Trouble With Painting Mouldings

[Brady]

My prep process.

- Wash with dish soap
- Sand with 180
- Scrub with SEM Soap
- Rinse
- Spray ahdesion promoter
- Spray with Krylon Paint

Result: This snowflaky shit, wtf do I jus wetsand it and paint it again? Has anyone run into this before?

What do I do? this is annoying, and my car looks hooptee as shit right now with no mouldings and the back trim removed (thats another shitty story)

thanks in advance

 

[Facime]

Might not be scuffed enough, might be the wrong kind of primer, or you may be painting over the adhesion promoter incorrectly (too soon or not soon enough?) Is the primer specifically for plastics?

 

[Brady]

Yes its made for plastics

Krylon doesnt need primer either

 

[Poodles]

yep, krylon/adhesion promoter reaction...

 

[Facime]

ohh god I hate krylon paint! If you are just rattle canning it, I recommend Plasticoat.

 

[Enraged]

that happened to mine too, but not the second time around? i followed the directions of the guy at the auto paint store, but it still happened... my trim is good enough for now, until the entire car gets painted.

 

[p5150]

I have only used adhesion promoter on plastics with quality paint. You are using junk paint. If you still want to use rattle can paint then dont use the adhesion promoter. 180 grit is too rough as well. You are going to see the sanding lines after paint application. 400 at the roughest.

 

[Brady]

whats quality paint than? sem?

 

[Enraged]

i had colormatched automotive paint, which the paint store put into a spray bomb for me, and i had the same problems. i must have had contamination at some point in the process, most likely from the tack cloth i used

 

[WhtMa71]

If rattle canning it, I would at least use Duplicolor. Also, some paint stores can custom tint paint for spray cans..Kinda expensive though. I would just grab a small cheap touch-up gravity fed paint gun from an autoparts store and get a little paint like a quart mixed up.

 

[87soup]

You shou8lda hit it with rubbing alcohol before paint!!! You have a chemical on the plastic!!!

the problem is Not the paint:naughty:

 

[WhtMa71]

^ That could be too. Use either paint thinner to clean before paint or some of the grease and wax remover cleaner.

 

[flubyux2]

its definitly contaminants in the material leeching out when the solvents of the paint are laid down. the paint itself is lifting.

also, just use 400 grit as mentioned before. thats the roughest you want to use before laying down any paint. also, painting the softer urethane strip isnt really a good idea since itll be much softer than any paint you can put on top of it and that material, i think, is so soft that it can retain chemicals.

what i did was peel that strip off all the moulding on my 91 and then repaint all of it with the proper Super Red II by duplicolor and then reattached the molding. it lookd 100% factory with the right amount of texture and everything. btw, that soft strip is supposed to be translucent and color-tinted. its not opaque or solid colored.

 

[Facime]

If rattle canning it, I would at least use Duplicolor.

Yes Duplicolor, that what I meant. The little 5oz "Import Color" stuff in the paint code of your choice. Thats what I used for my gauge bezel and fiberglass radio bezel.

 

[Brady]

Ok so I'm going to buy some liquid sandpaper or paint thinner to remove what is already on there (effectively making all the time I've spend on this useless ). Or can I just use rubbing alcohol? I'm sure I have some of that around.

Then I'll sand it down with 1000 grit sandpaper?

Than I'll spray with adhesive promoter.

Then duplicolor import (super white)

Does this sound right?

 

[p5150]

When I was talking about quality paint I was referring to a catalyst-based professional paint.

Sanding with 1000 grit is too smooth. You need some texture for the paint to stick to but the texture has to be smooth enough for the paint to flow out and not show the sanding lines. Usually 400-600 grit is what you want to use for that.

 

[WhtMa71]

And as for removing the paint, if parts of it really bonded well..you'll most likely have to use plastic paint stripper..That is, paint stripper thats safe for plastic.

 

[Brady]

do you know of any good plastic paint stripper?

 

[cuel]

Don't touch the part with your bare hands after it has been washed. The oils from your skin will cause the same problems. Buy a box of nitrile gloves at O'Rielly's or A.Z. They run about $12. If you use paint stripper on that soft rubber, it'll eat it. More than likely, even the stuff that is safe for plastics. Just sand it out with 220, then sand it again with 400. Once it's smooth, wash it with a mild soap and water mix, rinsing immediately. I usually wash and rinse everything once, then rinse again while scrubbing with a clean brush.

Personally, I like Flubyux2's idea best, but it's probably too late for you. If you've trashed that rubber strip, you might just peel it, and paint the moulding underneath.

 

[Brady]

so the top (larger portion of the moulding) is plastic but bottom is rubber?

at this point I think i'm gonna go witht he paint stripper and sand it again and jsut have a autobody shop paint it for me so i can be done with it