i know this has been covered, but ive tried looking it up,c ouldnt find the right page, i have a new z-kit for my ccavalier, and i need to repaint it, i know i need a scotch pad to scuff it up, then sand paper to wet sand it, i dont know what grit to get. also do i need to prime it? im planning on painting 3-5 coats of colour, and 2-3 coats of clearcoat.

well from my experiance i dont like to prime bumpers(unless you got that flex primer stuff) because it has always made the paint flake off

^^^lol, primer is not making the paint flake off.. not preparing the bumper correctly is.

to the OP, please answer these questions for me:
You got new bumper from GM or Aftermarket company?
Is it bare plastic or primered? That will make the biggest difference in prep.
What paint are you using? Why do you plan on putting 3-5 coats of paint on it? What color are you using? Does it have poor coverage or why do you feel that you will be putting that much paint on?



Now this is what I would do at work.. meaning this will vary with different people due to their paint manufacturers instructions.
If bumper is bare plastic(rare to get from GM in bare plastic although I painted a G8 bumper 2 weeks ago that was actually bare plastic from GM)
-First clean off the bumper with a plastic cleaner
-Check for any damage that will ruin the paint job(gouges, deep scratches, cracks)
-Use a 3M Grey Scuffpad with Scuffing paste for plastic and scuff the entire bumper, I normally go over it 2-3 times due to it only takes like 5minutes to do anyway
-Hose it off with water
-Reclean with a Plastic cleaner and get it in the paint booth
-Tack the bumper off
-Spray Plastic Adhesion Promoter over the entire bumper
-Seal or paint bumper (my paint manufacturer tells me I don't have to seal before paint on raw plastic or factory clear coat/primer, Sometimes I do anyway but this will vary on your paint maker)
-Clear the bumper, Normally just 2 coats is standard. Depending on the car if I will be doing some work with wet-sanding to get it flat I will use a different type of clear to be able to put 4 coats of clear on instead of 2
-Wetsand and Buff any dirt or orange peel if desired.

If bumper is primered from factory(GM or Aftermarket company)
-Check it for any damage
-Using 600grit on a D/A lightly sand the larger easy to access with a d/a areas to scuff the primer and remove any orange peel
-Use a 3M Red scuff pad to scuff any edges, grooves, grille area, anywhere you couldn't get the d/a, no need to put alot of pressure, depending on color you can actually scratch it too deep and it will show in the metallic paints
-Blow it off and check it over to make sure everywhere is scuffed or sanded
-Get it in the paint booth and clean it with a Wax and Grease remover
-Tack the bumper off
-Check it to make sure you did not sand the primer off the bumper in some areas and exposed raw plastic, if you find some areas like this, use plastic adhesion promoter on those areas
-Seal or paint bumper(again I am told I do not have to seal over factory clear coat/primer, or bare plastic if it is clean and has no sort of fillers, or other paint manufacturer base coat exposed)
-Clear the bumper, Normally just 2 coats is standard. Depending on the car if I will be doing some work with wet-sanding to get it flat I will use a different type of clear to be able to put 4 coats of clear on instead of 2
-Wetsand and Buff any dirt or orange peel if desired.

its a stock gm bumper, its black, im painting it white, so i figured i would need several coats. but 600 grit is good?

so its already painted black? or is primered black?



Edited 1 time(s). Last edited Sunday, February 28, 2010 12:04 PM

painted black, i bought an automotive sandpaper kit, primer, cans of automotive paint and come clearcoat and a tack cloth, im planning on progressively sanding it, then primer, painting a few coats til it looks good, sand if i get orangepeel, then clear coat it afterwards

why wetsand before clear.. Clear will fill in and level any orange peel in the base coat.. I don't ever wet sand the base coat unless I find a @!#$ up in the color.. and I've never heard of people wetsanding it unless there trying to fix something.

the paint on the bumpers is starting to flake in places, so im wet sanding to fix that before i paint over it. smooth it all out

I understand that, but you said you are going to paint it, then wetsand any orange peel out before clearing.. Sanding orange peel in the base isn't going to change how the clear coate lays and how smooth it will be
plus that has no meaning to your response being there shouldn't be any relation to fixing where the paint has flaked, and wet sanding the base coat.. if your spots where its flaking off is still showing up when your painting you didn't fix it right.

ok, my last post talking about wetsanding is wet sanding before i even prime it, i didnt know that the clearcoat would just fill it out, good to know, but img onna need to wet sand, then prime, do i need to sand in between priming and painting?

Well it depends.. When i use primer sealer, i do that before painting. wait 10minutes and just paint over it. but primer surfacer(probably what you have) you will need to sand before paint..

Now is this all rattle can stuff?

Stephen (manta z) wrote:^^^lol, primer is not making the paint flake off.. not preparing the bumper correctly is.

actually the bumper was prepped right, later found out that the material the bumper was made of shouldnt be primed, cant remember what it was though, but after it flaked, we sanded the new paint and primer off, re-prepped it and painted it without primer, looked like brand new and never had a problem with it after that

^^was it a textured color impregnated bumper?

it is all rattle can stuff, duplicolour automotive stuff

Stephen (manta z) wrote:^^was it a textured color impregnated bumper?

nope, front bumper from a 97 dodge stratus

bumpers has gone well so far, sanded with 220 on some rough spots, then used 800 and 1000 to finish everywhere else, and i primed them today.

this is the old front bumper, regular cavalier bumper

new primed z24 bumper