How to Gelcoat Fiberglass

Gelcoat protects fiberglass and maintains a shiny surface. Gelcoat is often used to protect the hull of a boat. With wear and tear, the gelcoat on fiberglass needs to be replaced. You can buy gelcoat from a boat manufacturer or marine supply store. Use these tips to apply gelcoat to a fiberglass surface.

Steps

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    Remove old layers of gelcoat.
    • Spread polishing compound or oxidation remover onto the fiberglass. Use a sponge or abrasive pad to spread the polishing compound or oxidation remover.
    • Wash the fiberglass with water.
    • Allow the fiberglass to dry.
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    Clean the fiberglass. Eliminate paint flecks or primer from the surface of the fiberglass. Use a paint scraper to remove paint or primer from the fiberglass.
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    Apply a polyester or better, vinyl ester primer/filler coat.
    • Use a foam roller to cover the fiberglass surface in 2 to 3 layers of resin. Each layer should be very fine.
    • Spread each new layer of resin over a wider area of the fiberglass than you did with the previous layer.
    • Place a heat lamp near the treated area.
    • Allow the area to dry.
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    Wash the fiberglass.
    • Go over the surface of the fiberglass with an abrasive pad and water.
    • Allow the fiberglass to dry.
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    Sand the fiberglass. Use sandpaper to smooth over the surface of the fiberglass.
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    Color the gelcoat. Mix the desired gelcoat pigment with the gelcoat to match the original gelcoat tint. Follow the instructions for your particular brand of pigment and gelcoat.
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    Fill the spray gun.
    • Strain the tinted gelcoat through a paper strainer.
    • Add 15 drops of hardener (Methyl Ethyl Ketone Peroxide or MEKP) to each ounce of Gelcoat.
    • Pour the gelcoat into the spray gun.
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    Apply the gelcoat.
    • Use the filled spray gun to apply a fine layer of gelcoat to the desired area of the fiberglass.
    • Wait a few minutes to allow the coat to set.
    • Repeat spraying and waiting, applying a total of at least 5 layers of gelcoat to the fiberglass.
    • Spray a wider surface with each new layer of gelcoat.
    • Apply enough layers of gelcoat so that you are unable to differentiate between the treated and untreated areas of the fiberglass.
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    Let the gelcoat rest. Allow the gelcoat and fiberglass to sit for 48 hours or more.
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    Sand the gelcoat. Use sandpaper to go over the treated fiberglass.
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    Buff the fiberglass.
    • Use a sponge or abrasive pad to buff the fiberglass with medium-cut, white rubbing compound.
    • Apply fine rubbing compound over the buffed fiberglass with a sponge or abrasive pad.
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    Wax the fiberglass.
    • Apply the wax to the treated fiberglass with a foam pad or cloth. Rub the wax into the area in a circular motion.
    • Allow the wax to dry.
    • Rub a soft cloth over the waxed area to make it shine.

Tips

  • Wear safety goggles and protective clothing, including gloves, when handling gelcoat.

Things You'll Need

  • Fiberglass surface
  • Sponge or abrasive pad
  • Polishing compound or oxidation remover
  • Water
  • Paint scraper
  • Epoxy
  • Sandpaper
  • Gelcoat
  • Gelcoat pigment
  • Paper strainer
  • Spray gun
  • Medium-cut rubbing compound
  • Fine rubbing compound
  • Fiberglass wax
  • Soft cloth
  • MEKP (Methyl Ethyl Ketone Peroxide) - key ingredient in Gelcoat

Article Info

Categories: Glass and Stained Glass Projects