Abstract: A process for making a particle board of substantial continuous thickness utilizing any of a wide assortment of comminuted lignocellulosic materials. The particle board is prepared by mixing dried lignocellulosic particles with one or more thermosetting or thermoplastic adhesive binders in predetermined proportions, and placing a measured amount of the resultant mixture in an elongate mold where it is bonded together under the influence of pressure and heat. The mold includes a movable pressure plate forming the top of an enclosure within which the material is compressed to a predetermined thickness by pressure applied to the exterior of the plate. The thickness of the compressed mixture is substantial, so as to enable the production of particle board pieces having sufficient continuous solid thickness that they may be used for such applications as dimension lumber or railroad ties, or may be sawed into multiple thinner pieces for other applications such as siding.