How to Repair Fiberglass

Fiberglass is a durable material made of fine glass fibers. It is commonly used in supporting plastic materials. Fiberglass can be used for mats, high strength fabrics, corrosion-resistant fabrics, insulation, reinforcement, sound absorption, and heat resistant fabrics. Panels of fiberglass are also often used for greenhouses or outdoor canopies.

While the material is durable, it can still get damaged if struck with enough force. There is a way to repair damaged fiberglass.




  • de-waxing solvent
  • gel coat
  • Methyl Ethyl Ketone Peroxide
  • polyester resin
  • fiberglass mat
  • fiberglass fabric




  • grinder
  • resin roller
  • tape
  • razor


Step By Step Instructions


  1. Find the damage on the fiberglass. If you can’t see any damage, it may be found inside the fiberglass. Get a hard tool and tap it; undamaged fiberglass will emit a sharp sound when it is tapped while damaged fiberglass will produce a dull sound.
  2. If the damage is found inside, repair should be done from the inside for a flawless finish.
  3. Slice off the damaged part of the fiberglass and taper down the hole using a grinder. Make sure that you make a good taper because this will ensure a good finish.
  4. Use a de-waxing solvent on the edges of the fiberglass. This will strengthen the bond of the fiberglass.
  5. Spread paste wax around the hole to ensure that unnecessary resin will stay away from the damaged area.
  6. Secure a waxed backer at the bottom of the hole by using a screw or tape. This will help you achieve a hard and string surface.
  7. Apply a gel coat to the waxed backer. Use a gel coat made of pigmented or colored resin so that you can match the coat’s color with the coat of your fiberglass.
  8. Cut the fiberglass mat and fabric similarly to the hole and position them in alternating layers. The thickness of the fiberglass will determine the amount of fabric and mat you will need. Avoid using more than four layers because it may soften the bond of the fiberglass.
  9. Use an epoxy or polyester resin to patch the fiberglass hole and strengthen the fabric and mat. If you use polyester resin, you will need a laminating resin to strengthen the bond.
  10. To strengthen the polyester resins, use Methyl Ethyl Ketone Peroxide. Even out protrusions or air bubbles by using a resin roller.

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