Might explain some problems people have when trying to remove grease and dirt (e.g. fingerprints, etc.) from copper coins by dipping in acetone:

Scientific article about the chemical reaction of acetone with water in the presence of copper and ambient light

Downright scary! (This is NOT an April 1st joke, BTW!)

Yep, bobh, it is an interesting read. jlueke kindly posted that link over in rcc in response to an experience I had with a Lincoln and acetone this morning...

Here are the pics (before and after I dipped the coin in acetone to remove a fingerprint I clumsily put on the coin after phorographing it). Personally, I think that there was a contaminant on the surface that the acetone reacted to. If memory serves me gxseries was warning about acetone and copper earlier - could have saved myself 50 cents if I would have listened.

Original pic (before I got my greasy mitts on it)


After a dip in acetone to remove my greasy print


Some before (left) after (right) comparisons

I knew this problem did exist! A bit late but it's better than never.

Lot's of people know the problem exists. The real problem is though that for every 6 people who tell you that the problem exists there are 6 others who who will swear it does not.

I'm in the first 6 by the way