How to Repair Fiberglass Damage

Protect the surrounding area: Use poly sheeting and masking tape to protect the areas adjacent to the area you’re going to repair.

Clean the surface: Dampen a clean cotton rag with acetone and wipe the surface of the repair area to remove contamination and loose debris.

Sand and grind: Use 36-80 grit sandpaper (depending in the severity of the damage) and an appropriate grinder to remove any loose gelcoat or fiberglass debris from the damaged area. For rounded edges, use an appropriate bit.

Clean the repair area thoroughly:

Vacuum the surface to remove sanding/grinding residue.

Remove any remaining surface residue or contamination by wiping the repair area with a clean rag dampened with acetone. Allow the solvent to dry completely.

To create this mixture, combine TotalBoat 5:1 Epoxy Resin & 5:1 Slow Hardener in a clean, plastic mixing cup. Always use the correct ratio of 5 parts epoxy resin to 1 part hardener (by volume) and mix thoroughly.

Next, add a little bit of TotalBoat Silica Thickener, and stir until the mixture is a ketchup consistency.

Dispense 5 parts 5:1 Epoxy Resin and 1 part 5:1 Slow Hardener into a clean mixing cup, and stir thoroughly.

If desired, pour mixed, unthickened epoxy into a small, clean, disposable plastic beaker or cup. Doing so can make it easier to dip a small brush in to wet out the fiberglass patches.

Start by making a template for the first piece of fiberglass, then use fiberglass shears to cut successively smaller pieces, until you have enough for your patch.

Use a small brush (e.g., an acid brush) to apply a thin layer of the mixed, thickened epoxy to the repair area. This epoxy layer will fill cracks/voids and create a bond for the pieces of the fiberglass patch.

In this example, we’ll build the fiberglass patch directly on the repair area.

Lay down the largest piece of fiberglass and press it gently into the thickened epoxy you applied in the previous step. Use a small brush to wet out this first layer. Apply only enough mixed epoxy to saturate the cloth.

Apply each successive piece of fiberglass, one at a time, wetting out each piece as you go.

Cut and position peel ply: Cut a piece of peel ply large enough to cover the repair area, and lay it on top of the final coat of epoxy.

Wet out peel ply: Use a small brush to apply a coat of mixed, unthickened epoxy on top of the peel ply fabric to prevent air bubbles.

Remove peel ply: When the repair area cures completely, remove the peel ply slowly and carefully. Removing the peel ply also removes any amine blush and some of the excess epoxy.

Sand and/or grind: Sand/grind to shape and smooth the repair.

Remove residue: Vacuum to remove sanding dust.

In general, gelcoat is not compatible with cured epoxy. However, if the repair is small, perfectly executed, and cosmetic in nature, you can overcoat it with gelcoat. Otherwise, use an epoxy tie-coat primer such as TotalBoat TotalProtect barrier coat or TotalBoat 2-Part Epoxy Primer over the cured epoxy repair, before applying gelcoat.

Before you begin any project, we recommend the following:

Carefully read the safety information on all product labels.

Review the information in the SDS (Safety Data Sheets) for each product, including Section 8: Exposure Controls/Personal Protection.

Gather the proper PPE items, as stated by the manufacturers. Items can include, but are not limited to, the following:

Proper respirators for product application and for sanding cured material.

Suitable gloves to protect your hands, and proper eye, face, skin, and clothing protection.