How to Apply Surfboard Fiberglass Finish

Making your first surfboard is an ambitious task but can be successfully completed with concentration and planning. Research what materials and tools you need for the entire process so that you are fully prepared. Once you have shaped a polyurethane foam blank into a surfboard shape, you must finish it by laminating it with fiberglass cloth and applying a final coat of finishing resin. The fiberglass finish on a surfboard gives it strength and protects the inner foam from water.

Things You'll Need

  • Protective gloves
  • Protective mask
  • Polyurethane blank
  • Fiberglass cloth
  • Scissors
  • Polyester laminating resin and hardener
  • Resin mixing cups
  • Mixing sticks
  • Hand-held squeegee
  • Polyester finishing resin and hardener
  • Foam-backed sanding block with medium grit sandpaper
  • Foam-backed sanding block with fine grit sandpaper
  • Water
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Instructions

  1. Applying Fiberglass Finish

    • 1

      Lay a sheet of fiberglass cloth over the shaped polyurethane blank. Ensure that all of the surface of the blank is covered and that there is an overhang of roughly 1 inch on all sides. Trim off any excess fiberglass cloth with a pair of scissors.

    • 2

      Pour some polyester laminating resin into a clean mixing cup and add hardener. The appropriate ratio will be listed on the container. Usie a mixing stick to mix the resin and hardener together thoroughly but slowly to avoid creating air bubbles in the mixture. To minimize waste, avoid mixing more resin and hardener that you can apply to the board in 15 to 20 minutes.

    • 3

      Pour most of the mixed laminating resin onto the center of the fiberglass cloth covering the blank, leaving a small amount in the mixing cup. Use a hand-held squeegee to spread the resin over the fiberglass cloth, working from the center to the edges, which on a surfboard are called rails. Saturate the entire surface with resin and work out air bubbles by applying extra pressure on the squeegee.

    • 4

      Use the excess laminating resin to stick the overhanging fiberglass cloth to the bottom surface of the blank. Use any leftover resin to cover holes or make thin patches of resin thicker.

    • 5

      Allow the laminating resin to cure overnight. Do not move or touch the blank until the resin has fully hardened. Then turn the blank over and repeat Steps 1 through 4 on the other side. Allow the resin to cure and do not touch it until fully hardened.

    • 6

      Mix polyester finishing resin with hardener in a clean mixing cup. Pour the mixed finishing resin onto the fiberglass-laminated blank and spread it equally over the surface until it is about 1/32 of an inch thick. Allow the finishing resin to dry and repeat the process on the other side.

    • 7

      Sand the board with a foam-backed sanding block with medium grit sandpaper. Stop sanding the board when the thickness is uniform and the surface is smooth.

    • 8

      Use a foam-backed sanding block with fine grit sandpaper soaked in water to wet sand all surfaces of the board until the desired finish is achieved.