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Polyurethane or Polystyrene foam? Which makes a better surfboard?

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Surfboard shaper shaping surfboard
Stephen Pennells/Photodisc/Getty Images
What type of surfboard foam should you chose for your next shred stick? Polyurethane or polystyrene? Those words bang around the surfboard industry, design forums and in the shaping room, but most surfers are confused as to their significance. The decision used to be simple. The long defunct Clark Foam ran the market on surfboard blanks up to 2005 with their top-dog formula for polyurethane blanks. Polyurethane foam was cheap and available, so it was the industry standard. End of story. But the abrupt loss of Clark Foam left a vacuum sending the surfboard world scrambling for alternatives. Suddenly epoxy resin and polystyrene foam floated to the top of the options. Neither was anything new, but they helped fill the void and draw the next generation of innovators into the fray.

Polyurethane

When you read about PU boards, you are reading about polyurethane foam blanks which are the most common blanks still among both daily surfers and pros. PU foam is easily shaped and airbrushed. Polyurethane foam is known for being more responsive in its performance but it also absorbs water and yellows (over time). Polyurethane surfboard blanks can be glassed with either polyester or epoxy resin, making it versatile in terms of giving riders more options. Polyurethane blanks are easily shaped thus making surfboards less expensive than Polystyrene since it takes less time to shape and finish each board. The most negative aspect of building PU boards is their impact on the environment since they contain carcinogens and are essentially impossible to recycle once in surfboard form. The big bonus: PU surfboards are the cheapest option.

Polystyrene

While there are different degrees of Expanded Polystyrene foam, it is regarded as lighter and more buoyant foam than polyurethane. However, it is not as easily shaped and cannot be used with polyester resins due to temperature/chemical sensitivity. It does not react well to polyester resin’s hot chemical reaction and will melt. Therefore, epoxy resin is the only option with polystyrene. Many surfers, however, find epoxy/polystyrene boards have less “life” to them, lacking flex energy, which is probably why most of the top pros still ride PU boards. Polystyrene foam cores sealed with epoxy resin, however, last much longer and emit fewer toxic gasses, so the idea is that the combination is better overall for the planet. In my own experience, I find no real discernible flex energy difference when comparing EPS/epoxy and PU/polyester boards. However, I have ridden some EPS pop-outs that do lack the feel and dynamic curves and unique edges that make a surfboard seem alive, but in fun surf, it’s all good.

EPS VS. XPS

You have two main choices when it comes to Polystyrene foam. Open celled Polystyrene is beaded foam similar to a Styrofoam cooler, but the open cells suck up water if dinged. Besides the afore mentioned lack of flex and memory and high water absorption, another drawback is that open celled polystyrene is difficult to shape, paint or airbrush.

Closed cell polystyrene (called extruded polystyrene foam), on the other hand, is more expensive to produce but absorbs very little water and will remain white and “full of life” for much longer. Closed cell polystyrene is durable AND lightweight and said to be more flexible than expanded polystyrene foam surfboards, this containing that elusive flex energy. And similar to traditional polyurethane foam, due to its closed cells, extruded surfboard foam is easy to airbrush and paint but does often delaminate very easily because closed cell polystyrene builds gas that forces the sealed resin to separate from the foam. Epoxy Pro has developed “Thermovent” technology, which uses small vents that allow the gas to escape and thus avoid delamination.

The Bottom Line

If you are on a strict surfboard budget and are an intermediate/advanced surfer, stick to the old school polyurethane foam core boards with polyester resin. They start out light and responsive but will wear out faster than the other options (just rip in the interim). If you have a little more cash on hand, pony up for an epoxy polystyrene model. I have a pretty fat quiver, and my 6’4” epoxy shortboard has been a favorite for a few years. It’s still light, but has shown some yellowing of late. Great board overall. If you are a beginner who just needs a solid board for learning that will be beaten for the next few years, after a cheap used board, epoxy/EPS is probably your best bet since you need something that will last.

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