Block Sanding

I want to get the body painted before the nice weather ends this year, so the past week I’ve been working on the car a lot. I’ve been block sanding the quarter panels and roof with 80 grit, dry, using various Durablock sanding blocks. I’ve applied polyester primer (Featherfill G2) a couple times more between sanding sessions. MOST of the stuff ends up sanded off, so my build thickness overall is still pretty thin. Since my blocking skills are nearly non existent, I’m having to do this in several passes, where an experienced pro could do it in one or two. Regardless, it’s getting pretty darn straight!

The roof has been a challenge since day one, since it has waves in it and it deflects very easily when sanding. I basically can’t put much of any pressure on the sanding block, or it will flex the roof panel creating the opposite of flat and straight. So easy does it, and it’s slow going.

Blocking the Roof

The pictures show it finished with 80 grit, which will now get top coated with one last coat of Featherfill G2 (thinned a bit with some Acetone). I’ll sand this last coat with 180, which is a much finer grit. This last session of blocking will be more about leveling off those 80 grit sand scratches than it is about fixing waves in the panels. However, some more last-minute flattening will happen too. Fine tuning, I guess!

After the final coat of Featherfill is blocked with 180, I’ll take special care to sand every tiny nook and cranny to prep for the final two coats of PPG K36 Urethane primer. The Urethane primer, since it is also a high(ish) build primer and a moisture barrier will allow me to do final blocking with 400 grit paper, wet. Wet sanding is almost essential at this stage, since 400 grit is fine enough that dry sanding with it would load the paper with dust very quickly. It’d be a real pain in the ass to dry sand the whole car in 400! I won’t get much flattening action using 400, but that’s ok… it should be pretty darn straight by this time.

I’ll also be sanding the door jambs and the visible areas inside the trunk. They’ll get some K36 on them too, since I’ll want to wet sand them with 400 grit as well.

Featherfill almost done
Categorized as Bodywork