How to Cure Fiberglass

Setting fiberglass requires the use of a resin. Cured polyester resin hardens fiberglass cloth, forming a rigid part. The resin itself will not cure unless mixed with a catalyst called a hardener. Adding too much hardener to the resin will cause the resin to cure nearly instantly. Adding too little hardener to the resin will cause the resin to remain tacky. Fiberglass that remains tacky can sometimes harden with an additional step.

Instructions

1

Cut multiple pieces of fiberglass cloth to fit inside of a fiberglass mold with a pair of scissors. Set the cut pieces aside.

2

Pour enough polyester resin into a stainless steel measuring cup to coat the cut pieces of fiberglass cloth.

3

Add the amount of MEKP hardener recommended on the hardener can to the measured resin. Mix the two parts thoroughly with a stir stick. Set the fiberglass cloth into the fiberglass mold. Coat each piece of fiberglass cloth with the mixed resin.

4

Allow the coated fiberglass to cure for three to eight hours. The cure time varies depending on air temperature. Temperatures warmer than 70 degrees Fahrenheit cause the resin to cure quickly, while cooler temperatures cause the resin to cure more slowly.

5

Touch the fiberglass with a finger. Allow the fiberglass to cure longer if it remains tacky. Set the fiberglass under a heat lamp to cure the fiberglass if it remains tacky after 12 to 24 hours.