Epoxy is a type of resin (liquid) it is not foam or fiberglass.
It requires two chemicals Part A (resin) and Part (B) hardener (both liquid), mixed together in exact ratios to become hard and gain a particular strength.
This resin is used in many industrial applications, from building aerospace parts, electronics, sail boats, to surfboards. Most of the epoxy resins are less polluting and more environmentally friendly than other resins like Polyester resins, they have very low VOC’s (Volatile Organic Compounds), so less material will evaporate and pollute the air.
Epoxy is the material of choice where strength, water impermeability and specific flex patterns are required. There are hundreds or thousands of epoxy resin styles and applications, each with its own unique properties.
Epoxy Pro after 20 years has developedit’s own custom epoxy resin formulation called XR-23. This resin is ideal for extreme surfing conditions. It has perfectly balanced optimal characteristics of clarity (lack of discoloration), light weight, strength, non toxicand flexibility. The formula doesn’t include any solvents, so it’s a green resin.
Why are some surfboards called epoxy?
Even epoxy is just a resin some shapers, surf shop sales personnel, webcast announcers, etc. they call epoxy surfboards to a group of boards that are glass with epoxy resin. Even when the foam (core) can be very different (EPS, PU, XTR, composite, etc).
The real problem is not what they call all of them epoxy surfboard, the problem is on the question, we need to ask, what construction is that board?
Types of surfboards
PU (Polyurethane, ex “Clark Foam”), your typical board can be glass with polyester resin (standard) or epoxy resin.
EPS (Expanded Polystyrene), Styrofoam, what you see in beer coolers with different densities, available everywhere and affordable needs to be glassed wit epoxy resin, and its open cell.
(XTR, extruded Polystyrene)XPS foam is 100% closed cell, XTR is a brand and needs to be glassed with epoxy resin.
Molded (pop out), They basically made of EPS, with a hard-molded core made with PVC or Divinicell. Surftech, Bic,Boardworks,etc. mainly made in Asia.
Firewire:Have different construction with EPS and different core stringers, needs to be glass with Epoxy resin.
How many types of XTR construction are there?
XTR offers:XTRS-l (stringerless), XTR C-K (Carbon Kevlar), XTR FX (carbon rails), and XTR with stringers. There is not a perfect flex, each one is designed for specific surfer and wave size.
What is the difference between Expanded and Extruded Polystyrene Foams?
Expanded (beaded foam) commonly known as Styrofoam (EPS)
It is made mainly for insulation applications in the construction industry.
The characteristics of this foam are like the ones you see in beer coolers and Christmas tree ornaments. It has small spheres of foam semi bonded together (the reason it is also called beaded foam). The structure is based on an open cell that allows water to penetrate and travel inside the foam.
The advantages of EPS are low price and availability. The disadvantages are the water aspiration, and low resistance to compression, it requires more fiberglass reinforcement. The appearance of spheres in some (beaded) foam is noticeable. The small visible spheres also make the board a little difficult to fine shape and airbrush, and basically the EPS don’t have the same memory and responsiveness of the XPS.
*Styrofoam is a trademark of DOW Chemical.
Extruded foam (XTR)
https://www.youtube.com/watch?v=eVIvy_-7oek (video Link)
The main advantages are strength and imperviousness to water absorption. It is very resistant to impact and compression.
One of the most significant and most misunderstood qualities of the close cell construction is that almost no water absorption occurs in open dings (less than 1%). This means that a surfboard with a ding will not gain weight or change color, resulting in longer memory (resilience) of the materials.
Also, the flex patterns of extruded foam when glassed properly can result in enormous advantage for a positive responsive surfboard. It generates more speed than any other surfboardconstruction.
The reason closed cell foam has not been popular with surfboard builders was the delaminations or bubbles that occurred mainly right under the front foot before ThermoVent was introduced by Epoxy Pro in 2003.
Epoxy Pro has a patent pending system called THERMOVENTING that solves the delamination problem 100%.
XTR foam can be hand shaped or CNC machine shaped for production, preferred by machine).
XTR extruded foam has a nice presentation. The foam has high whiteness and can be airbrushed for a custom surfboard.
Note: Epoxy Pro only uses only EXTRUDED closed cell foam. XTR is a trademark of Epoxy Pro.