LiveandLetDrive

The paint on my '70 has been slowly cracking/crazing over time but I thought a repaint would be on the distant horizon. Yesterday however I pulled the cover (actually it was double-covered) and found bubbles all over the damn thing! It is extremely humid here in the Santa Cruz mountains, especially with all the recent rain, so much so that I have even battled mold in the cockpit. The only thing truly new though was a recent bit of hail.

The thing is, this hail was tiny, like overgrown snow, maybe 1/8-3/16" diameter, and as mentioned the car was under two quality covers. Plus it only lasted a minute or two. So why did this happen? Was my (90's era) paint weak and just waiting for an excuse? Could the humidity have caused this? Is that tiny bit of hail so dangerous?

And perhaps most importantly now, what will I find when the paint is stripped? Is this just the outer layers seperating or am I in for a world of hurt?

The13Bats

I will let someone else do the long winded version but likely the hail didnt do much if anything, all covers no matter the type wreck paint...like a greenhouse effect.

LiveandLetDrive

Damn, even the "good" ones? (Cal car covers top-of-the-line one.) Maybe it was the double-covering that seemed to cause this overnight? I tossed my truck's RainX brand onto the Vette to give it a chance to air out. Otherwise it's been under its own cover, outside, for 2 years now with no bubbling.

USAFVeteran

That looks like what is called solvent pop. It's caused by contamination on the under layers. How deep? Don't know, but that's what it is. And there is no other way to fix it except to remove that paint, until you get to solid paint, or down to the fiberglass. Hail had nothing to do with it BTW....




Almost looks like you could scrape it off with a razor blade scraper.


Anybody have a better reason for it happening?

LiveandLetDrive

It does look like that but seems weird it'd happen all over 20 years after it was re-painted.

ENCSDOUG

This what I found on a different site,

Your not going to like my answer but here goes.

The paint bubbles are usually caused by one of two things and I'll explain both.
1 - Moisture trapped under a cover - As the temperature fluctuates the water can heat up under the cover and evaporate (for lack of a better term) under the paint. Once the car is uncovered the trapped vapor will heat up under the sun and start bubbling up as the air escapes, usually around low points and body seams but this can occur anywhere. If your paint guy is really good it can be repaired, if he isn't absolutely certain he can fix it don't let him touch it because you can end up with a polka dot Vette. You said it was stored in the driveway so it probably is moisture. All covers claim to prevent this damage but even the best cover should be removed every couple months on a clear day just to air out the paint and seals. If you get a lot of rain or humidity, you should do it even more often. And like Brad C said a good wax after a paint scrub can't hurt.
2 - Oil/grease in the fiberglass - This is a problem unique to fiberglass cars. If your car was ever stripped and repainted or ever had any body work done, grease or oil may be trapped in the glass. This doesn't mean anyone spilled it but rather something as simple as a greasy fingerprint could have ben left on the car prior to painting. If the grease isn't removed immediately it will seep into the glass and the only solution is to cut out that section of glass and replace because there is no way to get the oil out. Even if you strip the glass and scrub it clean the oil is still there below the surface and will always seep. I've actually seen these oil bubbles in the pattern of a handprint around the back of a hood.

The only way to know which one it is to cut a bubble out. I've never done this myself and would let a pro do it. If the bubble is only a couple of layers of paint, it's probably moisture vapor damage. If you see fiberglass it could be oil, you then have to test the surface. If it feels oily your through, if it doesn't, spray a mist on it and let sit for a minute to see if the oil bubbles out then feel it again. Oil damage can NOT be fixed without replacing fiberglass.

Since your bubbles are all over, you probably do have moisture damage. Even though either one really bites, I'd take moisture over oil any day. My car is garaged and even a cotton felt cover that breathes isn't foolproof.

Hope this helps and best of luck to you.

The13Bats

Like i said left the long version to others but its the cover

USAFVeteran

There is no painter that would try to "repair" that paint, short of repaint. There is no repair for it. It's very much like a delamination of fiberglass. You have to remove the delam before fixing it.


Oil on fiberglass can be removed without removing the fiberglass. Albeit not easy, but it can be cleaned with chemicals. I've had to do it on aircraft control surfaces in order to repair the fiberglass surface before reapplying the paint coat.

Alan 71

Hi LLD,
I'm really sorry to see what's happened! Has it just occurred on the car's horizontal surfaces?
I agree that the repair will require all the old paint to be removed before new paint is applied.
At this point I'd be curious enough to stab a couple of the large bubbles to see if there's anything trapped under there, or is it just air that forced the paint into a bubble.
Curious?
Regards,
Alan

The13Bats

Popping pimples?

crawfish333

Last year I visited a high end big volume antique car dealer here in Fort Worth and they had 2 or 3 C3s that looked like that. It made mention on the information sheet that a poor paint job had been applied. Reading this thread, it sounds like a lot more than just poor paint, meaning that if someone bought one of those cars and tried to strip it and paint it, the oil in the fiberglass would cause the same issue again if it were not removed?

540 vette

If there was oil on the fiberglass that caused the problem why do the headlight doors have the pimples? They are made of metal.

ENCSDOUG

I thinks it's more the moisture from being covered for so long.

The13Bats

I believe two things that ruin paint are being all convoluted combined,
Bad prep, oil contamination etc can cause paint to do something like this and being covered can cause it and combine both can cause it...in these cases the car has to be striped and care taken in prep so it doesnt come right back.

blue by you

post this in the paint and body section and let the pros tell you the problem

LiveandLetDrive

Well, it's officially not caused by the quality of the paint job! The other car in the driveway, a '64 Nova SS covered with an identical cover has developed the same bubbles! This is my life. Fortunately it needed new paint even more badly than the Corvette. It had its original paint (what's left of it) from 53 years ago, on steel.

My best guess is that there was a freeze and water trapped under the surface expanded. We have had more sub-zero nights than usual this year, which is to say, any. I had no idea paint was so porous! There needs to be a PSA for this issue. I imagine CA Car Covers has some nice fine print hidden somewhere... Guess I need to build some garages, or put my cars in giant plastic bubbles!

I guess the truck dodged the bullet because it gets driven most days.

TimAT

That hail would not have caused any damage. Just not big enough. When it gets to bigger than a nickel, we start to worry. Golfball size is a little spooky. I've seen softball size-- THAT causes some damage. But I live n the Midwest too.

ENCSDOUG

Good Luck to you and maybe you can get a 2 for 1 paint job. Hard lesson to learn though. I have a cover for my 72 but haven't used it. My Vette is kept in a garage. I do get surface rust due to the fluctuation from one day being 30 degrees to 65 the next.

bj1k

It was a poor prep on the paint job . Even though it took twenty years to show up it's still bad prep that was only waiting for the right conditions to start popping and the car covers caused the problem along with the weather that you described. ( Not the hail though ) . Sorry to have to tell you but the only way to fix it is to totally strip the car and properly prep and repaint .

lowbuck72

I can't be sure, but I think the cause is from moisture that got under the paint because after the rain, the water got trapped under the cover and got heated by the sun. It seems to reason that if the paint is porous enough to let moisture in, that maybe by leaving the car to air out in the warm sun may let the moisture out and the pimples may recede. It's been driving me crazy during the past rains in so cal, but after each rain, I'd uncover the car, hang the cover out to dry, dry off the car, open the windows and let it air out in the sun. Ended up doing this about 10 times, but the 11 year old paint job is still holding up.