United States Gypsum Company

Friedrich Failmezger

Richard B Stevens

Charles J Miller

Geronimo E Lat

Therese A Espinoza

The present invention relates to a method for minimizing the buildup of set gypsum on a tool used to apply a calcium sulfate hemihydrate-containing composition to a surface as well as to a method for cleaning a tool having set gypsum deposited thereon. The method for cleaning a tool having set gypsum deposited thereon comprises the steps of (a) contacting the tool with a cleaning solution having a pH of less than about 7, said cleaning solution which comprises a non-calcium phosphate, water, and, optionally, a pH modifier; (b) optionally agitating the solution; (c) removing the tool from the cleaning solution; and (d) rinsing the tool with water. The method for minimizing the buildup of set gypsum on a tool further comprises step (e) using the tool to apply a calcium sulfate hemihydrate-containing composition. An additional step (f), flushing the tool with water, may also be employed. Optionally, steps (a) through (e) or (a) through (f) may be repeated during the application of the calcium sulfate hemihydrate-containing composition. Examples of non-calcium phosphates which may be used in the cleaning solution are sodium, potassium, or ammonium salts such as tetrasodium pyrophosphate, tetrapotassium pyrophosphate and sodium tripolyphosphate.

Method for cleaning and minimizing the buildup of set gypsum

A composition and method for treating the surface of a metal structure adapted to be used for such purposes as a cornerbead and to have a cementitious material such as a joint compound applied to the surface thereto, the compound and composition and method resulting in the improvement of the adhesion between the surface of the metal structure and the cementitious compound applied thereto, which comprises preparing a composition such as that comprising a forming lubricant for processing the metal structure and a minor proportion of a polyfunctional aziridine incorporated therein. The presence of the aziridine enhances the adhesion properties between the surface of the metal and the cementitious compound even when less highly processed metals and less expensive compounds are utilized.

Method for treating the surface of a metal to improve the adhesion of a

A dried gypsum board article and a gypsum board to be dried, the latter comprising a wet gypsum core and a cover sheet to be securely laminated thereto in drying and a coating composition, the cover sheet having a porosity between about 90 and about 260 as determined by ASTM D 726-58; the coating composition comprising a pigment binder and expanded inorganic particles present in an amount sufficient to provide the coated cover sheet with a porosity of no higher number than about 2500 seconds as determined by ASTM D 726-58. Thereby the wet core, paper and coating composition are capable of being simultaneously dried without delaminating the sheet from the core.

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Dubuque, IA, United States of America

Friedrich Failmezger