Nothing circulates through the hands of as many people as money does, and because of this, money is often dirty. Pennies are usually the dirtiest of the coins since they are often found lying on the ground, where they can easily have been stepped on. You should never clean collectible coins with acetone since this can damage the coin's patina and decrease its value, but regular everyday pennies can be thoroughly cleaned with acetone.
Set the pennies in a bowl of warm water to rinse them. Remove any loose dirt by rubbing it off with your fingers.
Remove the pennies from the water and set them in a small bowl. Pour enough acetone into the bowl to completely submerge the coins. Let the pennies soak for 30 minutes.
Remove the pennies from the acetone and scrub them with a toothbrush using dish soap and water to remove the acetone.
Pat the pennies dry with a lint-free rag to remove the water from them.
Do not soak the pennies with any other types of coins.