how to use fiberglass resin
4. Mix the BondoÂ® All Purpose Fiberglass Resin in a paper cup with the BondoÂ® Fiberglass Resin Hardener. For small applications use 10 drops of hardener per ounce of resin.Working time will be 10 to 12 minutes. For larger applications, use half of the fiberglass resin hardener supplied, to half of the resin container.Using large amounts at one time will cut the working time in half of the mixed resin.o not mix the entire container with liquid hardener. Mix thoroughly. 5. Brush a coat of the mixed resin on the damaged area extending 2-3 inches beyond repair. Place the first layer of fiberglass cloth or mat onto the resin application and immediately apply another coat of resin over the fiberglass cloth or mat.