Fiberglassing over the epoxy fillets spreads the strength of the fillet into the plywood surfaces. For many of you this will be the first time working with epoxy and fibreglass but there is nothing to fear. Fiberglassing is nowhere need as hard some people think it is, personally I think it's easier than the epoxy fillets!
Our designs use fibreglass tape over the epoxy fillets on the inside of the board and on every edge on the outside. This way we know for certain the board is water tight and gives the edges of the plywood panels abrasion resistance.
If the board is to be stored outside you can fibreglass the whole board with a lightweight cloth but for boards that are kept out of weather when not in use it is not necessary.
The fibreglassing process...
Surface preparation - make sure the epoxy fillet is not tacky and the wood is clean (the fillet doesn't have to be fully cured)
Cut the fibreglass tape to length - position the fiberglass cloth over the fillet and cut it to length from bow to stern.
Mix a small quantity of epoxy - around 75-100ml per side is all you need.
Pour a small pool of epoxy resin - into the corner of the joint and center of the cloth.
- Use a disposable brush to spread the epoxy - over the fiberglass cloth surface with a disposable brush working the epoxy gently from the pool into the dry areas.
NOTE: Properly wet out fibreglass is transparent. White areas indicate dry fabric. Check for dry areas (especially over the plywood surfaces) and re-wet them as necessary.
Do not over apply epoxy as it can cause the fibreglass to 'float' above the fillet, only use just enough to fill the wave of the cloth. Avoid over working the epoxy into the fibreglass as it can disturb the weave of the cloth and create air bubbles under the fibreglass. Allow to cure overnight.