Acetone - many times it takes a less than a minute, but you cannot possibly hurt the coin with it being in the acetone longer.
Just put it in something covered so the acetone will not all evaporate. I use a baby food jar. I would be surprised if it took a couple of minutes.
How much squash could a Sasquatch squash if a Sasquatch would squash squash?
Download and read: Grading the graders
Costly
TPG ineptitude and No FG
Kennedy halveshttps://ln5.sync.com/dl/7ca91bdd0/w...i3b-rbj9fir2