i bought the name brand Elmer's fiberglass resin seeing how its a decent name brand. after the fact i used it, the stuff wouldn't harden . i ended up having to leave it on top of my wood stove to really heat it.though i was scared that it was gunna burst into flame it ended up hardening. so my advice, after recently using Bondo's fiber glass, is dont buy elmers fiberglass. i noticed as well that the helmet i used it on still has a slight smell of fiberglass. i have used fiberglass for well over 3 years on misc. projects so ik the ratios and the mixing instructions. i figured i'd give you guys a heads up.