Verdigris - wikipedia Verdigris This article is about the color. For other uses, see Verdigris ( disambiguation ). Verdigris Color coordinates Hex triplet # 43b3ae sRGB ( r, g, b ) ( 67, 179, 174 ) CMYK ( c, m, y, k ) ( 63, 0, 3, 30 ) HSV ( h, s, v ) ( 177 °, 46 %, 48 % ) Source Encycolorpedia B : Normalized to ( 0 -- 255 ) ( byte ) H : Normalized to ( 0 -- 100 ) ( hundred ) Verdigris is the common name for a green pigment obtained through the application of acetic acid to copper plates or the natural 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. If acetic acid is present at the time of weathering, it may consist of copper ( II ) acetate. The Statue of Liberty, showing advanced oxidization Contents 1 Etymology 2 Manufacture 3 Uses 3.1 Pigment 4 Chemical properties 5 See also 6 References 7 External links Etymology This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. ( July 2014 ) Look up verdigris in Wiktionary, the free dictionary. The name verdigris 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 ( `` green of grey '' ). It was used as a pigment in paintings and other art objects ( as green color ), mostly imported from Greece ( Grèce ). Manufacture It was originally made by hanging copper plates over hot vinegar in a sealed pot until a green crust formed on the copper. Another method of obtaining verdigris pigment, used in the Middle Ages, was to attach copper strips to a wooden block with acetic acid, then bury the sealed block in dung. A few weeks later the pot was dug up and the verdigris scraped off. In eighteenth - century Montpellier, France, it was manufactured in household cellars, `` where copper plates were stacked in clay pots filled with distilled wine. '' The verdigris was scraped off weekly by the women of the household. The chemical reaction exhibited between wine and copper to produce verdigris may be related to wine 's own oxidization process. Another method, used in the early nineteenth century, had to do with reacting copper sulfate solution with solutions of lead, barium, or calcium acetate. Their sulfates are insoluble, forming precipitates and leaving the copper acetate in solution. Uses Natural or artificially created coatings of verdigris is commonly used as a patina to protect copper or bronze objects, especially in architecture. It is also used industrially as a fungicide, a catalyst for organic reactions, and in dyeing ( The Merck Index, Ninth Ed., 1976 ). Verdigris has also been used in medicine. Pigment Verdigris in Prague Underground The vivid green color of copper ( II ) acetate made this form of verdigris a much used pigment. Until the 19th century, verdigris was the most vibrant green pigment available and was frequently used in painting. Verdigris is lightfast 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. 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. Chemical properties Copper ( II ) acetate is soluble in alcohol and water and slightly soluble in ether and glycerol. It melts at 115 ° C ( 239 ° F ) and decomposes at 240 ° C ( 464 ° F ). It can be prepared by reacting copper ( II ) oxide, CuO, or copper ( II ) carbonate, CuCO, with acetic acid, CH COOH. Verdigris is a variable chemical mixture of compounds, complexes and water. The primary components are copper salts of acetate, carbonate, chloride, formate, hydroxide and sulfate. The secondary components are other metallic salts, acids ( organic and mineral ), atmospheric gases and water. All the components are in an ever - changing and complex electrochemical reaction equilibrium that is dependent on the ambient environment. See also Bronze disease List of colors List of inorganic pigments Patina References Jump up ^ Encycolorpedia page on veridgris Jump up ^ `` Verdigris '' Oxford English Dictionary Jump up ^ Sharp, D.W. A : `` Penguin Dictionary of Chemistry '', page 419. Penguin Books, 1990 ( 2nd edition ) Jump up ^ 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. Jump up ^ `` Medical Uses of Copper in Antiquity ''. Copper Development Association. Retrieved 8 June 2014. Jump up ^ 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 Jump up ^ Verdigris, ColourLex External links National Pollutant Inventory - Copper and compounds fact sheet Verdigris, ColourLex Shades of cyan Alice blue Aqua Aquamarine Azure mist Celeste Cerulean Cyan Electric blue Jungle green Magic mint Mint Persian green Pine green Robin egg blue Sea green Skobeloff Sky blue Tiffany Blue Teal Turquoise Verdigris A typical sample is shown for each name ; a range of color - variations is commonly associated with each color - name. Retrieved from `` https://en.wikipedia.org/w/index.php?title=Verdigris&oldid=787752898 '' Categories : Shades of cyan Pigments Inorganic pigments Copper compounds Alchemical substances Shades of green Hidden categories : Articles needing additional references from July 2014 All articles needing additional references Talk Contents About Wikipedia Català Čeština Español Esperanto Français Gaeilge Ido Italiano Nederlands 日本 語 Norsk Polski Português Svenska Walon 粵語 中文 Edit links This page was last edited on 27 June 2017, at 10 : 00. About Wikipedia

Question: what's it called when copper turns green
Answer: Verdigris