Lincoln Cent Laminated

Looks like it was dipped in something.

you can be right incomplete plating the rest of the copper look good.

I would have to agree with HoosierDaddy that the coin had been dipped in something. It was most likely dipped in sulfuric acid. The sulfuric acid would react with the outer layer of copper creating an aqueous copper sulfate solution. This would explain the exposed zinc that appears to seamlessly blend with the remaining copper.

I would think if the coin were kept dipped long enough, the copper sulfate in the solution would begin to react with the exposed zinc creating zinc sulfate and pure (black) copper on the zinc. This would explain some of the dark spots we see in the zinc.


I should probably add that the coin was probably only partially dipped and held by some form of tong. This may also not be the first coin dipped in this matter in the solution as there appears to be reaction over the "I" on the reverse.

Contrary to popular belief, cent planchet are not plated by dipping in molten copper. Temperatures required to melt copper would vaporize the zinc core so the planchets are plated in an electrochemical bath. Improperly plated Zincolns can indeed have this splotchy liquid appearance and it does not help matters than zinc readily corrodes when subjected to the environment. The key test for a plating error is luster, a Zincoln with the copper plating removed will not have luster while an improperly plated coin will have its luster intact.