Fiberglassing Plywood Hull

[Alan Peck]

This will be my first attempt at using fiberglass cloth and epoxy. I have filled the 800 or so countersunk screw heads with epoxy putty. The result is that each area above the screws is fairly smooth, but many have very slight depressions. I know that with paint even the most minor imperfection will show through. But with 6 oz. fiberglass cloth and resin, how smooth does the surface underneath really need to be? Do I need to go back and try to obtain a perfectly smooth finish over each countersunk screw or will the fiberglass cloth smooth things out?

Any advice appreciated.

[Ian McColgin]

Get it smooth. Just a little thickened epoxy swabbed over the holes and then sanded. You don't want dimpled chads after all.

[NormMessinger]

Yes, get it smooth. Use microballons if you have them to thicken the epoxy. That mix sands much easier. If you don't have them you can fill the holes, strike them off with a flat insturment and lay the glass on before the filler cures. Sanding soft wood with hard filler can leave the filled areas standing up a bit. However, better a slight depression. High build primer can fix some imperfections as will raw epoxy as you fill the weave of the glass.

--Norm