be sure to sand well away from where your gona stop priming, let it blow out so you dont have a heavy line to sand out, plus dont be tepmted to blow it on heavy( dont try to "fill in" anything with the primer!) it will build on its own, you may see scratches still after priming but they will sand out when blocking the area, if you spray it heavy it can swell the scratches underneath plus will shrink and make the repair appear wavy