The Difference Between Epoxy and Polyurethane Surfboards

We occasionally receive a message from an Amiga asking to be able to ride a “fiberglass board” on their Surf With Amigas Retreat as opposed to an epoxy board. The question always makes us grimace.

Unless the board is made from some unusual material like carbon fiber, ALL surfboards are wrapped in fiberglass. I think what most surfers are actually wanting is to avoid riding a “pop-out” board – as in the mass-produced SurfTech or NSP variety. When choosing a surfboard the actual factor to consider is whether the board is made with polyurethane (PU) or epoxy (EPS) foam.

Let’s Start with the Basics: How are Surfboards Made?

In case you have no idea how surfboards are constructed, we’ll start with the basics. Of course there are always experimental surfboards out there, but the vast majority of boards are made of a foam core wrapped in layers of fiberglass and laminated with resin. 

In the diagram here you see a foam core which can be “EPS” or “PU” (more on that in a bit), covered in layers of different weight fiberglass (in this case 4oz on top, 6oz on bottom), then laminated with resin. You can see the wooden stringer down the center represented as blue lines.

The surfboard starts as a “blank” which is a chunk of foam already in the general size and shape of a finished surfboard. The foam core, or blank, is formed in a large, cement mold roughly the shape of the surfboard. The mold is constructed in two halves, and the inside is lined with a special paper that keeps the foam from sticking to the mold. The two halves are clamped together and the mold is heated. When the liquid polyurethane chemicals are poured into the mold, the heat triggers a chemical reaction which begins forming a dense, white foam. Surfboard builders call this process, “blowing the blank.” After 25 minutes, the mold is opened and the foam core is taken out and allowed to finish hardening. Once the core is hard, it is cut in half vertically from the nose to the tail. A thin stringer is glued between the two halves, and the core is then clamped back together to dry. Stringers provide stiffness, strength, and the right amount of spring when the board is compressed through turns.

This process creates a blank that looks like a rough surfboard. It’s thicker, longer, and rougher than the finished product, but already more or less in the final shape. Surfboard shapers choose a blank closest in size to the board they want to make as the density is not uniform throughout. There is generally a slightly more dense outer layer and a softer inner layer. The shaper will then just use a planer to cut the blank down to the desired thickness, rail shape, tail shape and add bottom contour.

Here’s a Surfboard Shaping History Lesson:

From 1961-2005, 90% of American-made and 60% of surfboards made worldwide began as polyurethane foam (PU) blanks blown by Clark Foam in southern California. In 2005, citing difficulties from environmental regulatory agencies, he abruptly shut down his factory which sent shockwaves through the industry.

Vintage Gordon “Grubby” Clark in his foam factory, along with a lineup of three iconic Clark Foam “blanks”.

The sudden closing and destruction of the Clark Foam factory was seen as a big “f*ck you” to the industry and led to mild panic in some circles. Such was the power of this man and his near complete domination of the surfboard industry. See the photo on the right of the destroyed blank molds.

After the initial panic subsided, most shapers began to view the closure of Clark Foam as a good thing for surfboard material innovation. It ended a period of monopolistic control and created a new, free, open market for blank builders to come in with new technology and ideas. It also encouraged shapers to put more energy into experimentation with the more environmentally-friendly expanded polystyrene blanks. There are some benefits to the newer technology. For one, the density is uniform throughout the blank.

These new blanks are laminated with epoxy resins. Epoxy emits 50-75% fewer VOCs (volatile organic compounds) than polyester resin. Also epoxy is lighter than polyester. Under most circumstances, resin makes up a large part of a completed board’s overall weight. Not only is epoxy resin lighter than polyester, but less is needed per coat. This ends up meaning a much lighter surfboard – a big plus for most surfers. The biggest bonus however is the durability and strength of epoxy boards, not to mention the benefits to the environment.


1. EXPANDED Polystyrene (EPS, beaded foam)

Expanded, or beaded, foam (EPS) is a relatively inexpensive and incredibly lightweight surfboard core. Manufacturers produce sheets of EPS by feeding tiny polystyrene spheres into a machine, then introducing steam coupled with a tiny amount of pentane gas to expand the beads and mold them to one another. The end result is an open cell foam, meaning that is very water absorbent. To combat this issue, shapers who use EPS foam usually add extra layers of fiberglass and epoxy resin to prevent any dings from penetrating deep enough to reach the foam. Epoxy resin is the only resin that can be used with EPS boards. The extra layers of fiberglass and resin make the boards stiffer and more solid feeling. It leads to a less flexible feel than a “traditional” board. A beginner surfer would not be able to tell the difference, but an advanced surfer who is compressing her board into high speed turns will definitely notice.

“Pop-out” boards are made using EPS foam, because the beads can be formed into specific molds. Often times these blanks are used without stringers relying on just the strength of the blank and the thicker layers of fiberglass in the glassing. The entire board is made in a mold or with vacuum bagging technology. This leads to the boards being less refined. They will be cheaper and more durable which makes them excellent for beginners who are not ready to invest in a more expensive surfboard. They are perfectly fine to learn on.

Originally, very few hand shapers use this type of EPS foam, because it is difficult to work with and nearly impossible to fine-tune with shaping tools (the beads retain their spherical shapes so well that any sanding causes whole chunks of foam to fall off, leaving the edges jagged). But recently better EPS with smaller cells has been created so that it now works for hand shaped boards as well. When Holly was a pro surfer getting boards from Rusty Surfboards, almost all of her boards were made of EPS foam and looking at the boards even up close, it would be very difficult for anyone to tell the difference of EPS vs PU in the finished board.

These days EPS foam technology has improved and high performance EPS blanks are available. Professional surfers and recreational surfers alike will choose EPS boards because of their environmentally friendly characteristics. They are also a lot lighter which makes them ideal for smaller waves or smaller surfers carrying bigger boards.

Characteristics of boards with Expanded Polystyrene (EPS) epoxy foam:

  • more water absorbent foam
  • lightweight
  • extra layers of fiberglass + epoxy resin for ding prevention
  • potentially more solid feel because of extra fiberglass + resin (less flexible for advanced surfers)
Holly Beck, rusty surfboard
Holly with an EPS and Epoxy board by Rusty Surfboards

2. EXTRUDED (XTR, closed cell)

Extruded foam (XTR) is made using expensive machinery and computers. The machines melt polystyrene crystals down, using additives and a blowing agent to essentially deflate and combine all of the ingredients together. The result is a fluid that expands as it cools, forming solid blocks of XTR foam. The foam is closed cell, so it blocks out moisture – a good thing in case you get a ding.

The process of making XTR foam is time-consuming and costly. The price of the foam itself, coupled with the fact that most XTR epoxy boards are hand-shaped, does unfortunately lead to a more expensive finished board – but one with several benefits. Not only is the foam core moisture-wicking and stronger than other types of foam, it is also extremely resistant to dings and compression-caused dents. XTR foam also has a good flex pattern, so it’s responsive on the water.

The problem with closed cell foam is two-fold. First, as mentioned above, it is expensive. You will almost always pay more for an XTR board than one made from EPS. Second, there have been reports of bubbles and delamination in the decks of some closed cell boards, caused by gas build-up between the foam, fiberglass and resin layers. However, some companies have made huge developments in XTR-constructed boards, finding ways to allow the gases to escape without compromising the integrity of the surfboard.

Holly has an XTR board that she’s been riding hard for over 15 years that is still in very good condition, something virtually impossible with other types of construction.

Characteristics of boards with Extruded Polystyrene (XTR) foam:

  • more expensive
  • moisture wicking foam core (doesn’t absorb water even when dinged)
  • stronger foam core
  • good flex for advanced surfers
  • extremely resistant to dings and pressure dents

Riding my XTR board in really fun waves about 15 years ago. It still looks good and works just as well today.


TL2 by SurfTech

SurfTech makes a Techlite core (fused cell foam, virtually waterproof) technology they call the TL2 design. The Techlite core is further improved upon with the addition of an Acrylite skin, which is glassed onto the board using epoxy resin. The Acrylite skin and the epoxy coating work with the core material to create an incredibly strong, responsive surfboard. The extra strength means that no stringer is needed, so the board is more flexible and springy in the water as well.

Hayden Shapes

Hayden Shapes is a quality surfboard manufacturer, also experimenting with different materials and designs. The Hypto Krypto is an awesome design for surfers wanting to go down in length but still keep paddle power since it has a wider nose for more planing but a narrower turn for high performance turns.

The construction combines a stringer-less, high-density custom shaped EPS core, laminated with biaxial fiberglass, epoxy resin and a parabolic carbon fiber frame. The carbon fiber frame within the laminate is the key to the performance vitality. Designed to maximize speed and drive while minimizing twist, FutureFlex essentially stores and releases energy as the surfer transitions through a turn. The FutureFlex construction creates a fast, dynamic and highly responsive surfboard that’s been design engineered for performance surfing ranging from the intermediate to advanced level.

This is Holly riding a surfboard made by a company called Aviso that no longer exists. It’s a hollow-core (no blank at all) carbon fiber board. The construction is similar to the SCore in that it is hollow, but made fully of carbon fiber so they are all black. (Tricky to keep the wax on when surfing one in the tropics as they get really hot). 

In summary – Epoxy vs Polyurethane

As described above, epoxy is lighter, stronger, and more environmentally friendly. An old EPS blank can be broken down and recycled into a new blank. The epoxy resin is less toxic to the board builder and the environment.

So what are the benefits of a lighter board? A lighter board is easier to carry, easier to paddle, and will often feel faster when riding them along the face of the wave. These all lead to more fun and froth, which is what it is all about. They are also very durable and maintain their integrity a lot longer than PU boards.

But, the epoxy boards can be stiffer and lighter which makes them tend to feel more “buoyant” and ride on top of the water, rather than in the wave. Since they are much more buoyant than PU boards, it is possible to ride shorter boards which can also enhance performance as the board fits better in the curve of the wave. Even pros ride EPS boards in smaller to medium-sized waves.

However, this buoyant feeling can make some people not like them. Also “pop-out” boards are made from this technology which can give the materials a bad name since they are associated with the image of cheaply produced junk.

In smaller, weaker surf, or for a beginner, the lightness is a really good thing. You will get the best weight to strength ratio with EPS/Epoxy construction; hand-built, composite, molded or otherwise. You’ll be able to lift a large board and carry it more easily to the water. For a surfer that is doing fast turns, the lightness of an EPS core combined with the strength of epoxy resin, will make for a more responsive, lively board.

It’s important to note that in bigger surf or choppy conditions, experienced surfers may actually prefer a slightly heavier board. Some older surfers who’ve gotten used to their PU boards will tell you that the feel and flex of a PU board is a feeling that will stick with you. Epoxy boards can have a “corky” feeling to them that can take some getting used to. Also, chop and windy conditions can make a lighter board feel like it’s bouncing more rather than plowing through the chop. Bigger waves are nice on heavier boards, especially if it’s also windy. In that case a PU blank with Polyester resin may be better.

A middle ground option is using a PU blank with Epoxy resin. Polyester resin will eat away (think: more nasty chemicals) EPS foam, but you can use epoxy resin with PU blanks so that’s a good compromise if you’re looking for the flex and weight of a PU blank with the environmental friendliness and durability of Epoxy.

Our advice: Get the board that you have the most fun on and makes you the happiest, because in the end, it doesn’t matter what you ride, as long as you are stoked.

Any guesses which of these are EPS and which are PU? It’s impossible to tell at a distance. 

Release Your Spine – Advice from Physical Therapist Sofia Costa

10926393_10204781003818710_5984368933912640093_nSofia Costa joined Surf With Amigas on a retreat towards the end of 2014. She is a Dr. of physical therapy originally from Puerto Rico, now living and treating surfers in Santa Monica, CA.

Sofia has offered to provide some physical therapy content that Amigas can use to treat their bodies right in between surf sessions. See below for a little introduction and her first offering!

Life doesn’t hold still for us. If we don’t move with it,nlife is just going to pass us right by. Surfing teaches us to go with the flow smoothly, and live in the moment spontaneously to get the most out of the wave and out of life.” – Gerry Lopez


Surfing is an experience that allows you to co-exist with nature and with yourself!

As a Doctor of Physical Therapy, my mission is to create body awareness, mindfulness, and teach you exercises that are specific for you and for surfing. I have a great passion to give back to surfers; to aid with recovery and provide skills necessary to self-manage and prevent injury; and as a gain, you can experience the addicting “stoke” that keeps you going out for more.

Contact Sofia at [email protected] or follow her on Instagram @costasurfpt


Advice from Nikki – Making Space

Living in Nicaragua for the last three years has taught me the importance and value of simplicity. While I have known this for some time, during my last visit to the States it became very apparent to me. Our tendency to over-consume and over-accumulate may be causing us more stress than we realize.

Did you know that physical clutter or unnecessary “stuff” could be detrimental to your health? Science even says so!

Clutter doesn’t only impact us physically. When our space is cluttered, we often feel chaotic mentally – unable to make decisions, scattered thoughts, feeling over being overwhelmed or stuck, etc.

By creating more space and organization in our homes and places of work and play, we gain clarity, focus, energy and productivity. By freeing the stagnant energy of the clutter, we make room for more of the things we want. In doing this, we are also able to let go of things that we have held onto mentally and emotionally. By the release and freeing of extra ‘stuff’ we feel lighter and more open. Some people even lose weight after de-cluttering their homes!

I recently moved into a new home and took the opportunity to purge myself of clothes that I never wore. Here’s a picture of my new closet spacecloset.

Tips for making more space in your home

* clear things you do not use or have not used in over a year
* purge things that you no longer find beautiful and useful
* shed things that are not uplifting and inspiring
* be easy on yourself. don’t try to get rid off too much at once, it can be overwhelming especially if you have a LOT of stuff.

In my yoga practice, stretching the sides of my body make me feel light, and spacious.


Surf Completely – Learn to Generate Speed on a Surfboard by Practicing on a Skateboard

After catching a wave and standing up, learning how to generate your own speed is the most important skill in learning to surf. The success of every turn relies on having enough speed. Unfortunately, it can be tricky to learn how to pump, but practicing on land on a skateboard is a great way to learn!

Having the right skateboard for the lesson is important. A longboard skateboard is key, and I prefer a Sector9 Sidewinder series skateboard. Check out the video for tips on how to improve your pumping by playing around on a skateboard.

Want to get your own Sector 9 Skateboard with the Sidewinder trucks? Click here!
sector 9 skate

5 Tips for Beginner Surfers

Learning to surf is tricky. There’s the physical part, the mental part, and the ocean part. The physical part you can practice. The mental part you can overcome. The ocean part you can learn. But all of that takes time. It’s a process. Whether you’ve come to a retreat and learned the basics and are now testing your new skills in your home waters without the protective guidance of an Amigas instructor, or you are struggling on your own while you count down the days to your retreat, here are a few tips to get you in the water with more confidence.

Watch the waves. The hardest part of surfing is reading waves. Even if you aren’t going surfing, actively watch the waves. Imagine where you’d paddle out, where you’d take off, and in which direction you’d ride. The more you pay attention, the more you’ll see the subtleties that will help you read waves better.

Admit your skill level. As a beginner surfer, it’s intimidating to paddle out into a crowded lineup of surfers waiting to catch waves. Don’t be afraid to ask for help. Pick out someone who looks like they know what they’re doing and has a smile on their face, and approach them. Compliment them on their last ride, explain that you’re a beginner and need a little help figuring out the best place to sit to catch a wave.

Be determined. Don’t give up when something goes wrong. You will feel off balance and think you’re going to fall, but…try to regain your balance and adjust your footing. If mentally you are thinking, ‘Uh-oh, I’m falling,’ you will definitely fall. If you think, ‘Stay on, stay on,’ you just might.

Ride the wave all the way in. When you are first learning to catch waves, you ride green waves, which are the unbroken part of the wave that comes before the white water. A lot of people stand up, ride for a few seconds and then jump off their board so they don’t have to deal with the hassle of paddling back out through the white water. Even if it’s just whitewash, the more time you spend actually riding a wave, the more you’ll improve, so ride it all the way to the sand.

Focus on fun. Every wave is different, which makes it really hard to practice consistently. Focus on the joy of being out in the ocean, the thrill of getting pushed by a wave. If you remember it’s all about fun, you’ll be a happier surfer, which makes you a better surfer.

The 80/20 Lifestyle by Kris Wilcox


Kris Wilcox is a surfer, yoga teacher, massage therapist and life coach from San Diego who also happened to be one of the most colorful characters we’ve ever had at a retreat. She is energetic, full of stories, and eager to solve your problems and help you figure out what you want in life. She lives her life with balance, focusing 80% of her energy on healthful living but allowing herself 20% to let loose!

Healthy Living Advice from Jee Mee in Nicaragua


Jee Mee Kim lives at Rockaway Beach in New York, runs triathlons, has a young son, and rides all types of boards. She and I agree that too many people think longboards aren’t cool, and fun shapes are for kooks. A good surfer should be able to ride anything and if you know how to turn a longboard, shredding on a shortboard is even easier. On top of that, it’s all about fun so whatever board allows you to have the most fun is the one you should ride!

Check out this video for some advice on healthy living. Eat Right, Get in Shape, Be Outside, and Ride Something Fun!