I have an 85GT that i had painted about 5 years ago. I had the painter sand it back down to bare parts and repaint it all off the body, then reassemble.
This year, the paint has started to bubble off the car. I took it back to him and he is going to repaint it for me.
He sliced into one of the bubbles and peeled the paint. He was able to take a good chunk of paint off of the car. So none of it is sticking. He is at a loss as to what to use to get this new paint job to work.
I know many, many of you have painted your cars with success. Can you help me out by letting me know what my paint guys needs to do to get the paint to stick and look good?
If the primer is peeling off then I would say that the surface cleaning/prep was insufficient. Oil / wax residue may have remained on the surface prior to sealing.
Our resident paint experts have been quiet for the last few months....
If the plastic panels were ever treated with paint remover instead of sanding, the chemicals stay in the plastic and cause trouble later. Also, the surface needs to be a little rough for the primer...maybe about 180 grit or so.
Our resident paint experts have been quiet for the last few months....
If the plastic panels were ever treated with paint remover instead of sanding, the chemicals stay in the plastic and cause trouble later. Also, the surface needs to be a little rough for the primer...maybe about 180 grit or so.
Garrison is too busy playing Dirty Harry, kicking in thug's chests at his front door
But thats the question....which parts are bubbling? The roof, decklid, and hood..... or just the flexible panels?
[This message has been edited by IMSA GT (edited 06-14-2016).]
Hood (below the headlight covers), passenger quarter panel (directly behind the door handle but not on the door), roof (around the sunroof and down along the sides of the front window).
The painter maintains that he did not use chemicals originally and that they used 180 grit.
the Paint is sticking to the pimer, but the primer is lifting. The primer used was: Sherwin Williams Primer 27 Grey.
He wondered about using an airborne primer as he used to use them on Corvettes back in the day.
Your painter may have done everything right. One problem with SMC panels is that if there is a cut in the paint, water can get into the fiber resin and expand it. Does it look like this picture?
[This message has been edited by Gall757 (edited 06-14-2016).]
Its an adhesion issue due to sanding it down to the white SMC. Common problem and there seems to be no right answer. To me its due to water. If you look under the hood and headlight doors wear the upper and lower panels are glued together there needs to be a bead of seam sealer along the seam. Water gets in there and is absorbed by the SMC. Eventually it reaches the top. I've taken the headlight doors apart and there is NO primer underneath. I can only assume that the underside of the hood skin isn't either. The sunroof does this from leaking. Water seeps into the SMC from sitting underneath the rubber seal. Try using an epoxy primer like PPG DPLFor DPLV. Grind the bubbles and let them air out in the sun or under a heat lamp for a day or two. Then prime it (follow the directions to a T). Then put any filler over top the primer. Prime again with regular primer as long as no white SMC is showing. If it is epoxy prime it again. But unless something is done underneath the panels, it will probably happen again unfortunitly.
Thank you for that information. it makes sense. just since the spring it has had to sit outside and the paint issue popped up shortly after it was sitting outside.
I will talk to my paint guy and give him the information. Then i will get the sunroof looked at as I know it leaks.
"SpectraPrime ® 2.1 VOC Color Primer Surfacer is a premium quality 2K-urethane primer-sur facer that utilizes state of the art Ure-Flex™ Technology to provide the ultimate in performance, versatility, and productivity in areas that require low VOC coatings.
and
SUITABLE SUBSTRATES
Treated Steel OEM Enamels Body Filler Treated Galvanized Steel Refinish Enamels Etching Primer Treated Aluminum Fiberglass SW Plastic Adhesion Promoter
Note SMC (Sheet Molded Component) is not listed as a suitable substrate.
If the SMC panel had any white showing it had to be sealed with epoxy primer before putting the 2K-urethane primer-surfacer on.
Also regular Bondo will not stick to SMC, you have to use something like Vette Panel Adhesive/Filler. It is designed to stick to the SMC. "
------------------ 88 GT 5 Speed Black with gray interior 3800 SCII Swap Complete. Paint Complete Detailing in Progress
IT RUNS!! IT'S QUICK!!
"Real integrity is doing the right thing, knowing that nobody's going to know whether you did it or not."
We had a 97? Sunfire. Minor front end bump and the paint chipped on the plastic bumper. I was only a kid but I remember the shop tried repainting it like 3 times. Everytime it would eventually chip off. That's why I'm Vinyl wrapping my car
A while back I was checking into what I would need to redo an engine cover that had a luggage rack. The holes where the rack mounted, had little chips which exposed the SMC. The biggest difference between SMC and fiberglass panels is the amount of epoxy used. On normal fiberglass there is sometimes enough epoxy in the substrate to keep stuff from "wicking". On SMC, if any of the fibers are exposed anything will wick down into the substrate. Like stated before, you will need something to draw out the water. And many days of keeping it dry, including humidity. While checking what it would need to do that hood right, it was also suggested to use a skim coat of epoxy that you would use to repair fiberglass to seal off the fibers. Then fill or if level enough 2 part prime. Lightly sand and prime again. Being careful not to go through the skim coat of epoxy.
One problem is coefficient expansion the plastic , fibreglass and putty, primer and paint all expand at different rates. Painting on coldest or hottest day of the year isn't the best idea. Another problem is chemical If you have even the slightest hint of enamel paint over spray near acrylic it will bubble. If the two pack primer sits on the car more than a few days after sanding back and painting it really needs to be re-primed. No point sanding down to bare material as not metal you will need to build it up with primer to make everything perfect. Make the hard finish with your two pack keep spraying it on and sanding back build up your hardened layer.
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