What is the method for measuring coating thickness?

1. Instrumentation: Lever micrometer – with a precision of 2 micrometers； Magnetic thickness gauge: accuracy of 2 microns. 2. Method A: Lever micrometer method (1) Calibration of the “0” position on the lever micrometer: First, clean the two measuring surfaces with silk cloth. Rotate the differential tube until the two surfaces are in light contact with each other. Once the pointer aligns with the “0” line on the dial, stop rotating the differential tube. At this point, the “0” line on the differential tube should also align with the axial markings on the fixed sleeve; the edge of the differential tube should be in perfect touch with the left edge of the “0” line on the fixed sleeve. This indicates that the “0” position is correct. If the “0” bit is incorrect, it must be adjusted. Adjustment method: First, align the pointer with the “0” mark on the dial. Use the stopper to secure the movable rod. Open the back cover, then adjust so that the “0” mark on the differential cylinder aligns with the axial markings on the fixed sleeve; the edge of the differential cylinder should be in exact contact with the left side of the “0” mark on the fixed sleeve. After that, tighten the back cover and release the stopper. Check whether the dial pointer is aligned with “0”. If not, repeat the above steps to zero the instrument again. (2) Measurement: Measurements are taken at three positions—upper, middle, and lower—each at a distance of no less than 1 centimeter from the edge. First, place the unpainted base plate between the micrometer rod and the movable rod. Slowly rotate the differential cylinder so that the pointer falls between the pointers of the two tolerance bands. Then align one of the lines on the differential cylinder with the axial markings on the fixed sleeve. To eliminate measurement errors, it is possible to take multiple readings at the same location. When reading the values, add the numbers indicated on the fixed sleeve, the differential cylinder, and the dial together to obtain the measured thickness. After applying the paint sample and allowing it to dry for the specified time, measure again at the same location using this method; the difference between the two readings represents the thickness of the paint film. It is also possible to first measure the thickness of the painted sample, then use an appropriate method to remove the paint layer at the measurement points, and subsequently measure the thickness of the base material. The difference between these two values represents the thickness of the paint layer. The arithmetic average of the thicknesses taken at various points gives the average thickness of the paint layer. 3. Method B: Magnetic thickness gauge method (1) Zeroing: Remove the probe and insert it into the socket of the instrument. Wipe the polished, unpainted base plate (the same as that of the paint film to be tested) clean, place the probe on the base plate, press the button, and then press the magnetic core; if the magnetic core does not return to its zero position when released, turn the zero adjustment potentiometer to bring the pointer back to zero. This process needs to be repeated several times. If zeroing is not possible, a new battery must be used. (2) Calibration: Place a standard thickness sheet on the zeroing base plate, then place the probe on the standard thickness sheet. Press the button, followed by the core button; once the core moves away, rotate the adjustment knob until the pointer returns to the value corresponding to the standard sheet thickness. This process needs to be repeated several times. (3) Measurement: Measurements should be taken at three positions—upper, middle, and lower—each at a distance of no less than 1 centimeter from the edge of the template. Place the probe on the sample, press the button, and then press the core so that it makes full contact with the paint film being tested. At this point, the pointer will descend slowly; once the core releases and the pointer stabilizes, the thickness of the paint film can be read. The arithmetic average of the thicknesses at each point is taken as the average thickness of the paint film.

The method used upstairs is a bit outdated; it still relies on mechanical measurement. We just place a paint film thickness gauge on the paint surface and get an immediate reading

Coating thickness inspection should be performed after each coating has dried. After all coating is completed, the total thickness is then measured. Testing method: Measure using a paint film thickness gauge; each 10㎡ area of the paint film (or 10㎡ if the area is less than 10㎡) is considered one test site, and each elongated section 3–4 meters in length is also regarded as one test site. 3–5 points are measured at each site. The average thickness of each measured point at each location shall not be less than 90% of the specified total coating thickness, nor more than 120% of it. The minimum thickness at each measured point shall not be less than 70% of the specified total coating thickness.

A coated thickness gauge will do; it’s very simple and practical. Generally, the better ones available on the market cost around 6,000

Measurement must be carried out using a dry film thickness gauge after the coating has fully dried. Commonly used dry film thickness gauges include: magnetic thickness gauges, fixed-probe thickness gauges, eddy current gauges, and destructive thickness gauges. Magnetic thickness gauges are currently widely used

4# YBHX actually has a wet film applicator, but it is generally used only in laboratories. Hehe