Chemicals -- Someone put a chemical on the coin's surface, and you can see the copper plating on the rims. The 'bubbles' are usually because of copper-plating anomalies, but in this case, I'd say it's part of the alteration of the surfaces, due to the chemicals applied. It didn't leave the Mint like that - sorry
Yikes! Where do you FIND cents like these? Wow. Around here, at least our corroded cents have the common sense (see what I did there?) to just be loaded with green crud or the white residues of zinc oxide. I never see just blisters like the coin had poison oak. What are people doing to these?
It left the Mint with that line on it, Fred. That line is a long plating bubble, Sarah. Those bubbles form because the plating doesn't always stick to the core on those plated cents and air gets in between there.
It's possible, but it's also possible that the chemicals used to remove the copper plating did it - but in all actuality, it doesn't matter because of the altered surfaces of the coin. The chemical that removed the copper plating would have normally removed the copper plating bubbles too, at the same time.
The copper remaining on the rim, chin and forehead is strange I think for a chemical-dip. That may just be due to weathering, which is more random.
