It is a tough time for most of us as the whole world is suffering from COVID-19 impacts economically, mentally and physically. As necessary social distancing and quarantine keep you away from the beaches and waves, keeping fit indoors seems less exciting, not to mention adventures. As an outdoor person born with optimism, we believe the pandemic will fade away and everything would return to normal eventually. Here is a cyber journey we’d like to walk you through. 

With six parts as the list below, this series articles will walk you through how a surfboard is made, after which you can make decision on your own as you choose your next surfboard.

●  Foam blank/core

●  Density

●  Skin

●  Stringer

●  Rocker

●  Trail

Here we begin with the 1st part: Foam Blank/Core

A blank or core consists of the foundation and soul of a surfboard as everything else is built on it. There are two major types of blanks existing on today’s markets, one is Polyurethane (PU) Blanks and the other is Expanded Polystyrene (EPS) Blanks. Of course, you may find other material like XPE (extruded polystyrene) and wood like Balsa and Paulownia.

I.Polyurethane (PU) Blanks:

Polyurethane (PUR and PU) is a polymer firstly invented by German chemist Otto Beyar in 1937 by mixing the liquid isocyanate and resin blend together at a certain ratio until a homogeneous blend is obtained. Polyurethane finished goods produced in bulk have been widely used in many segments with various forms since 1940s in Germany and US and then expanded to other countries with endless innovations, hence rigid PU foam used as surfboard core has become one of the most accessible material and comparatively the cheapest of all since 1960s. Thanks to its properties, lighter, easy of shaping with better performance, PU foam blank became preferred on markets and replaced wooden balsa blank almost overnight ever since.

A molded rigid PU foam blank usually comes with a 3-ply wooden stringer through the middle of the board for strengthening purpose because PU foam blank is brittle and flex and prone to twist inside as punching heavily against waves. In the real world, shapers usually receive PU foam blanks molded at various desired sizes, contour, etc. which closely meet the requirements of shapers to reduce waste and for further shaping and trimming.

Advantages of PU foam blank compared to old school balsa wood blank:


-Cheaper due to bulk production 

-More accessible

-Easier to shape

-Enhanced performance

-Closed cell – not soak up resin or water

-Smooth surface for better graphics design

Environment protection and Sustainability:

A Truth: the important reason that the main supplier of PU foam blank, The Clark Foam Factory, shut down on Dec. 5, 2005 is its less environment-friendly production, to be specific, the polyurethane fumes in his factory contained toulene di isocynate or TDI, listed in California as a carcinogen.

PU foam blanks themselves are environment friendly, however, HCFC & HFC, the popular physical foaming agent used for producing PU foam, are greenhouse gases, whose Global Warming Potentials are approximately 1000-1300 times that of CO2!

The powder sanded off PU blanks is toxic to skin and mucosa so your eyes and wounded skin would be hurt once it reaches to a certain concentration.

PU foam blanks are not of natural degradation and most of them are treated as waste in landfills every year. Of course, the blanks can be recycled but it requires complicated physical and/or chemical means for this purpose. 

PU foam is sensitive to ultraviolet light if it contains no UV-resistant agent. We recommend you don’t expose the board in sunlight even the board suppliers claim that it contains UV-resistant agent.

II.EPS foam Blanks:

As mentioned above, after the shutdown of the main supplier of PU foam blank, The Clark Foam Factory, in 2005, EPS became very popular as the alternative foam of choice for shaping surfboards.


EPS is made of solid particles/beads of polystyrene. It is a closed cell (same as PU foam blanks), white rigid plastic foam material produced from two hydrocarbon compounds that are obtained from petroleum and natural gas byproducts:

Styrene – which forms the cellular structure

Pentane – which is used as a blowing agent

Manufacturing of Expanded Polystyrene Sheets/Molds

The raw beads are impregnated with the foaming agent pentane (eco-friendly agent compared to HCFC & HFC) and inflated the thermoplastic base material to 20-50 times its original size.

It is amazing that EPS foam blanks consist of 98% air, which makes them less lightweight than PU foam blank in general. Besides, EPS foam blanks are stiffer and rigid than PU ones, delivering more buoyancy and better maneuverability. Normally, surfboards made of EPS foam blanks requires no stringers since it is strong enough, but Beyoung Outdoors adds bamboo stringers in the EPS foams for stronger products.

Originally, shapers found this type of foam a little more challenging to shape due to its larger cell (diameter ranges from 0.4mm – 1.8mm) and any sanding would cause whole chunks of foam to fall off. Recently, that with cell diameters of less than 1mm performs much better. Besides, compared to PU surfboards, old surfers found that EPS surfboards have a poor flex pattern leading to less responsive than PU ones.

EPS foam is closed cell material but with channels among the cells, which makes the foam soaks up water easily and it requires to be glassed by epoxy resin for water penetration.

NOTE: EPS foam blanks can only be glassed by epoxy resin but not polyester resin because the latter will melt the foam.

Compared to PU foam blanks, EPS foam blanks have:


-More expensive


-More difficult to shape

-More difficult to brush

-Less friendly for graphic design


-Less lightweight

-More resistant and durable

-Less Toxic than PU blanks and resins

-More buoyant and maneuverable

Cross sections of EPS foam on the left vs. PU foam on the right. You can find that the EPS foam consists of large cells fused together while PU foam consists of fine particles like powders.

Environment protection and Sustainability:

-EPS is safe & healthy throughout its life cycle. It is an inert material with no harmful chemicals that off-gas or leach during use and disposal. 

-It is food grade used widely as packaging material.

-100% recyclable.

Credit: EPS-foreningen on Youtube


Both PU foam blanks and EPS foam blanks are popular on the markets nowadays. The market share of each kind probably is, say, half and half. A lot of pro surfers prefer PU foam blanks as they surf on larger and fierce waves while EPS foam blanks as on flatter waves.

In short term, few people pay attention to environment protection and carbon footprint along the surfing but the trend to be sustainable and eco-friendly is inevitable in long term.

Beyoung Outdoors knows the importance of sustainability and environment protection. We practise principles and rules to shorten carbon footprint through the production processes while offer high quality soft top surfboards to clients globally.


See you in the 2nd part soon.

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