Abstract: The invention generally provides gypsum-containing slurries including stucco, a hydroxyethylated starch, naphthalenesulfonate dispersant, and sodium trimetaphosphate. The naphthalenesulfonate dispersant is present in an amount of about 0.1%-3.0% by weight based on the weight of dry stucco. The hydroxyethylated starch is present in an amount of from about 0.5% by weight to about 10% by weight based on the weight of dry stucco in the formulation. The sodium trimetaphosphate is present in an amount of about 0.1%-0.4% by weight based on the weight of dry stucco. Other slurry additives can include accelerators, binders, paper fiber, glass fiber, and other known ingredients. The invention also comprises the gypsum-containing products made with such slurries, for example, lightweight gypsum wallboard, and a method of making lightweight gypsum wallboard.

Abstract: A gypsum slurry is described that includes water, a hydraulic component comprising at least 50% calcined gypsum by weight based on the dry weight of the hydraulic component, foam, a defoamer and a polycarboxylate dispersant. In some embodiments of the invention, the defoamer is combined with the dispersant prior to being added to the gypsum slurry. The defoamer and dispersant can be added as a physical mixture, wherein the defoamer is attached onto the dispersant polymer, or a combination thereof. In some embodiments, a gypsum building panel is made from the gypsum slurry.