Sanding Tips

[Matthan]

I know there are many different options  on sanding but what grit do you use and in what order. Also do you wet sand the primer before paint? I am not very experienced on body work but I don't care if I mess up because I want to learn so I am will to try.

[tricky lugnuts]

I'm not an expert and certainly not advocating what I say as the good word, but as far as what grit to start with, it of course depends on what you're doing...

If you've got heavy rust to knock down, or want to hog out a bunch of old body filler, well, then you want something tough like 36 grit to make short work of it. If you're using power tools and something heavy like 36 or 40 grit, be careful and don't "sand" too much in one spot. It can warp the panel if it gets too hot, I've always been told.

If you're looking to sand down body filler that you've applied, I think people generally start with 80, work to 150, and so on, always using a block of some sort and sanding from different directions. The ultimate goal, other than a straight panel, is to make sure there are no visible scratches/gouges left in the body filler and that everything is "feathering" out nicely.

If you're just looking to do a scuff and repaint over existing paint, we used to start (after trim removal, a wash, dry, de-wax and degrease) with wet sanding using something like 400 grit (with block) to knock it down. Prime any areas you burn through.

I would block the primer before paint, it's not necessary, but it will certainly help the finished look. Final sanding before paint is with a fine Scotchbrite pad, the way I've always done, followed by cleaning with some sort of Prepsall solvent. And of course, then you can always wet sand with something fine like 2000 grit and buff when you're done.

I'm sure there are better lessons out there on the Internet. Maybe some of the body guys will chime in... It's been years since I've done anything like that... And now my girlfriend is dragging me off to help her try and fix her rusty, crusty 1988 Jeep...

Good Luck!!! And take your time. Good body work takes patience!!!

[Silver R/T]

usually you start off by sanding your filler with 40 grit, then 80. Primer surfacer/filler will will 80 grit scratches. You follow by sanding primer with 400-600 grit before sealer and then seal it, paint it, clear it. Clear coat you can start out with 1000-1200 and up to 3000.

[dads_69]

I've changed my old habits.
First off, make sure your body work/metal work is almost even, meaning the less ripples in body the better for mud/filler.
Sand first coat of bondo/thin/short hair fiberglass with 36 or 40 grit.
Second coat with 80 grit using a long board cross hatch style.
Only straight line your body work on edges but very carefully to not make them rigid.
Skim coat bondo with fill in glaze sand  with 80 at first then finish that with 100 or 120 grit.
Prime, preferably two coats when using a actual primer gun 1.8 tip or so then block down with 220 or 240 depending on how straight you want your ride.
Re-prime with two coats or three if need be.
Block with 320 wet dry or 400 if desired, seal base coat/clear.
Single stage paint, seal and paint.

Mark