Today I worked on sanding the driver's side door using a 12" hard sanding block with 80 grit sand paper. First I put some guide coat on the door and then sanded the door. The guide coat is great for showing where the low spots are located, and I recommend everyone use it when sanding. Once I get the low spots leveled, I will sand the door again with 180 grit sand paper, and then the door will be ready for primer.