John Robinson
Well-known member
Back in junior high school, high school and later I used to repair and build surfboards. I've been out of it a long time but back then we used two different types of polyester resin; laminating resin for the fiberglass cloth and finishing resin for the gloss coat. The laminating resin was too soft to sand and polish, it sort of smeared, sort of like trying to sand epoxy that hasn't hardened enough.
The process was to wet out the fiberglass cloth with a squeegy like we do, the poly resin seemed to wet out the class easier, there was no need to pre soak the cloth in resin. Anyway, you would squeegy out as much resin as possible to keep the weight of the board down. This left a prominent cloth weave showing after the resing hardened. Rather than sand the texture out for a smooth but weaker surface, we would keep the weave of the fiberglass cloth intact and fill the texture with finishing resin which was much harder. After this hardened we would sand, then polish the board with rubbing compound and wax.
My question relates to the finish coat on the hull. I read in the directions about sanding, then rolling on a finish coat of epoxy. Is the sanding just a light roughing of the surface so the resin sticks better? How does the epoxy do as a hard finish coat? Would there be any point in using a finish coat of polyester resin of the laminated epoxy? I'm worried about sanding through the weave of the cloth eliminating some of its strength.
The process was to wet out the fiberglass cloth with a squeegy like we do, the poly resin seemed to wet out the class easier, there was no need to pre soak the cloth in resin. Anyway, you would squeegy out as much resin as possible to keep the weight of the board down. This left a prominent cloth weave showing after the resing hardened. Rather than sand the texture out for a smooth but weaker surface, we would keep the weave of the fiberglass cloth intact and fill the texture with finishing resin which was much harder. After this hardened we would sand, then polish the board with rubbing compound and wax.
My question relates to the finish coat on the hull. I read in the directions about sanding, then rolling on a finish coat of epoxy. Is the sanding just a light roughing of the surface so the resin sticks better? How does the epoxy do as a hard finish coat? Would there be any point in using a finish coat of polyester resin of the laminated epoxy? I'm worried about sanding through the weave of the cloth eliminating some of its strength.