I have 5 Morgan's. All have been stored in plastic flips for at least 20 years. Each has a varying degree of green gunk- mainly around the rim. Is this PVC damage? What, if anything, can be done about it? Pics here: http://www.monshaugenfamily.com/CoinCollection/index.html
It is very likely PVC residue. The plastic flips contained PVC in order to keep them soft for easier coin storage. After long periods of storage, the PVC residue builds on the coin. If the PVC hasn't damaged the coin, it may be able to be removed by using pure acetone.
It does look like PVC damage to me. 20 years would be about the correct time frame as well. I quick dip in Acetone. Not fingernail polish, but the stuff you get in thepaint dpet at your local hardware store will get the green off. DO NOT RUB on the coins, give them a quick bath, rinse them off with distilled water. I lost several thousand dollars back in the 70-80's because of this from a coin album that I used that contained PVC.
It might take more than a quick bath, you might need to soak them a bit and then rinse them in clean acetone and then rinse them in distilled water and let air dry.
