Carbon Spots

[TPring]

I am interested in a coin that has a few small black spots on the reverse and have always heard of them referred to as carbon spots. In doing a little research, I came across this article that explains that it is NOT carbon but sulfur that causes these tiny black spots that tarnish coins...Interesting.


That being said: 1) Do these spots continue to grow over time or can they be mitigated?
2) I keep my finds in 'coin envelopes', Would they cause spots over time?


Thanks,

[Petespockets55]

T, I would NOT keep them only in the little manilla envelopes because they will tarnish and turn brown.

I bought some envelopes at an auction in Fl. thinking they were older coins from a knowledgeable collector but all of the ones only in the envelopes were all deep brown. The ones that were in a wax paper "pre-envelope" faired much better.
(I'm sure the original collector was trying to find some way to battle PVC damage from the old holders.)

[VAB2013]

Tpring, I use Saflips for valuable finds. MS coins go into a tube

And for the not so valuable finds I put them in these baseball card sleeves, use a sharpie to write what it is, staple the top and I have this stuff sorted in brick boxes.

Jon just found a nice deal on tubes for his Ed System, maybe he will chime in!

[jfines69]

The way to mitigate the growth of carbon spots or verdigris is to remove oxygen from the equation... Carbon spots can be lessened some what by conservation but will not be completely removed... Verdigris, if memory serves me correctly, can be completely removed but take a lot of patience... When done the best thing so far to protect the coin is verdi care... It was created by our local chemist badthad http://www.lincolncentforum.com/foru...hp?323-BadThad Hope that helps a bit!!!

[TPring]

The way to mitigate the growth of carbon spots or verdigris is to remove oxygen from the equation... Carbon spots can be lessened some what by conservation but will not be completely removed... Hope that helps a bit!!!

Thanks. Yes it does.

Any comments about the article basically calling them sulfur-induced spots instead of carbon-induced spots?

[Petespockets55]

Thanks. Yes it does.

Any comments about the article basically calling them sulfur-induced spots instead of carbon-induced spots?

Not sure of the authors credentials, but I don't feel qualified to confirming or critique the information about sulpfur in the article.
But I can say this information would explain why Lincolns in just the paper coin envelopes tarnish, Sulfur in the paper manufacturing process!

I'll see if I can get my phone to cooperated and get some images to share with you of coins in just paper envelopes vs. wax paper and paper envelopes.

[jfines69]

Since sulfur turns to sulfuric acid when exposed to air/water I suppose it could be related to carbon spots??? One of the reasons birds can not have anything with onion... Birds have no saliva to dilute the acid created from the sulfur!!!

[GrumpyEd]

I think it's like Jim just said.

They're sped up by moisture, and acids. Sulfur or things with it like some paper speeds them up. The spots are where metal turns to oxide. You can't reverse carbon spots or verdigris since some metal was turned to oxide, you can only slow it down or stop it from getting worse or remove the oxide but you still have the missing metal.

I'm not sure why they call them carbon spots, because they're black like carbon? Or they are carbon left from the reaction? Or did numismatists think they were from carbon inclusions in the coins?

I think carbon itself does not cause problems, like isn't charcoal mostly carbon and they use it as a desiccant to absorb the unwanted moisture that helps in the reaction like Jim said.

[WaterSport]

To me, carbon spots are caused by spital, or spit drops from people talking over coins. They are a magnet to a proof coin. And there is nothing you can do to remove them short of a wire brush. The contaminate etches below the surface of the coin beside the black surfice spot. Thus when you try to remove it, its like it has roots. Its no going anywhere. Thats my non-scientific explanation. Sulfur is more likely to cause toning. The higher the sulfer content in paper, the more dramatic. Thats why certain proof coins (2009 and 1970 & 1971) have a high number of toned proofs. Since you can not do a test with out great expense to determine how much sulfur (or other ingredients) are in a paper envelope, why use them?? As Viv said, archive quietly safe flips is the ONLY way to store coins these days. JMHO.

WS