Process for the manufacture of ceiling tile

Claim 1

A process for manufacturing ceiling tiles comprising the steps of: preparing a mixture which includes water, starch, boric acid and fire clay, heating said mixture to form a gel, shredding scrap fiber glass prior to its addition to said gel to form shredded fiber glass, adding fibrous material comprising said shredded fiber glass to said gel to form a pulp, wherein said pulp comprises the following components: ______________________________________ COMPONENT PER CENT BY WEIGHT ______________________________________ Water about 80 to about 85 Starch about 2 to about 5 Boric Acid about 0.15 to about 0.35 Fire Clay about 0.7 to about 0.95 Planer Dust about 0 to about 8 Silicone Emulsion about 0 to about 0.1 Scrap Fiber glass about 5 to about 15 ______________________________________ feeding said pulp into trays to form slabs, drying said slabs in an oven to form dried slabs in accordance with a temperature schedule as follows: a. raise to about 250° F. in about 1/2 hour b. hold at about 250° F. for about 2 hours c. hold at about 275° F. in about 1/2 hour d. hold at about 375° F. for about 4 hours e. reduce to about 350° F. and hold for about 2 hours f. reduce to about 325° F. and hold for about 2 hours g. reduce to about 300° F. and hold for about 2 hours h. reduce to about 250° F. and hold for about 3 hours, and finishing said dried slabs to form said ceiling tiles.