Abstract: A hardboard lapped siding panel of wet processed wood fibers with substantial variations in density to provide a desired combination of improved characteristics. The panel is molded from a mat of wet wood fibers between a pair of heated upper and lower contoured plates. The upper plate is contoured to form the desired configuration of the front surface of the siding panel. The lower plate is contoured to provide the desired variations in density other improved characteristics of the panel. Preferably, the mat is molded on an underlying wire screen with a contour which is essentially the same as the contour of the lower plate.

Abstract: A siding panel with a cover sheet of hardboard fixed by an adhesive to an underlying backerboard of resin foam. Preferably the panels are installed with their longitudes extending horizontally. Each panel is secured to a wall frame by nails passing through spaced apart holes through the cover sheet adjacent its upper longitudinal edge and a locking structure adjacent the lower longitudinal edge of the panel. In the first course of panels the locking structure engages a starter strip nailed to the wall frame and in each succeeding course of panels engages the upper edge of an adjacent panel in the immediately preceding course. The locking structure is a tongue and preferably an adjacent recess in the lower longitudinal edge of the backerboard which when installed receives and interlocks with the upper nailed edge of the cover sheet of an immediately adjacent panel or a flange of a starter strip simulating an upper edge of a panel.

Abstract: Hardboard is produced by a process wherein wood solubles or sugars released principally during the pulp preparation stage are retained in a closed water system by collecting the process waters released during mechanical dewatering of the pulp to form a mat and returning such water to the system. The mat is dried by thermal evaporation with substantial quantities of sugars being deposited on the mat surfaces as a result. The mat is then pressed under conditions such as to cause flowing and caramelization of the surface sugars thus forming a crust or skin of the sugars on the mat surfaces, which sugars improve the board surface characteristics. A paper overlay may be applied to the mat prior to pressing and bonded thereto by the sugars to provide a paper overlaid hardboard.