My car is old - 1999 and had tons of small scratches oxidation, etc.. so got a strong compound Meguiars Ultimate cut. When I applied it with my microfiber towel, I noticed my towel getting black from the paint. I hadn't expected that - shouldn't it just work on the clearcoat - I don't think it is single stage paint - it's a Lexus es 300. Did I pick too strong an abrasive? Or should I be using foam instead. Or is this normal?