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	HISTORY of POLYURETHANE & EPS CORES & BLANKS
	March 28, 2023

POLYURETHANE FOAM & BLANK HISTORY In the 1930s Central and South American balsa wood became a popular material for shaped blanks or the core of surfboards. The end of World War II opened up new possibilities in surfboard construction, technology, and ultimately design. New materials became available through advances in technology during the war. Wartime chemistry and imaginative surfboard shapers and manufacturers pioneered surfing's progression into polyurethane foam shaped blank cores. Balsa wood remained the primary material for the shaped core or blank of surfboards through the late '50s and remained relevant while shapers and board builders experimented with polyurethane foam. Shapers invested a significant amount of time creating balsa blanks milling and gluing balsa planks into a suitable blank for shaping surfboards. Polyurethanes trace their origins back to 1937, when a German chemist, Friedrich Otto Bayer, developed the earliest prototype of Polyurethane fibres known as Perlon U. By the end of World War II a wide variety of polyurethanes were being manufactured including polyurethane foam. In 1955 Dana Point surfer and board builder Whitey Harrison successfully made a polyurethane foam blank in his barn. In 1957, a resin salesman provided Hobie Alter a sample of polyurethane foam, a synthetic material developed during World War II introducing polyurethane foam to the commercial surfboard industry. Polyurethane foam was a material that allowed shapers to create a lighter, easy to shape, readily available, cheaper material for the core of surfboards. Unlike EPS foam which was extremely difficult to shape, polyurethane foam could be shaped with common hand and electric wood working tools such as electric planers, block planes, sand paper on sanding blocks, shaping screens, and other tools. And most importantly it bonded with polyester resin to form a high strength to weight ratio composite. Hobie Alter received credit in 1958 for introducing and promoting polyurethane foam boards to surfboard manufacturing and surfing. However, a full year before Hobie and Gordon Clark started developing their molded polyurethane surfboard blanks another Southern California shaper, Dave Sweet had already created a rideable polyurethane foam surfboard. When Hobie Alter and Grubby Clark were developing their version of a polyurethane foam blank in 1957 they were unaware that Dave Sweet had already created a polyurethane foam blank and had shaped, glassed, and surfed the first polyurethane foam surfboards. Later all three agreed that they separately developed the polyurethane foam surfboard blank. Hobie Alter got credit for introducing polyurethane foam to the surfboard shaping and manufacturing industry and Dave Sweet was overlooked as the original pioneer of the polyurethane core surfboard. The Smithsonian Museum has a Dave Sweet board in their collection, acknowledging that he was the first to make a polyurethane foam surfboard blank and surfboard. He is correctly remembered as the father of the foam surfboard. In 1961, Hobie Alter and Gordon Clark agreed to split their interests with Hobie focusing on shaping and manufacturing surfboards and Grubby, as he was known, focusing on further developing polyurethane foam and molds to create polyurethane foam blanks. In just a few years, Clark Foam was dominating the market with exceptional surfboard blanks. At its peak, Clark Foam produced an estimated 90% of blanks sold in America and 60% of those sold worldwide. On December 5th 2005 the surfboard industry changed forever overnight when Grubby Clark shut down Clark Foam. The abrupt closing of Clark Foam shocked the surfboard shaping and manufacturing industry. Shapers and board builders scrambled for new suppliers of polyurethane foam. Just a year later, two former Clark executives, Kim Thress and Jeff Holtby launched US Blanks, a company that today is the gold standard of the market. As abruptly as Clark Foam shut down, US Blanks designed dozens of molds of various sizes for shortboards, fish, eggs, XXL guns, longboards, and SUPs. They offered their polyurethane foam blanks in a variety densities from ultra light to extremely high density and a wide variety of wood and foam stringers. And just like Clark Foam, US Blanks offered custom rockers for diverse designs and most importantly for close tolerance shaping as polyurethane foam blanks are denser on their skin than deeper into their cores. US Blanks manufactures a water blown, TDI Polyurethane foam. Today polyurethane foam is still the most widely used core for surfboard production. US Blanks offered excellent polyurethane foam blanks filling the void left by the closure of Clark Foam and they also offer molded and block cut high quality super fused EPS foam blanks in multiple densities with the same custom stringers and rocker features of their polyurethane foam blanks. During the immediate short term absence of the high quality polyurethane foam blanks and their reliable distribution shapers and board builders turned to alternative, new, and innovative blanks and materials. This set the stage for the relevance and growth of EPS / Epoxy surfboards.

EPS FOAM & BLANK HISTORY Expanded Polystyrene or EPS Foam is a versatile plastic polymer that dates to the 19th century. Commercial manufacturing of EPS dates to the 1930's. Scientists from BASF and Dow Chemical introduced "Styrofoam" to the US market for multiple applications including marine products. In the fall of 1950 two young Mission Beach Life Guards, John Blankenship and Bill McKusick built the first all EPS foam, fiberglass, and resin surfboard. They sealed the EPS foam core with white glue (with marginal success) to prevent the polyester resin they used from desolving the EPS core. Weighing less than ten pounds their bords created quite a sensation among surfers at Windansea in La Jolla. They were aware that Bob Simmons had created a sandwich construction board with an EPS foam core earlier that year. Simmons' EPS foam core was sealed from the resin with a thin balsa wood veneer. In the summer of 1951 Don Okey heard of the use of epoxy resin in the aircraft industry. He obtained experimental epoxy resins from the Shell Oil Company and several catalysts and monomers from other manufacturers. With these he formulated an epoxy resin and proceeded to make the first EPS foam surfboard glassed with epoxy resin. Commercially, EPS foam blanks have been used in surfboard construction since the 1970's. Prior to 2005 EPS foam blanks Epoxy construction technology had a minor role in custom and high performance surfboard shaping and manufacturing. Production boards and a few forward and progressive thinking custom shapers being the exception. The closure of Clark Foam and the rapidly increasing use of CNC shaping ushered in a new era for EPS foam blanks and EPS / Epoxy composite technology. Alternative blanks and shaped blank cores for custom surfboards were sought after by shapers and manufacturers world wide. EPS foam gained popularity with advancements in their technology that made shaping and working with EPS foam easier. This demand for premium quality and easily shaped blanks led to significant improvements in EPS foam particularly cell fusion. The proliferation of shaping machines and design software solved considerable technical problems shaping EPS blanks. And improvements in the properties of Epoxy resins, their clarity and ease of use, made epoxy resins practical for manufacturing custom boards. These factors made Epoxy technology and boards an integral part of the custom and high performance surfboard industry.

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