Swingable arcuate trowelling blade for mastic applicator

Claim 1

IN A MASTIC APPLYING TOOL; (A) MEANS FOR EXTRUDING A LAYER OF MASTIC ONTO A WALLBOARD SURFACE AS THE TOOL IS MOVED OVER THE SURFACE IN A CERTAIN DIRECTION; AND (B) AN ARCUATE TROWELLING BLADE FOR FORMING A CROWN ON THE MASTIC LAYER AND HAVING ITS ENDS PIVOTALLY CARRIED BY THE TOOL, SAID ARCUATE BLADE LYING IN A PLANE THAT IS PARALLEL TO SAID PIVOTAL AXIS AND SAID AXIS EXTENDING TRANSVERSELY TO THE LINE OF TOOL MOVEMENT WHEN DISPENSING THE MASTIC LAYER ONTO THE WALLBOARD; (C) WHEREBY SAID BLADE WILL CONTACT WITH ANY SURFACE HIGH POINT LYING BETWEEN THE BLADE ENDS, THE ARCUATE SHAPE OF THE BLADE FORMING A SHAPED CROWN ON THE MASTIC LAYER THAT WILL CONCEAL THE HIGH POINT, THE ENDS OF SAID BLADE CONTACTING WITH SAID WALLBOARD SURFACE SO AS TO FEATHER THE SIDE EDGES OF THE MASTIC LAYER AND CAUSE THEM TO MERGE INTO THE ADJACENT WALLBOARD SURFACE.