Verdigris ()["Its pronunciation in English is still unsettled" ( Fowler's Dictionary of Modern English Usage (4 ed.) edited by: Jeremy Butterfield). The pronunciation /-ɡriːs/ is the first one given by Merriam-Webster's dictionary, but /-ɡriː/ is first in the Oxford Dictionary of English (3 ed.) (2015).] is a common name for any of a variety of somewhat toxic[H. Kühn, Verdigris and Copper Resinate, in Artists' Pigments. A Handbook of Their History and Characteristics, Vol. 2: A. Roy (Ed.) Oxford University Press 1993, p. 131 – 158] Once used as a medicine[ Verdigris, ColourLex] However, due to its instability, its popularity declined as other green pigments became readily available.
History
Etymology
The name
verdigris comes from the
Middle English vertegrez, from the
Old French verte grez. According to one view, it comes from
vert d'aigre,
"green made of vinegar". The modern French writing of this word is
vert-de-gris ("green of grey"), sounding like the older name
verdet gris ("grey greenish"), itself a deformation of
verte grez. It was used as a pigment in paintings and other art objects (as green color), mostly imported from Greece, and hence it is more usually given another etymology as
vert-de-Grèce ("green of
Greece").
[ The Concise Oxford Dictionary of English Etymology, edited by T. F. Hoad (1996), and Merriam-Webster's dictionary give only this second etymology.]
Production
Copper(II) acetate is prepared by treatment of copper(II) hydroxide with
acetic acid.
The historical methods used for producing verdigris have been recorded in artistic treaties,
on alchemy, works in natural history, and texts on medicine.
The most common ingredients used were copper and vinegar. Throughout history, recipes changed. In the
Middle Ages, copper strips were attached to a wooden block with acetic acid; the block was then buried in
Feces. A few weeks later, the block was to be dug up, and the verdigris scraped off.
[Darnton, Robert. "A Bourgeois Puts His World in Order" in The Great Cat Massacre --and other Episodes in French Cultural History. New York: Vintage Books, 1985. p. 114.] Another method of production was developed in 18th-century
Montpellier, France, a locale which had the ideal climate to produce verdigris for
pulverization.
The industry there was long dominated by women, with verdigris manufactured in household cellars using copper plates stacked in clay pots that were filled with
distilled wine.
The acid in the grapes caused the copper to develop crystals. The crystals ripened into verdigris and were scraped off when matured.
It was a profitable business, and 80% of production was sold abroad through certified female brokers. At the height of its popularity, in the 1710s, the government had to enforce inspection systems to address growing fraudulent practices. By the 20th century, the production of verdigris had moved away from Montpellier and more cost-efficient methods of producing green pigments sent the industry into decline after
WWI.
Chemical composition
Verdigris is a collective term for copper acetate, whose chemical varieties produce different hues. The technical literature is inconsistent in describing these variations. Some sources refer to "neutral verdigris" as copper(II) acetate
monohydrate () and to "blue verdigris" as .
Other sources describe the main copper salt in natural verdigris as (
brochantite).
Still, other sources describe it as basic copper carbonate (),
[Sharp, D. W. A: Penguin Dictionary of Chemistry, page 419. Penguin Books, 1990 (2nd edition)] or as where
n varies from 0 to 3.
In marine environments, the main copper salt is tribasic copper chloride ().
Overall, variations of verdigris can be divided into two groups: basic verdigris and neutral verdigris.
Toxicity
Verdigris, which was once used as a medicine
[ and pharmaceutical preparation
][ Women and the Verdigris Industry in Montpellier, European Women and Preindustrial Craft. Project MUSE, Indiana University Press, 1995] Nontoxic substitutes have been developed for some applications, such as art pigments.
Uses
Verdigris is a naturally occurring protective layer on metals such as copper, brass, and bronze. In addition to being a desirable artistic effect, it has been used primarily as a pigment and in now-outdated medicinal preparations.
When burned, verdigris produces a green flame.
Pigment
Verdigris has been used as a pigment since antiquity, including in paintings in Rome and Pompeii. The use of verdigris continued into the Middle Ages, Renaissance and Baroque paintings.
Stability
As a pigment, verdigris is subject to colour change. The changes are most pronounced during the first month of exposure to air. The changes also depend on the type of binding agent and type of verdigris used. For example, changes are less pronounced with neutral verdigris in oil and Tempera compared to basic verdigris.
Verdigris pigment is Lightfastness in oil paint, as numerous examples of 15th-century paintings show. However, its lightfastness and air resistance are very low in other media. Copper resinate, made from verdigris by boiling it in a resin, is not lightfast, even in oil paint. In the presence of light and air, green copper resinate becomes stable brown copper oxide.
In previous literature on painting, verdigris has been described as unstable when combined with other pigments which leads to further deterioration. Due to the fickle nature of the pigment, it required special preparation of paint, carefully layered application, and immediate sealing with varnish to avoid rapid discoloration (but not in the case of oil paint).
Medicine
Verdigris has also been used in medicine,[ and is identified in the Pharmacologia of John Ayrton Paris as the healing rust of the Spear of Telephus mentioned by Homer.][ Verdigris solids were also used for pharmaceutical preparations]
See also
External links
