Copper acetate, basic

Description

A blue green crystalline powder called Verdigris. Basic copper acetate has been prepared since ancient times by exposing copper to vapors of fermenting grape skin solutions. It is a complex compound that contains cupric acetate, cupric hydroxide and water in varying proportions. Common verdigris, or green verdigris, has the proportions of 2:1:5 (cupric acetate: cupric hydroxide:water) while French verdigris, or blue verdigris, has the proportions of 1:1:5, respectively. When combined with terpenoid resins, such as Venice turpentine, verdigris forms copper resinate. Verdigris is also used as a pesticide, fungicide, catalyst, textile dye and pigment for paints, ceramics.

Note: The term verdigris is also commonly, but incorrectly, applied to any blue-green patina formed on outdoor copper.

Synonyms and Related Terms

verdigris, acetato básico de cobre (Esp.); cardenillo (Esp.); acetate de cuivre (Fr.); acetato di rame basico (It.); acetato básico de cobre (Port.); copper subacetate; common verdigris; green verdigris; French verdigris; blue verdigris

Other Properties

Soluble in acids and ammonia. Slightly soluble in ethanol, water.

Composition	Cu(C2H3O2).CuO(OH)2
Refractive Index	1.53; 1.56

Hazards and Safety

Toxic by ingestion.

May turn brown or black in contact with air.

Authority

• Richard S. Lewis, Hawley's Condensed Chemical Dictionary, Van Nostrand Reinhold, New York, 10th ed., 1993

• The Merck Index, Martha Windholz (ed.), Merck Research Labs, Rahway NJ, 10th edition, 1983 Comment: entry #2691

• R. J. Gettens, G.L. Stout, Painting Materials, A Short Encyclopaedia, Dover Publications, New York, 1966

• Dictionary of Building Preservation, Ward Bucher, ed., John Wiley & Sons, Inc., New York City, 1996

• Susan E. Schur, Conservation Terminology: A review of Past & Current Nomenclature of Materials, Technology and Conservation, Spring (p.34-39); Summer (p.35-38); Fall (p.25-36), 1985