A handheld wet slurry thickness gauge and method for its use. The thickness gauge includes a distance displacement measurement gauge, a skirt, a platen and support legs. The distance displacement measurement gauge includes a case, a vertical stem, and a vertical spindle. The stem extends from the case. The spindle is slidably supported to move in an axial direction within the stem. The case body has a display for indicating a linear displacement of the spindle. The skirt has a central through-hole for receiving the stem of the gauge and retaining the stem in an upright position. The measuring platen has a platen base and a platen shaft extending upwardly from the platen base and attached to the spindle. The support legs extend downwardly from the skirt. The platen is below the skirt.