What are the advantages, if any, of using epoxy on Clark Foam over polyester?
Epoxy is a tougher resin and there are advantages simply because of that. But the real advantage is in resin to fiber ratio. There is nothing more important to the strength of a composite than this. Simply put there is less resin weight in an epoxy lamination than in a polyester. This allows that there is more room for increased fiber in the laminating schedule. In laminating a Clark blank you are able to put 2 more ounces per side in a laminate of epoxy than in a laminate of polyester. That would be a 6 oz bottom and a 4-6 oz deck instead of 4 oz. all the way around. Significant strength improvment at the same weight. The other way this can work is that you can simply use the next weight of foam. In other words insead of using a blue blank, as you would with polyester, instead use a green. With the same glass the epoxy/green will be the same weight as the polyester/blue and guess which one is stronger?
I’m not sure I follow. How come an epoxy laminate is lighter than a polyester laminate? Is polyester resin heavier (specific gravity) than epoxy?
anton- epoxy is a little thinner than poly- wet out takes less resin with the cloth, and as greg stated, more layers of fiber constitute less resin needed to bond the lamination together and ‘glue’ it to the blank- more fiber = stonger.
another advantage: NO STINK!!!
Thinner? Every rare time in which I use polyester, I always marvel at how much thinner it is than epoxy and how quickly it wets out the cloth. Did you mean epoxy is THICKER, and requires less to wet out the cloth. I guess I could see that. I only use epoxy in a vacuum bag setup, so all my excess resin is squeezed out and soaked up by the breather. I really can’t use polyester because it just doesn’t give me enough time to work and get the bag setup before the resin kicks. Once it gels, I can’t pull the excess out and I end up with a heavy laminate. I guess I was just wondering what the weight difference would be between a 6 ounce patch of cloth layed up with epoxy and one layed up with polyester (open layup done by an expert, of course). I never really figured epoxy as being a lighter laminate, just a stronger, tougher and less smelly one. So you’re saying it takes MORE polyester to sufficiently wet out the figerglass?
Yes, epoxy does come out significantly lighter with the same glass schedule. Our resin is thicker than polyester but can be sqeegeed drier. Thus lighter weights.
Cool. That’s what I was wondering about. That’s just even another reason to use epoxy, but I guess it’s one everyone else already knew 