

White shellac

Orange shellac

White

Bright pastel orange

Polyvinylacetate (PVA) Elmer’s glue

Milky bluish

Acrylic resins No fluorescence

From Marie Carden, APT Bulletin, No. 3, 1991and Martha Simpson Grant, “The Use Of Ultraviolet Induced Visible-Fluorescence In The Examination Of Museum Objects, Part II,” Conserv-o-gram,National Park Service, 2000,

www.cr.nps.gov/museum/publications/ conserveogram/01-10.pdf

UV fluorescence colors of white pigments in linseed oil

Date Pigment Fluorescence color

To 1850 Basic carbonate white lead

2PbCO3·(OH)2

Rose-white or bluish white to white

Circa 1850 Zinc oxide white

(ZnO)

Bright canary yellow

Circa 1855-96 Leaded zinc oxide

(Lead white or lead sulfate and zinc white)

Yellow to yellowish white

Circa 1901 - circa 1950

Lithopone (ZnS + BaSO4)

(zinc sulfide/ barium sulfate)

White

Circa 1920 - Titanium dioxide

(TiO2)

Rose to rose-violet

From Marie Carden, APT Bulletin, No. 3, 1991