Ammonia seems to work very well on proof silver coins...removes haze but not spots or stains. I rarely use it on mint state silver as there are many more issues to deal with. Copper coins have even more issues to deal with. Copper proofs are easier to conserve than M S coppers but only to remove light haze. I don,t know of any good method of dipping M S copper, as mentioned in prior threads, it changes the look of the coin from red to pinkish. You cannot remove brown toning from copper to my knowledge.
Who, me ? Nahhh, I was a little angel I was one of "those" kids. Had an older sister and brother, 6 and 8 years older - I started doing their homework them when I was 5. And the adults, I was always everybody's "favorite" Of course they only thought that because I never, ever, got caught