I am reading the Apr 2012 copy of The Numismatist, and they have a one page article on "The Perils of PVC". It includes two pictures of silver coins that have been exposed to PVC (polyvinyl chloride), and in the body of the article it says that be recognised in various ways by how it looks and smells (I won't copy it because it's not my article). I would like to hear what some of the talented (yes, I'm buttering you up) and well-versed numismatists here have to say about learning to recognise the first tell-tale signs of PVC damage, and what can be done to mitigate it. And if you can post pictures to illustrate. Thanks!
At first you can't see it at all,but it is there. Then it appears as a clear, cloudy film on the coin. Then as more and more gets deposited on the coin it will look whitish in color, then a pale green. And as it dries it gets crusty and changes color again, first a paler green, then tan or light brown, then it will get darker sometimes and can even go black. But as it dries some might also flake off and it might get paler in color. There are many, many different stages and possible colors. edit - it's like so many other things with this hobby, it requires a certain level of experience to recognize it. But once you gain that experience you recognize it right off.
This is a before and after. One where acetone made a big difference. It will probably never grade but it sure looks better.
This one could have been helped but I let it go too long. I'll probably crack it out some day but the spots will still show after an acetone bath.
This coin resides in a "Mexico Mint Set 1966". The entire set is enveloped in PVC plastic. Note the nice blueish greens.
