Paint Bubbles on Replacement Fiberglass

[Greg Madden]

About 4 years ago, as part of a restoration, I had my body shop replace the front clip and rear fenders on my '65. The front fiberglass was from Vendor 'A' and had aged for several years in my garage. The rear fenders were from Vendor 'B'. Both arewell known, high quality 'press molded' parts suppliers. All parts were the 'smooth both sides' 'press molded' type.

After installation the whole body was gelcoated, then aged about a month, then painted. About 6-9 months later, small bubbles appeared on the rear fenders. The shop stripped the affected area, hit it with a heat lamp for a couple of weeks, then gelcoated it and repainted it. So far so good (but I don't want to go out to the garage to check it either!) We assumed the problem was related to pockets of resin or something. Vendor 'B' claimed that this had never happened before, but I find that very unlikely. To their credit, they paid the shop for the repair. Anybody else encounter this problem or have a theory on what it is? I'd like to avoid it in the future!

Regards,

- Greg

[Jerry Clark]

Re: Paint Bubbles on Replacement Fiberglass

Hi Greg:

I had some very good quality ZL1 flares, (don't go there guys, it WAS thirty years ago.), that reacted in a very similar fashion and like you the vendor covered the repair cost but speculated that the contamination may have been traced to the mold release agent they had used at the time. It seems you made all the right moves to ensure a good result, it is a shame you weren't rewarded for your patience.

jerry

[g.r.rogers]

Re: Paint Bubbles on Replacement Fiberglass

Please look up County Corvette on the web and check their process for glass work under refinishing. They have the answers to sealing the gel coat and will explain the problems with after market glass. Call em up they make a living restoring corvettes. Regards GRR.

[Steve Steffensen]

Re: Paint Bubbles on Replacement Fiberglass

I have seen this type of problem in fiberglass in the past. There are two times that the problem could have occurred by your discription. #1 - when the part was made, if the glass and resin were chopper gunned in place, it is possible to have a leaking seal on the catalyst inject system that will leave raw catalyst in the laminate. This will bubble later (normally in heat or the sun) and have a rancid smell when the bubble is popped. #2 The same thing can happen if the gel coat is not mixed well or if it was sprayed on the part with a catalyst inject system. It is very important that the catalyst is well mixed to eliminate these types of problems.