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Abstract

A process for making a thin, sealant-coated, fire and indentation resistant gypsum panel. A layer of a mixture of cellulosic fibers moistened with water and an additive to restrict the adhesion of cellulosic fibers to one another, is deposited on at least two separate conveyors to form a fibrous matt on each conveyor. A layer of dry calcined gypsum containing set accelerator is deposited on the fibrous matt on each conveyor which contains, by weight on a dry weight basis, about 70-90% gypsum, about 10%-19% cellulosic fiber and about 1%-9% of combined additive and set accelerator. Each layer on each conveyor is directed to a mixing station to form a homogeneous layer, and the formed homogeneous layers on separate conveyors are placed atop one another on a single conveyor to form a combined homogeneous layer. Water is added to the layer or layers to rehydrate calcined gypsum. The combined homogeneous layer is subjected to pressure to form a pressed, homogeneous fiber-reinforced gypsum panel, and dried. The surface of the dried panel is sealed with wax-free, water resistant sealant. Sealant-coated, fire resistant, indentation resistant gypsum panels having a thickness of about 0.25 inch and a density of about 60 to 80 lbs./ft..sup.3 are made from 2 homogeneous layers of fiber-reinforced gypsum.

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First Claim