The choice of color is mainly based on the matching with the surrounding environment and the owner’s preference. However, from the perspective of use technology, light color coatings have a wide choice of pigments. Inorganic pigments (such as titanium dioxide) with excellent durability can be selected. Moreover, the coatings have strong thermal reflection capacity (the reflection coefficient is twice that of dark color coatings). The temperature of the coatings in summer is relatively low, which is beneficial to the extension of the coating life. In addition, even if the coating is discolored or powdery, the contrast between the light color film and the original color is small after the change, which has little impact on the appearance. The dark color (especially the bright color) mostly adopts organic color, which is easy to fade when exposed to ultraviolet radiation, and will 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 is quite different. When the ambient temperature changes, expansion or contraction stress will occur at the interface between substrate and coating, and coating cracking will occur if it is not properly released.
In addition, here are two points to explain:
One is that there are a large number of white primers in China. The purpose of using white primer is to reduce the thickness of the top coat, because the corrosion resistant primer used in normal construction is yellow green (so there is strontium chromate pigment), and it must have enough thickness of the top coat
The second is that the color coated steel plates used in the same project are made by different manufacturers and batches of color coated steel plates, which seem to have the same color during construction. However, after several years of sunlight, the color change trends of different coating manufacturers are different, leading to serious color differences. There are too many such examples. Even products from the same supplier are strongly recommended to be ordered at the same time for the same project, because different batch numbers may use products from different paint suppliers, increasing the possibility of color difference.
Post time: Dec-12-2022