Abstract: This invention provides a ceiling board having a durable edge portion. The durable edge portion is obtained by applying a latex composition to the edge portion. The latex composition includes a binder and filler particles of two particle size ranges. The first filler particles have a median diameter of about 0.5 micron to about 5 microns. The second filler particles have a median diameter of about 20 microns to about 300 microns. The ratio of first filler particles to second filler particles is about 2:1 to about 1:8 by weight. The binder is preferably an epoxy, a urethane, a polyester, an acrylic, a melamine, or a vinyl based polymer latex. The binder preferably has a Tg of at least 10.degree. C., and the ratio of filler to binder is about 2:1 to about 12:1 by weight.

Abstract: For sag-resistant ceiling boards, a board has at least two coatings, one on the front face (coating A) of the board and at least one other coating (coating B) on the back face of the ceiling board. Both of these coatings must have an elastic modulus of at least about 400,000 psi to make the board rigid. In addition to this, coating B, on the back face of the board, must have a higher coefficient of humidity expansion than coating A of the front face.