The title says it all. I have quite a few proofs and wondered if anyone had succeeded in cleaning one up to make it look nice without making it look "cleaned". Just need to remove a few spots and a fingerprint or two.
Put a bit of bakng soda in a pan. Pour some very hot water over it, shake it around a bit and turn the coin over so the coin gets clean on both sides.
Rinse clean with cold water ,and dry with a towel.
I have used acetone in the past to clean prints off of 90% silver proofs. I have not tried it on the clad proofs. It is my understanding that the acetone only works on fresh prints. Once the prints have etched into the surface it is impossible to get them off without damaging the coin further. Just for kicks I have put a NiCu proof in some acetone and I will let you know how it goes.
The acetone didn't seem to work to remove the fingerprint. Apparently it was on too long or the acid in the fingerprint interacts differently with CuNi proofs.
In the past I traded them to Silver Fox. We agreed on a ratio of 2 proofs for 1 40% half. Years ago I was getting 1:1 for 40% and in fact on ebay I sold a roll for $27.00 but this was a long time ago.