[GradySailfish]

I don't think this is a temperature issue, as even with those temps the mix should have cured. I think you may have gotten your ratios off and therefore the epoxy won't cure.

Quickfair is great stuff, but expensive. For minor fairing you can't beat Evercoats polyester fairing compounds. I know its not Marine or epoxy but I was turned on to it by one of the best local fiberglass/retoration shops on Long Island. I have no complaints other then a very fast working time in hot weather.