Epoxy versus Polyurethane

Currently, the vast majority of the world’s surfboards are made of polyurethane (PU) foam and then skinned with a matrix of fibreglass cloth and polyurethane resin.

Epoxy is a similar two-part resin to polyester, though it is much less toxic, has a higher compressive and impact strength and can be laminated over almost any type of foam, unlike polyester which will melt any but PU foam. The glassing process is similar, but not identical to polyester. The fibreglass cloth used is the same. Also, due to epoxy’s higher strength and non-reliance on PU foam, the lighter and less toxic expanded polystyrene (EPS) foam can be used. Thus, a board of the same dimensions will be stronger and lighter. Rather than embracing these characteristics and redesigning boards around them (ie, lower volume), many shapers and glassers see these characteristics, as well as the increased cost, different techniques and increased lifespan as negatives and shun epoxy.

In December 2005 Clark Foam, the world’s largest manufacturer of surfboard blanks was shut down by the EPA. A substantial part of the closure was due to their use of chemicals such as Toluene Di Isocynate (TDI) and polyester resin. This set the surf world on end, and for many sounded like the death of surfing as we knew it. Epoxy technology and indeed surfboards had existed for decades, but was never as popular.

In the wake of Clark’s shutdown, many shapers experimented with epoxy, some of them hating it and some embracing it. EPS and epoxy boards have started appearing wearing ‘green’ credentials. Compared with a PU board, they require much gentler chemicals and last longer. It should be remembered though that it is still a short lifespan product made entirely from petrochemicals (excepting the stringer).

Another factor working against epoxy has been the pop-out phenomenon. A result of the different chemical properties of foam and handling techniques, epoxy has allowed the factories to mass-produce moulded epoxy boards, known colloquially as pop-outs. The ride quality, however, is usually terrible. They tend to be heavy, dull boards, and give epoxy a bad name—a bit like how fast food chains give hamburgers and pizzas a bad rep.

Even after the demise of the supplier of 80% of the world’s PU blanks, PU boards still dominate the market. From my perspectives, there are no good reasons for me to use PU, and I couldn’t recommend anyone else buy or shape a PU board.

Epoxy is far from perfect from an environmental perspective but so far it seems to me to be the best and most responsible way to build surfboards—in timber or foam. It has lower environmental and direct health implications, as well as building the most robust surfboards possible without compromising the ride.

Take a look at the bio-resin essay for more.
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