I've flatted my white PK frame with 1500 to get rid of some of the "FLA" effect that powder (or paint) can leave.
Then went over it with 2000 followed by T-Cut on a mop and to finish with auto glym polish again wet mop'd
Remember its only a thin coat of paint so you can rub it away very easy
Sam's right it takes forever
And you'll get the worse case of w&nkers cramp in your hands ever....