Patent ID: 7703243

Claim:
A ceiling tile having a rectangular shape and having nominal dimensions of approximately between 2 foot by 2 foot and 5 foot by 5 foot, the tile being formed of gypsum and cellulose fibers, the gypsum and cellulose fibers being formed into a board by uniformly mixing the fibers and gypsum in a water-based slurry that is felted and, thereafter, pressed and dried with a desired board thickness, the dried board being processed to form a plurality of holes in a face thereof by removal of board material through at least the majority of the thickness of the board, the collective volume of the holes and corresponding removed material being sufficient to reduce the weight of the board by at least 10% and to increase the NRC exhibited by the board over that which would otherwise be found in a board of the same composition and devoid of holes, said holes being cut from a side of the board associated with said face and being blind at a side opposite said face, said board being made of cellulose fiber and gypsum, in a ratio of between about 8% to about 30% weight, which has been calcined in a water slurry under pressure and thereafter recrystallized in the voids and crevices of the fiber to intimately bond the particles of gypsum with the cellulose fibers such that sifting from said cut holes of loose gypsum is reduced when the tile is thereafter handled, shipped, installed or serviced.