How do you tell if foam is EPS or PU by looking at a surfboard?

To differentiate between EPS (Expanded Polystyrene) and PU (Polyurethane) foam in a surfboard, observe the texture and density. EPS is typically lighter and has a more uniform, closed-cell structure with a shiny appearance, while PU is denser, feels heavier, and has a more porous, slightly uneven surface. Additionally, if the board has a stringer, PU boards often have a more pronounced stringer due to the manufacturing process. Checking the board’s weight and feel can also provide clues, as EPS boards are generally lighter than their PU counterparts.