Determination of paint film thickness (GB 1761-89) This standard is applicable to the determination of paint film thickness by using a lever micrometer or a magnetic Thickness Gauge, expressed in µm.
(1) Instruments and equipment
Lever micrometer: the accuracy is 2㎛.
Magnetic Thickness Gauge: Accuracy is 2µm.
(2) Measurement method
①A method: lever micrometer method.
a. Check the "0" position of the lever micrometer.
b. Measurement: Take the upper, middle and lower positions not less than 1m away from the edge to measure, first measure the unpainted bottom plate, in order to eliminate the measurement error, you can measure several times at the original place. Then apply the paint sample in the same way, after dry operation according to the specified time, measure at the same position according to the above method, the difference between the two is the paint film thickness. It is also possible to measure the thickness of the painted sample first, then use a suitable method to remove the paint film at the measurement point, and then measure the thickness of the bottom plate, and the difference between the two is the paint film thickness. The arithmetic mean of the thickness of each point is the average thickness of the film.
② Method B: Magnetic Thickness Gauge method.
First zero, then calibrate, and then measure.
Take the measurement at the upper, middle and lower positions not less than 1cm away from the edge of the sample board, place the probe on the sample board, press the button, and then press the magnetic core to make it completely attract with the paint film to be tested. The hour hand drops slowly, and when the magnetic core jumps away and the hands are stable, the paint film thickness value can be read, and the arithmetic mean value of the thickness of each point is taken as the average thickness value of the paint film.
