Greetings, I am not a car guy and have an issue with a 2002 Chevy Roadtrek with a fiberglass body. I would appreciate some input on this.

This is a Class B RV and the fiberglass does not appear to be gel coated, instead it has factory paint. The bubbles are small and are not delamination. There are 2 different types of bubbles/blisters. The first are a permanent bubble, from reading on the net they need to be opened, clean out and allowed to dry, common on boats. There are a couple hundred of these about the size of a small finger nail.

The ones that have me confused are tiny average about the size of a pencil eraser. When it is cool and the van is not in the sun they disappear. As soon as the sun hits the vehicle they appear, sun goes away the bubbles disappear. They do not seem to harm the paint, there are thousands of them!

Any idea how to deal with these before paint, any input appreciated. Even the proper name for them as looking online has lead nowhere.

Ahh, this is easy.... the bubbles that do the appear/disappearing act are more than likely trapped solvents or even simple moisture trapped down in the layers. Sun comes out heats the surface enough to turn them into a gas and Boom!..... bubbles. No sun, surface cools, gas goes back to a liquid and crawls back down in it's crevice for the next time..... Only way your are going to fix those is by letting the sun heat the surface as much as possible, sand them open, and use a heat gun and possibly an air blow off or shop vac to get those liquids out. We see this in kit cars all the time. The fantastic/plastic old production car the Pontiac Fiero can suffer from this a lot as well. I've seen silver dollar size bubbles on Fiero front hoods. Personally, once I think I've evacuated the liquid I like to take a Dreml tool with an engraving bit and get down in there to make sure I've gotten to the bottom of the area, then let thing dry out in the sun for another day or two, then finally fill with fiberglass repair resin.....

Thanks for the response. That is what I was afraid of, I will guess it will be expensive to fix?

Do this type of bubble have a proper name??

Well, unless you are doing it yourself sure.... takes time, time is money in a pro shop. Might want to check around your area and see if there are hobbyists/semi-pro garage guys. This type of bubbling kind of falls under the "solvent pop" area however to my knowledge I've never heard it called anything but paint bubbling.

Thanks for the response. I did prep an RV long time ago and had it painted at Maaco. Painter had 30 years experience and was an artist with a spray gun. This would likely be beyond my minimal skill level. Will look for hobbyist, side job type of person.

Osmotic blisters!

Yeah, if you go by the newer strict definition of osmotic it does now include solvents as well as moisture. When I was younger it only covered water as the form of moisture down in there....

stopped by a paint shop today for an estimate. Was told that the van needed to be sanded down to fiberglass and possibly skim coated to remove the blisters. Insisted on base/clear even though I told him I prefer single stage. $12-$15,000 and due to backlog of hurricane damaged cars cannot get to it for several months.

No talk of popping bubbles and filling with resin?? Any thoughts? At $12-$15000 I will wash it and paint with a roller.

For a production shop it's a lot easier to sand everything down and re-dress the entire surface to ensure that bubbles cannot come back up. Can't say their logic is flawed because if you spend that kind of money on a paint job it had better come with a warranty. Doing a skim coat should properly seal off anymore reactions.....

DarrelK wrote: Doing a skim coat should properly seal off anymore reactions.....

would epoxy primer work in this situation to seal?