Hey CLZinTX
There are quite a few chemicals that can be used to clean off the vandalism.
Rubbing alcohol is good.
Anyting that does not attack oxides but is an organic solvent is best. Just be sure if its a collectible not to rub the thing as that can scratch or polish.
Ok things to use are
Rubbing Alcohol.
Acetone is amazing,
ethanol is good
Ammonia works well.
I have an ultrasonic cleaner that is mainly used for jewelry but ammonia heated with the vibration of the ultrasonic destroys ink in seconds. It also vibrates off dirt and oxides to a degree.
heat will always speed up any reaction, but with some of these cleaners the fumes from heating can be unpleasant. So ventilate and be safe. Just as you dont want to go crazy from inhaling sharpie fumes you dont want to inhale other cleaning fumes as well. Unless you dont mind useing ethanol. Then you may just get a little tipsy.
Stay away from acids and basis for cleaning as they will eat oxides, this is why hot sauce, vinegar and citric acid will clean copper so well, its eating the oxides but the oxides pull off a tiny layer of copper with it, witch makes the coin look cleaned or such an unnatural color.
To put oxides back on a coin to darken it a little bit of salt and ammonia heated will darken copper to red/brown. If gold is present in the alloy it will turn black. Also gentile heating will allow oxygen to attack the copper to bring it back to a worn or darker color. Copper sulfite will also darken the metal, and liver of sulfer will blacken and darken it quite nicely, also ferric chloride.
But only if one were inclined to undo a cleaning. But as any metal detectors knows, you can always bury it outside and let random elements dot he job for you too...but it takes more time
