1. Apparatus and Materials
(1) Sag Tester As shown in Figure 1-25, it consists of three multi-groove scrapers, a base, and a test plate rack; the measuring range is 50-675 µm. Each scraper can scrape the sample to be tested into 0 parallel wet films of different thicknesses, the wet film width is 6mm, the distance between the strips is 1.5mm, and the thickness difference between adjacent strips is 25 µm. The base is a flat-surfaced steel member with draw-down guides and glass test panel stops .
(2) Test board
20 0mm X 120mmX (2-3)mm flat and smooth glass plate (conforming to GB 116 14 — 1999 requirements) or other agreed test plate.
2. Measurement method
(1) Put the base of the Tester on a platform, and then put the test plate on the appropriate position of the base. Place the squeegee on the top of the test panel with the scale facing the operator.
(2) Stir the sample thoroughly, and place a sufficient amount of sample at the opening in front of the scraper. Hold both ends of the scraper with two hands so that one end is always in close contact with the guide edge, and scrape smoothly and continuously from top to bottom, while keeping it straight without ups and downs, and complete this operation in about 2-3 seconds.
(3) Immediately place the test panel after scraping the coating film vertically. When placing the strip film, it should be placed horizontally and keep "thin at the top and thick at the bottom" . If the coating film of this thickness does not flow to the next thickness, observe its sag situation. If the coating film of this thickness does not flow into the film of the next thickness, it means that the coating film of this thickness does not flow. The area within 20mm of both ends of the coating film is not counted. For example , as shown in Figure 1-26, 1-5 coating films are no-sag, and the wet film thickness of the 5th is the no-sag reading.
3. Result presentation
The same sample was tested in parallel with three samples. The test results are expressed in micrometers (µm) as the consistent maximum wet film thickness .
4. Reference standards
National standard GB/T 926 4-198 8 .
