Removing patina from copper
Recently I made a helms chain weave necklace, bracelet, and earring set using copper for the large rings and Argentium Silver for the smaller rings. Not thinking (imagine that)..I threw it all in a patina and of course the Argentium did not patinate. How can I remove the patina from the copper without harming the Argentium Silver?
You won't harm the silver if you put the whole thing in a pickle solution like Sparex No.2. This will remove all oxidation from the metal. It will also require that you polish the metal (both the silver and copper) after removing it from the pickle.
To bring the piece back to a high polish, you may put it in a tumbler with stainless steel shot, etc. and tumble for a few hours. If you leave the copper as-is, it will tarnish on it's own, but will go through some ugly stages until it develops a nice patina. The silver, even Argentium will oxidize. Try heating the piece in near boiling water before adding it to your LOS solution that is also very hot! Copper oxidizes within seconds, the silver will take a bit longer.
If you want the copper oxidized, but not the silver, simply use a polishing cloth and buff by hand without pickling the piece. I've found that the Sunshine Polishing Clothes from Rio Grande work best for copper. I think the oxidized copper hand polished giving you bright copper highlights along with the bright silver would look very nice!