A secret I have shared over the years for cleaning anything is charcoal lighter fluid. It is particularly good on left over glue from tape and on glass windows or tar on cars. It is very mild, and excellent grease remover and overall engine cleaner - i could go on and on - I use a quart a month out in the garage on everything. It is way better to clean your hands than anything else and wont dry out your skin or leave an odor. I have also noticed it does not seem to remove wax so, as you can see it's uses are, many fold.