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Plastic Bumper

#1
Somehow I got roped into doing some collision work for a friend. She wants me to shoot a new fender and plastic front bumper for her daughters Civic. It is the generic Silver they have used for years. I have a new can of adhesion promoter on the shelf but I also have a lot of white epoxy. I am thinking of just shooting some thinned white epoxy then base then UC. Is that reasonable approach? Should I use the adhesion promoter on the plastic bumper first?
 
#2
What I have been told is modern polyurethanes are enough to go right on top of the plastic since they are basically the same material. I changed and did the bumper ends on our 99 GMC Jimmy work truck, have cracked them up again and they are just broken, no paint is lifting.
 
#4
This is a new aftermarket bumper. It said it was painted already with a solvent based primer and to just scuff and paint so I just hit it with a scotchbrite.
 
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#5
This is a new aftermarket bumper. It said it was painted already with a solvent based primer and to just scuff and paint so I just hit it with a scotchbrite.
If it's primed already you'll be fine, I usually scrub the primered ones with a sanding paste and a gray Scotch pad first.
If I'm going to reprime I use a red one.
If you scuff it real good and it's primered already, you'll get black primer on the scuff pad. If you don't then you need
adhesion promoter.
The only bumper I have ever had a come back on was one I bought new and forgot the adhesion promoter.
Even though I scuffed it real good first with a red scuff pad and used epoxy primer it still flaked off two years later.
 
#6
If it's primed already you'll be fine, I usually scrub the primered ones with a sanding paste and a gray Scotch pad first.
If I'm going to reprime I use a red one.
If you scuff it real good and it's primered already, you'll get black primer on the scuff pad. If you don't then you need
adhesion promoter.
The only bumper I have ever had a come back on was one I bought new and forgot the adhesion promoter.
Even though I scuffed it real good first with a red scuff pad and used epoxy primer it still flaked off two years later.
Thanks, yes it has primer and I got black dust with the scuff pad.
 
#7
I have SPI adpro and my sons Mazda 3 bumper needs a repaint. What do you do with a plastic bumper which is mostly still topcoat intact but has a few gouges and scratches down to the plastic? I've read here that putting adpro onto a painted surface is not a good idea, so do you carefully put it on just the bare plastic scratches with an acid brush or similar then epoxy the whole bumper?
 
#8
What I do is just use a touch up gun with the fan narrowed to spray the bare plastic area. A little overspray onto the paint doesn't seem to hurt anything as long as you just spray a medium coat and don't flood it. Also let it dry 30 minutes to let the overspray flash off real good.
 
#9
I use adhesion promoter on painted surfaces all the time-never a problem.
It fills the scratches before base coat and make a uniform surface on the repair and
surrounding paint area so the base blends better with the existing paint.
A lot of painters use it a lot for hard to prep areas like door jambs just to increase adhesion
where sanding may not be thorough.
 

Chris_Hamilton

Trying to be the best me, I can be
#10
What I have been told is modern polyurethanes are enough to go right on top of the plastic since they are basically the same material. I changed and did the bumper ends on our 99 GMC Jimmy work truck, have cracked them up again and they are just broken, no paint is lifting.
Only material that what you are talking about is applicable to is PU (polyurethane) which is almost never used for bumpers anymore. Vast majority (all?)of stuff now is TPO which if you paint over it without adpro, is going to peel like an onion as soon as the paint starts to cure. Coworker painted one recently, "didn't realize" that it wasn't primed.:mad::rolleyes:. 95% of the paint on that one came off with the blow gun.
If it's primed I generally don't use ad pro, just a light scrubbing with scuff-stuff and a grey scotchbrite.
 
#11
The aftermarket bumpers come in different qualities and types of primer, some are solvent based primed, others waterborne primed, some others seem with lacquer primer, the worst kind...

If the bumper is primed with waterborne/based primer, it is usually pretty thick, has lots of substrate ,it just needs light sanding and ready for sealer and base,,

Solvent type primed bumpers are trickier, the primer is thin, easy to burn tru, so better to apply adhesion pro, sealer and basecoat..

Now if the bumper has primer on it and it feels “greasy”, the water slides off it fast, the back of bumper feels oily, then that is trouble despite being primed, it must be treated as bar plastic....this winter I have had 3 Capa certified bumpers like that, learned the hard lesson on one of them.
 
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