观察彩涂板涂料是否结皮、胶凝、分层、沉淀和细度等情况，有条件的单位，最好按照国家标准 GB 6753.3-86 测定涂料的储存稳定性。
Observe whether the coating is skinned, gelled, layered, precipitated and fineness. If possible, it is better to measure the storage stability of the coating according to the national standard GB 6753.3-86.
(1) Crusts. After the coating is opened, it is often found that there is a layer of crust on the top layer, which is formed by the oxidation and curing of alkyd coatings. Observe the degree of crusts, if any, separate and remove along the inner wall of the container. The crust can't be used any more. The lower coating can be used continuously, and it can be stirred evenly. The paint to remove the crusts should be used up as soon as possible, otherwise there will be crusts after a period of time, or even scrapped.
(2) Gelation. When gelation occurs in the coating, it can be stirred or added with solvent, and filtered when used. If it can't disperse into normal state, the coating will be scrapped.
(3) Stratification. After the coating is stored for a period of time, the coating will be layered, the coating particles will sink, and a layer of water solution will be formed in more than one fourth of the upper layer. When selecting, we can see that this layer of liquid is colorless or yellowish, clear and clean, without floating objects or few, which indicates that the coating quality is very good. If the water solution is turbid, showing a lot of paint color or internal floating objects, or even covered with the surface of the solution, it indicates that the quality of the paint is poor or the shelf life of the storage has passed, so it is not suitable to use the paint
(4) Fineness of coating particles. We can use a cup of water to test, take a small amount of paint into the water, gently stir, if the water in the cup is still clear to the bottom, the paint particles are relatively independent in the water, there is no bonding phenomenon, and the particle size is relatively uniform, indicating that the quality of the paint is very good. If once stirred, the water in the cup becomes turbid immediately, and the particle size is differentiated, indicating that the quality of the coating is not up to standard, so it is better not to use it. In addition, the paint can be mixed well by inserting a wooden stick into the barrel, and then picked up by a wooden stick. When the high-quality paint flows down, it will become a fan shape. Touch it with your fingers. The authentic paint should feel smooth and delicate. Decision on the book of instruments
(5) Appearance color. The coating used in the color coating production line is colloidal particles with color. The normal appearance requirements are consistent color, no floating color, and no deep or light color. Check the color of the coating, usually with the naked eye, can also be compared with the standard color plate provided by the manufacturer, should meet the specified range of color difference.