Abstract: An extruder for delivering foamed glue from a foamer selectively to a plurality of spaced apart outlet orifices for extrusion onto a substrate surface and to bypass passageways for diverting the foamed glue to a defoamer for subsequent return to the foamer, is formed of three elongated flat blocks secured together releasably in face-abutting relationship. The surfaces of the outer, inlet and bypass blocks facing the center coupling block are recessed to provide a plurality of passageways all of which extend substantially equal distances from inlet and bypass ports in the inlet and bypass blocks, respectively, to a plurality of coupling ports in the coupling block. An air pressure operated selector valve in the bypass block is operable to communicate the coupling ports selectively with the bypass passageways for bypassing foamed glue to the defoamer and with the outlet orifices for extruding foamed onto a substrate surface.

Abstract: Foamed liquid mixtures are applied to substrates, in particular foamed plywood glues, are spread on traveling wood veneers in the manufacture of plywood by a method comprising the following steps: The liquid is withdrawn from a source of the same, is subjected to a mechanical beating action wherein its density is reduced and is then passed to a reservoir or feed storage vessel. Density-reduced liquid is then foamed and the foam is continuously extruded or otherwise spread on an intermittently-moving substrate during the periods of motion of the substrate. The foamed liquid is continuously diverted from the substrate during the periods of rest of the substrate. The diverted foamed liquid then is defoamed by subjecting it to the same mechanical beating action applied to the liquid thereby increasing its density to substantially that of the density-reduced liquid.

Abstract: Plywood and other glued, laminated assemblies are made by spreading a liquid foamed glue on a surface of a first lamina. A second lamina is superimposed and, while the glue is in a fluid condition, the resulting assembly is prepressed under pressure sufficient to spread the glue and to wet and unite the opposed faces of the laminae. This forms a flat, self-sustaining intermediate laminate which thereafter may be pressed further to develop the glue bond between the laminae.

Abstract: Plywood is made by continuously propelling a liquid plywood glue in unfoamed condition at a predetermined flow rate, continuously foaming the glue as it is propelled, and continuously extruding or otherwise applying the foamed glue to the surface of a plurality of wood veneers. The flow rate of the unfoamed and foamed glue is maintained substantially the same on a unit weight of liquid glue per unit time basis. The veneers then are laid up into a plywood assembly and pressed into a plywood panel. The veneers may be preheated to expedite setting of the glue. The method is applicable generally to the application of a foamed liquid to a solid surface.