Going through this original bank roll of 1985 - D cents and around 40 have these extreme zinc zits. The remainder have what appears to be heavy flow lines. Is it possible to be this severe on this many uncirculated cents? Interestingly, the coins not affected have the same die mark (red arrow), while none of the affected coins have this. Damage seems to work it’s way out from the center of the coin.
Hi Imho, zinc tends to corrode more quickly than copper, newer pennies tend to form darker green or black layers as they corrode. The change from green to black is a sign of progressive corrosion. It occurs when the copper-hydroxide-carbonate on the penny's surface reacts further with oxygen and moisture in the air to form copper sulfides. Older pennies may never reach this level of corrosion and thus maintain a lighter green coat.
Hey! I guess I should have taken a step back and looked at it with fresh eyes, instead I only saw everything I’d already seen in person. Not what someone looking at the pictures would see. The color on these hasn’t changed and anything other than mild toning is just the lighting and shadows. Unless you’re referring to the zinc core which ant visible..
You asked “ is it possible to be this severe on uncirculated?” A. Yes. Why? Once the coin is cooled from being created it starts to deteriorate from being exposed to the elements. Imho, it can start anywhere on the zinc cent. The less it is exposed to air. The longer it will retain its luster.
Plating blisters like this are common on all the early zLincolns. The mint was having a problem bonding the copper plating to the zinc core. IMO it really doesn't have anything to do with corrosion or any kind of elemental exposure. This is the way a lot of the cents looked, some of the cents are covered on all the reverse and the whole reverse. We can also look at this another way. Most of the cents that do not show this are usually early die state coins. As the die began to wear, the metal flows differently and thus would cause more problems with the thinly bonded copper plate. Most of the coins that look like this either blisters or linear blisters are late to fully deteriorated dies. Just my two cents. I have not done the full research.
basic things to know about zincolns surface https://www.coinworld.com/news/us-coins/2016/08/unexpected-bumps-on-coins-surfaces-vary.all.html 5. Plating blisters Plating blisters develop in the coin in the immediate aftermath of the strike, as gas expands between the core and poorly bonded plating. Among domestic coins, plating blisters are the exclusive province of copper-plated zinc cents. Blisters are generally small and subcircular, with a smooth surface and soft outline. They can occur anywhere on the field and design. The design continues uninterrupted as it crosses a blister. 6. Occluded gas bubbles Solely the province of solid-alloy coins, occluded gas bubbles form just beneath the surface and push up the overlying metal immediately after the strike. Like plating blisters, the surface is smooth and the edges soft. The design is uninterrupted. 7. Corrosion domes Contaminants trapped beneath or penetrating the surface of aluminum, plated zinc, and plated steel coins can react with surrounding metal to form an expanding front of spongy, corroded metal. The resulting solid dome will superficially resemble a hollow plating blister or occluded gas bubble. In many cases the corroded metal bursts through and may fall out, leaving a crater.
