As a silversmith, we always used a 2750 rpm motor with at least 1/2 HP. This was usually with a 6 inch swansdown mop. However I now use a well worn 4 inch mop as it is less aggressive. You need to get it warm enough for the rouge to melt and move the sliver molecules about on the surface but not press so hard that you are removing them. I often get between 100-150 goes from one plate at 20 microns of silver plate before I go though. If you press too hard to get rid of a nasty scratch you can go straight though to the base metal easily.