MITRA Forum Question Details

​Update: I'm reading the document "Rigid Supports" found in the Resources section, and I intend to study all the relevant documents in the Resources section. I've also read previous discussion threads about copper. So I may not need any fresh information, unless someone has something to say about copper on a substrate of aluminum composite material. If I do develop such a panel, my plan is to adhere copper to ACM with Beva 371 film, following the advice of a customer-service rep at Museum Services Corporation. Thanks.  

​I suppose it's expected that each commenter signs his or her comment. 

Amanda Teicher, Seattle

Just a quick additional comment: it's not true that copper is "incredibly prone to corrosion." In fact, copper is incredibly resistent to corrosion, which is why it is so often used for outdoor architectural elements (i.e. rain gutters, roofing, the Statue of Liberty). But, it won't stay shiny. A layer of cuprous oxide will inevitably form on the surface, which takes it from being shiny and reflective to looking more like an old penny. If subjected to enough moisture, it will form a greenish patina (like the Statue of Liberty), but this is unlikely to happen on copper that is kept indoors. 

Unlike oxidation on iron (rust is fragile and tends to flake off), this oxidation layer adheres strongly to the copper and helps to protect it against further corrosion. The only real downside is that you lose the shininess. So I'd be careful about employing copper in such a way that the shiny, new copper surface is critical to the aesthetics of the work. There's a good chance that will go away eventually, and then there' won't be any practical way of getting it back. Historically, copper used as a support for oil painting was primed with white lead, so oxidation at the surface of the copper would not impact the appearance of the painting. 

-Ben

​Right, copper covered in paint does corrode at the paint-metal interface; I was speaking more to the behavior of copper without paint on it (as you'd have in areas of a painting where the copper was left exposed for effect, as the original poster suggested). On its own, copper doesn't tend to form a green patina unless it's in a high humidity environment.

​Thank you very much, Kristin and Ben. Perhaps it's best to conclude that oil paintings made on copper will inevitably lose that bright, shiny look, and a painter would be wise to embrase the aging. Perhaps an artist's process would be easier if the copper panel arrived at the studio already aged. I'll continue reading, and I appreciate your help. 

Amanda Teicher