Acetone Mishap On Copper Coins

Styrofoam, bad idea with any chemicals. Should be fine on copper followed by distilled water rinse.

I suppose it should be said every time that the use of acetone is suggested - DON'T use plastic containers to hold the acetone; at least, test it first to see if the acetone has any effect on the plastic. Acetone is very good at depolymerizing certain types of plastics. Use glass or china bowls to soak your coins in.

Ditto - Pickel Jar works great. Just a note, if you use a glass canning jar, the acetone will also melt the rubber seal ring on the lid, but not near as fast a styrofoam cup. I used to work in a fiberglass shop, we used acetone to clean tools and brushes and wipe down molds. PS EXTREMELY FLAMABLE - I found out when I took the trash out one day and put it into our burn barrel. There was a lot of shop rags soaked in acetone in the trash. Took a match to lite the trash and it exploded. Didn't need a haircut for 3 months after that.

Another note, gasoline can also melt Styrofoam.

I used a Pyrex covered dish with a paper towel folded into quarters a few times I suppose to slow evaporation I could have put another paper under the lid for a bit of a seal.
Using a flat bottom and fairly large dish made it easier to get to the coins.

If your doing this for coins, your just wasting time. As I mentioned I have some coins in a jar with Acetone for weeks now. Still there and absolutely no difference after the first few minutes. I don't need them so might just leave them there for a few years.

I've read silly stuff like that previously and maybe even that one. Way, way back I thought there was a possibility that for some odd reason it would be possible. I placed several coins, pennies, Nickels, Dimes and a Quarter in a jar of Acetone. For one day that jar sat on the inside of my garage window sill. I then moved it to the outside of that same window sill, but it was only in the Sun for a few hours. I then moved that same jar directly into the Sun, on a picnic table where it sat for the entire day. After several days of this and absolutely nothing, I removed the coins. There was nothing in the way of anything to any of the coins except the Roosevelt dime did appear a little cleaner. None of the Pennies (cents) vanished, corroded, tarnished, rusted, etc. They just looked the same as when I put them in.
Of course I would really need to place such a jar on a rocket ship, shoot out into space, move into an orbit around the Sun, exposing these coins. Then possibly something would happen.

One more thing is to be carefull of internet articles and stories where they want you to pay for additional information. If you noted on the one you mentioned, they want $31.50 for details. They discuss Ambient Light whatever that is supposed to be. And Water Vapor, not just water, moisture, ice cubes in a Martini.
I presently have about 10 pennies in a jar of Acetone. I'll move them out into the Sun for a few weeks as soon as the rain stops here.