How to Do Fiberglass Gel Coat Repairs
Gel coat is fiberglass resin that is pigmented with any color. For outside applications such as boats and industrial tanks, there are additives that you can mix in the gel coat to protect against ultraviolet rays. Gel coat acts as paint and as a protective layer at the same time. The consistency of gel coat is very thick and is sprayed using a special gel coat gun. Over time, gel coat can get dings and cracks in the surface, which can almost always be repaired. You can find a gel coat gun and gel coat at your local marine supply store.
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Things You'll Need
- Respirator
- Coarse-grit sandpaper
- Fine-grit sandpaper
- Superfine-grit wet sandpaper
- Fiberglass filler
- Methyl ethyl ketone peroxide (hardener)
- Putty knife
- Rags
- Acetone
- Painters tape
- Gel coat
- Gel coat gun
- Boat wax
Instructions
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1
Wearing a respirator, sand the surface that you are repairing using a coarse-grit sandpaper. If there is a crack or gouge in the gel coat, sand the edges of the crack or gouge to a very gradual taper. Sand around the repair 5 to 6 in. bigger than needed. Scuff the entire area until there is no shine left on the surface.
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2
Fill in the cracks or gouges using a fiberglass filler. Mix the filler with the hardener as directed on the containers. Using a putty knife, fill in the repair until the surface of the repair is level with the surrounding area.
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3
Sand the repair area or areas using a palm sander and fine-grit sandpaper. Get the surface as smooth as possible.
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4
Clean the surface using a rag and acetone. Remove all the grease and dust from the surface.
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5
Tape off the perimeter of the repair using painters tape.
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6
Add the hardener to the gel coat gun as directed on the containers and spray the first coat of gel coat on the repair. The first coat should be a heavy mist for a base coat. Let the first coat begin to get tacky, which will take about 15 minutes. Once the first coat is tacky, spray the second coat. If the second coat is not fully covering the area, you can spray a third layer. Let it harden until it's cool to the touch.
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7
Remove the tape and wet-sand the surface using a superfine-grit sandpaper. Wet-sand until the fresh gel coat is level with the surrounding gel coat and smooth.
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8
Apply a couple of layers of boat wax and buff out using clean rags.
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Tips & Warnings
Always wear a respirator when working with fiberglass.
