How to Use Fiberglass to Patch

Fiberglass is a very strong and durable material that will bond to almost any surface. Many times fiberglass is used to build boats, tubs, surf boards, tanks, and industrial duct work. Fiberglass is also commonly used to patch different materials such as metal, plastic, wood and fiberglass. The waterproof and corrosion proof elements of the fiberglass make it a good patching material for land and water applications. Fiberglass materials can be found at your local marine supply store.

Things You'll Need

• Dye grinder
• Rags
• Acetone
• Aluminum tape
• Scrap board
• Fine grit sandpaper
• Fiberglass mat
• Razor knife
• Fiberglass resin
• Methyl ethyl ketone peroxide (hardener)
• Small bucket
• Stir stick
• Felt roller
• Air roller
• Palm sander

Instructions

1. Grind the edges of the repair using a dye grinder. Gradually taper the edges so the fiberglass has a larger surface to bond to. Remove any rough or dry fiberglass on the edges so the surface is smooth.

2. Clean the surface using a rag and acetone. Remove any grease or dust that may be on the surface. Any grease or oil residue can cause the fiberglass to delaminate which will cause an air bubble in the fiberglass.

3. Cover the hole using aluminum tape. Place something hard on the back of the hole to prevent the tape from sinking in when you apply the fiberglass. Smooth out the edges of the aluminum tape using sandpaper.

4. Cut the fiberglass mat using a razor knife. The mat should be cut in as many layers as it takes to make the material the same thickness as the rest of the piece or a little thicker. Cut the first layer the size of the repair and make each layer that follows gradually smaller.

5. Mix the fiberglass resin with the hardener following the recommendations on the containers. Use a small bucket and a stir stick to thoroughly mix the resin. When the fiberglass is one consistent color it is ready for application.

6. Wet the surface of the repair with the resin mixture using a felt roller. Apply the smallest layer first and wet it out with the resin mixture. Saturate the entire layer of mat until it is the same color as the resin with no dry white spots. Remove any air bubbles with an air roller. Repeat this process until all of the layers are applied to the repair. Apply the mat from smallest to largest centering each layer. Let cure until the fiberglass is hard and cool to the touch.

7. Sand the hardened fiberglass patch using fine grit sand paper and a palm sander until it is smooth and level with the rest of the surface.

References

• American Marine Supply
• Boat Us
• Fibreglast