During the construction process, due to various reasons, the defective parts of the coating film caused by the wet film not being leveled will become the starting point of corrosion, cracking affects the decorative appearance of the coating film, but also affects its protection. sex. Therefore, the most important thing is that after the coating is applied, it should achieve qualified leveling. For this reason, before explaining the pathological state of the coating film, we should first be familiar with and master the measurement method of the leveling property of the coating film , so as to provide objective quantitative data for evaluating the leveling property. The methods currently used are as follows.
① Use a specially designed scraper (see the picture below) that is the ASTM D2801 standard.
ASTM D2801 standard scraper
The unit in the figure is in, 1in=2.54cm; the width of the notch is 0.064in, in pairs; the distance between the notches is 0.10in
② Leneta leveling test scraper method
Schematic diagram of New York Paint Council (NYPC) scraper and Leneta scraper for leveling
The unit in the figure is cm, and the total length of the notch of the rod-shaped scraper is 11.0cm
③ A serrated leveling scraper designed by the British Paint Research Association (PRA). This scraper accurately simulates the effect of brushing conditions (shear time, shear rate, and effect on coating structure) on Newtonian and non-Newtonian coatings, measured flow properties, leveling levels and simple The results obtained from the brush samples are in good agreement.
④ Measure the leveling property by a gloss meter (use a 60° gloss meter to measure the difference between the gloss readings ), but this method has poor accuracy.
⑤Comparison of the brushed sample to be tested for leveling with the standard sample (standardized test method for brushing by the New York Institute of Coatings Technologists).
⑥ Use a wedge-shaped gap Film Applicator to create streaks on the wet film and measure the leveling property (AMTM D823 standard method).
⑦ Use a clear image Tester to measure the leveling of the coating film, which is a widely used inspection method in automotive coatings (see Figure 17-70, using a clear image Tester from BYK, Germany).
⑧Visual inspection of the hanging tendency of the applied coating on the vertical substrate, and grading according to the visual grading chart.
⑨Other leveling Film Applicators rely on a series of angular notches on the paint scraper rod to measure the leveling property, and grind a series of triangular notches on the paint scraper rod for measurement.
