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Surfboard Construction Guide

Surfboard Construction Guide: What is the difference between an epoxy board and a fiberglass board?

I get the same question every day, “What is the difference between and epoxy board and a fiberglass board?”  First of all, all surf boards have fiberglass.  Epoxy is just different type of resin.  It is questions like this that made me realize the consumer really has no idea what they are buying.  I made up this list of types of surfboard construction to help customers understand the different types of construction.

(1) PU or polyurethane production is traditional surfboard construction.   This was started in the early 60s and to this day is an industry standard.  It’s just one of those rare times where we got it right the first time.  Polyurethane blank can have a density as low as 2 lbs which is Ultra Light Foam or as high as 12 lbs which is Tow Foam.  There are several densities between these but you have to figure out what is the best strength to weight ratio for you. 

Obviously, a light board is going to feel the best but it will get destroyed much faster.  Can you afford to buy a new short board every two months?  A heavy board might last you five to ten years but ride like a slug. Ultra Light Foam is used in the pro short boards and the pro long boards.  Since, this foam is light it has the least amount of strength.  You should expect to get pressure dings in all boards but this foam will get pressure dings much more frequently.

The best way to reduce pressure dings is to add an extra layer, deck patch or tail patch.  Look at the board you have now and see where the most pressure dings are.  That is probably where you need a patch.  If you are heavy on your back foot a tail patch is fine.  If you are heavy only on your front foot a front foot patch is all you need.  You may want a ½ deck patch or even a 2/3 patch.  There is no sense in a full extra layer unless you are nose riding or looking for a heavier board.

More layers of lighter fiberglass cloth is stronger than an equal weight of less layers.  For example, a triple 4oz deck is 12 oz of glass.  A double 6oz deck is 12 oz of glass but the triple 4oz deck is going to be much stronger.  This is why a deck patch is the best way to reduce pressure dings.

S-cloth is a stronger stiffer cloth than traditional E-glass.  It costs more than regular E-cloth but is much stronger for overall strength of the board.  If you are breaking boards, you may want to spend a little more on s-cloth for your next board.   S-cloth does help in reducing pressure dings but the strength of S-cloth really shines in the over strength of the board.  You only need to use S-cloth on the lapping layers to get the benefits of S-cloth.

If you are breaking boards and do not want to spend more money you can ask the laminator to cut bigger laps.  This is no additional charge because the excess fiberglass is thrown away.  The bigger lap will create a bigger I-Beam on the rail.  It will add a little more weight.  Most customers ordering big guns will request big laps along with layers of S-cloth.

Another option if you are worried about breaking a board is order a thicker stringer or triple stringer.  More lumber equals more strength.  It also equals more weight.  Most stringers are 3/16 to ¼ inch.  US blanks will usually have 3/8 stringers in stock and sometimes ½ inch in stock.

Epoxy is another option for adding strength.  Epoxy laminations will add $75 to $200 to the cost of the board depending on the size.  Epoxy laminations must be cooked in an oven to cure.  If you laminator did not cook your epoxy board it is not cured.  This defeats the purpose of spending more money for epoxy.

The strongest board you can order would be a PU blank, laminated in S-cloth and epoxy.  The lightest board you could order is a EPS blank laminated in epoxy.


(2) EPS or expanded polystyrene is like beer cooler foam.  It is big bead foam that is mostly air.  EPS boards cost a lot more.  The EPS blanks cost about the same as a PU blank but the foam is much harder to work with.  If your EPS board is hand shaped, the shaper has to change his planer to a drum instead of blades.  The shaper will also have to work much slower to avoid melting the foam.  If you board is being cut a computer milling operation the machine has to be slowed down, more time equals more money.

EPS foam can only be laminated in epoxy.  Traditional resin will melt the foam.  The blanks have to be sealed with a mix of micro balloons and epoxy.  If the blank is not sealed, resin will drain into the board while laminating making the board heavy and leaving air in the lamination.  Sealing the blanks adds more cost to the board.

The epoxy needs to be sanded in between every step and the hot coat is doubled to get the weave free finish customers expect.  Double the labor this also adds to the cost.  Epoxy takes longer to go off so this ties up space in the factory and slows production which also adds to the cost.

Since EPS is big bead foam it is very difficult to hide the texture.  Foam stains and air brush designs will not be as crisp compared to PU foam.  This is why most customers order a opaque lamination or a marble foam stain.  Solid color foam stains can have streaks and areas of uneven color.

In order to get a crisp air brush on an EPS board the board will have to be spackled.  This is sheet rock mud applied to blank and fine sanded smooth.  This costs more and is not recommended.  If you get a ding that takes in water the sheet rock mud will suck in water causing de-lamination.  

Why would you order an EPS board?  You want it light.  EPS blanks are 1.5 or 1.7 pound density which is much lighter than the PU Ultra Light which is 2.2 pound density.  If you want a super light short board you should consider EPS.  Just because it is laminated in epoxy does not mean it is going to be stronger.  The core is less dense which means pressure more than a PU blank.  Most customers ordering EPS boards will get slightly heavier glassing than they would on a PU board. 

The pro long boarders are all on EPS now.  The competition boards weigh in at 9 pounds which is 6 pounds lighter than a standard board.  Stand Up Paddle boards have to be EPS because they are just too big to make out of PU.

Another advantage to EPS is more buoyancy.  You can ride a thinner board which is more responsive.  Most of our pro long boarders were riding 9’1 boards at 2 ½ to 2 5/8 on PU.  They have now dropped down to 2 ¼ on an EPS board.  If you are a plus size surfer you can get more float out of EPS.  If you are over 200lbs and riding a really thick board you could probably go ½ thinner and get the same float.

Strength and weight are at opposite ends of the scale.  A strong board is a heavy board.  A light board is a weak board.  Each surfer needs to find a balance between strength and weight.  All surfers want a super light board because it is more responsive but not every surfer can afford to buy a new board every couple months. 

Fiberglass is on every board unless has been vacuum bagged to have carbon, texilium or some kind of wood veneer.  Fiberglass is usually in 4oz, 6oz and 7.5 oz.  These weights are available in silene which disappears when laminated.  7.5 oz is also available in Volan.  Volan is a boat cloth that was used in the 50s and 60s.  It has a heavy weave and requires a cut lap which adds to the cost.  The weave is visible even when colored. Without color Volan leaves a coke bottle tint on the whole board.

The color on a board can be done in tint, opaque, foam stain or air brush.

Tint laminations look like hard candy after they have been glossed and polished.  A sand finish tint will not have the same glow. In a tint, the laminator will fill a bucket with resin and add the colored tint to that bucket.  The colored resin is then applied while wetting out the fiberglass.  The finish shape on a tint must be perfect.  Any imperfection in the foam will show up on as a concentration of color.  This is why we do not recommend getting a tint on EPS foam.  The foam is too coarse.  Since the color is in the fiberglass a cut lap is required.  This adds to the cost.

Opaque lamination is applied the same way a tint is but the color is opaque.  This is great if you are trying to cover something up.  EPS foam is so coarse an opaque lamination makes the board look much better.   Since the color is in the resin it requires a cut lap.  The opaque resin covers the shapers signature so we usually get them to sign the board after the board has been laminated.

A foam stain is done by adding color to the resin and pouring on the blank before it is laminated.  The excess resin is then squeegeed off.  This primes your surface before you laminate which gives you a stronger bond.  The color is also pigment which will not fade over time.

If you want a detailed design it will have to be air brushed.  Almost any design can be done by with air brush but the artist charges by how many times he has to tape off the board.  Air brush colors are UV sensitive and can fade over time.