Patent ID: 8734582

Claim:
A dry gypsum composition consisting essentially of: hemihydrate gypsum prepared by blending β-hemihydrate gypsum and α-hemihydrate gypsum at a ratio from 30:1 to 2:1; at least one pigment; a crystal habit modifier; rosin; a hydrazide compound; at least one retarder; and an additive, wherein the crystal habit modifier is at least one compound selected from the group consisting of sulfate salts, carboxylate salts, carbonate salts and inorganic chlorides, the additive is at least one material selected from the group consisting of diatomaceous earth and calcium carbonate, and a content of the at least one compound is in a range from 0.1 to 5 parts by mass per 100 parts by mass of the hemihydrate gypsum, whereby upon hydration of the hemihydrate gypsum into dihydrate gypsum, the dihydrate gypsum is controlled to become plate crystals having an aspect ratio from 1 to 9.