I have yet to meet a painter who would voluntarily remove a door in order to seal the bottom edge. The Painting Pal is a skinny brush that makes it possible to perform this vital task on a swinging door. It costs about $1. Give a bunch to your painting contractor and you may never get another callback because of a binding door. Marshalltown Co., 800/888-0127, marshalltown.com.
Door-Bottom Brush
Painting Pal.