Interior panel paint

[steve from staten island]

Im having trouble painting the smooth upper part of the rear interior panels for a 69 satellite convertible. Ive tried everything and the trouble started when i used some of the prep products for plastic. The paint either lifts or cracks no matter what or how i prep or paint. Ive sanded down to bare plastic used a primer, not used a primer same thing. I was using Herbs interior and now used a regular satin plastic paint. I thought i had it decent but looked at it after a few weeks and the paint again had cracking all through it
Im out of ideas, any suggestions are appreciated,

 

[moparnation74]

Are you slowly bringing the color out and allowing time between coats?

It is not sprayed like paint and too much build up on an initial first coat will cause issues...

You dust it on, multi coats and a long process...

 

[texas69bee]

I'm not familiar with the part you are painting but it sounds like you have oil left in the plastic. You can use something like Naptha for a deeper cleaning then go over it with bulldog adhesion promoter.
Are you using Herbs products all the way through the process. If not contact them to find out if they are comparable.

 

[gkent]

I think ...
1) remove the old paint
2) clean with a good wax and grease remover - use a clean rag to wipe away the residue, its pointless if you just let it dry on the surface
3) use a SEM product

But there are two dilemma's
1) you should remove the paint you've sprayed on and lacquer thinner will likely melt the plastic.
2) I'm betting its actually age cracking in the plastic, not a paint issue. After a couple weeks of expansion and contraction the cracks appear in the paint. The clue here is the paint is cracking - not lifting.

If you use a SEM product, it has some flexibility so it may be able to span those minute cracks in the plastic - if that's the cause.

 

[eldubb440]

X2 on the Bulldog and light coats

 

[moparnation74]

If you spray the BD thick you will have the same cracking problem....every coat is a dusting.....

Clean and clean and reclean...

Also you will have to remove what you sprayed if you can....sometimes you can't and have to find another part

 

[PurpleBeeper]

All is not lost. I agree with these guys about removing old paint & checking for cracks in the plastic. When you remove the old paint, test THE BACK of the panel in a small spot to make sure you're not using something that attacks the plastic. "Usually" solvents containing "ketones" attack a lot of plastics (e.g. methyle ethyl ketone MEK, acetone....basically any chemical that ends in "one" you should be careful with). Most alcohols (e.g. rubbing alcohol aka isopropyl alcohol or denatured ethanol) won't hurt most plastics. Some weird exceptions are toluene which can be incorrectly named "toluol" or xylene (aka "xylol") are NOT alcohols, so be a little careful with those too.

In all cases.... test on back in a small spot first. If the plastic softens or gets sticky, try something else.

Now the good news..... if it's JUST the smooth top portion of the rear interior panels, then a much safer (& more time consuming) process is to sand it...maybe 1000 grit or something super fine. It takes a while, but you won't damage the panels.

And like these guys say... clean, clean, clean before painting... probably rubbing alcohol (safe for plastic) or toluene/xylene if they don't attack the plastic...these take up oil better, but might hurt the plastic, so check on a test spot on back of the panels first.

I had good luck using vinyl interior paint in very light coats on mine.

 

[dieseldazzle]

Lightly sand blast it in a cabinet and from there use only sem low gloss interior paint. There is a post on my 68 charger where I did this if you search

 

[Beekeeper]

Hey Steve,
One thing to remember when sanding plastic interior parts is to clean them very well before sanding. If there were any oils or types of protectants used on it sanding before cleaning will
only embed the oils in the plastic making it nearly impossible to remove.