Opened a new roll of pennies and a quick glimpse at this one and it was on the verge of flying into the “rejects” bucket when something registered that it wasn’t quite right. Took another look it hit me: Abe had what appears to be an excess of hair on the back of his head. Please don’t tell me I’m having flashbacks to the 70s. What is this?
First thanks for the link. I read it and the only other article I could find on zinc deterioration. ZD was described as a white powder and if kept wet is unadherent. What is on the coin I showed the additional mass is not a white powder and appears to mirror the hair shown on Abe’s head. And there appears to be a much smaller patch, again mimicking hair. So how sure are you in your diagnoses?
Hydrozyncite is the deterioration of the substrate zinc so what happens is that once the copper plate/flash is compromised and exposed to the elements the destruction begins below the surface. I cringe when I find a high grade specimen Zincoln but can visually see split plating. Only a mater of time. Many folks are tricked into seeing RPMs and DDOs because of the trouble below. Given this would have been a major DDO, it would have been realized a long while ago. It’s reasonable to conclude what we are seeing is an optical ‘delusion’.
@Chip Kirkpatrick You can think of zinc rot (corrosion) as being similar to rust on your car. When you get a scratch on your fender, the iron in the exposed steel will begin to rust. Over time, rust will progress under the paint and cause it to bubble and blister. The copper plating is approx 8 microns thick (less than 1/1000 of an inch. It doesn't take much to breech that plating and once The zinc is exposed, even with a very tiny hole, corrosion can start of exposed to the right environment. Now look at the discoloration and environmental damage of your coin. You think that the plating could have been breached? The chemistry isnt exactly the same as iron rusting, but you get the idea.
