100% Acetone is fine for copper coins, sealed glass jar since we are dealing with a flammable liquid and away from any source of spark or flame...A coin like this could soak for up to 2 days with no noticeable change in appearance...With 82 and up zinc cents 20 minutes to an hour max after that coin will/could turn black...Use the search box it holds unlimited amount of info....Did you try it on my search suggestion on your 1944
LWC posted on 3/12?