Abstract: Ultrasonic thickness measurement of layers of paint on a substrate produces pulse echoes indicative of each layer interface. Several ultrasonic waveforms are averaged in a digital oscilloscope and the resultant waveform is analyzed by a computer programmed to recognize wave forms resembling pulse echoes, compare such waveforms to stored reference waveform characteristics, and selecting the waveform having the best fit to the reference. Each selected pulse echo is graded based on amplitude, peak separation, peak symmetry, and spacing from a previous echo to determine the quality of the waveform. Layer thickness is calculated from the spacing between pulse echoes and the velocity of sound in the layer material.