United States Gypsum Company

Peter M Attard

Robert H Negri

Richard B Stevens

Charles J Miller

Michael R Lynn

Adelaida L Carbo

Therese A Espinoza

Therese A Fults

John D Halm

Aida L Carbo

A rough-surfaced substrate, such as a fiberboard, is provided with a smoother surface by applying a coating comprising calcium sulfate hemihydrate which has been prevented from hydrating to gypsum by set preventer, and which sets when brought into contact with a set initiator, e.g. aluminum sulfate, preferably present on the surface of the substrate.

Substrate smoothed by coating with gypsum-containing composition and method of making

A paperless gypsum/fiber board with improved surface characteristics has at least one surface comprising a combination of fully hydrated gypsum and reinforcing fiber and has been coated with a primer comprising an aqueous emulsion of a film-forming polymeric material.

Gypsum/fiber board with improved surface characteristics

A clay-free, asbestos-free and glass microbubble-free, drying type Joint compound containing an in-situ or associative thickener as a substitute for asbestos and any clay substitute therefor. In particular, these drying type joint compounds contain no attapulgus clay thereby improving viscosity stability, crack resistance and shrinkage. The lightweight joint compounds contain treated expanded perlite, treated to render it water-insensitive. The preferred in-situ thickeners are acidic acrylate copolymers. It has been found that the in-situ thickeners should be used in combination with the normal cellulosic thickeners used in joint compounds Instead of as replacements therefor. The joint compounds contain the usual fillers and latex emulsion binders, with at least about 50% by weight of the drying type joint compound being a filler selected from the group consisting of calcium carbonate and calcium sulfate dihydrate.

Clay-free, asbestos-free and glass microbubble-free drying type joint

The unequal porosity and different textures of a drywall reinforced with joint tape and joint compound are concealed by a paint made from a low cost, easily dispersible powder in which the pigment volume concentration is about 70% to about 75%. A vinyl acetate/ethylene copolymer serves as the principle binder and a water soluble cellulose ether thickens the water dispersion of kaolin, attapulgus clay, mica, sodium potassium aluminum silicate and calcium carbonate.

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Elk Grove Village, IL, United States of America

Peter M Attard