Guide to Epoxy Surfboard Construction

Surfers Guide to Epoxy Surfboard Construction

Isle manufactures the highest quality epoxy surfboards and this is a helpful guide to explain the sometimes confusing details between the different surfboard construction methods of Epoxy Vrs Fiberglass.

What is an Epoxy surfboard?

Epoxy surfboards are stronger and lighter than traditional fiberglass boards. Epoxy resin is used in many applications other than surfboard building such as boats, electronics and aerospace parts. The epoxy resin is stronger and more ding resistant than the polyester resin used in traditional boards. Epoxy resin can only be used with EPS foam and boards made in this fashion are referred to as EPOXY/EPS surfboards. EPOXY for the resin and EPS for the core.

Understanding the Acronyms for Epoxy vs. Fiberglass Surfboards

Let’s get our surfboard terms straight - In order to speak like you know a thing or two about surfboards you need to learn and understand these below terms and  exactly what they mean -

EPOXY - This is a hard type of resin used in the construction of epoxy surfboards with an EPS foam core

- Acronym for Expanded Polystyrene, This is light weight beaded foam used in the production of all epoxy surfboards

- Acronym for Polyester resin used in the production of the (traditional) polyurethane foam core surfboard

- Acronym for Polyurethane blank used as the core of a board glassed with polyester resin

- Weighted cloth used in the construction of epoxy glassed surfboards and poly glassed surfboards.

All surfboards use FIBERGLASS CLOTH for the most part and the type of construction is determined by the type of resin used and foam in the core. Here are the standards:  EPOXY/EPS and POLY/PU. The first acronym describes the resin and the second the core. Both of these methods of construction are laid up with FIBERGLASS CLOTH. So when you say the phrase "fiberglass surfboard" it is not correct. You need to specify EPOXY/EPS or POLY/PU.  This determines one type from the other. We know it's a bit confusing! So first we will explain the traditional “fiberglass” surfboard construction and then go on to explain the most popular types of epoxy surfboard constructions.

Traditional “Fiberglass” Vs. Epoxy

  1. Traditional Fiberglass (POLY/PU) Surfboard Technology: PU or polyurethane foam is the foam of the traditional fiberglass board along with polyester resin and fiberglass cloth. The correct way to refer to this type of board is POLY/PU.  POLY for the polyester resin and PU for the polyurethane core. This type of board is hand shaped or CNC machine shaped out of a PU foam core. The foam core is laid up with weighted fiberglass cloth and laminated with POLY resin. The board is cured and then sanded to a desired smoothness and voila! you have a traditional “fiberglass” surfboard or POLY/PU.

  1. Epoxy Surfboard Technology (EPOXY/EPS): Epoxy surfboards have risen in popularity for many reasons in the last 20 years and especially in the last decade. The boards are constructed from EPOXY resin and EPS foam cores and glassed with fiberglass cloth. The epoxy resin is much stronger and less toxic than polyester resin and the EPS foam core is much lighter than a polyurethane core found in a traditional POLY/PU board. This makes for less toxic, stronger and lighter boards than a typically POLY/PU.

The 2 types of foam cores used with Epoxy Resin

  1. Expanded Polystyrene: The EPS is beaded foam and the foam is much like that of your beer coolers in the grocery store or inside your bumper on your Mazda Miata. Since the foam maintains a structure based on an open cell it will absorb water like a sponge if exposed to water. Some limitations are the poor strength, low resistance to compression, and difficulty of shaping due to the small round spheres. If you are buying a lower priced epoxy board you can basically count on it to be expanded polystyrene in the core. These epoxy boards hold up well when paired with epoxy resin. Just make sure that if you crack your expanded polystyrene epoxy board, that you repair it before taking it back into the water! Isle Ecore Epoxy Surfboards are constructed of EPS foam.

  1. Extruded Polystyrene Core: This is a closed cell core and since it is “closed” it repels water and is more resistant to compression and damage. One of the most notable differences from the Expanded Styrene Cores is the flex patterns are greatly enhanced due to its closed cell structure which will allow for greater response under pressure. All your higher end epoxy boards utilize this type of construction. Our Isle XPS Epoxy Surfboards are made with this type of core.

3 Types of Epoxy Surfboard Layups

  1. Hand Shaped Epoxy Surfboard:.This type of EPOXY surfboard is quite similar to the fiberglass board as explained above. The only difference is the polyester resin is substituted for epoxy resin and the polyurethane core is substituted for an EPS core. The EPS is hand shaped or machine shaped and then laminated with EPOXY resin and FIBERGLASS CLOTH. In the aftermath of the Clark foam shutdown, many shapers quickly switched to this method as EPS foam cores were readily available in the marketplace in order to meet demand when traditional polyurethane foam was unavailable. They are very common amongst big brand name shapers and are widely available and customizable due to the fact they are all finished by hand. Our Isle Ecore Epoxy Surfboards and Isle XPS Epoxy Surfboards are both hand shaped

  1. Molded (POP-OUT) Epoxy Surfboard: In this type of epoxy rather than hand shape the polystyrene core, a mold is created based on the dimensions of a traditional fiberglass plug. The hollow mold is then injected with the EPS foam to mold it into shape based on the master, and then covered with several layers of FIBERGLASS COTH, EPOXY RESIN, and typically a layer of high density foam to reinforce the structure and placed in a vacuum or press to compress all the materials together, hence the term sandwich construction. Typically a heating element can be built into the mold to allow the EPOXY resin to cure at a higher temp increasing the strength. The techniques employed during these steps can be varied by different companies to get the desired strength, flex, weight, etc..

  1. Epoxy with High Density PVC Compression Step: A very strong PVC (lightweight composite) layer is compressed onto the EPS and glassed with epoxy resin. This compression step adds tremendous extra strength. It is much more difficult to build and is typically adhered to the core with vacuum compression. These boards are all either molded or machine shaped and refined to duplicate the master copy it is being modeled after.

    For everything you would want to know about EPS foam check out

Marc Miller fro Isle Surf and SUP

About the Author -is the founding partner of Isle Surf & SUP an online retailer of paddle boards & surfboards. He has been involved in board manufacturing, product development and website management for Isle since its inception in 2004. He also writes the Isle Surf & SUP Blog. An avid surfer and paddler for the past 2 decades when hes not in the office he can be found on foreign shores searching for waves and fun.