This standard specifies a method for the measurement of nonconductive Coating thickness on nonmagnetic base metals using an eddy current thickness gauge. It is suitable for coatings with a large thickness, but not for chemically permeable coatings that are too thin. The principle is to use the linear relationship between eddy current amplitude and Coating thickness for measurement. Calibrate requires the use of a master standard that is the same as the base material being tested and has a thickness greater than the limit value. Remove the dirt before measurement, select the appropriate range, and calibrate the zero and reading.