Any option for this coin? Specks of PVC

This is a wheat penny that I recently purchased and like except for the fact that there are two specks of PVC on the reverse. Is there any method of salvation for this coin?

 

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I was considering using acetone, but I heard acetone and copper dont mix well

 

Pure acetone won't hurt the coin and will remove PVC residue. However, if copper has a layer of oil on it, acetone will remove that as well so the coin may look somewhat different. It can always be re-oiled. If there is corrosion where the PVC spots were, nothing will fix that. If the coin is really valuable, I'd have PCGS or NCS do the conservation.

Cal

 

Acetone is only capable of reacting with copper in the presence of bright light and water, and even that's not proven science - to date, all the rumors you're hearing to that effect are based on one single scientific article from a group affiliated with people who have a product which competes with acetone.

Never stopped me from soaking copper in acetone just like any other coin. I'm unsure that's a PVC plasticizer problem on your coin, though; it doesn't usually manifest in two single small spots like that. If I were doing it myself, I'd start with a 24-hour soak and then pick at the green spots with a sharp thorn (roses and hawthorns are both terrific) with a vertical action to see if stuff breaks loose. Check around the Forum with the Search function for one of the numerous times we've discussed acetone use in detail.

 

It looks like it's in a slab.

 

Use a product called VerdiCare. Its sold at wizard soon supply as well as eBay. Its was formulated by a Lincoln lovin' scientist member here @BadThad. The small bottle is around $15 and its well worth it especially if you think you'll be removing verdigris from more coins in the future. If not, acetone should work. VerdiCare is specially formulated for verdigris on copper coinage. Its very gentle and safe, and works well.

 

Does it happen occasionally across ALL coins or only on specific coins (e.g. potentially something in the alloy used by X or at time Y)?

 

Here's an article about a reaction that occurs when copper, oxygen, and acetone are exposed to light. The paper mentions that the reaction does not occur when the reactants are not exposed to light.

Full article: https://www.researchgate.net/profil...tochemical-breakdown-of-acetone-on-copper.pdf

Abridged version:
http://www.stonybrook.edu/vescalab/research/research7.html

 

Those spots are verdigris... a reaction that copper has to oxidation.... You can try Verdicare... or, soak it in olive oil and use a rose thorn to remove it. There is very likely damage beneath the verdigris though....

 

Interesting...

"X-ray Photoelectron Spectroscopy studies have shown that acetone, when used as a cleaning agent for copper in the presence of ambient light and water vapor, slowly reacts to form acetic acid. This reaction does not occur in the absence of light. This suggests that copper acts as a photocatalyst for the reaction between acetone and water vapor."

Also that they let the acetone soak 17 hours until it evaporated. And if you read the paper, the beakers containing acetone were placed into a water bath to ensure humidity. Finally, in the absence of light the reaction was completely inhibited.

So using low levels of light in a dry environment for short periods should be safe. But if you need long soaks, definitely use a dark environment with desicants.

 

So, Doug, do you think the changes you saw when copper coins were treated with acetone were genuine chemical changes or due to removal of oil, varnish, etc., which then allowed the true color and luster to be seen?

Cal

 

Whoever knew chemistry could be so complicated...

 

I've been unable to duplicate the reaction in experimentation. The results would be plain, because the positive outcome to the experiment would be close to what you'd get by reacting copper directly with vinegar as a control (not that I'm disclosing experimental method here).

I imagine it possible, but I couldn't do it.

 

If you read the article, they sanded each copper "coupon" (their word). That would remove the outer layer of oxide...

 

It would be interesting to see if acetone can even react on a toned copper coin or if it would have to be a relatively untoned coin to react.

 

Acetone won't fix the spots on the OP's coin. Those are verdigris spots, where "verdigris" is a fancy term for "green rust."

 

It is. An ANACS slab. Coin looks good otherwise