Orginally posted by Nancy D
Is fiberglass resin like bondo that the more hardener you put in the faster it dries? *I can remember years ago when working with bondo if you were a newbie at it, we were, you could use less hardener and it would give a longer working time.
The problem with adding more hardener with fiberglass is that it cures too fast and becomes brittle, and consequently isn't as strong. Fiberglass is an exothermic reaction so if you mix too much, it gets too hot which also affects the integrity. In extreme cases, I've seen it get so hot as to melt the tupperware container it was mixed in. I find that the most I can mix and work with before it starts to gel up, is about 1/4 cup.
If working with cloth, cut your cloth to shape first, then mix your resin. Use disposable paint
brushes and a sheet of cardboard. Brush some resin on the cardboard, then place the cloth on the resin, and then impregnate the cloth with resin using the paintbrush until the cloth becomes somewhat translucent. then with the brush, pickup the cloth and position it on the spot you're repairing (unless the piece is big enough to want to slide off the brush, then you'll have to use your fingers). Using the end of the bristles on the brush, dab the cloth until it blends in and all the airholes are gone. You can brush some more epoxy on the surface to smoothen it off once you're finished layering your cloth. Having a thicker layer of resin on the top layer of cloth, also gives you some sanding room so you don't take off too much of the cloth.
After each round of cloth, I soak the brush in acetone while I'm preparing the next cut of cloth and mixing resin. When I'm ready to start, I shake the brush dry and get started.
I did about 12 layers of cloth to fix the drivers side rear corner of my Boler
before I painted the outside. You can see the damaged piece in these pictures: http://www.beer.org/boler/
Disclaimer: I'm not a professional body man or fiberglasser. I was taught how to do repairs by a boat builder in Sidney BC and the skill has come in immensely handy over the years.
Hope that's helpful.