View Full Version : anyone get bubbles in hood?


supersport
09-12-2006, 12:56 AM
1982 L-82 claret red, claret red interior. Excellent car! Base/Clear paint NEW! Have painted hood 5 times, stripped it down to the fiberglass each time, ground out the fiberglass each time and still some bubbles come up toward the center/rear of hood but only after a while. Heat perhaps? Anyone else have this problem, or anyone know solution? Painted the rest of the car the same way with the same paint, no problems anywhere else.

C3 Starship
09-12-2006, 01:12 AM
If this makes you feel any better, you're not alone. Saw a C3 this last weekend with the same prob., but the bubbles were in the center and left.
Do the bubbles come up in the same places? 'Cause I'm thinking oil seepage from the underside:eek:. Heat is a likely guess, but why not on all Vettes? My C3 doesn't do it.
I'm really shootin' in the dark, so this is my best guess. Most times this is from prep. but it sounds like you're doing every thing right.

pg
09-12-2006, 11:47 PM
Do you have hood insulation, if not the heat from the motor will cause this. Hope this helps.

drdenny
09-15-2006, 01:23 AM
Have had my 68 since new, 95000 miles on it . had original British racing green on it which, after 20 years had some very small bubbles rise uo toward front of hood. After repaint (once) had bubbles again toward same areas. Original hood had no insullation. Painter said it was due to expanding fiberglass. Whatever!! I Live in Ca., temps may make a difference.
sounds like you have yo live with it. SORT OF LIKE HAVING PIMPLES AT AN EARLY AGE.
















g

corvette king
09-15-2006, 11:55 PM
ORIGINAL: supersport

1982 L-82 claret red, claret red interior. Excellent car! Base/Clear paint NEW! Have painted hood 5 times, stripped it down to the fiberglass each time, ground out the fiberglass each time and still some bubbles come up toward the center/rear of hood but only after a while. Heat perhaps? Anyone else have this problem, or anyone know solution? Painted the rest of the car the same way with the same paint, no problems anywhere else.
hello.... what kind of primer is on the car.........when i first started painting glass cars i ran into this problem it was my primer ... i now use polyester resin primer never had this problem again...the glass does shrink and exspand and if the primer cant shrink on the glass you get bubbles...also if you any contamanation you will get bubbles to .... if the paint is really new you can poke with a needle ..i would heat the needle up then poke bubble to let the air out,,:D

local://upfiles/1664/BBBF9A228B0F44D58B8DC356F83B286D.jpg

SCHOON
09-18-2006, 03:55 PM
I know other guys who had this problem. It turned out to be from the engine heat.
They tried to insulate better but that didn't do it either.
End result they bought new hoods and no more problems.

corvette king
09-18-2006, 06:36 PM
ORIGINAL: SCHOON

I know other guys who had this problem. It turned out to be from the engine heat.
They tried to insulate better but that didn't do it either.
End result they bought new hoods and no more problems.


buying a new hood is a waste of money,,,, the hood you have can be fixed right:)

supersport
09-20-2006, 02:44 AM
I don't want to sound like a pro, but this ain't my first rodeo as far as painting fiberglass or anything else. I would agree with you about the poly resin primer but as I stated, absolutely no where else on the car has a blemish or bubble and it was all painted the same way/same time. The bubbles are really large blisters and they seem to come up at the same place every time. The real funny thing is, I painted the car in November of last year, and everything was just fine until we started driving the car alot and the weather heated up around May/June time frame, that is why I am thinking heat is the problem. As far as primer........I used 2 part Urethane primer, and again no problems anywhere else.

C3 Starship
09-20-2006, 03:16 AM
I am by no means a body man, done some painting though. (although not on glass)
Just curious, did you do the underside of the hood too?
Would a sealer on the underside help? I have heard that glass can get small fractures and seep when subjected to a lot of movement. Ex: The glass flexing when closing the hood, if drop closed as opposed to set closed.
A friend who collects Vettes told me to always release the lock, set the hood with your hand in the middle of the hood where it meets the windshield, and set the hood down. Then go to each side and firmly but gently press the corners to latch.
How about insulation, is it there?
I'm tryin' to learn too, just in case I end up with this prob down the line!

73shark
09-24-2006, 12:57 AM
When you close each corner separately, you actually put more stress on the hood than when you do a straight drop.

BTW, I've run my 73' without the hood insulation since day one. No problem with the factory paint or the current lacquer with clear.

graycav56
09-05-2007, 10:39 AM
I am having the same issue on my 66. This will be the fourth time for the bubbles on the nose...not on the hood but the nose piece. A real bummer since the rest of the car is flawless.

Not sure how to add a pix to this post to show you.

ax
09-05-2007, 08:32 PM
Sounds to me that there was some sort of contamination that got on the glass at some point in it's life, maybe even from the factory.Could beoil, siliconeor something similar. It will soak into the glass and rasie to the top(or create fumes)when exposed to heat. Hood insulation may help, but the heat itself is prolly not the actual cause, just a contributing factor. Not sure what a good fix for this would be other than to strip the paint and throughly degrease the area with acetone or some other fairly aggressive degreaser.don't leave iton the glass to longthough.

Phill
09-06-2007, 07:54 AM
ive got a few. i think mine are coming from a combination of oil being shoot up on to the under side of the hood(pan gasket leak) and heat. the reason i say this is becasue the bubbles are on the same spot as the oil was when i cleaned it.i dont have an insulator by the way im planning on getting one as soon as the leak is fixed.

bruiserman
09-06-2007, 10:52 PM
Happened to me too. Hood has bubbles on the middle passenger side. Will be putting insulation underneath. My only concern with that is the insulation catching fire. I did get the foil insulation so hopefully that will reflect most of the heat.

cwb
09-07-2007, 12:24 AM
bumping...

84corvetteC4
09-12-2007, 02:13 AM
sounds like to much flex in the paint and not enough hardener, tell the person who painted it he used the wrong mix for a fiberglass car , most people dont pain fiberglass cars often so they dont understand how it works! get the best advise you can get is from a person who paints boats

73shark
09-14-2007, 11:44 PM
Might try putting on new gel coat next time you paint.

blueshark
09-15-2007, 08:55 AM
Clean the under side of the hood or effected area with MEK(methylethyl keatone) and paint it with a polyester based paint or gelcoat to seal it. Then replace your insulation.

wrwalke
09-17-2007, 08:00 PM
Even if the problem isn't with the primer, the right primer coat can help in alot of cases. With any primer, make sure it is FULLY cured before you paint over it. A little extra time in the booth can do wonders. Some of the resin and catalyst (hardener) can be left unreacted in the paint, and "fume off" as much as a year or more later. I too like the polyester resin high build primers on glass, and have always done a double bake (once after spray, once after sand and wipe).

You can also have leftover resin and hardener in the fiberglass itself or gelcoat, which can seep *years* and even decades after the glass and gelcoat are laid out. Bad mixtures can have "blisters" from heat or excessive moisture triggers over time. Nothing you can do about it except pop them, dig a bit, sand them down, seal them, gel or bondo over them, and pray. A good cleaning, and a good sealer can keep this from showing up most of the time, but...

bill.