Types of Surfboard Foam Cores & Resin

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One of the most defining factors in things like a surfboard’s overall strength, flex, ding resistance, longevity, and sustainability is the type of foam and the type of resin that’s used in its construction.

The surfboard industry in general does seem to be shifting towards more sustainable and environmentally friendly processes and materials, but old habits and traditions die hard.

When you’re looking for a new surfboard off the rack or ordering a custom board from a shaper, you’ll probably run into two main options for foam and two main options for resin:

  • Polyurethane Foam (PU)
  • Expanded Polystyrene Foam (EPS)
  • Epoxy Resin
  • Polyester Resin

From the materials above, you’ll have the options of the following combinations in what makes up your surfboard:

  • PU finished with Polyester Resin
  • PU finished with Epoxy Resin
  • EPS finished with Epoxy Resin

While PU foam can accept any type of resin, EPS will begin to melt when you put polyester resin on it.

While we’ve covered some of the merits of each of these materials on their own, this page will take a look at the combinations. You can find some of those other pages here:

PU Foam & Polyester Resin Surfboards

PU & polyester resin surfboards were what sparked the foam revolution and the step away from wood-construction boards. The new materials helped usher in some great advancements in surfboard construction and design – boards were way lighter, flex properties could be explored more, and new designs could be tested more quickly.

PU is light and easy to shape, and polyester resin is relatively inexpensive.

The big drawback was that this makes for a pretty toxic and unsustainable materials combination – it can be harmful to work with and harmful to the environment to dispose.

That said, PU/Polyester Resin surfboards make for a super light, rigid board, that has a more “knifey” feel to it.

Aside from the toxicity, another downside to this combo is its strength and ding resistance and flexibility is less than its epoxy counterpart.

PU Foam & Epoxy Resin Surfboards

A PU board finished with epoxy is going to feel very similar to a PU board finished with polyester resin, as described above.

However, finishing the PU blank with epoxy gives you the following benefits:

  • Stronger, more ding resistant finish.
  • Less toxic and volatile materials.
  • Option for bio-based (plant-based) epoxy resin.

The result will be a PU surfboard that’s going to be stronger, last longer, and be a bit more environmentally friendly.

If you’re ordering a custom, hand-shaped surfboard, chances are that you will be limited to a PU blank.

EPS Foam & Epoxy Resin Surfboards

EPS foam and epoxy resin surfboards have grown in popularity ever since Clark Foam’s closure in 2005.

EPS foam is a super lightweight, non-toxic, and recyclable material that can greatly reduce the environmental impacts of a surfboard.

Epoxy resin is also more environmentally friendly than its polyester counterpart, and even comes in bio-based, low-to-no VOC versions.

EPS and Epoxy surfboards are:

  • Very light and buoyant.
  • Super strong.
  • Flexible.
  • More environmentally friendly and the foam is recyclable.

An EPS/Epoxy surfboard is going to feel more “floaty” than a PU surfboard.

An EPS blank can be more difficult to shape by hand that a PU blank, so most EPS boards you’ll find are machine-molded. Epoxy is also a little more forgiving to work with.

That doesn’t rule out EPS for hand-shaped boards, but it does certainly make them less common.

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