Clearcoat Failure

I am not a bodyman.

The clear coat on the old Miata has decided to fail on the rear bumper, right under the licence plate. It very quick lifted up in large bubbles, and has almost all peeled off now.

Why would it do that? And is there anything I can to to stop it / repair it that won't involve repainting the whole bumper?

Nope, you're boned. It's a chemical reaction like rust. Sand it all off and start over.

single stage red ftw!

foxtrapper wrote: Why would it do that?

Because in the early 90's, manufacturers hadn't quite figured out water based paints yet. You should see my '95 Dodge...

Ian F wrote:

foxtrapper wrote: Why would it do that?

Because in the early 90's, manufacturers hadn't quite figured out water based paints yet. You should see my '95 Dodge...

gota throw the EPA under the bus here as they where the reason for the switch... talk to any body man who sprayed in the 70's and he'll tell you how great it was be painting back in the day... lol

kinda like in the late 70's early 80's auto manufacturers hadn't figured out how to make make power while being clean.... so we had a corvette with 5.7L and only 180hp...

Sand it off carefully and re-clear it. Or sand it off and paint with a single stage red. You probably could do a pretty decent cheap job using spray bombs also.

donalson wrote: gota throw the EPA under the bus here as they where the reason for the switch... talk to any body man who sprayed in the 70's and he'll tell you how great it was be painting back in the day... lol

Yeah, paint manufacturers didn't put all that harsh crap in the paints for fun. They did it because it made better paint.

My father used to have a '33 Chevy phaeton, and the lacquer-painted undersides of those big fenders were still like black mirrors 40 years after it was originally shot.

Really? it's very localized, which made me think it might be a bad repair, but I can't see any edge.

I remember the Dodges with whole sections of paint flaking off. I guess in some ways, that is what the clear coat has done.

Sand and repaint? Pff, it's a plastic bumper, ain't gonna bother. Well, maybe I'll try and it'll be a father and son learning thing. I guess I can always teach him how to do body work wrong. Cause I am not good at it.

Yep. That seems to be normal. On my truck, sections of the clear have separated from the color coat. Looks... lovely... one of my many projects is to $50-paint the whole thing.

foxtrapper wrote: I remember the Dodges with whole sections of paint flaking off. I guess in some ways, that is what the clear coat has done.

My brother was an engineer at Chrysler back when they switched to water based paints, he said they did struggle to get the process to work right.

Nowadays it seems all the auto manufacturers have figured it out so it's not a problem anymore.

"My brother was an engineer at Chrysler back when they switched to water based paints, he said they did struggle to get the process to work right."

I've heard that if you were caught wearing deodorant in the paint shop you were fired right then. The out-gassing was thought to be one of the problems. Man who would want to work in a paint booth with a bunch of ripe smelly workers....stinky.

bravenrace wrote: Sand it off carefully and re-clear it.

THIS does not work.

Clear fails for a couple of reasons. Generally, it goes bad because it was applied too thin or because it's aged and thinned thanks to environmental issues. If it's peeling, it's likely an adhesion issue (improper prep) and/or moisture has found it's way between the coats.

My Scirocco's hood and front genders are doing this. I think it had a minor fender bender years ago and got resprayed back decades ago. 80's German paint tends to fade to dull, no clear coat peel.

All things equal I'd prefer to just remove the clearcoat and have it a uniform dull red until I can get a proper respray.

The back bumper of my Civic is doing that badly.

In reply to ddavidv:

That's interesting, since I've done it several times with success. Do you think I'd give advice on it if I didn't know it works? Perhaps it didn't work for you because you didn't do it properly.

I've not done it, but I've also never (until today) found one single person, in all the eternal threads on this subject, who has A) actually attempted it and then B) had it actually look like something other than complete crap.

If it's on a Miata, it may be a respray. Most Miata colors aren't clear coated. And if it was resprayed on a budget, part of the problem could simply be the quality of the materials used. Cheap clear will suffer more from UV.