If it is just tape residue, soak them in hot water. This will loosen and remove the residue. I did this with some Kennedy half's that had been taped into a birthday card and it worked great.
If you use acetone to remove the tape residue - make sure you do it in a well ventilated area. The fumes are hazardous to breathe as well as explosive. It may only take a few minutes - it may take several hours. But when you are satisfied that the residue is gone - dip the coin one more time in clean acetone to remove the contaminants that were disolved in the acetone the first time. Then just allow the coin to dry - should only take a minute or less. If you use water, use distilled water, room temperature not hot. This will take longer, maybe an hour, maybe a day or two. But again, when finished do a final rinse in clean water. Then gently pat the coin dry with soft cotton taking care to NOT wipe or move the cloth around - but merely using it to blot the water from the coin.
