Another thread that ties. Does a carbon spot on a cent immediately classify the coin as corroded ? I have seen hundreds, maybe thousands, of cents with these spots on them in Tpg plastic. Is it post slab corrosion ?,, would they no longer grade ? Obviously pitting is a sign, as would be a blob of green gunk or apparent signs of the big V. on a cent.... Question is, how bad does it have to be before a coin is classified as corroded.. would a single .01mm pit do the trick, or a .1mm carbon spot,, or simply the feel of the grader ?
Technically any combination of the metal of the coin with other elements to form oxides, sulfides, carbonates etc is corrosion. (so toning is also corrosion as well.) Typically though they aren't described as corrosion unless there is visible pitting of the metal surface. So tiny carbon spots probably would not be called corrosion, but a large spot that disrupts the surface would be.
It is a subjective evaluation, and I don't think you will ever get an authoritative answer to it outside of "it depends".
Heh, that goes for just about everything in life.. "It Depends". It's like the reply of "Maybe" when asked a yes or no question and drives my wife nuts because I always say maybe, which she should learn by now usually means "no".
What drives me nuts is that the TPGs will slab coin A, B, C, and D, etc that are obviously corroded. And no I don't mean toned coins, I mean coins that are heavily pitted. And yet not slab coin E, F, G, and H etc that are obviously corroded. There should not be different rules for different coins. They are either corroded or they are not. If you don't slab one when it's corroded then you don't slab any when they are corroded.
