like charlest said, Alcohol is good and fine.
or any regular basic cleaner (remedy rx, power wash, ebonite ball cleaner, etc etc)
you are just getting the sanded plastic off of the ball so I wouldnt go crazy. When I do clean my balls I use clean n dull and I recommend it. If you prefer a liquid cleaner I had good success with black magic rejuvenator... It doesnt get the belt marks off but it emulsifies / breaks down oil fast!
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Hammer has set the trap Hammerheads.
"Get them kiiids of the STREET!" -)