Can you tell me what is contaminating my 1962 mint sets?
georgiacop50
Posts: 2,909 ✭✭✭✭
This green crud commonly forms on the Denver mint cents and nickels in my still sealed in OGP sets.
I have noticed that the Denver cellophane in 1961 & 1962 sets is "different" than the cello used at Philadelphia fpr packaging the mint sets.
The Denver cello tends to age normally and lay flat; whereas the Pilly cello tends to curl and shrink and doesn't lay flat. Philly cello also develops a bit of a greasy feel as it ages.
The green crud that deposits on the Denver coins has a liquid/gel appearance that looks for all the world like PVC residue. But there should not be any PVC in cellophane, right?
Any plastics chemists out there that know if plasticizers are used in cellophane. Or is this verdigris that for some reason forms preferentially in the Denver sets? If so, why? What is different about the Denver packaging that would cause verdigris?
I have seen the same stuff in 1963 sets but only very occasionally and the contamination is much less abundant.
The deposits in this photo are on a 1962-D Lincoln:
Comments
humid Georgia air and perhaps plastic holders not being fully sealed? Just a thought
That sure looks to be PVC, but I haven't been a chemist in a long, long time.
Everyone should keep in mind that it is highly unusual for a plastic used in any application to be 100% pure. There are all sorts of additives mixed with most plastics. These include antioxidants, UV stabilizers, processing aides, clarifiers, colorants, heat stabilizers, anti-stats, release agents, etc, etc, etc. What you see on this coin may appear to be a plasticizer commonly used in PVC, but it is very likely some other commercial additive.
I will never know what thought process the mint used in regards to packaging 50+ years ago, but something that is forever stable was likely not part of it.
It's a damn shame as I just came across a 1962-D Jeff that looks like it would have a VERY good shot at MS66 except for a HUGE glob of the stuff on the dome. Dang this stuff!
How about giving the nickel an acetone soak and see if the stuff comes off? (course you have to take it out of the OGP).
That is nasty looking stuff.... I would remove any coins like that ... give them an acetone soak first... If it goes away without damage, fine... but the packaging really destroyed any 'original' value the coins had in that state...if damaged, well... spend them. Cheers, RickO
It's a bummer, for sure, but I'd be at a loss to explain it, other than as Shamika said, some sort of contaminant at the time of packaging.
Little bit of corrosion/deposition going on there for sure. Haven't run across any like that myself on the mint sets, so not much insight I can give you on it.
PVC?
Fan of the Oxford Comma
CCAC Representative of the General Public
2021 Young Numismatist of the Year
Are your nickels turning a lilac color?
This.
And it could have been worse. I had my hands on a 1964 French mint set once. The mint packaging was full of PVC. The coins were covered with goo. Took a while to get it off both the coins and my fingers. What a mess.
Keeper of the VAM Catalog • Professional Coin Imaging • Prime Number Set • World Coins in Early America • British Trade Dollars • Variety Attribution