Looking for the proper technique to polish axles. I have read that when wet sanding, if you apply to much pressure, a black residue will form on your sanding sheet indicating you are taking to much material off the axle. . Also that it is best to use a flat surface like a balsa block to keep the axle surface uniform while wet sanding. What is the best technique - wet sand/polish with a balsa block backer, add just enough pressure so the black residue is not created, slow to medium RPM? What say you?