Verdigris


Verdigris

Verdigris is the common name for the green coating or patina formed when copper, brass or bronze is weathered and exposed to air or seawater over a period of time. It is usually a basic copper carbonate, but near the sea will be a basic copper chloride. [Sharp, D. W. A: "Penguin Dictionary of Chemistry", page 419. Penguin Books, 1990 (2nd edition)] If acetic acid is present at the time of weathering, it may consist of copper(II) acetate. Its name comes from the Middle English "vertegrez", from the Old French "verte grez", an alteration of "vert-de-Grèce" ("green of Greece"). The modern French spelling of this word is "vert-de-gris".

The vivid green color of copper(II) acetate makes this form of verdigris 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, isn't 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 such as Jan van Eyck, 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 (but not 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.Verdigris fell out of use by artists as more stable green pigments became available.

Verdigris 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 115 °C and decomposes at 240 °C. It can be prepared by reacting copper(II) oxide, CuO, or copper(II) carbonate, CuCO3, with acetic acid, CH3COOH . It is used industrially as a fungicide, a catalyst for organic reactions, and in dyeing ("The Merck Index ", Ninth Ed., 1976).

External links

* [http://www.npi.gov.au/database/substance-info/profiles/27.html National Pollutant Inventory - Copper and compounds fact sheet]

References


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  • Verdigris — Ver di*gris, n. [F. vert de gris, apparently from verd, vert, green + de of + gris gray, but really a corruption of LL. viride aeris (equivalent to L. aerugo), from L. viridis green + aes, aeris, brass. See {Verdant}, and 2d {Ore}.] 1. (Chem.) A… …   The Collaborative International Dictionary of English

  • Verdigris — puede referirse a: Cardenillo, una mezcla venenosa de acetatos de cobre que aparece en las pátinas verdosas o azuladas de materiales de cobre y algunas de sus aleaciones y que es utilizado como pigmento. Río Verdigris, un río de Oklahoma y Kansas …   Wikipedia Español

  • Verdigris — Ver di*gris, v. t. To cover, or coat, with verdigris. [R.] An old verdigrised brass bugle. Hawthorne. [1913 Webster] …   The Collaborative International Dictionary of English

  • verdigris — [vʉr′di grēs΄, vʉr′digris] n. [ME vertegrez < MFr verdegris < OFr vert de Grece, lit., green of Greece < verd, green (see VERT1) + de, of + Grece, Greece] 1. a green or greenish blue poisonous compound, a basic acetate of copper,… …   English World dictionary

  • verdigris — c.1300, from O.Fr. verte grez (13c.), verte de Grece (late 12c.), lit. green of Greece, from obsolete Fr. verd, from L. viridis (see VERDURE (Cf. verdure)). The reason for it being called that is not known. In chemistry, confined to a basic… …   Etymology dictionary

  • verdigris — ► NOUN ▪ a bright bluish green encrustation or patina formed on copper or brass by atmospheric oxidation. ORIGIN from Old French vert de Grece green of Greece …   English terms dictionary

  • verdigris — noun a) A blue green patina that forms on copper containing metals. Lets to the museum. Cannon balls, arrow heads; Roman glass and a forceps green with verdigris. b) Copper acetate …   Wiktionary

  • Verdigris — Original name in latin Verdigris Name in other language State code US Continent/City America/Chicago longitude 36.23482 latitude 95.69109 altitude 192 Population 3993 Date 2011 05 14 …   Cities with a population over 1000 database

  • verdigris — [14] Etymologically, verdigris means ‘green of Greece’. It comes from Old French vertegrez, a conflation of vert de Grece ‘green of Greece’ (vert came from Latin viridis ‘green’, which also gave English verdant [16] and verdure [14] and may be… …   The Hutchinson dictionary of word origins

  • verdigris — [[t]vɜ͟ː(r)dɪgrɪs, griːs[/t]] N UNCOUNT Verdigris is a greenish blue substance that forms on the metals copper, brass, and bronze after they have been left in wet or damp conditions …   English dictionary