Acetone works real well on Silver without removing the patina or accumulated wear and tear. If you are cleaning copper, the best way is with Olive oil. I cleaned a 1939 British Colonies Large cent with Olive oil over a couple of weeks. It came out looking
perfect. I have an old 18?? Large Liberty Head Penny that is going to get the treatment this week. It takes over two weeks to completely clean the coin, but it truly does work.
I am planning on posting before and after pics when I am done. It is a $20.00 dollar coin (Price Paid) so I experimented on a coin that is virtually worthless first....

. The results were astonishing to say the least, enough to let me go ahead and
try with complete confidence in what it will do.