Observe whether the coating is crust, gelation, stratification, precipitation and fineness, etc. Conditional units, it is best to determine the storage stability of the coating in accordance with the national standard CB6753.3-86.
(1) Crust. When the coating is opened, it is often found that there is a layer of crust on the top layer, which is formed by oxidation curing of alkyd coatings. Observe the degree of crust. If there is crust, it will be removed along the inner wall of the container. The crust layer can no longer be used in the lower coatings, and can be mixed evenly when used. Removal of crust paint should be used up as soon as possible, otherwise, after a period of time there will be crust, or even scrap.
(2) Cementing. When gelling occurs, the paint can be stirred or mixed with solvent, and filtered when used. If it can not be dispersed into normal state, the paint will be scrapped.
(3) stratification. After storage for a period of time, the coating will be stratified. The particles of the coating will sink and form a layer of water quality solution over a quarter of the upper layer. When choosing, we can see that the liquid is colorless or yellowish, clearer and cleaner, and there is no float or very little. This shows that the quality of the coating is very good. If the water quality solution is turbid, showing paint color or a large number of internal floats, or even covered with the surface of the solution, it indicates that the quality of the paint is not good or the shelf life has passed, it is not suitable for use.
(4) Coating particle size. We can use a cup of water to test, take a small amount of paint into the water, gently agitate the water in the cup is still clear to the bottom, paint particles in clear water are relatively independent, there is no bonding phenomenon, and the particle size is more uniform, indicating that the paint quality is good. If once agitated, the water in the cup becomes turbid immediately, and the particle size is differentiated, indicating that the quality of the paint is not good, not good. Then you can use wooden sticks into the cylinder to mix the paint, and then use wooden sticks to pick up, high-quality paint downstream will become fan-shaped, touch with your fingers, genuine paint should feel smooth and delicate.
(5) Appearance color. Coatings used in color coating production line are colloidal particles with color. The normal appearance requirement is color, no float, no darkness or shade of color is allowed. Checking paint color, usually with naked eye observation, can also be compared with the standard color plate provided by the manufacturer, should meet the specified range of color difference.