How to Reinforce Holes in Fiberglass
When it is installed, fiberglass is constructed in sheets of both fiberglass weave and resin. When holes manifest, they can become weak points in the fiberglass. These weak points can spread, particularly if the fiberglass section is designed to be a wall or shelter such as in a shed roof or a boat hull. Repairing such cavities requires exposing the fiberglass section and reapplying new fiberglass to fill the area. Does this Spark an idea?
Things You'll Need
- One-handle saw
- Dewaxing solvent
- Goggles
- Safety mask
- Disk sander
- Paste wax
- Plastic sheet or laminate
- Industrial tape
- Alcohol mold release
- Scissors
- New fiberglass sheets
- New fiberglass resin
- Disposable paint brush
- Rag
- Acetone
- Roller brush
- Paint brush
Instructions
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1
Use a one-handle small saw to cut a clean edge around the entire original hole. Make sure that you have cut out any cracks that may have emanated from the original hole.
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2
Position yourself on the inside of the fiberglass surface if it is used as an exterior wall or layer. Wash the surrounding edges of the hole with a dewaxing solvent.
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3
Put on goggles and a safety mask to prevent fiberglass dust inhalation. Apply a disk sander to roughen the surrounding fiberglass area of the hole, to make a good contact area for the new patch.
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4
Surround the sanded area with a perimeter of paste wax so that resin runoff won't adhere to undamaged fiberglass in the greater surrounding area of the hole. Use a hand brush to clear the dust as it collects from the grinding. Clean the treated area with a rag dipped in a solvent such as acetone.
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5
Treat the area surrounding the hole on the external surface of the fiberglass with a paste wax rub. Do not get any wax on the hole edge or the internal surface. Use a plastic sheet or plastic laminate as a backer on the outside surface and tape it over the hole with industrial tape to provide a mask for the internal application. Use an alcohol mold release on the part of the backer that will cover the hole so when you take it off, it separates from the new fiberglass.
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6
Cut enough fiberglass sheet with your scissors to completely cover the hole. Do this a couple of times to produce enough layers to be as thick as the layer to be filled inside the hole. Make each sheet progressively bigger than the first.
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7
Apply the first layer of resin into the hole against the mask with a paint brush. Lay down the first sheet of fiberglass on it. Use a paint roller to flatten out any air bubbles. Repeat until you have a maximum of four layers of sheet and resin applied -- you can do three on the first round. Let the first layer harden, and then apply four more sheets with resin. Continue the application, hardening and re-application until the hole thickness is sufficiently filled.
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8
Wait for the fiberglass fill to completely cure and harden. Check that the fill cured correctly without any cracking. Repeat Steps 1 through 7 on areas where the job did not cure or shows bubbling or cracking. Remove the mask and its tape when finished. Sand the residue and extra ends down to create a smooth transition surface from the old fiberglass to the new patch area. Paint as necessary.
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Tips & Warnings
Applying thin layers and allowing them to cure works better than trying to rush the job all at once. Hardening can generally take between 30 minutes to an hour, so a new layer can be applied the same day.
Fiberglass and resin are extremely toxic. Perform the work in a well-ventilated area as the fumes involves can be harmful to your health. Wear gloves to protect your hands and skin.
References
- Photo Credit Jupiterimages/Photos.com/Getty Images
