Ok. Working on painting a plastic grill for paint. I've done 30 of these. This one had some adhesive glue on it. Would not come off with the eraser wheel. Took my DA sander to it with some 220 grit.. Guess I went too far and went to bare shell. When I prime that area, it lifts.

Figured no way around it but to sand it all down..

How do you guys address this issue??

E-coat? On plastic? Unlikely.

What kind of finish do these grilles have? Painted?

Doesn't matter anyway. If the edge reacts when you prime then you'll have to remove it all although an epoxy sealer may work.

See my post here for some more, probably relevant, information.

use a waterborne primer,

sikkens makes a nice one or sherwin williams makes a nice 1k waterborne primer.

it will seal off any areas lifting on you


or strip it all off

This black coating is what is making the paint lift, even the primer around the edge. No matter what I do, try to feather it or not, still lifts. I even tried clear to see if it would seal it.. no dice.

It's just a basic black grill from Ram/Dodge/FCA.. "paintable" as they say..

I've always just had to scuff these with a 3M pad and had great results. But since this one had some sort of glue/gunk on it.. I know now.. don't go past that coating whatever it is..

I've got about 98% of it sanded off. I'll work on the rest tonight.. the tight corners will have to be done by hand... but then FINALLY be able to prime it.

Things like this make me want to quick doing side work!!!

It's almost like when you sand through to the adhesion promoter.. huh?

Maybe that is what it is..

what kind of primer were you using and was the part an aftermarket part. I've never really had a lifting problem with Ecoat. and as Dave suggested waterborn primer does work, its handy to have around.
Jay D.

Could be a grill a customer sanded then decided it didn't fit and repeated some crap black on it to return it. E coat don't lift like that.

Just sand it all off.

Adheasion promotoer and prime it. Done

Yeah, I have it almost gone. Just need to touch up a few corners and I should have it ready by tonight.

Sucks, a lot of work. Would have been easier to paint a chrome grill almost!!! haha

So, would a waterborn primer have covered this without the lifting shown in the above pictures?

Do that area, and the rest with HB primer and would have been ok?
May need to check into that! Just incase.

Just use waterborne on the whole thing.

But it's just a cover up of a mess and should not be the first choice.

Stripping to a sound substrate you'll have piece of mind knowing it will last.

Not sure why people keep speaking of e-coat on a plastic part. If proper procedures were followed and a failure ensued, I would simply ask for a replacement part instead of stripping a part to the substrate. I would not waste shop time and money carrying another's error. Shop owners have a different outlook.