Measuring levelling performance with black and white cardboard, Tinplate and levelling scraper

Leveling refers to the ability of the paint film to flow from an irregular and uneven surface to a flat and smooth surface after construction. Paint leveling is the combined effect of gravity, surface tension and shear. This method is applicable to the determination of the leveling property of coatings, and can be divided into brush coating method, spray coating method and scraping coating method. The time required for brushing, spraying or scraping paint on a flat surface to disappear the brush lines and form a smooth paint film surface, expressed in minutes.

1. Apparatus and Materials

Tin plate, flat surface, 50mmX120mmX ( 0.2-0.3)mm; black and white half test paper, see Figure 1-23; paint brush, 25-35mm wide; Spray Gun; stopwatch; leveling Tester, see Figure 1 -24, is a corrosion-resistant, stainless steel scraper, with a set of five pairs of grooves at equal intervals on the incision, and the groove depths are 100pm, 200pm, 300pm, 500pm and 1000pm.

2. Measurement method

(1) Brushing method Under the condition of constant temperature and humidity, according to the brushing method in Chapter 1, use a paint brush to prepare a paint film on the tinplate. When brushing, it should be painted vertically first and then horizontally quickly, and the brushing time should not exceed 2-3 minutes. Then apply one coat longitudinally from side to side in the middle of the template (with brush marks but no bottom showing). At the same time when the brush leaves the sample, start the stopwatch to measure the time required for the disappearance of the brush marks scratched by the brush and the formation of a completely smooth paint film surface.

(2) Spraying method According to the brushing method in Chapter 1, prepare a paint film on the surface of the tinplate plate, place the sample plate under constant temperature and humidity conditions, and observe that the painted surface is uniform, smooth, wrinkle-free (no orange peel or The time required for the state of goose skin, whether it is qualified or not shall be stipulated in the product standard.

(3) Scrape coating method Under constant temperature and humidity conditions, use a leveling Tester to scrape the sample on the test cardboard to produce five pairs of stripes with various film thicknesses. Keep the test card in a horizontal position, observe which pair of stripes close together, and record the time for close together.