Polyurethane Foam

This is a family of materials which includes both rigid and flexible materials, a great many choices of density and several different chemical versions. In the composites realm, we only use the rigid foams. Clark foam was used widely for manufacturing surf boards, but is not offered as a precision sliced material for use in sandwich core structures.

A couple of words of caution regarding all of the urethane foam materials:

  • All can be very flammable and all of them, with no exceptions, will produce extremely poisonous gases when burning.
  • The other caution concerns the practice of foaming in place to provide contoured cores. Many composite supply shops offer two-part, foam-in-place urethane liquids for use in providing flotation in boats. The process seems so simple and obvious that many builders have tried to make this material work as a structural core for a sandwich having a complex shape, but the success rate has been almost zero. The problem lies in the fact that urethane chemistry is an extremely complex process, depending not just on the two components mixed in the bucket, but also on such things as humidity, barometric pressure, exact temperature of each of the components, as well as the exact temperature of both the bucket and the mould, and many other difficult-to-control factors.
  • One additional caution regarding the urethane materials should be noted. Most urethane foam materials become extremely fragile and somewhat unreliable at densities under 60D, and this figure should normally be considered the minimum for good structural performance.

We do not supply polyurethane foam but can inform of reputable companies that you can contact.