Heat damage can cause bubbles or blisters on coins.
We get several post per year asking about a bubble or blister on a coin that turns out to be heat damage. I found both of these in a roll. It would appear to be heat damage and my guess is a car fire. I have seen and smelled quite a few cars that burned and these quarters smell just like that. It was not my car that burned and I did not heat these coins so I can't say 100% that this is heat damage. I think most will agree they look like they have been in a fire. I did a before and after a little cleaning photos. I wanted to clean them a bit to get a little better photos. The first one is a rather large bubble that is one sided and did not distort the reverse of the coin, the second one there is a bubble on both sides. It is easy to understand how a newer collector would think this is some type of error. I am kinda curious about what it looks like inside the bubble and don't know if anyone has cut one open. I can't decide if I want to try to cut, drill or grind but will post additional photos if I do anything.
Do I need to call Dr. Pimple Popper before I start?