How to clean hammered coppers

[Hookka]

Hey guys and gals, I've got several dozen hammered coppers and silvers that I've found over here in the desert. Many were found in beach sand or heavily salted sand. They have very thick Patinas and corrosion on them I've soaked most of them in olive oil for a while but I don't think it's going to do the trick . You can see detail on some of them but the coins are for the most part undocumented or poorly documented from this region (don't confuse that for meaning they are that rare ) I'd really like to lift some detail out of them without using vinegar and am at a loss now. Thanks everyone HH