Originally Posted by Davie B
Why polyester resin? And, yes, very helpful.
Sent from my iPhone using Fiberglass RV
According to some youtube sites, a boat repair show, in particular, polyester resin is more flexible. Epoxy resin is stronger. The person uses polyester resin only on curves where flexibility is key, and insists he uses epoxy everywhere else.
Polyester resin is, as far as we can tell, more "dangerous" than epoxy. The epoxy can states if you start to get a headache or feel dizzy from the fumes, get the sufferer out into fresh air until he feels better. (Or she.) You need a gas mask or tons of ventilation to work with polyester...as far as we can tell. You also need to do something special to get the polyester resin to harden: cover it with clear plastic (like saran wrap) or wax. That is, it hardens in the absence of air.
Epoxy resin hardens in air just fine.
If you're really interested in the discussion here about that, why don't you check out the "Fear of Fiberglassing
" thread? It was ours to start with, and we got a LOT of good adivce.
One fellow here says ONLY to use polyester, but a LOT of us use epoxy for repairs. Paul has found the epoxy to be relatively simple to use. I'm relatively certain Bondo-Hair is epoxy, for the simple reason that you don't have to cover it with saran wrap or wax to get it to harden, and it has been sticking to the original material just fine..
Epoxy will stick to EVERYTHING. Polyester won't stick to epoxy, though why on earth it would work that way since epoxy sticks to IT, is beyond me.