What is the best type of foam?
PU - Polyurethane Foam
Polyurethane blanks have been around for decades and have long
been the choice in surfboard production throughout the world.
They are the banchmark to which all other materials are compared
to. A polyurethane core makes for a very responsive surfboard
due to its great flex pattern. It is the easiest to
manufacture and is a good surface for airbrushing designs on before
laminating. The downside of this foam is that due to the good
flex patterns, they have a tendency to deaden over time, losing
alot of the life the board originally had. A PU with a strong
glass job will give you a good dent resistant board but for optimum
performance one layer of 4oz cloth top and bottom will give you a
pretty amazing feel to your board. Of course with a glass job
like that you may end up with 2 halves in a short while. That
is cool if you get your boards for free like the pro's, but
generally a compromise between the two is sufficient.
EPS - Expanded Polystyrene Foam
EPS Foam, or beaded foam as it is somethings called, is the same
type of foam that you would find an old fashioned chilly bin to be
made of. This is a very inexpensive foam and widely available
but the best EPS foam for surfboard manufacturing has a higher
density than you would find at your local building depot. The
foam is more buoyant and lighter than PU foam giving the board good
flotation / paddle power. This all sounds great but of course
there is a reason why this foam has struggled to find acceptance in
the surfboard industry for the last twenty-five years. EPS
boards tend to have a poor flex pattern and are prone to
compression dents. To combat denting these boards are
generally loaded up with glass or a thin hard layer of dyvinacel
foam which in turn tends to over stiffen the board. This
stiffness coupled with lots of buoyancy makes for poor performance
in bumpier conditions and the board sits on top of the water making
it harder to carve turns. Another drawback with EPS is that
it is an open celled foam so that if you put a hole in your board,
it's probably going to suck in water faster than you can drink a
can of coke (if you drink that stuff).
IXPS - Extruded Polystyrene Foam
In the last couple of years IXPS foam has started to be used in
surfboard manufacturing. Not to be confused with XTR foam
used by some overseas companies, IXPS foam does not have any
de-lamination problems. It is a closed cell foam, therefore
has very low water absorption when dinged. This foam is very
light and strong and is resistant to denting. Extruded foam
surfboards are more responsive than EPS foam cored boards due to a
better flex pattern. To top this off the foam is totally
recyclable. The IXPS foam boards surf as well as the PU foam
boards and some say it is more responsive. Although
relatively new on the scene, all the indicators are saying that
IXPS foam makes for a very durable, light and very lively
board.