I do silversmithing as well as pen turning. I recently had a request for a pendant with a copper back. Copper is beautiful, easy to work and MUCH cheaper than silver. Copper tarnishes like crazy, especially when it touches skin, also can leave skin black. (That's why people don't usually wear copper rings) So, I mixed up some Epoxy (5 min) diluted it with acetone and coated the Copper. It worked. The thing is the back of that pendant felt softer than only Epoxy. It was tacky for a day or two and about 1 week later if finally felt dry and hard, not as hard as plain Epoxy. (I live in Phoenix, AZ so it wasn't humidity or cool weather, LOL). So, what in the world does all this mean? You got me. The lady who got the pendant loves it, the Copper will not tarnish as long as there is epoxy on it and she won't wear the epoxy off anytime soon, as I put a fairly thick coat on. It was NOT a thin, highly diluted mixture as you are suggesting PaulDoug. I'm just sharing what happened with me. Side note: Another jewelry maker suggested: "plasti-kote" hi-performance classic fast dry lacquer, which is a spray automotive lacquer which I buy at Pep Boys automotive." Her husband is a painter and she and he say that works best. Haven't tested that one yet. Maybe it was soft and took a while to dry because it was the 5 minute epoxy. This is like a science experiment now! Cool.
Tony
Phoenix, AZ