Fibreglass Repairs
The Process
Preparation
Fibreglass repairs are usually done on the back of the laminate. This is to reinforce the laminate prior to finishing the outer surface. The surface to be repaired must be free from oil, grease, paint or any other contaminant to ensure maximum adhesion. If solvents are used, dry the surface before roughly sanding a minimum of 75mm around the area to be repaired.
Application
- Tape over any holes on the outer surface.
- Cut or rip the glass (fibreglass) to the size of the sanded area. Several layers will be necessary to build the laminate to the required thickness for strength. If the area to be repaired is larger than 200 square mm, tear the glass into manageable sizes for ease of wetting out.
- Use the guide below to calculate the amount of resin needed:
- 500mm x 500mm fibreglass mat - use 500ml resin and 10ml catalyst (MEKP)
- 1m x 1m fibreglass mat - use 1L resin and 20ml catalyst (MEKP)
- Wear safety gear as recommended. Have a piece of cardboard, plastic etc. on which to wet out the fibreglass.
- Thoroughly mix the resin and catalyst (MEKP). Working time is around 15 minutes in warm conditions. Lay the glass patch on the cardboard and thoroughly wet out with resin - use a clean paintbrush for application. Coat the sanded area with resin and lay on the wetted out fibreglass patch. Work the area with a paintbrush to remove any air bubbles or wrinkles. Build up 3-4 layers and allow to cure (about 1 hour in warm conditions). Sand the area and apply extra layers as required.
- Remove tape from outer surface before curing is completed. It may be necessary to fill any deep cavities in this area but leave surface slightly underfilled.
- Sand underfilled area to provide good adhesion with fillers or finishing coats.
For a gelcoat finish, apply gelcoat to slightly overfill the repaired area and allow to cure. When cured, sand smooth with wet & dry sandpaper, finishing with a very fine grit paper, and polishing.
- Clean up brushes etc. with acetone.
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