How to Use Fiberglass Cloths

Woven fiberglass

Fiberglass cloth is made up of woven strands of fiberglass that come in different size rolls. There are many different types of fiberglass cloth. Some have tight closely woven fiberglass strands; some are thicker and heavier weaves. Fiberglass cloth is used in between layers of fiberglass mat for strength and to increase the overall thickness of fiberglass lay ups. Fiberglass is applied in layers of "mat" or "cloth" that is saturated with a catalyzed resin. When the resin hardens the layers of mat and cloth fuse together and form a solid piece of fiberglass.

Things You'll Need

• 100-grit sandpaper
• Rags
• Acetone
• Rubber gloves
• Razor knife
• Fiberglass cloth
• Fiberglass mat
• Fiberglass resin
• Small bucket
• Catalyst (methyl ethyl ketone peroxide)
• Stir stick
• Felt roller
• Air roller

Instructions

1. Prepare the surface you are applying fiberglass to by lightly sanding it with 100-grit sandpaper. Clean the surface and remove any dust using a rag dampened with acetone. Let the acetone completely dry.

2. Determine the size and shape needed for the fiberglass mat and cloth and cut them to size using a razor knife. Use the amount of layers that the job you are doing calls for.

3. Put on rubber gloves and fill a small bucket with resin. Add the recommended amount of catalyst, according to the container, and thoroughly mix it in with a stir stick.

4. Wet the surface of the piece you are applying the cloth to with resin using a 4-inch felt roller. Apply the first layer of mat to the piece and saturate it with resin using the felt roller.

5. Flatten and remove any air bubbles that may be trapped under the mat using an air roller. Apply the next layer and continue the same process until all layers of mat and cloth are applied to the piece. Let the fiberglass harden.

Tips & Warnings

• Always wear skin protection when handling catalyzed resin.

References

• US Composites; Fiberglass cloths
• Fiberglass Warehouse; Fiberglass information