Helping a friend to paint some black plastic fender flares on a small truck want to paint them body color silver.
After doing some research, first would be Scotch Brite, 2nd Adhesion Promoter, 3rd Sealer then base.

Is this a good Adhesion Promoter? https://www.amazon.com/Kleanstrip-Promoter-15OZ-AERO-KLE-ETPO123B/dp/B005IUBMS6
What sealer?
Do I need to ask my paint dealer to add flex agent in the base? I was going to use Nason or Eastwood
I saw some people using adhesion promoter and primer sealer in one. Any good?
Thanks for any info. Trying to learn to do more paint and body.

I know some better paint and body guys will chime in but I buy my paint from an automotive paint store, not a parts store or general paint store, because they are invaluable about information.

My favorite supplier told me how to fix stuff the books said couldn't be fixed without a sand off and reshoot.

Maybe they can help.

Personally I would use the flex agent. Flex agent on a rigid part will be fine so it won't hurt.

i am a PPG certified painter. i pant plastic all of the time.
the first step is find out if they have primer on them or not. i use a lighter colored fine grit, 600+. sand paper and lightly sane it in a hidden area. if the lighter colored s paper shows primer. then scuff with red scotch brite, seal and paint. IF you apply adhesion promoter over primer this can cause a adhesion problem.

if no primer.
then look on the back side for type of plastic. there should be a plastic type code molded into it. poly propylene based plastic and their mixes need adhesion promoter for paint to stick properly to it. ABS type doesn't need adhesion promotor. .
if you can't see any identify marks just cut a SMALL sliver off and place it in some water. try to force it under the surface. surface tension will usually float all plastic until you force it under the surface. PP plastic and their mixes will float 100% of the time. ABS type will sink.
another difference is ABS type plastic is usually rigid and PP is flexible.

kleanstrip is a quality product it should work fine.

now the kicker.
if they are primed with cheap primer the paint can fall off no mater what you do. i just ran into this on a cheap aftermarket Ford Edge lower tail gate molding the cheap primer peeled off taking the top coat with it.
fast test is wipe the primer down with some enamel reducer or possibly thinner. thinner can attack plastic so i don't like using it. reducer usually doesn't. a solvent based wax and grease remover usually removes cheap primer and usually doesn't attack plastic. if it does it will be less aggressive than reducer.
if it wipes off easily remove it all and go back to the top and find out what plastic they are made of.
also if the priner doesn't have a good film build and it's over PP plastic. the primer can fall off taking the paint with it.

i forgot about flex agent. i haven't used flex agent in over 20 years. don't ever remember having problems without it. decent quality URETHANE paint has enough flex to it so it isn't necessary. if you use it. this makes wet sanding and buffing dirt much more difficult.

Thanks for the info. Good tips.
It doesn't look it has primer just unpainted plastic.
It is an OEM Toyota flare most are black but some are painted body color.All the same flare.

I do usually buy from an automotive paint store since I live in a low voc state most places won't ship to us.

from my experiences Toyota plastics are usually sold without primer on it. also their plastics are usually the cars you see on the road with the paint falling off it.

i also forgot to add.
if there isn't primer on it. DON'T aggressively sand it.
if you sand with a red scotch brite and spray with adhesion promoter will swell up the scratches and create a BIG mess.
use the least aggressive scotch brite you can find.
i use the PPG 3 step one choice plastic prep system. this is the best plastic prep system on the market today. the su4901 plastic cleaner has a green scotch brite bonded to a sponge. the su4902 adhesion wipe and the su4903 adhesion promotor spray. i haven't ever seen or heard of a adhesion problem when using it in 15 years. the su4903 has been replaced with a newer product. i don't have the # for it.


i would add CLEANLENESS of PP based plastic is extremely important when prepping to paint.
before the SU system was developed i used to use clean with a gray scotch brite and white wall cleaner. i would rinse down with water, spray with WW cleaner, LIGHTLY scrub with a gray scotch brite and rinse. blow dry and apply adhesion promoter ASAP, best results if applied within 15 min after washing it down. PP plastic has wax as part of it's chemistry. the wax floats to the top when it contacts to the air. this is the biggest reason why the paint falls off this plastic. the WW cleaner removes this wax on the surface and lets the AP bite into the plastic.

Thank You, I will get the prep system.
I will start when weather permits.

certified PPG as well. My suggestions is follow this p sheet. Toyota will be bare plastic. https://max.ppg.com/adaptivemedia/rendition?id=cb8b03926903cd9cf5f4341751f0098be0d912aa