Instructions for Fiberglassing
When bound to a surface with epoxy, fiberglass increases the strength and weather resistance of the underlying material. Fiberglass is widely used in building watercraft. From foam-core surfboards to wood-frame luxury yachts, fiberglass is a primary surfacing choice. Many custom car projects use foam-core composite with fiberglass as well. With preparation and practice, you can successfully apply fiberglass on your next project.
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Things You'll Need
- Sandpaper
- Sanding block or power sander
- Tack cloth
- Rubber gloves
- Respirator
- Scissors
- Fiberglass cloth
- Epoxy
- Mixing can
- Stir stick
- Plastic squeegee
- Orange-juice can
- Utility knife
- Paintbrush
Instructions
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1
Sand the surface of your project until it is flat and smooth. A sanding block or power sander helps prevent gouging or low spots in the surface.
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2
Remove sanding dust with a tack cloth. Any residue left on the surface keeps the fiberglass cloth from lying flat and causes air bubbles in the finish.
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3
Put on rubber gloves and the respirator. Handling fiberglass and epoxy without proper protection can cause skin and lung irritation.
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4
Place the fiberglass over the surface of your project. Smooth out any wrinkles.
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Cut the fiberglass slightly larger than the surface of the project. An inch or two of overhang along the entire circumference of the project allows for slippage when you apply the epoxy.
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Combine the epoxy resin and catalyst in a mixing can. Follow the manufacturer's instructions for the proper mixing ratios; these usually are 1:1 or 2:1, depending on the type of resin being used. Mix the epoxy slowly and thoroughly by hand with a stir stick. Rapid mixing introduces air bubbles in the resin that are unsightly and difficult to remove.
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Cut a 1-inch slice in the top of an orange-juice container. This will be used to clean the excess epoxy off of your squeegee as you work.
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Pour a small amount of epoxy in the center of your project over the fiberglass. Use the squeegee to spread the epoxy toward the edges. The fiberglass becomes clear as it soaks up the epoxy. Continue to squeegee the glass until you can feel the texture of the cloth underneath the squeegee.
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Continue pouring epoxy and working it in with the squeegee until you have coated the entire surface. Occasionally clean the squeegee by drawing it through the slot in the orange juice container. The epoxy is collected inside the can.
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Allow the initial application to dry. Consult the manufacturer's instructions for drying time between coats.
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Trim the excess fiberglass around the edges of your project when the epoxy becomes stiff. It is most easily trimmed with a sharp utility knife before it hardens completely.
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Apply subsequent coats of epoxy with a paintbrush. Two or three coats usually is sufficient for adequate protection and a smooth surface.
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Tips & Warnings
Epoxy resin degrades when exposed to direct sunlight. If your project will be exposed to the elements, use spar varnish or a UV-resistant paint to finish the job.
Mix epoxy in small batches while working. Once mixed, epoxy hardens within a few hours and is no longer usable.
Epoxy generates heat as it cures--sometimes quite a bit of heat. Do not dispose of mixed epoxy in a container with flammable materials.
Fumes from epoxy and related solvents can be toxic. Always wear proper breathing protection while working with chemicals. Work only in well-ventilated areas.
Small amounts of sanding dust can prevent a smooth bond between the fiberglass and substrate. Once the epoxy is cured, there is no way to sand out the imperfections without sanding through the glass.
References
- Photo Credit motor boat. power boat image by L. Shat from Fotolia.com
