Gelcoat Application Guide For a Mold

- 304, 306, 307, 308 GELCOATS ARE DESIGNED FOR USE IN A MOLD AND WILL NOT CURE “TACK FREE.”
- In a mold that has been prepared with mold release, apply 15-20 mils (check with wet film thickness gauge) of gelcoat with a brush, roller, or spray gun.
- Gelcoat is quite thick so take care to apply as even a coat as possible, taking more care with a brush or roller. Too Thick may distort and pull away from the mold as it cures. Too thin, the mold will be attacked by the resin/glass build-up laminate causing it to crinkle up or “alligator.”
- Ventilate or fan the gelcoat while it is curing to remove the styrene vapor which can cause the gelcoat to cure unevenly and pull away from the mold creating unwanted waves, “Heat Sinks,” in the finished part.
- As soon as the gel coat is cured (so that it doesn’t come off on your fingers) its time to back up the gelcoat with a laminate.
- Apply a layer of .75 or 1.5 oz mat with polyester or vinylester resin. Once stabilized with the cured “backup” layer, proceed with the rest of the laminate.