Patent ID: 11891336
Assignee: UNITED STATES GYPSUM COMPANY
Field: Materials, metallurgy (Chemistry)
Classification: CPC C  B  E | IPC B  C  E

Claim 6:
7. A method of making gypsum board, the method comprising:
(a) mixing at least water and stucco containing a high salt impurity content, comprising at least about 150 ppm chloride anion per 1,000,000 parts by weight of stucco, to form a first slurry;
(b) applying the first slurry to form a board core in a bonding relation to a face cover sheet, the board core having a first face and a second face, the first face facing the face cover sheet;
(c) applying a back cover sheet in bonding relation to the second face of the board core to form a board precursor, the back cover sheet comprising paper having a bond side Cobb value of at least about 2.1 g/100 cm2 according to the Cobb test, the paper having a basis weight of from about 35 lb/msf to about 65 lb/msf, and the paper having a thickness of about 0.005 inch to about 0.015 inch, wherein the paper allows for a superior bond between the board core and the back cover sheet as compared with the board prepared with the back cover sheet comprising paper having a bond side Cobb value below 2.1 g/100 cm2;
(d) drying the board precursor to form a board.