Best primer for long lasting job on bumper?

V

VB

Hey guys,

I will be painting a bumper soon and I would like some input on the best procedure for a long lasting job. It's for my buddy's car and he plans on keeping it a long time. The bumper will be brand new, so no existing paint is already on it.

Here was my plan:

-Scotchbrite pad (not sure if I should use red or grey) with 3M scuff it gel
-Apply 2 coats of SPI Epoxy, then wait 3 or 4 days
-Wet sand it with 600 grit
-Basecoat and clear coat

Do I need an adhesion promoter? The manufacturer lists the bumper is made from PP, not sure what that is. I would assume it's some type of plastic, I know it's not fiberglass that's for sure.

Any advice would be greatly appreciated.

Thanks!
 
Polypropylene needs an adhesion promoter. Are there any defects that need to be corrected?
 
Use the gray only, too avoid burring.
ALSO, skip the 600 wet, could be a bad deal.
Treat PP, same as TPO or TEO amd PE.
After adhesion promoter spray one wet coat of epoxy, let set a couple of hours and ACTIVATE your base and shoot base.
Use a slower activator in the clear is also very important, since you will live with this bumper the rest of your life, it sounds like.
 
Bob Hollinshead;27589 said:
Polypropylene needs an adhesion promoter. Are there any defects that need to be corrected?
Click to expand...

No defects, it's a brand new bumper.

Barry;27594 said:
Use the gray only, too avoid burring.
ALSO, skip the 600 wet, could be a bad deal.
Treat PP, same as TPO or TEO amd PE.
After adhesion promoter spray one wet coat of epoxy, let set a couple of hours and ACTIVATE your base and shoot base.
Use a slower activator in the clear is also very important, since you will live with this bumper the rest of your life, it sounds like.
Click to expand...

OK so I will stick with the grey pad.

What happens if I get some dirt in my epoxy coat? This is why I wanted to sand it, I figured some dirt will end up in it since I'm spraying at home.

I plan on using the Universal clear, should I activate the base coat with the same activator?
 
Activate your base with the spi activator-works great. A cap full of activator to a mixed quart is what I do but many use a shot glass-if you're within that range all will be fine. Shoot your epoxy then a couple coats of color and allow it to flash off to the point you can denib sand, then shoot a couple more coats of color, let it flash good so you don't trap any solvent and apply your clear. Caution some basecoats shouldn't be sanded-what basecoat are you using?
 
Bob Hollinshead;27605 said:
Activate your base with the spi activator-works great. A cap full of activator to a mixed quart is what I do but many use a shot glass-if you're within that range all will be fine. Shoot your epoxy then a couple coats of color and allow it to flash off to the point you can denib sand, then shoot a couple more coats of color, let it flash good so you don't trap any solvent and apply your clear. Caution some basecoats shouldn't be sanded-what basecoat are you using?
Click to expand...

I believe it will be either Dupont or PPG base coat, it depends what I can get locally.
 
Plastic adhesion promotor

VB;27586 said:
Hey guys,

I will be painting a bumper soon and I would like some input on the best procedure for a long lasting job. It's for my buddy's car and he plans on keeping it a long time. The bumper will be brand new, so no existing paint is already on it.

Here was my plan:

-Scotchbrite pad (not sure if I should use red or grey) with 3M scuff it gel
-Apply 2 coats of SPI Epoxy, then wait 3 or 4 days
-Wet sand it with 600 grit
-Basecoat and clear coat

Do I need an adhesion promoter? The manufacturer lists the bumper is made from PP, not sure what that is. I would assume it's some type of plastic, I know it's not fiberglass that's for sure.

Any advice would be greatly appreciated.

Thanks!
Click to expand...

If this is a new bumper cover you need to check if it already has primer on it from the factory OEM or aftermarket. If it has primer on it do not use plastic adhesion promotor. Plastic adhesion promotor is for bare untreated plastic only not to be used over primed urethane bumper covers. If the plastic is bare then scotchbrite with sanding paste wash with soap & water. Dry then reclean with water bourne pre -cleaner dry again making sure you have removed all sanding paste residue. (Very important) apply plastic adhesion promotor to bare plastic. Follow with epoxy as a sealer or some prefer to apply urethane primer flexed & then sand & paint. If the cover has primer on it you do not need adhesion promotor. Epoxy as a sealer & paint or Urethane prime, sand & paint. As suggested in other posts for best durability use clear activator in your solvent base at 1 cap full per sprayable QT. Slow solvent in base with 20-30 min flash between coates & slow activator in clear for best durability & results. SPI products do not require flex additive but on really flexable plastic parts or for extra insurance I add flex to those jobs that you know you will have to live with. (family, friends, etc.) Will extend dry times but i feel it is worth it on the right jobs.
 
Hey guys
Why use slow activator for "best durability". Thanks for info
Pat
 
streamlinecollision;27696 said:
SPI products do not require flex additive but on really flexable plastic parts or for extra insurance I add flex to those jobs that you know you will have to live with. (family, friends, etc.) Will extend dry times but i feel it is worth it on the right jobs.
Click to expand...
What flex additive do you put in SPI clear, and how did you find out it was compatible? I have Standox flex additive that I use in their Nonstop primer-sealer, but have never considered putting it in SPI clear because I assumed that if SPI clear needed a flex additive, they'd sell one.
 
No need for flex in SPI clear, I've got some samples sprayed on saran wrap that are a few years old and I can still fold them without cracking.
 
Bob Hollinshead;27768 said:
No need for flex in SPI clear, I've got some samples sprayed on saran wrap that are a few years old and I can still fold them without cracking.
Click to expand...

:encouragement:
 
We use sikkens elastoactive flex additive in it. As i said I only use it in clear on those jobs that I want the little bit extra flex like really soft plastics or the jobs that i feel require a bit of extra protection.
 
Slow activator allows the clear to stay open longer ensuring the solvent has more time to come out of product. Also once it is dry it will have a harder finish than fast or med for the first few weeks. My opinion is it just looks better as well apperance wise.
 
So I can use the Universal Clear slow activator in base coats such as Diamont, PPG, and Lesonal base coats? Can I use the normal or fast Universal clear activator too, or just slow?
 
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