Learn more about the patina development at Zahner by signing up for the Zahner newsletter, or contact a member of the Zahner sales team to see how we can develop a custom surface for your design. In dry climates, the green patina may never develop. Thus, it takes considerably longer today to naturally develop the green patina in many areas world. The reason is that the atmosphere is cleaner and less polluted with sulfur compounds necessary to form the green patina. Today, the development of these green copper sulfate patinas has greatly diminished. Water intermixes the reaction, and, over time, the surface develops a hydrated copper sulfate not unlike that of the mineral bronchantite. This patina is typically the result of sulfur and oxygen from the air combining with the surface copper atoms. Further change is inhibited.įor instance, copper roofing, exposed for a century or more, develops a thick, beautiful green patina. Once this occurs, the copper compounds are defiant and stubborn. Over long periods of time, the metal surface develops compounds that resemble closely their mineral equivalent. Essentially, the copper surface, like most metal surfaces, seeks components in the atmosphere and surroundings to combine with. Copper seeks other elements to develop compounds that possess unique color attributes.
No other metal comes close to offering the variety of color that copper can develop. They actually remove pollutants from the air, albeit very slowly, by combining with sulfur dioxide and carbon monoxide to form mineral compounds that effectively trap the pollutants.Ĭopper is a fascinating metal to use when considering color. On a molecular level they seek various compounds from the atmosphere and readily combine with them. These relatively uniform corrosion products are difficult to artificially create.Īll copper and copper alloy surfaces exposed to the atmosphere undergo changes. The carbonate mineral forms are malachite and azurite. The minerals of copper undergo a very slow aging process, though the process is somewhat faster when near the sea. Another somewhat common mineral formation on copper alloys combines carbon dioxide and forms carbonates over the initial cuprous oxide layer. The color is reddish brown, but often exhibits a range of color from orange to yellow, even purples, as can be seen in the Dirty Penny copper material developed by Zahner. This oxide is essentially the mineral cuprite. The predominant oxide to develop on the surface of copper alloys exposed to the atmosphere is cuprous oxide, Cu2O. These localized changes are the product of natural pollutants and the further aging of the surface. For example, bronze statues, exposed to the weather for centuries, often develop a darkish “bloom” in the form of a spot or streak. Over time, this transformation will occur at a progressively slower rate as the copper surface reaches a chemical equilibrium. For immediate help, use our live chat feature by clicking the blue help button. This happens more rapidly when exposed to moisture, sun, and pollutants. Contact us at (252) 491-2812 or email for assistance. Copper alloys, whether they are prepatinated or not, will continue to transform as the surfaces age.
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