Try a little of DAWN liquid soap (I find the Green is best) in a Rx bottle, hot water, shake well (few times during day), for 2-3 days, rinse well with hot water, tap dry with soft towel or napkin. I do all my silver dimes I find, takes off a lot of the oily film & stains off coin on most coins. Try it if you can. Just trying to help, DozerD, HH