How to Repair Fiberglass

Fiberglass is a material used in garage doors, boats and tubs among many others. While it is very strong, holes or cracks can appear. If you want to know how to repair fiberglass, here’s how to do it.

Required Tools and Materials

Fiberglass fabric
Razor
De-waxing solvent
Grinder
Tape
Methyl ethyl ketone peroxide
Polyester resin
Gel coat
Resin roller
Fiberglass mat

Step 1

If you can’t find the damaged area, tap the fiberglass with a hammer or another hard tool. The damaged part will sound dull.

Step 2

Use the razor to cut off the damaged part. You can also taper the hole using a grinder. Making a taper provides the laminate more room to work with. This makes repair work simpler too.

Step 3

Apply de-waxing solvent on the hole’s exterior border. This is for bonding purposes.

Step 4

Put paste wax around the area of the hole. This step is important when you study how to repair fiberglass. It will keep resin from bonding on the parts not damaged.

Step 5

Tape or screw a waxed backer on the hole’s bottom. This will provide you with a suitable working surface.

Step 6

Put gel coat on the waxed backer. This will be the exterior finish that will correspond with the fiberglass. Gel coat consists of pigmented resin. This means you have to do some color matching here.

Step 7

Slice the fiberglass mat to the dimensions of the hole. Apply a couple of layers of the mat. Put the fabric on. Alternate the layers of mat and fabric. Don’t put in more than four alternating layers. It will reduce the bond strength.

Step 8

Apply epoxy or polyester resin on the hole. If you use polyester resin, laminating resin has to be applied as well.

Step 9

Put on methyl ethyl ketone peroxide to strengthen the polyester resin. Application will vary per product; follow the instructions. Remove air bubbles and bumps with the resin roller.

Step 10

Take out the wax backer. Put more gel coat on the exterior if needed. Polish and sand the surface.

Tips and Warnings

Ensure the tape hole is tapered. Otherwise, the surface area will be too weak. If you used laminating resin, seal it with plastic. If you want a more polished look, wax the parts surrounding the hole. You should also use a waxed backer.

Before you repair fiberglass, be certain you have all the materials listed. Make sure you follow the directions so the fiberglass will come out looking all right.

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