Before sealing a playfield with something rather permanent like Flecto
VARATHANE Diamond Finish you will need to make sure the playfield
surface is clean. Most cleaners contain some wax which will then need to be
stripped. Wax can be effectively be stripped by using rubbing alcohol
sparingly. Alcohol is also effective for removing other finishes like
shellac. As always, check the results on an inconspicuous corner first.