This standard provides a procedure for the measurement of wet film thickness using Wet Film Comb (also known as step gauges or notch gauges). The measurement of wet film thickness is crucial for dry-film thickness control of coatings, especially during construction. Since wet film thickness directly affects the final result of dry-film thickness, timely measurement of wet-film helps to make adjustments during construction to avoid the impact on coating mass after drying. Measuring methods are divided into two types: Program A is suitable for flat substrates and items of various complex shapes, and Program B is suitable for a wider range of wet film thickness measurements. Although this method is not as accurate as some professional instruments, it is particularly effective for uneven surfaces in practical applications.