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Series editors' preface - Wood Tools

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226 Conservation of Furniture<br />

Table 5.3 Pigments – continued<br />

Colour/group Chemical composition Origin/date Properties Refractive<br />

Pigment and description Index<br />

name<br />

Green<br />

Green earth<br />

(terre verte)<br />

Malachite<br />

Verdigris<br />

Copper<br />

resinate<br />

Cobalt<br />

green<br />

(Rinman’s<br />

green, Zinc<br />

green)<br />

Chromium<br />

oxide<br />

(opaque)<br />

Viridian<br />

(Guignet’s<br />

green)<br />

Chrome<br />

green<br />

Scheele’s<br />

green<br />

Emerald<br />

green (Paris<br />

green,<br />

Schweinfurt<br />

green),<br />

Veronese<br />

green<br />

Complex mixture of variable<br />

composition including glauconite<br />

and celadonite (hydro silicates of<br />

iron, magnesium, aluminium and<br />

potassium) ranging from neutral<br />

yellow to pale greenish grey.<br />

Coarse crystalline particles<br />

Basic copper carbonate<br />

(CuCO 3.Cu(OH) 2). Similar in<br />

chemical composition to azurite<br />

and often occurring in conjunction<br />

with it but containing more<br />

combined water. Crystalline<br />

fragments of a rather pale bluegreen<br />

colour.<br />

Verdigris of commerce is dibasic<br />

copper acetate (Cu(C 2H 3O 2) 2.<br />

2Cu(OH) 2) but the term sometimes<br />

used for copper carbonate or other<br />

blue green corrosion products on<br />

copper. Clear blue-green crystals<br />

sometimes with pointed needles.<br />

Colour often very strong. Acetic<br />

odour<br />

Not strictly a pigment. Green<br />

compound (e.g. copper abietate)<br />

formed by dissolving verdigris in<br />

Venice turpentine or similar<br />

oleoresin<br />

Similar to cobalt blue but with<br />

aluminium oxide wholly or partly<br />

replaced by zinc oxide. Fine regular<br />

rounded transparent particles blue<br />

green in reflected light but pure<br />

green by transmitted light<br />

Cr 2O 3. Dull opaque olive green of<br />

irregular and fairly coarse particle<br />

size<br />

Transparent chromium oxide<br />

(Cr 2O 3.2H 2O). Deep cool green of<br />

great purity and transparency.<br />

Particles fairly large, irregular in<br />

size and slightly rounded<br />

Homogeneous mixture of Prussian<br />

blue with chrome yellow. Colour<br />

varies from grass green to blue<br />

green. Blue and yellow particles<br />

cannot be separately distinguished<br />

as the blue coats the yellow<br />

Copper hydro-arsenite (CuHAsO 3).<br />

Composition varies according to<br />

method of preparation. Rather<br />

opaque bright lime green. Irregularly<br />

shaped flakes of varying size<br />

Copper aceto-arsenite<br />

(Cu(C 2H 3O 2) 2.3Cu(AsO 2) 2). Bright<br />

blue green. One of the most<br />

brilliant inorganic colours. Small<br />

rounded grains some appearing as<br />

trefoil or quatrefoil shapes<br />

From ancient times<br />

Natural mineral. Perhaps<br />

the oldest known bright<br />

green pigment. Widely<br />

used up to about 1800<br />

Prepared from ancient<br />

times by action of<br />

vinegar on copper.<br />

Numerous medieval<br />

recipes exist<br />

May have been used as<br />

early as the eighth<br />

century<br />

Synthetic pigment<br />

discovered in 1780 but<br />

not in general use until<br />

the nineteenth century.<br />

Expensive<br />

First used as artists’<br />

pigment c.1862.<br />

Synthetic. First prepared<br />

in 1838. Introduced as<br />

artists’ pigment c.1860<br />

Described in 1809. In<br />

use from first quarter of<br />

the nineteenth century.<br />

Inexpensive<br />

Synthetic. First prepared<br />

in 1778<br />

First prepared in 1814<br />

Very stable and unaffected by light<br />

or chemical reagents such as acids<br />

and alkalis<br />

Decomposed by acids. Unaffected<br />

by light<br />

Reactive and unstable pigment.<br />

Readily soluble in acids. Blackens<br />

readily with sulphur. Decomposes<br />

when heated. Fugitive unless<br />

locked up in protective coating<br />

Clear grass green when in good<br />

condition decaying to brown<br />

Semi-transparent pigment of low<br />

hiding power. Stable and inert and<br />

can be used safely in mixtures in<br />

all techniques<br />

Light-fast, stable and permanent in<br />

all painting techniques<br />

Exceptionally transparent pigment.<br />

High tinting strength. Stable in all<br />

media. Light-fast and unaffected by<br />

acids and alkalis<br />

Very good hiding power.<br />

Commercially important but not<br />

sufficiently light-fast for use as<br />

artists’ pigment. Sensitive to acids<br />

(turns blue) and to alkalis (turns<br />

dark orange)<br />

Blackened by lead. Decomposed<br />

by acids. Fades rapidly. Replaced<br />

by emerald green<br />

Fair hiding power. Very toxic and<br />

dangerous to handle. Blackened by<br />

sulphur gases and pigments<br />

containing sulphur. Fairly<br />

permanent in oil or varnish media<br />

1.62<br />

1.66–1.91<br />

1.53–1.56<br />

1.94–2.0<br />

2.5<br />

1.82–2.12<br />

2.4<br />

1.71–1.78<br />

continued

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