Kerfed edge gypsum board having improved edge strength

Abstract

Disclosed is a gypsum board having a kerfed edge along substantially the full length of at least one edge wherein the kerf has sidewalls inclined opposingly inwardly toward one another but do not intersect and are joined by a bottom surface of uneven profile characterized by alternately and irregularly spaced projections and depressions. The uneven bottom surface and each sidewall meet at a jagged intersection. Said kerfed edge provides enhanced strength in a direction perpendicular to the sidewalls providing improved board retention by flanged supports over that of conventional mechanically sawn kerfed edge boards. A process for providing kerfed edge gypsum board is also disclosed which comprises projecting into the board edge a first and second fine stream of aqueous liquid which incline toward one another at angles of incidence to a line perpendicular to the board edge which provides a combined angle therebetween of from about 3.degree. to about 20.degree.. Both first and second fine streams of aqueous liquid are projected at a pressure sufficient to cut to substantially the same depth of from about one-quarter to about three-quarter inches. The process is dustless and provides a kerf having two opposing sidewalls inclined toward one another and joined by a bottom uneven jagged surface providing increased strength exceeding that of boards kerfed by conventional mechanical sawing processes.