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The art of imitating the effects of aging and exposure on copper and brass.We
have all seen the
green colour on old bronze and on the roofs of public buildings.
Verdigris is simple to do because the more random and uneven you apply the
paint, the more natural it looks. Just so long as you do everything in the
right order you can forget about finesse.|
1. Give your surface a gold or bronzy coloured base coat.
2. Apply a coat of fairly thin(in the ratio of 1:4, paint:water) dark green emulsion and leave to dry.
3. To make verdigris paste; mix emulsion paint with methylated spirits(1:2) and thicken up with whiting(powder) until buttery. You may have to keep adding more methylated spirits to keep workable.
4. Mix up two verdigris pastes. One light blue and the other light green.
5. Slap your two pastes all over the surface but not with an even thickness.
6. Before the pastes are completely dry spray a yellowish colour here and there lightly about the surface using a small can aerosol of the type you find in car accessory shops.
7. When dry soak the entire surface with water; dont brush it on, just splash it on.
8. Sprinkle the wet surface with whiting powder, pressing it into any deep recesses.
9. When half dry, wipe the raised areas with a piece of towelling to expose the underlying colours. Dont wipe all of the surface, just enough so you feel its looking reasonable.
10. Allow to dry, then seal with a coat of diluted(1:3 ratio PVA:water) PVA.
The vivid green color of verdigris makes it a very common pigment. Until the 19th century, verdigris was the most vibrant green pigment available and frequently used in painting. Verdigris is lightfast in oil paint, as numerous examples of 15th century paintings show.
However, its lightfastness and air resistance is very low in other media. Copper resinate, made from verdigris, is not lightfast, even in oil paint. In the presence of light and air, green copper resinate becomes stable brown copper oxide.
This degradation is to blame for the brown or bronze color of grass or foliage in many old paintings, although not typically those of the 'Flemish primitive' painters who often used normal verdigris.
In addition, verdigris is a fickle pigment requiring special preparation of paint, careful layered application and immediate sealing with varnish to avoid rapid discoloration except in the case of oil paint.
Verdigris has the curious property in oil painting that it is initially bluish-green, but turns a rich foliage green over the course of about a month. This green is stable. Vergidris fell out of use by artists as more stable green pigments became available.
Verdigris is poisonous and has also been used in medicine and as a fungicide.
Copper(II) acetate is soluble in alcohol and water and slightly soluble in ether and glycerol. It melts at one hundred and fifteen °C and decomposes at two hundred and forty °C.
It can be prepared by reacting copper oxide, or copper carbonate, with acetic acid. It is used industrially as a fungicide, a catalyst for organic reactions, and in dyeing.
Verdigris is the common name for the chemical Cu 2 , or copper(II) acetate. It commonly occurs by the action of acetic acid when copper, brass or bronze is weathered and exposed to air or seawater over a period of time. Its name comes from the Old French verte grez, an alteration of vert-de-Grice — verd (green), de (of), and Grice (Greece)— "green of Greece".