Abstract: An elongated grid runner, and its manufacture, comprising a pair of overlying metal strips roll-formed together into a shape suitable for use in a rectangular grid to support ceiling panels, one of said strips serving as a visible cap for concealing the other strip forming the main body of the grid runner when the grid member is employed in a completed ceiling, the strips being lanced at each end of the grid runner to lock the cap strip on the main body strip whereby when the overlying strips are simultaneously cut to a finish length prior to finish roll-forming, the ends of the strip are maintained in substantially overlying end-to-end registration where the cap is visible in a finished ceiling.

Abstract: A roll-formed grid runner comprising a sheet metal strip folded into an upper hollow single wall reinforcing bulb, a double wall web below the bulb, a channel extending laterally from both sides of a lower end of the web to a bend and upwardly from the bend to a panel supporting elevation, the bend on each side of the web existing at a longitudinally extending score line where a thickness of the strip is locally reduced.

Abstract: Building panels such as ceiling tiles have compositions including starch as a binder and a coagulant for the starch. The building panels also can include a fibrous material and a filler. In one aspect, the starch is coagulated by the coagulant resulting in the starch being distributed substantially uniformly through a thickness of the building panels, whereby certain physical properties of the building panels and a wet-felting process for manufacturing the building panels are improved. The coagulant can comprise at least one aluminum salt. In the wet-felting process for manufacturing the ceiling tiles, a slurry comprising an aqueous dispersion of at least one fibrous material, at least one filler material, at least starch as a binder and a coagulant for the starch is delivered onto a foraminous wire frame. The slurry is dewatered to form a basemat and the basemat is dried to remove any residual moisture.