Fibreglass is a very durable and lightweight material commonly used for boats, showers, tubs, cars and many other applications. Many times fibreglass is used for reinforcement over things such as wood or foam. Fibreglass is a waterproof and corrosion-proof material applied in layers of dry fibreglass mat. The mat is bonded together using a fibreglass resin that comes in a thick liquid and requires a catalyst to harden. Fibreglass is very strong and long-lasting, if applied correctly.
Wearing a respirator, lightly sand the plywood surface. Use a palm sander and coarse-grit sandpaper. Remove any raised chips of wood and make the surface as smooth as possible for the best bond.
Remove any dust or grease from the surface of the plywood. Grease or oil residue can cause the fibreglass to bond incorrectly. Use a clean rag and acetone to thoroughly clean the surface.
Cut the fibreglass mat to size using a razor knife. If using more that two layers, cut each layer ¼ inch smaller than the last. This will let the edges lay down without a ledge.
Mix the fibreglass resin with the hardener as directed on the containers. Use a small bucket and a stir stick to thoroughly mix the resin. When the resin mixture is one solid colour, it is ready to apply.
Wet the surface of the plywood with the resin mixture, using a felt roller. Apply the first layer of fibreglass mat to the plywood and saturate it in resin, using the felt roller. When there are no dry spots remaining on the mat, remove all the air bubbles using an air roller. Repeat this process for every layer of mat. Let the resin cure until it is hard and cool to the touch.