Removing Porsche primer
 

I'm involved in a project to have plain, black plastic side mirrors. Wanting to retain my regular painted ones, I ordered a set of new mirror housings, but they come primered with white paint. I want to remove this primer without "crazing" or otherwise damaging the black plastic of the housing. (I scraped off some primer from the inside to make sure the housing is black plastic, and it is.)

This white primer Porsche uses is incredibly tough. To remove it, I have tried soaking the housings in brake fluid, lacquer thinner, oil-base paint thinner, denatured alcohol, and acetone. None of these have had any effect. I'm stumped!

Anyone got any other ideas? Thanks!

Sand it off and polish them?

I may not be following the logic but why not just paint the white primer w/ black primer or black gloss or even plastic-coat? Seems a much easier and more durable option.

Good luck :)

That was my question as well.

Paint remover

Well, I actually did find a black matte spray, but I am such a miserable painter they came out awful. Plus, being matte-painted, in another place on the car, I am getting wicked chipping from tiny rocks, sand, etc., revealing the white primer. Ugh. Even if I could get a good black paint finish, the housing is going to be right next to the unpainted black plastic mirror mount. So I figure it is best to go with unpainted black plastic. If I can.

I am getting the black spray paint off, but so far nothing touches this white primer. Porsche musta been using water-base acrylics since before 2001, right? So what removes water-base acrylic paint?

That won't work. If you want get off that primer chemically, you'll destroy the ABS plastic.

If you want to have a dull black plastic look you can use something like black Plasti Dip: PLASTIDIP.EU ... The EU supplier of USA PlastiDip!

Also i have to say that it is no wonder that the paint came out bad if you put the mirror housings in brake fluid, lacquer thinner, oil-base paint thinner, denatured alcohol, and acetone. That will affect the primer and the later on paint will never come out perfect if it reacts with the things you've put on.

Regards, Markus.

Thanks, Markus, but no, all the paint removal attempts came AFTER the spray painting.

I received two perfectly primered housings. How hard could it be to spray matte black paint, right? So I sprayed, but had a flaw, like a hair. So I sanded that part and sprayed again. This time it was a particle of dirt in a different place. Sand, spray again. Got runs or drips. Before I knew it, I had WAY too much paint on the housings.

Okay, so have to start all over again. Brake fluid has worked for me before, and does NOT affect the underlying plastic. But the brake fluid won't soften and remove the primer. I tell ya, this primer is like ceramic powder coating or something. It is hard as nails.

I looked on the Web, and the suggestion was to try rubbing alcohol on acrylic. No effect. So that can be added to the list of things I've tried.

Hi Auf los!

this is a 2K primer (2 components). You will only get rid off mechanically. But that means in general to harm the ABS plastic structure.

So i would suggest to learn how to spray ;) – which is easy – or to bring it to a local paint shop for spraying.

Spraying means 90% preparation and 10% spraying. You can get good results with a spray can, but you will not get lasting results, because if you use a 2K paint the paint will be more adhesive and durable and if you use a pro spray gun the paint spray will be much finer, which also means a much adhesive result and a better paint picture (hope that is the right term – means a much finer paint surface.) Also 1K paint doesn't always adhere to 2K primer very good.

Regards, Markus

Well, I hope you're wrong about the primer, Markus. I am familiar with the 2-part paint process, but I would think primer would be a single paint. Whether it's 2-part or 1-part, it WAS a paint that could be thinned before spraying, and if it could be thinned, it must be soluble. I just have to find the right chemical remover.

I have an airbrush and can successfully paint small models...it's only when I try to paint large pieces like the mirror housing that I have such rotten results.

A modeling website I visited suggests that a Lestoil soak might remove the remaining paint and primer without affecting the plastic. I'm giving that a try.