Carbon spots grow? Really? Show me!

[Prethen]

I spoke with an ex-professional grader (no, not Mark Feld) about carbon spots on coins like 3CN's. He noted that they all grow and don't remain dormant. I believe this might have been reinforced by information from the ANA Advanced Grading Course as well.

 

If that's true, then are there extraordinary examples of coins where a carbon spot was known to be quite tiny and actually has grown? Or worse yet, if you take this to its obvious conclusion, the carbon spot should cover a noticeable portion of the coin and eventually the entire surface...right? Any examples of anything this gross?

 

[James_OldeTowne]

There are definitely such coins, and you could follow the progress of the carbon spots if you can pedigree the coin to a plate in a catalog somewhere. I have (sadly) owned such coins. One was a Liberty nickel in an NGC MS-64 slab. I had to get it NCS-ed, and that took care of the problem.

 

As for carbon spots completely overtaking a coin, I'm sure it's theoretically possible, but I haven't seen that. I have seen huge mushroom-sized carbon spots, though! I surmise that the problem is that the wrong environment will contribute to the spot's continued growth.

[Prethen]

I didn't think that a carbon spot can be dealt with in any way short of digging it out. Aren't they basically bonded to the metal and part of the coin. Can NCS really deal with it in an aesthetic manner? This is quite surprising.

 

James, would you agree that all carbon is active? Or, is only some of it active and is there a way to tell?

[WoodenJefferson]

I don’t know who first coined the phrase “carbon spots” to describe a dark spot on a coins surface, although it looks like carbon, it is actually a sulphatization process due to external reactions. In other words, the carbon is NOT in or on the coin and it grows, a chemical reaction is occurring between the base metals in the coin and influences from water, sneezing, rubber bands, sulphur laden products, coin albums and a host of other man made and natural occurring elements the coin might be exposed to..

 

Yes, once a reaction starts, it will grow until the reaction no longer has anything left to draw from, much like feeding a fire. Once the combustible material is all consumed, the fire will go out. Same as in a coin. Remove it from the source and the degrading will diminish and then finally stop.

 

[James_OldeTowne]

James, would you agree that all carbon is active? Or, is only some of it active and is there a way to tell?

I don't think all carbon is active, but it may be accurate that all carbon can be activated. My suspicion would be that the carbon spot can become patinated as a coin might, thus insulating it from external conditions and rendering it inert. However, remove that insulation, and it may reactivate. Please understand that I am speculating here!

 

NCS evidently can remove carbon, as I described in my scenario involving the Liberty nickel. I may have "before and after" images, and will post them if I can find them.

[PCcoins]

Won't a quick dip take care of a smaller carbon spot?

[Prethen]

Won't a quick dip take care of a smaller carbon spot?

NO!

[Raybo55]

I really don't think that "active carbon spots" started at the mint, but shure as shootin' they might spread because of the anomolies in the alloy.

 

I think it just depends.

 

Ray

[Raybo55]

I have been working on this coin for the better part of a year (mineral oil), and I don't think this method will make the coin look any better.

 

 

I will let you know how it turns out.

 

Ray

 

 

[Boss-migration]

I think that's a nice Large cent either way. What year is it?