i am about to have my car primered but i have to "rough" the old paint up first. Is there a specific type of sand paper that i should use as compared to regular sandpaper? thanks in advance.

Professionally primered? You can just use 220 or 320 grit... just make sure there's no shiny spots when you're done sanding or the primer won't stick. Just whatever you do, DO NOT EVER use rattle can paint stuff. Not saying you are, but it's a horrible idea in the end.

No my friend works at a local dealership in the body shop and he is going to primer it for me as long as i sand it a lil bit first.

Ahh ok... 220 or 320 should be fine I suppose... depends really... just make sure there's no shiny spots or the primer won't stick.

Actually check your existing finish and if it looks good (no dents or major knicks) then you can simply wetsand it with 400 grit w/ a DA, if it's not then sand with 220 and refinsh the surface

No need to wetsand with 400 if he's getting the whole car primered...

Primer is a scratch filler... so using 220 or so will cut through the paint faster, and won't hurt anything since it's getting primered. It'll save him some time in the end if all he's doing for now is priming it.

Again, make sure there's NO shiny spots.

(auto body tech/painter with years of experience speaking here)

Just do like Fallen Angel says ..........but one question ....why prime the whole car, just sand it and then paint it. Unless of course you have fixed some damage, just prime those spots.

coolfire

i just used a red scotch bright. It will last longer than sand paper, and you'll be done in about 20 minutes.