How surfboards are made

A surfboard is carved from a block of foam, then sealed in fiberglass cloth and resin.

stations: 8
things upstream: 37
raw sources: 14
steps from the ground: 7

The short version

A surfboard starts as a block of foam, called a blank, with a thin wooden strip down the middle. A shaper cuts and sands it to the final outline and curves. The board is wrapped in fiberglass cloth soaked in resin. Fins and a leash plug are added, and the surface is glossed and sanded.

Mold the foam blank

Polyurethane foam is molded into a blank in the rough shape of a board. Some blanks are polystyrene foam instead, which weighs less.

Goes in
Polyurethane Polystyrene
Set in the wooden stringer

A thin, stiff slat of wood runs from nose to tail down the middle, adding strength. Some blanks have one or more stringers.

Goes in
Timber
Cut the outline

The blank is cut to the board's outline in plan view, either by a machine or by a shaper with a saw.
Shape the curves

The shaper planes down the foam to give the board its rocker, rails and bottom contours. Polyurethane is brittle, so it is easy to form by hand with sandpaper.
Wrap in fiberglass and resin

Fiberglass cloth is draped over the foam and brushed with resin. Polyester resin is used with polyurethane foam, but it would melt polystyrene foam, so those boards use epoxy resin.

Goes in
Fiberglass Epoxy
Let the resin cure

The resin hardens into a hard, clear skin. The shell is light and strong enough to take a beating from waves.
Install fins and leash plug

Fin boxes or fixed fins are glassed onto the bottom, and a plug for the leash goes in near the tail.
Sand and gloss

A final coat of resin is sanded and polished smooth. Surfers apply wax to the deck themselves.

End of the lineSurfboard

Worth repeating

Balsa wood was long considered perfect for surfboards, but fiberglass skins made foam blanks practical after World War II.
Fin choices were made adjustable, so surfers can change how a board rides by changing its fins.