Filmbacking, Rhombic and Mesh abrasive material is more durable and does not tear.
Sandpaper required for sanding (filler and sanding) is grain 80 and 120. Sanding with 150, 180 and 240 grit before applying primer. Grain 60 is only for the rough work. Sandpaper required for primer coating is 320 and 400 grit.