The New Word on Surfboard Foam
Deciding whether to ride polyurethane or polystyrene surfboard foam will affect several other factors in your next surfboard design. Being such a crucial decision, it is important to realize the different characteristics of each material and conduct a good amount of research in your quest for the perfect surfboard. To help you gather the facts SurfScience attended the October 2009 Sacred Craft Surfboard Expo to learn the latest thoughts on polystyrene vs. polyurethane.
Most surfboard manufacturers now offer a choice of polyurethane or a variation of polystyrene (Styrofoam). When Grubby Clark shut down Clark Foam December 5, 2005 it triggered an intense interest in other technologies. This is due in part because Clark’s foam recipe offered a superior ride to other polyurethane blanks available on the market. The lack of quality polyurethane blanks caused the industry to take a hard look at alternative foams and resins, including polystyrene and epoxies.
The Polystyrene foam and epoxy resin combination continues to offer strong lightweight surfboard, with a perceived lower impact on the environment.
“Standard polyurethane surfboards use a three pound foam,” explains Surftech’s Robert Hyland. “What that means is if you have a one foot cube of foam it would weigh three pounds. Expanded polystyrene, like the foam found in Surftech models, is typically one pound foam. Blank to blank you’re looking at cutting a third of the weight.”
One of the major drawbacks to using polystyrene blanks in the past was the quick absorption of water. This material is made up of many styrene beads stuck together. As a result, some versions of the material had many voids for water to seep into. This has been addressed in recent years.
“Our Ultraflex boards have the normal Techlite fused cell EPS core (Fused Expanded Polystyrene),” continues Hyland. “It doesn’t have any voids and it doesn’t absorb any water. All the cells are completely fused together. When we’re blowing the EPS foam, we pressurize the mold. As we pressurize the foam, it forces the foam cells to fuse together completely so there are no voids or gaps in the foam. Closed cell EPS doesn’t transmit water from cell to cell. Bad EPS, on the other hand, will be full of voids.”
Toxicity and Strength
Another reason a shaper may use polystyrene is because it emits less volatile organic compounds (VOCs). Given this fact it was no surprise to learn Fletcher Chouinard, surfboard builder for Patagonia, uses extruded polystyrene foam in his surfboards. According to their website, this foam is also 73% more resistant to taking on water than normal surfboard foam.
“It starts with an extruded polystyrene foam core; a real fine cell structure,” tells Roy Koffman of the Patagonia surf shop in San Diego County. “It’s a real lightweight, high density foam core. It allows us to glass with epoxy resin and a much stronger glassing schedule. This particular board here has a triple 4 oz deck, which is significantly more than you would find on a typical stock board. That core is so light, yet it has much more durability built into it. It’s a fine line between building a more durable board but at the same time be able to surf at a high level of performance.”
The Case For Polyurethane
Just when I thought EPS had arrived as the preferred foam of all riders and shapers I heard some very conflicting views from La Jolla based shaper Tim Bessell.
Bessell does not shy away from using alternative materials, such as carbon fiber, to build a stronger and better performing product. He offers his surfboard designs in Aviso because he considers it the most advanced surfboard technology available today. Knowing this you might think he would be on the polystyrene bandwagon, but he was quick to point out polystyrene’s deficiencies.
“Styrofoam has heat and absorption issues,” says Bessell. “XTR can’t go over 140 degrees or it will start delaminating and out-gassing. The EPS has problems because it has absorption problems. If you get a ding in an EPS board it will suck water like no tomorrow. They have these round pellets they’re trying to form together. It’s just not ever going to work. Polyurethane foam is still, I believe, the best foam in the world. Its weight to strength ratio is comparable to any of the best polystyrene blanks.”
Bessell goes on to comment on how bad styrene is for the human body.
“I’m not a big fan of Styrofoam. First of all, it’s bad for your body. I know so many veteran board builders who have gotten out of the industry because they have bad allergic reactions. I have bad allergic reactions. Our society is a fast food society. They’ve found that people have way too much styrene in their systems. I can’t even shape Styrofoam anymore.
“I’m not a big fan. It doesn’t make boards better. And the only thing better about making epoxy is they don’t use any acetone. If you want to be a naturalist then you ought to get a wood board and rub seed oil on it, but we’re kind of beyond that.
“EPS is just the wrong way to go. They’ve been blowing polyurethane foam for fifty years. Styrofoam is not the same deal. It doesn’t look good, it doesn’t take color well, and you have to use epoxy resin. With polyurethane you can use both polyester or epoxy resins.”
All three people we spoke to for this article prefer different surfboard foam…and they’re all right. Each foam has its own benefits and drawbacks. XTR and Fused EPS may resist water absorption, but will they delaminate? Standard expanded polystyrene may take on water like a sponge, but it is still much lighter than traditional Polyurethane. Polyurethane may still give the very best ride, but what can we do to make it less toxic? These are all questions that deserve attention. Any good shaper worth his salt will be glad to help you answer them.