Thread: Fiberglass Question

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I was adding glass to the mounting flange on my hood top today and followed all the steps - grind away the gel coat and about 1/2 of the thickness of the existing flange; cut strips of mat to fit the new area, plus more to span the new and old area; wax the metal form piece; etc. When it came time to mix the resin I added hardner from memory, using the 12 drops per small batch instruction. Problem is the 12 drops is per ounce of resin, and I was doing the six tablespoon measure which needed 1/4 ounce. I figure I was off by at least 1/3, and perhaps 1/2 on hardner. After four hours it is mostly hard with a few tacky spots, but seems to be hardened. Do I need to be concerned with strength? Do I need to do anything special, like let it bake in the sun for a few hours?

Most resins are called "air inhibited", and will cure, leaving the surface uncured for a while, so you can add more layers. Just because it's feels tacky, that may not mean anything.

I always just add a thin coat of bodyfiller to finish the curing, then you have a head start on smoothing it out.

Another option would be to put a heat lamp on it, or a light bulb with reflector, for an hour or two. Don't put it so close that it gets hot... just "very warm" to the touch. This will help to cure it.

Also make sure your hardener is fresh. If old it will lose it's ability to catalyze the resin. I had some stale hardener one time and the mixture never did cure, had to get it all up and start over.

Don

Thanks, guys. On the hardner, luckily it was a brand new tube, just broke the seal on a new can of resin & a new tube of hardner. It seems to be setting up, just pretty slow. I will check it in the morning and see how it has done overnight. Sounds like if it hardens strength is not an issue so I may be OK on this round.

No, you will be fine. I had some on my 27 floor that wasn't curing so I brushed a hot mix of resin over the top of it and it cured fine. That was 20 years ago and it still is holding like it should. Fiberglas is a pretty forgiving medium.

Don

Originally Posted by Itoldyouso

.....so I brushed a hot mix of resin over the top of it and it cured fine.

Don

I had thought about doing just that, mixing an ounce with a heavy dose of hardner, and laying a thin layer on top to hasten the set. Hotrodpaint also mentioned a skim coat of bondo, which is the same concept.