Help Paint Blisters!

[Wolfman3002]

While waiting for my dash to get recovered, my GT has been sitting w/o a windshield, but is covered w/ a tarp and then a car cover (the tarp is to ensure no water got into the car, as the car cover is older and far from waterproof). It has been this way for a couple of months. Then, yesterday I decided to take off the cover to open the hood to look at something in the engine compartment (and of course, I forgot I had closed the hood w/o the hood release hooked up, so it's latched tight, but that's another story).
What I found was that not only did I get a lot of mildew in the interior (which is no biggie, since everything will get replaced eventually), but most everywhere that the tarp was sitting directly on the paint, I got a whole bunch of small blisters in the paint . The blisters are flexible, and I can press them down easily w/ me fingernail. And they were only where the tarp was sitting. I am assuming that it was because any moisture that got trapped under the tarp sat against the car, and got under the paint somehow. It was only where the tarp was, not where only the car cover was the only layer. I guess this was because the car cover allowed the moisture to evaporate.
The paint job wasn't perfect to begin with, I knew that. But I was hoping it would at least last a few years til I got all the mechanicals and interior done, then I could afford my "dream" paint job.
My questions are, when the tarp is finally removed (hopefully, my dash will be done in about a week, then I can reinstall it and the windshield), will these blisters disappear when it dries out? And, is this a sign of anything under the paint that I should be worried about now, or will it be OK for awhile as long as I keep it well waxed? And finally, is this just going to get worse until the blisters pop and the paint starts to flake off?
I feel like one of my children is sick, and I can't do anything about it. Hopefully, someone can give me some hope for the future of my baby. I can't afford to give it the paint job I want to give it, and I don't want to compromise w/ a $199 "special".
Thanks,
Randy
AKA "Wolfman"

[namba209]

Much as I hate to say it, you have rust forming under the paint, that's what made it blister up. It will not get any better but will get worse after time.

[Sparky73]

This doesn't sound good.. If this wasn't a newly done paint job, I don't see how moisture could have even gotten under the paint? I am pretty confused on this one.. sorry!

How long WAS the cover on for? Namba is probably right, but only if the cover was on for a LONG time.

[newman27]

I have an old fabric tarp that is coated in a "resin" of some kind presumably to make it waterproof. Pure speculation - but I wonder if the tarp was coated with something that reacted with the paint when water was introduced...

[timemachine]

That's absolutely possible. Only way to know is to put it out in the sun and see what you've got when it dries out.

Jim

[heimue]

If your paint blisters after being covered for two month, the paint wasn't good to begin with. You need to find out the difference between "paint blisters" and "rust underneath paint". Two month is normally not enough time for extensive rust to build underneath paint, unless the paint is already old and cracked. In your case, it sounds more likely to me that the plastic sheeting may have released some kind of PVC softener, which too often chemically reacts with synthetic lacquer. A better quality acrylic lacquer would have been more resistant against this kind of mis-treatment.
Without seeing it in person I can only make this assumption. If I'm right, your solution is to have yor GT repainted

Dieter

[wrangler]

Not sure if this applies or not, let alone what the chemical process underlying it was, but years back I had an older GMC P/U that had what appeared to be a nice but boring yellow paint job on it. To spruce the look up a bit I decided to apply a few of those static cling designs on it. They went on easy enough, and definitely helped the look, but a few months later I noticed that along all the edges of the decals it had sterted to eat through the paint. I had thought that maybe it was where the heavy pollen here had collected and/or where the moisture didnt dissipate, but like I said, I dont know. But it does sound a bit similar to the problem you encountered. Hate to say it, but you might want to wait to install you new dash and winshield and look into repainting before things get worse...

[Mike Trout]

Time to sand her down re-prime and re-paint her
Ive had many cars like that come into work

[Wolfman3002]

Thanks for all the replies, guys. As it was fairly nice afternoon today, I decided to take the cover and tarp off to do a more thorough inspection. I noticed some of the blisters had shrunk (unfortunately, leaving a little wrinkled circle behind, I was hoping they might disappear when they shrank). None of the blisters are more than about 3/8" in diameter, so are not too visible from a few feet away. I pressed in on one of the bigger ones, the top of it split, and out came....water. So then I took a small screwdriver, and took off the top of the blister. The good news, no rust. The clearcoat and the blue paint, along w/ the white primer under it, seemed to be part of the surface of the blister. Under that, I found a very thin (less than 1/32") tan or flesh colored layer (bondo?), then under that, the original blue paint, and then a yellow primer (I decided not to dig into that). The bondo looked and felt doughey. Was that due to the water sitting on it inside the blister? So, it looks like the primer is not adhering to the bondo layer. Was this caused by bad paint (or a bad paint job?) allowing moisture under the paint, or was it bad prep before the primer, or a little of both? I put in a couple of pics below to show what it looks like.
Dieter, I think you may be right, and that the paint wasn't applied very good to begin with. This paint job is something like 3 years old, and was done at a paint shop by a friend of the PO, in trade for another GT he had. So the paint should be a more modern variety (it's a Corvette blue). I don't know if this has any bearing on the problem, but after the car was painted and rubbed out, the rubbing compound residue was left on the car for about 2 years, until I bought it and cleaned it off (which is not easy!).
Randy

[heimue]

Randy,

this looks & sounds typically for what I assumed: The PVC softener softened and partially dissolved the paint. This doesn't happen to acrylic paint, but to PU and/or synthetic lacquer. I make another assumption: the painter used synthetic lacquer with an improper amount of hardener (too much is as bad as too little) and sprayed it over an acrylic primer. This explained why your (good quality) primer adheres to the sheet metal/bondo, but the (bad) top coat gets dissolved from the primer, because of 1. the reason explained on top and 2. because it doesn't adhere to acrylic primer in the first place.
Sand down to the primer, have the primer tested to be acrylic (I'm too far away to guarantee my assumptions ), and get a new acrylic paint job. Sorry to be the bearer of bad news, but that's how I see it.

Dieter

[Wolfman3002]

Dieter,
Thanks. I'm not too terribly distraught, as I assumed my solution was going to have to be a new paint job, and I was planning on one eventually anyway. What I'm wondering is whether I can live w/ this one for a little longer, or if the water under the blisters is going to start a bad rust problem quickly. As I said earlier, I don't want a cheap paint job to cover a bad paint job, but I don't think I can afford the paint job I really want. My dream paint job wass going to be one of the last things I got done to the car. Maybe midnight blue w/ gray ghost flames, or something like that.
Randy

[timemachine]

Water on bare metal is never a good idea for any amount of time. I'd say it's time to feather sand it out at least and fix the old repairs. I know it's not what you want, but flat black is "in" right now and would be an improvement until you can afford your next paint job. Better than watching your car deteriorate.

Jim