hi, i keep reading that you are able to use less epoxy than poly in surfboard but from my own point i am unable to see it ,i have used both methods and the techniques are the same,ie squeege out the excess, sandcoat,finish coat where can you use any less resin.
Pete, my experience with epoxy is that it’s longer, more gentle gelling Vs. MEKP poly is one of the biggest factors in using less resin. As you know, one of the hardest things for a poly laminator is getting the laps thoroughly drenched with very little resin-loss to the floor, while still getting good wet-out and consolidation of the main area of the surface being glassed - all within 15 minutes or less!The easy solution is to just flood the laps and focus on consolidating your deck or hull glass ASAP. With UV poly, or epoxy, the lap-wetting can be slower and more controlled using a really small thin squeegee instead of the big 12" Thalco type you need if using a fast MEKP poly mix.Having more time alone has allowed me to use 30% less resin when working with epoxy.Also; skipping the hotcoat stage, as epoxy cures to a ready-to-sand finish, saves almost the weight in resin for laminating one whole side of the board !
John, This may be a silly question, but I’m new to this. If you don’t hotcoat with epoxy. When you sand, don’t you sand into the weave of the cloth?, I thought that sanding into the weave weakened the laminate.
John is right about wetting the laps. That is certainly a place where a lot of resin hits the floor. Another problem with polyester is that if you shoot the resin slow, so you have time to work, the blank soaks up a lot and you end up with a heavy board. Epoxy tends to want to stay in the fabric. Like John said above too, we use hard plastic sqeegees which moves the resin more effectivly so you don’t need excess there either. Also the resin is high solids which means there is no evaporation going on. Even with the UV cure polys, if you don’t finish in a reasonable time the stuff starts getting sticky and hard to work with. Epoxy doesn’t have that issue. As far as sanding the laminate, you can put a sanding cloth layer on the board which acts like a hot coat layer. It can be done the same time as the laminate. Usually use 4 oz or 2 oz for this and we’ve found that doing a reverse lap comes out cleaner.
What is a reverse lap?
Laminating the deck first. You are able to fair the lap into the rail easier than fairing the lap into the flatter bottom on your second side.
That reverse lap mentioned by Greg sounds interesting ! I’ve found the hardest part is sanding the stuff - i’m using a post-curing resin (Baked Epoxy) that is like concrete to sand, so having a smaller less dramatic lap to sand sounds good - thanks again Greg ! The finishing side of epoxy board-building is much harder, in my experience, than poly building.I’ve been playing around with ultra-fine satin weave cloths approx. 1.5 - 3 ounces as sort of a drape to provide a super slick finish that can be lightly deburred with grit discs but basically just wet rubbed ( ideally i want to purchase a pneumatic-powered random orbital wet sander).But a high-build water-based clear polyurethane spray finish is my aim !Does such a finish exist ?
As far as sanding the laminate, you can put a sanding cloth layer on the board >which acts like a hot coat layer. It can be done the same time as the >laminate. Usually use 4 oz or 2 oz for this and we’ve found that doing a >reverse lap comes out cleaner. Do you still use cloth for this or glass mat? What glassing schedule does this add up to, 4+4+2 bottom, 4+4+4+2 top? regards, Håvard
You use cloth, not mat. And yes that would be the schedule on polystyrene if you were using the 2 oz. That stuff is pretty smooth.