Polyester v Epoxy: Which one is best?

Polyester Resin has ruled the industry for decades – for nearly 80 years Polyester Resin has been used to make marine craft of all types. Surfboard construction, in the early days, was from a simple boat resin, quite dark, and only basic woven fibreglass cloths were widely available; cloths finished in two types of finish (added after weaving to attract resin to the fibres), Silane and Volan. Silmar Resin, the industry standard for decades, is found in most surf shops due to its consistency, clarity and ease of use. Later resins improved the impact strength of Polyester Resin (known for its relative brittleness) and ISO 10X, an Isophthalic Resin became known for its consistency, excellent clarity, high UV resistance, and its tough but flexible nature – a characteristic of Isophthalic Resins. ISO 10X is a non-inhibited Isophthalic Resin still found in good surf shops Europe wide.

These days the new Epoxy Resins are changing the nature of surfing in many ways. Unlike Polyester, Epoxy Resin has greater strength in a matrix (any structure using reinforcement) and benefits from a total lack of solvent, which was a factor in the decay in strength of Polyester Resin, when it remained uncured or trapped, as it often was. For example, an inhibitor (a chemical that floats to the top of a laminate) traps solvent release, and was originally never added to resins. Serious examples of trapped solvents caused osmosis, or delamination, when the solvent expanded under heat or stress. To enhance quicker turnover, enhancing productivity, paraffin wax in solution was added to act as an inhibitor, and still is, in various forms of hydrocarbons, today. This helped reduce solvent emissions, especially of Styrene, which has been shown to affect nervous systems. (So that’s why I’ve got a twitch – ed) but still left the issue of solvents affecting many laminates.

The early issues with Epoxy Resin related to its image associated with pop-out surfboards. Those boards were stiff, often broke easily due to a lack of flexibility in the laminate, and always hid a multitude of manufacturing sins. Even today, in surfing areas like France, Epoxy Resin is still viewed with suspicion.

None of those limits apply these days. The newest clear, fast and safe Epoxies, especially the Resin Research Epoxy Resins, contain qualities unheard of ten years ago. They have a good elongation at break – up to 6% – equaling the best Polyester Resins. They are tough, with vastly improved qualities in Compressive Strength and impact resistance. Modern Epoxy surfboards – such as those made by Quiver Surfboards – have been proven to be “unbreakable” in every day use. They last far longer, with less damage, improving dramatically their green credentials (by over 300% in many cases).  When used with recyclable US Blanks super-fused EPS cores, the boards have feel and performance beyond anything achievable with Polyester Resin.

Best of all, the new Epoxies are safe and easy to use. Resin Research Epoxies have a simple 2:1 mix ratio by volume – far easier than estimating 2% of an unknown quantity in a jug. They are quick – the newest resins have a pot life equaling many Polyesters, while cure times are vastly reduced over older type epoxies. Dial in clarity, and UV resistance, and the case for Epoxy Resin gets impregnable.

Polyester Resin is still the choice of most surf shops  – mostly because the cost differential makes Epoxy more than twice as expensive, but in reality the cost of production is probably only 35% greater, and given the advantages – extra feel, performance, longevity, responsiveness – Epoxy is the choice of a growing number of smart users and smarter surfers. Safe, tough, easy to use and cost effective – it is our choice for the Quiver Surfboards and our prediction for the future of all surfboards and marine craft.