Abstract: A mat formed of a mixture of board particles and a bonding agent is conveyed to oppositely rotating rollers which compress said mat to a desired thickness as the mat passes therethrough. A conveyor associated with the rollers is provided for carrying the compressed mat between a pair of platens mounted in a fixed relationship with respect to the continuously moving mat. As it passes between the platens, the mat is supported by a fluid bearing and is exposed to heat to cure the bonding agent.