Mica-free joint compound
AssigneeNational Gypsum Company
InventorsRichard E. Smith, William R. Burke
Life of this patent
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Abstract
A joint compound, having crack resistance substantially equal to joint compounds containing mica, wherein the mica has been replaced by low length to width ratio gypsum crystals formed by the hydration of calcium sulfate to calcium sulfate dihydrate, particularly crystals formed in the presence of citric acid.
Claims10
A joint compound for concealing the joints between wallboards, consisting essentially of a filler, a binder, additives for providing working properties during application to a wallboard when mixed with water, and a special additive for minimizing shrinkage during drying, said special additive consisting of calcium sulfate dihydrate, said calcium sulfate dihydrate comprising a substantial portion of individual crystals having a length to width ratio of about 1.0 to 1.5, with the length being about 50 to 100.mu..
Dependencies are inferred from the claim text.