Microstructural Analysis of Artificially Formed Patinas on Copper

Abstract

We analyzed artificially formed copper patinas to obtain microstructural information by means of transmission electron microscopy, energy dispersed X-ray spectroscopy, electron diffraction ͑ED͒, and X-ray diffraction ͑XRD͒. We found that there were two different phases in the patinas. One was a well-crystallized phase composed of copper, sulfur, and oxygen, and whose ED pattern exhibited many spots. The ED and XRD patterns revealed that this crystalline phase was antlerite Cu 3 SO 4 (OH) 4 . The other phase was a noncrystalline phase with no spots but with a diffused pattern. This phase also contained copper, sulfur, and oxygen; however, the sulfur X-ray intensity was much stronger than that from the crystallized phase. We believe this phase to be composed of cuprite Cu 2 O and sulfate.

Study of copper nitrate‐based patinas

“…7 The scientific study of patination techniques has therefore become a necessity. 8 -10 Multiple studies have been conducted on copper corrosion, and corrosion products formed via electrochemistry, 11 artificial aging methods 12 or by contact with corrosive species 13 have been investigated. However, only a few projects have started to investigate patinas realized according to traditional recipes.…”