Color selection of color steel plate coating: the color selection is mainly considering the matching with the surrounding environment and the owner's hobby. However, from the perspective of technology, there is a wide choice of pigments for light color coatings, and inorganic pigments (such as titanium dioxide, etc.) with superior durability can be selected, Moreover, the heat reflection ability of the coating is strong (the reflection coefficient is twice that of the dark coating), and the temperature of the coating itself is relatively low in summer, which is beneficial to prolong the service life of the coating. In addition, even if the coating is discolored or powdered, the contrast between the light color coating and the original color is small, which has little effect on the appearance. Dark colors (especially bright colors) are mostly organic colors, which are easy to fade when exposed to ultraviolet light, and change color in a short period of 3 months. For color coated steel plate, the thermal expansion rate of coating and steel plate is usually different, especially the linear expansion coefficient of metal substrate and organic coating. When the ambient temperature changes, the expansion or contraction stress will occur at the interface between substrate and coating. If it can not be released properly, the coating will crack. In addition, here to explain two current domestic market choice errors: one is that there are a large number of domestic white primer. The purpose of using white primer is to reduce the thickness of the top coat, because the corrosion-resistant primer used in normal buildings is yellow green (so there is strontium chromate pigment), so there must be enough thickness of the top coat. The second is the color coated steel plate used in construction engineering. The same project uses color coated steel plates from different manufacturers and different batches, which seem to have the same color in the construction, but after several years of sunlight exposure, the color of the top coat is not uniform, There are too many examples of serious color difference caused by different coatings and different manufacturers. Even for the same supplier's products, it is strongly recommended to order the same project at one time, because different batch numbers may use products from different coating suppliers, which increases the possibility of color difference.