The Difference Between PU and EPS Surfboard Blanks

Since Clark Foam closed in 2005 and the industry scrambled for alternatives, surfers have argued about foam. Today, two surfboard core materials dominate that conversation: polyurethane (PU) and expanded polystyrene (EPS). This is a PU and EPS surfboard blank comparison: honestly, what each foam does well, and why the range here is EPS.

The short answer is weight and construction. EPS is generally lighter and offers a higher strength-to-weight ratio, while PU is denser and traditionally paired with a timber stringer. The rest is detail worth understanding before you order.

The Traditional Core, PU

Polyurethane has been the surfboard core for over sixty years, and plenty of great boards are still built on it. PU foam shapes cleanly, takes colour and artwork well, and has a flex a lot of surfers grew up on. Most PU surfboards use a timber stringer to add stiffness and strength, although stringerless PU constructions also exist. The trade is weight and lifespan. PU is denser and heavier. Over time, PU foam is generally more prone to yellowing and gradual changes in flex compared with EPS/epoxy construction. 

The Modern Core, EPS

Expanded polystyrene is a closed-cell foam of fused beads, and it is lighter and stronger for its weight than PU. 

When laminated with a clear epoxy like Kinetix 104 epoxy laminating resin, an EPS blank offers a better strength-to-weight ratio and often provides excellent impact resistance when paired with an appropriate epoxy glass schedule.

EPS blanks are often built without a stringer because the combination of the foam, epoxy laminate, and board design provides the required strength. One firm rule comes with it. Polyester resin dissolves EPS foam and should not be used with polystyrene blanks. Although EPS is a closed-cell foam, water can still penetrate a damaged board through cracks in the laminate, so dings should be repaired promptly. 

Weight, Strength, And Feel

The PU and EPS surfboard blanks debate usually starts with weight. EPS is generally lighter and offers a higher strength-to-weight ratio, which is why it has become popular for many performance and small-wave surfboards. PU keeps a following for its flex and traditional feel, especially in bigger, more powerful surf where some surfers want the extra weight to settle the board down. Neither is simply better, but the modern strength-to-weight argument favours EPS across a wide range of builds.

Why The Range Here Is EPS

Put together, the reasons line up on one side for this catalogue. The blanks here are EPS, machine-shaped and stringerless, built to be glassed in epoxy. That is a deliberate call. EPS gives the lighter board with an excellent strength-to-weight ratio and long-lasting performance. If you want a PU board, plenty of shapers still build them, but the foam on the rack here is EPS, and the whole range is set up to get the best out of it.

Choosing Between PU and EPS Surfboard Blanks

Choosing between PU and EPS surfboard blanks comes down to what you want from the board. PU for a traditional flex and feel, EPS for a lighter, stronger, more durable board built on epoxy. The range here backs EPS for those reasons, paired with the epoxy resin it needs and the surfboard fins to finish the build. Shapers Surf Co. Bali stocks EPS blanks and related materials. Have a look at the blanks collection and start from the foam the range is built on.