How to Fix a Soft Patch in Fiberglass
Fiberglass is a strong material but it is still vulnerable to failures. Many times from the sun or other factors, fiberglass can become soft in spots. This can also be due to poor application. An advantage about fiberglass is that, no matter what the size of the repair is, it can be restored to the original strength and surface. Fiberglass is applied in layers of fiberglass mat that are bonded together using fiberglass resin mixed with a hardener. This is an inexpensive and simple process that can be done with little experience. All supplies that are needed can be found at your local marine supply store.
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Things You'll Need
- Respirator
- Dye grinder
- Rags
- Acetone
- Fiberglass mat
- Razor knife
- Fiberglass resin
- Methyl ethyl ketone peroxide (hardener)
- Small bucket
- Stir stick
- Felt roller
- Air roller
- Fine grit sandpaper
- Palm sander
Instructions
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1
Put on a respirator and grind the soft fiberglass out using a dye grinder. Remove all the soft material and gradually taper the edges of the indent. The more gradual the edges are, the more surface area the new fiberglass will have to bond to. Scuff a few extra inches around the entire repair.
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2
Clean the surface using a rag and acetone. Remove any dust or grease that is on the repair surface.
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3
Cut the fiberglass mat using a razor knife. Make the first layer the size of the entire repair and make each following layer smaller than the last. Cut as many layers as it takes to build the wall of fiberglass back to the original thickness.
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4
Mix the fiberglass resin and hardener, following the directions on the containers. Use a small bucket and a stir stick to mix the resin meticulously. When the resin is one solid color, it is ready for application.
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5
Wet the surface of the repair with the resin mixture, using a felt roller. Apply the smallest layer of mat first and saturate it with resin. Apply the resin until the mat is the same color as the resin and has no dry white spots left. Remove all the air bubbles from beneath the mat using an air roller. Repeat this process for each layer until all the mat is applied to the repair. Let the fiberglass cure until it is hard and cool to the touch.
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6
Sand the repair using fine grit sandpaper and a palm sander. When the repair is complete, it will be level with the surrounding fiberglass and smooth.
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Tips & Warnings
Always wear a respirator when working with fiberglass materials.
