Fiberglass Tools

Use a metal or paddle laminating roller to compact the laminate and drive out trapped air after you wet out the glass, which prevents weak, bubble-filled spots. Reach for a corner roller on inside corners, a radius roller on curves, and a detail roller in tight areas. Wet out first with a chip brush or squeegee, then roll until no more air bubbles rise.

Disposable natural-bristle chip brushes are the shop standard for resin and gelcoat. They are cheap enough to throw away after a batch, and the bristles hold up to the styrene in polyester. Foam brushes work for thin coats and small touch-ups but can break down in solvent-heavy resin. Buy chip brushes in bulk, since resin ruins them and they are not worth cleaning.

Use graduated mixing cups to measure resin and hardener or catalyst to the ratio on the label, then stir with a flat stick for at least a minute, scraping the sides and bottom so it blends fully. Epoxy must be measured to its exact ratio and is not forgiving; polyester takes a small percentage of MEKP by volume. Mix only what you can use within the pot life.

Match the grit to the stage. Knock down cured laminate or heavy gelcoat with 80 to 120 grit, fair and smooth with 220 to 320, then wet-sand gelcoat for polishing with 400, 600, and on up to 1000 or finer before you buff. Sanding sponges follow curves better than flat paper. Always sand cured surfaces and wear a dust mask, since fiberglass dust irritates skin and lungs.

Use sharp scissors or a rotary cutter on a clean surface. To reduce fraying, run masking tape along the cut line and cut through the middle of the tape, and handle cut edges gently. Keep the cloth dry before layup, since moisture on the glass weakens the resin bond.

Wear nitrile gloves, eye protection, and a Tyvek or disposable coverall to keep resin and glass fibers off your skin and clothes. Use an organic-vapor respirator when working with polyester resin, gelcoat, MEKP, or solvents, and always keep the area ventilated. A simple dust mask is enough only for sanding cured glass, not for liquid resin or solvent fumes.