Once you breach the protective coating of the playfield, it would take 5 seconds to remove the paint and you are left with a white base paint. Seconds later you hit wood.

It is a VERY FINE line - but if you take your time, and use less pressure in the area (as you spend time in that area), then you will get it right. If you have removed 10 "swirls" and you have one stubborn swirl left - move on - because that one swirl will look better than paint loss.