Natural Weathering of Copper Alloys
Copper is a fascinating metal to use when considering color. No other metal comes close to offering the variety of color that copper can develop. Copper seeks other elements to develop compounds that possess unique color attributes. Essentially, the copper surface, like most metal surfaces, seeks components in the atmosphere and surroundings to combine with. Over long periods of time, the metal surface develops compounds that resemble closely their mineral equivalent. Once this occurs, the copper compounds are defiant and stubborn. Further change is inhibited.
For instance, copper roofing, exposed for a century or more, develops a thick, beautiful green patina. This patina is typically the result of sulfur and oxygen from the air combining with the surface copper atoms. Water intermixes the reaction, and, over time, the surface develops a hydrated copper sulfate not unlike that of the mineral bronchantite.
Today, the development of these green copper sulfate patinas has greatly diminished. The reason is that the atmosphere is cleaner and less polluted with sulfur compounds necessary to form the green patina. Thus, it takes considerably longer today to naturally develop the green patina in many areas world. In dry climates, the green patina may never develop.
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.
