It's primer. Purpose is to dehydrate the nail for better adhesion. Also can kill any surface bacteria, according to the type used. I never used a drill for top filing, just used a file, lightly. The deal is to apply it right, so you don't need to file much. Oh yeah, Don, wasn't kidding. You could concievably use a dremel.........lowest speed, with a stone conical bit. That is basically what the drill in any salon is.