Surfboard Resins By: Nicolas Guerrero and Ross Vedder 12/1/04 Engr. 45

History of Surfboards Hawaii Surfboards were originally made from various solid hard woods. These boards boards were strong but also very heavy. Lighter woods were used like balsa then foam was introduced.

Modern Surfboards Surfboards are constructed with a foam core, wrapped in fiberglass and covered with resin.

Introduction of Foam, Fiberglass and Resins resulted in much smaller, lighter and more versatile boards that performed differently. Surfers could perform tighter and quicker maneuvers than ever before. This resulted in a very different style of surfing…

Surfing Styles When surfing had evolved as a result of the size of boards surfers desired a lighter and stronger board to keep pushing the boundaries of surfing Traditional Longboards Modern Shortboards

Resins The outer layer of resin on a surfboard has two main functions. The resin protects the foam core from damage due to physical impact from waves and from the surfer. The resin also prevents water from coming in contact with the foam core. When the foam absorbs water the board becomes less buoyant. This is why it is very important that the resin needs to be strong so that it can protect the surfboard well. Being a major component of the surfboard, surfboard makers can control the weight of the board by using a lighter resin.Two forms of resins are used in surfboard manufacturing, Polyester and Epoxy. Polyester resins are mixed with a catalyst to cure. Epoxy resins are mixed with a hardener to harden. Both resins are applied to the fiberglass layer of a surfboard in similar manners. Epoxy resins are much lighter, stronger and practical for surfboards than polyester resins. In this presentation we will discuss the major differences and benefits between polyester resins.

Experiment Purpose: To compare behavior of Polyester and Epoxy resins under stress. Purpose: To compare behavior of Polyester and Epoxy resins under stress. Method: Bend Test Method: Bend Test Set-up: Set-up: 1. Pieces of wood are coated with resins 2. Loads are applied 3. Stress and strain are calculated to compare elastic properties of the resins

Stress-Strain Behavior Comparison Epoxy vs. Polyester

Results Wood coated with single coat of epoxy showed higher modulus of elasticity than single and double coats of polyester resin. From this we concluded that the epoxy resin provides the best protection to what it is coated on.

Polyester Epoxy Pros  Less expensive than epoxy  Easier to work with and cure - desirable for the novice or garage board builders Cons  About 9% shrinkage causing defects that may result in greater risk of fracture  Is used on polyurethane foam because it dissolves Polystirene foam due to shared components Pros  Lighter  Stronger  Can be used with Polystirene foam with is very light and tougher than Polyeurothane  Less than 2% shrinkage while curing resulting in minimal defects Cons  Sensitive to extremely precise mixing for proper curing

Surfboards Made with Epoxy Resin Cost Effectiveness – Longer lasting board and more resistance to damage requiring less repairs Cost Effectiveness – Longer lasting board and more resistance to damage requiring less repairs Light - Better Performance Light - Better Performance Environmentally Friendly – Surfboards are not easily recyclable so a stronger board is less likely to end up in a landfill Environmentally Friendly – Surfboards are not easily recyclable so a stronger board is less likely to end up in a landfill

The Future KevlarKevlar Carbon FiberCarbon Fiber Epoxy ResinEpoxy Resin Aluminum HoneycombAluminum Honeycomb AirAir

References Movie clips borrowed from The September Sessions DVD 1993 The Moon Shine Conspiracy Company Movie clips borrowed from The September Sessions DVD 1993 The Moon Shine Conspiracy Company