Polyurethane Surfboards Also known as PU (polyurethane) or associated with the "Clark Foam Era". A blank is the very core of your surf board and the term “close tolerance” refers the how the close the surfboard mold is to the actual shape. Clark held a virtual monopoly on this surfboard blank market until his closure in December 2005. Now the polyurethane surfboard blanks are produced by several companies each with its own close tolerance molds. In addition to polyurethane many shapers are now using EPS foam blanks. These EPS foam blanks are more friendly towards mother earth and have become the blank of choice for stand up paddle boards.
Surfboard Blanks: Polyester based urethane surfboard foam blanks are shaped to close tolerance for various designs. Since the Clark Foam closure, EPS surfboard blanks used with epoxy resin have come on the scene.
Fiberglass Cloth: Glass fibers that are woven into a cloth with weights of 4oz and 6oz, 10oz, etc.. This particular weight refers to 1 square yard of cloth. The heavier the weight the stronger the fibers.
Polyster Resin, Epoxy Resin, and Catalyst: Many types of resins can be used in the production of a polyester surfboard. In order to get the polyester resin to harden it is mixed with a specific amount of catalyst. Varying the amount of catalyst will cause the resin to set faster or slower in the surfboard. Changes in air temperature can cause the resin to harden faster or slower and the catalyst quantity muster be adjusted.
In the wake of the Clark foam shutdown, surfboard shapers of the world have turned to Expanded Polystyrene foam as an alternative method of surfboard production. EPS surfboard foam is used with Epoxy resin , as the styrene present in standard polyester resin will dissolve the EPS foam. The EPS foam has a large cell structure which makes it harder for a shaper to maintain fine details into a blank. In addition the blanks are extremely lightweight thus making it appropriate for the surfboard blanks to be weighted down during shaping. Since the blanks are so lightweight the amount of resin and weight in the outer skin can be increased thus making the boards very strong and lightweight. However another form of Foam has been developed termed Extruded Polystyrene Foam. It has higher strength, greater resistance to water and a closed cell structure.
As of now the surfing world is mostly committed to traditional polyurethane blanks. The alternative technologies are advancing rapidly yet still remain a pace behind in popularity. Only the future will tell us what will soon dominate the marketplace for surfboards….