When repairing a surfboard, you must know the type of foam core you have, as using the wrong resin will instantly damage your board. Surfboards are made of one of two types of foam: Polyurethane (PU) or Expanded Polystyrene (EPS/Styrofoam).
Key Takeaways & Tips
Two Foam Types
Surfboards are made from two core materials: Polyurethane (PU), which is the traditional foam, and Expanded Polystyrene (EPS), which is essentially styrofoam.
The Repair Rule
The simple rule of ding repair is: Epoxy resin can go on anything. The second type, Polyester resin, can only go on the traditional PU foam. Never use polyester resin on an EPS board.
The Risk
If you use polyester resin on an EPS (styrofoam) board, the chemicals in the resin will instantly burn a hole in your board, causing irreparable damage to the foam core.
The Solution
When in doubt about your board’s core material, always use epoxy resin for the repair, as it is safe for use on both PU and EPS foam boards.
Common Mistakes to Avoid
Using Poly on EPS
The most critical mistake is using polyester resin on an EPS (styrofoam) core. The resin will instantly burn and melt the foam.