How Long To Soak A Coin In Acetone?

That's cool, I just like to be technical.

You may or may not be correct but remember that not all lighter fluids are the same. If you can find and purchase several different brands you may want to read the lables carefully. So what has worked for you in the past may not work for others and even you if you change brands.
As to Acetone, I've left coins in Acetone for weeks with little to no effects. However, although it has been mentioned many times that Acetone will not effect coins, when those were removed from the Actone, one Large Cent and one Indian Head cent turned a REAL RED. Not the so called red of a new penny, an actual RED. Numersou other coins in that same jar came out as they went in, no change at all. Although may have had some reaction with the other coins in that same jar.