PU boards have been around since 1957, when a resin salesman walked into the surf shop owned by Hobie Alter and handed him a chunk of polyurethane foam for the first time.

Before that, cutting-edge surfboards were made out of balsa wood, with a hard, plastic shell made of fiberglass and polyester resin. Balsa had a number of advantages, not the least of which was how light and buoyant it was. It had been adopted from airplane wing technology and adapted to the ocean, and for most of the 1950s was the universally accepted standard for surfboards.

But when Hobie first held that chunk of polyurethane foam, he knew he had something revolutionary in his hand. Polyurethane had been popularized during World War II, and became commercial to the public in 1952, and polyurethane foam in particular began to be produced in 1954. The foam had a number of advantages over balsa when it came to surfboards, including being even lighter, easier to shape, and maintaining better flex memory and buoyancy ratios, which provided an all-around better ride.

By the early 1960s, PU boards (which technically refer to boards that use a polyurethane blank and a polyester resin, along with fiberglass) were the industry standard. Grubby Clark worked with Hobie to create molds that took injected polyurethane foam and created “blanks”—rough board shapes that could be easily shaped into surfboards. And for the next 50 years, Clark Foam’s polyurethane blanks dominated the surfboard industry.

In the late 1990s and early 2000s, a number of brands started experimenting with epoxy resin on polyurethane blanks (referred to as PE boards). Epoxy resin was lighter and stronger than polyester resin, but it also had the advantage of being usable with extruded polystyrene (EPS) foam, which meant that technically polyurethane (and by extension PU and PE boards) were no longer mandatory. Whereas polyester resin melts EPS foam when it cures, epoxy resin doesn’t, which meant that suddenly the surfboard industry had a lot of new potentials to explore in terms of surfboard construction.

Early epoxy boards were widely panned as being little more than chincy pop-outs that were too stiff and floaty. But when the FDA changed its rules governing the use of toluene (an essential ingredient in polyurethane blanks) in US factories around 2010, the industry was ripe for change.

While Clark Foam shut its doors and the PU blank industry moved across the border to Mexico, most major board brands started tinkering with epoxy. Firewire Surfboards was an early innovator and proved that it was possible to build handmade epoxy boards that felt pretty close to “normal” surfboards—“normal” meaning PU boards. Because regardless of the various advantages of the new EPS/epoxy boards (lighter, stronger, and impervious to water seepage after dings, in the case of closed-cell EPS foam), there was just a certain feel that PU boards had that most surfers still preferred.

That feel became the crux of a decade-long debate between PU purists and epoxy futurists. More than a few world tour surfers were technically sponsored by brands that made epoxy boards, but secretly still rode PU boards in contests (even painting their boards to look like sponsors’ epoxy boards). But eventually, the market started to equalize, with most major brands creating their own proprietary epoxy-based construction process. Examples include Firewire’s TimberTek, Linear Flex Technology, and Helium Tech; Thunderbolt’s carbon/epoxy longboards/ …Lost’s EPS/cork-based C4 technology; and JS’s HyFi tech.

Each of these technologies has its own particular benefits and has become popular with different portions of the surfing population, but interestingly, all of these companies (or the brands that they build boards for, in the case of Thunderbolt) continue to offer their boards in PU construction as well.

The reason for this is the classic, inarguable feel that PU boards have. They might not be quite as light as epoxy boards, and they are certainly not as strong or durable, but there’s just a certain feel that polyurethane/polyester boards have. This feel is likely related to a number of factors—the way the foam sits in the water, the flex characteristics of PU foam and polyester resin, the fact that PU boards still use wooden stringers, and any number of other factors that play into the board’s feel. PU boards also remain the simplest and easiest boards to shape and glass by hand. Despite the huge surge in epoxy board sales over the past few years, PU boards still made up around 35 percent of surfboard sales in 2022—and that takes into account PU, PE, EPS/epoxy, wooden boards, and soft-tops (the latter of which surprisingly make up nearly 15 percent of board sales).

So, what does all of this mean for your next surfboard purchase, and for the surfboard industry in general? Despite the movement toward futuristic board construction processes and newer, modern technology, the most commonly made surfboard on the market is still built with pretty much the exact same materials and process as those made by Hobie Alter and Grubby Clark nearly 70 years ago—and that just goes to show that sometimes you can’t beat a classic.