Methods and apparatus for measuring the thickness of wet films

A gauge for measuring the thickness of a wet film on a surface, comprising a substantially circular disc having a thickness in the range of from 0.032 to 0.125 inches, said disc including a plurality of circumferentially spaced, calibrated measuring notches disposed around the outer periphery thereof, said notches each including a pair of generally radially extending side walls and a generally circumferentially extending end wall connecting radially inner ends of said side walls, radially outer ends of said side walls extending to the outer periphery of said disc and being spaced apart to form an open end of each notch, the radially outer end of a side wall of each notch being circumferentially spaced from the radially outer end of the nearest side wall of an immediately adjacent notch to form a generally circumferentially extending face between such adjacent notches, the depths of said notches being graduated, said disc being rotatable about a central axis thereof along the film-containing surface so that at least some of said measuring notches travel through the film and become wetted thereby to measure the film thickness.