best grit of sandpaper for bare metal?

Someone feel free to point it out if there's something wrong with doin it this way.. but I take it down to bare metal with like 60 but I'm not too rough with the 60 and I find that it doesn't fuck up the metal but the sanding does leave it etched to the point where an average build primer sticks well and levels out nicely with like 2 good coats.

You could even knock down the layers of paint with as coarse as 40, then 80 it the rest of the way and smooth it out with 180, it will not remove too much metal, but before priming, I'd definitley 180 it, or you could possibly have sand scratch swelling from the 80 scratches. Self etch primer would be ideal, but if you don't have it, or whatever, you could even use an epoxy primer on the bare metal for now to stop any corrosion. Later you'd need to scuff it real good if you wanted to high build or whatever, but that's also an option. I wouldn't just spray high build primer surfacer over bare steel though.

You could just hit it with 80 on a mud hog but just be careful not to get the surface to hot. You dont really have to hit BARE METAL with 180 as long as the paint is gone.

Originally posted by Lo94S-10



Self etch primer would be ideal, but if you don't have it, or whatever, you could even use an epoxy primer on the bare metal for now to stop any corrosion. Later you'd need to scuff it real good if you wanted to high build or whatever, but that's also an option.

if going the epoxy route, follow the directions to topcoat w/ sandable primer BEFORE its fully cured, that shit is a bitch to scuff up later!

Edited: 11/10/2006 1:12:11 PM by BclassBD

80 grit is the heaviest you should ever use on baremetal, anything else is just going to cause you to go through the building up of primer process. waste of money. 80 grit is fine, even 120 is fine, but like he said, just get it down to bare metal. You can use a paint stripper, a scotch bright wheel, and wire wheels as well as a different direction to getting to bare metal

You should always use a zinc rich etching primer whenever you go to bare metal..yeah you can use an epoxy primer and get away with itfor a few years ..maybe even never have problems..I know I've done it before..but to make sure there arent any proiblems..use etching primer..cause you know if you dont ..that will be the one time it doesnt work and 6 months after you paint your truck the primer will let loose or start corroding under the surface creating lil rust bubbles..ask anyone thats ASE certified or have I-CAR experience..they know..

I know that with PPG'S NCP271 primer you can prime bare metal even with 40 grit scratches and you wont get shrink back or swelling, and it is an etching and high build primer in one. And I have never had a problem with a mudhog takeing away tomuch metal or any grit of sandpaper, the grit wears off before you can do much damage, And just for the doubters one of the trucks we did this too is over 6 years old and not a sign of problems.

chemical strip
50 grit roloc
etch prime-one like coat
epoxy primer
any body work you need to do
urathane high build primer for block sanding
then paint

you could substatute the 50 grit roloc for a red scothcbrite roloc and that would help save the metal

Originally posted by jonesn



chemical strip50 grit roloc etch prime-one like coat epoxy primerany body work you need to dourathane high build primer for block sandingthen paint

Wasting money and material with an epoxy primer. Also, all of your body work should be on bare metal and not on top of existing paint that may have a chance to fail sometime in the future. Then etch the bare metal that is left, Prime everything, let the primer FULLY dry, block it, paint it.