Environmental Damage Understanding
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8 posts in this topic

Reaching out to you experts for better understanding.  So earlier this year I acquired a small Cents collection.  ~10k "pennies" sorted by date/mint mark in BU tubes - 1958-1980.  6 of the tubes were the old M. Meghrig & Sons tubes that tend to seal up. (I've got 4 set aside to tackle as a project later.) Anyhow, one of the tubes opened freely and the top 6 coins exhibited this dark purplish, almost black, "toning".  Regardless of grade, I thought them unique enough and visually appealing myself to have slabbed.  4 of them at least, I left out 2 with less dramatic coloration but really nice iridescent purple in the fields.

That being said, what type of environmental damage would you say it is that causes this?  As I understand toning on silver coins, essentially tarnish, that's the metal reacting the environment itself.  Copper is copper so I know I can't compare equivocally.  The other coins under these in the tube, and none in the other 200 or so tubes, have any coloration like this so I'm at a loss for explanation.

Looking forward to your thoughts!  Have a great day! 

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That's PVC, at least on some of it. (Could be all; can't be sure; can only speak to what looks like what I have seen.) I was in a similar situation one time with about forty old deteriorating plastic tubes of Lincs. The plastic has begun to break down, leaking a corrosive slime onto the coins. It will eat away at them in time, though the fact that these pieces are isolated from further contamination should place some limit on the future damage.

The way I dealt with it was to soak the coins repeatedly in fresh acetone until the acetone was no longer blue. That did away with most of it. What remained was copper corrosion on a few pieces that was probably unrelated to PVC.

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PVC?  I've had some on some silver Franklin's before but it looked quite different.  Definitely a green coloring and not covering as much area.  Not disputing your knowledge in this area, just trying to make sure I know what to look out for in the future.

Just looked up the NGC definition for Environmental Damage:  ENVIRONMENTAL DAMAGE is the result of a hostile storage environment, where the exact cause of the surface damage is indeterminable.

But if it's PVC contamination wouldn't it not be slabbed at all?  Wouldn't that fall under their "Coins that Require Conservation" category?  Coins with active surface residues and a handful of other conditions cannot be graded by NGC until they have been professionally conserved. Numismatic Conservation Services (NCS), an independent affiliate of NGC, can carefully conserve coins and then seamlessly transfer them to NGC for grading.

https://www.ngccoin.com/coin-grading/details-grading/ 

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I don't know anything about slabbing or the associated labeling and designations; I've never sent a coin in for grading. I am thus ignorant of why and how any grading company does what it does.

All the pennies had a coating of clear slime; some also had little partial sheets of bluish stuff that looked exactly like what I see on some of those penny surfaces. Acetone cleaned them off. They had been in deteriorating old plastic tubes. I did not precisely certify that they were PVC, I guess, because what I was seeing and feeling plus the age of storage matched with how I'd seen it described.

I suspect that the sort of teal color of the slime looks different when backed by silver than when backed by copper. I think it's translucent and partly transparent.

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JKK is exactly correct on this (as he tends to be on these things).  Environmental damage comes in many forms.  It can come from PVC, the coin being buried and dug up when found by a metal detector and many other sources.  Exposure to moisture can do it to zinc coins.  Basically, any hostile storage environment or exposure to a contaminant can cause environmental damage.  But I agree with JKK again in that your problem likely came from the tubes the cents were stored in.  A lot of those older coin storage options (tubes, flips and even some albums) contain PVC.  PVC was viewed as a good material for coin storage back in the day because it was flexible, so you wouldn't scratch your coins trying to store them.  However, once a few decades had passed, it was found that the PVC was absolutely toxic to coins as it released a nasty slime on the coins as it broke down.  Most modern coin storage options are PVC free but you have to be careful as there are still many PVC coins storage options floating around out there.  About a year ago, I ordered a 100 pack of some flips from a large and established coin supply company through one of their eBay listings.  When I got the flips they were all PVC flips, though they were sold as non-PVC safe flips.  One way that I know of discerning PVC storage options (at least with flips and album slides) is to feel them and smell them.  If they are stiff and scentless, you're okay but if they're flexible and smell like a shower curtain, remove any coins contained in them and throw them right in the trash.  As far as the harder containers like tubes, just remove the coins and throw them out.  I don't think the shower curtain smell test works on them.  Better safe than sorry.  Tubes are cheap.

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Thanks @JKK and @Mohawk

I guess I would still expect PVC to fall under the "active surface residues" and eliminate the grading/slabbing option until conserved.  But now that I think of it I'm fairly sure I've seen a slabbed coin or 2 that still had PVC on it somewhere along the way.

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2 minutes ago, CRAWTOMATIC said:

Thanks @JKK and @Mohawk

I guess I would still expect PVC to fall under the "active surface residues" and eliminate the grading/slabbing option until conserved.  But now that I think of it I'm fairly sure I've seen a slabbed coin or 2 that still had PVC on it somewhere along the way.

You're right, it should, but sometimes they sneak through.  And it's also a possibility that once the PVC is removed from the coin, the damage has already been done hence the Environmental Damage grade.  I think that's seen more often than coins with active PVC slime in slabs/

Edited by Mohawk
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  • Member: Seasoned Veteran

Cents can get that coloration just from being left in someone's pants pocket and going through the wash cycle. There's no way to know whether that happened in this instance.

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