What the hell happened?

K

kenseth17

Was a car show nearby today, and seen a fiberglass hood I repaired for a guy- 1968 mustang with Eleanor body i think around 2 years ago?
Its bubbling blistering. lots of em, but not huge size, where I reglassed around the hinges that cracked when his hood flew up forgetting to attach his hood pins. And the bodywork got wavy and where there was bodyfiller starting to show in that area too. Now that bodywork matches the bodywork of the shop that built the car.

I believe I put on a couple coats of epoxy primer, block sanded and some more epoxy. I know I only used epoxy primer. I know about leaving time for anything the glass would soak up to get out before doing any priming painting, ect.
Other than those two areas, everything looks pretty good, I fiberglassed some other areas, nothing has cracked anywhere.

Gassing, contaminated fiberglass, air bubbles? Whats most likely to be the cause?
He hasn't said anything, but a while ago he wanted me to look at repairing a tonneau cover on his truck. I might have to stop over and look at it and talk to him about his hood, and talk about fixing it and maybe some pictures.
 
Once you open up the failure areas you might find some clues to what the problem is, post up some pics when you can. Bubbles usually are from contaminants, gassing, or moisture.
 
No stripper used.
Yeah Bob, figured any of those things. Will try to get some pics, and If I redo someday, will have to investigate.
Thing is I do a lot of fiberglass repairs on big rigs at work. Occasionally see some back in again for new damage, and haven't ever seen blisters appearing in anything. And all we use at work is urethane primer, no epoxy and things are rushed more. Only difference at work use the pricey fiberglass and smc resin, since we get both types, and I just used the cheap polyester resin on the mustang, and at home I do wet sand, all dry sanding at work. Have done other fiberglass repairs at home too, and never heard off or seen this problem appear. I often seem to get an air bubble or two to dig out no matter how much I saturated the matt.

Thought I did everything right, but guess not. But blisters do seem to be a common enough problem people experience on vettes and boats.
 
Most likely, if it was new, it was not cured in the sun for 7 days before starting work, only thing I can think of with it blowing up like it did, more common then you think.
 
Barry;38372 said:
Most likely, if it was new, it was not cured in the sun for 7 days before starting work, only thing I can thing of with it blowing up like it did, more common then you think.
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I have to agree here...all to common...since it has happened, wrap it in black plastic in the sun for 7 days, then repair and you should be fine
 
my answer would just start something but i wish you well. redo's suck no mater what happened . been there done that .
 
Really , what you think you will start Shine? I know you deal with a lot of fiberglass. Unfortunately screwups and failures is a way things are often learned.

Hood was not brand new, I repaired around the hinges inside and out, and a few other spots I found some voids in the layup from the company that made the hood. Or are you saying by the prior shop not baking in sun for 7 days before painting. Because so far blisters are only showing on two repair areas that I did.

I repaired a lot larger areas on the inside of the hood, and none of these are showing anything at this point (of course these are not baking in the sun like the outside), only the two spots on the outside at the back of the hood by the hinges where i did repairs. The rest of the hood is not blistering and still looks very good. The blistering took two years to appear.
No wax and grease remover was used on the raw glass, most likely wiped down before paint after spots were primed though. Didn't cure resin out in the sun or anything, but not aware of having this problem occur before even though cheap polyester resin was used.
Guess will maybe know more when I get into repairing. Stopped by the guys house today, and offered to fix this fall/winter, even though he never said anything about it, when I get some of my own stuff done for a change, and he is done driving it for the year.

If you seen some of the crapola thats showing in the bodywork on the rest of the car from the shop that built it, you would be amazed, why i ground through two inches of mud everywhere i did a repair is beyond me, but still the car gets a lot of attention, probably had the most people around it while I was there, at the little show on sunday.

At work awhile back we had an rv that kept blistering, but real obvious what that problem was, and that was moisture. Glass was soaking wet through from the inside and they had a dehumidifyer inside it going for a week and it still wasn't dry. Someone else repaired at work, and then later came back bubbled up and lots delaminated. I started grinding a spot at the top, and it kept chipping off further and further. Then I grabbed the glass and was able to pull off it all in a huge sheet.
 
About to put a new front clip on a 59 Vette, we got it about 3 weeks ago and its been sitting out in the sun since then to cure out and settle, seems a lot of people stick them right on the car and end up with problems down the road.
 
i learned in the 70's that polyester resin can be worthless . every problem i ever had was tied directly back to it. fortunately i had a friend who mfg fiberglass products. he gave me quite an education on resins. the very first thing he told me was just about every polyester resin sold retail was not worth using. he had different grades for different products . i started buying resin from him and never looked back . his good resins were commercial grade and somewhat on the upper tier . today i will not use polyester resin on any glass work unless building a speaker enclosure or a console. which i do very little of.

problems i have had with polyester , large bubbles from gassing out , terrible solvent pop , delamination and mapping . i've had resin not finish cure even in the sun . hope this helps a little .
 
Maybe urethane primers are more forgiving on "green" 'glass repairs because they are more porous and will allow a certain amount of outgassing. Epoxy on the other hand is a far better barrier, which is usually good, but might sometimes trap something under it.
 
shine;38414 said:
i learned in the 70's that polyester resin can be worthless . every problem i ever had was tied directly back to it. fortunately i had a friend who mfg fiberglass products. he gave me quite an education on resins. the very first thing he told me was just about every polyester resin sold retail was not worth using. he had different grades for different products . i started buying resin from him and never looked back . his good resins were commercial grade and somewhat on the upper tier . today i will not use polyester resin on any glass work unless building a speaker enclosure or a console. which i do very little of.

problems i have had with polyester , large bubbles from gassing out , terrible solvent pop , delamination and mapping . i've had resin not finish cure even in the sun . hope this helps a little .
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Thanks for that post shine.. I do very little glass work and am always scared to take on big glass projects for the fact that I just don't know enough about it..
 
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