Color coated steel plate was born in the United States in the 1930s. The color coated steel plate manufacturer originated in China in the late 1980s. The color coated steel plate industry has grown rapidly in recent decades. Until 2005, there was a surplus of color coated steel plate in China. Especially after the adjustment of several years after the 2008 economic crisis, the color-coated steel plate was revived again.
Pencil scratch hardness tester was used to measure the hardness of the coatings, even if the coatings were ploughed through the core of 14 labels with known hardness from 6H to 6B, of which 6H was harder and 6B was softer. Manual pencil method and instrument pencil method can be used in the determination. A Manual pencil method uses a sharpener to sharpen the pencil to expose the 4-6mm columnar pencil core. Hold the pencil and make it vertical to the surface of 400 sand paper, and grind on the sand paper until the end of the pen is flat and sharp.
Humidity and heat resistance test, also known as humidity test, is used to evaluate the resistance of coatings to high temperature and humidity. Humidity and heat resistance test is also a method to test the corrosion resistance of coatings, so it is usually carried out at the same time as salt spray test. Because temperature and humidity are the main influencing factors in the humidity and heat resistance test, special attention should be paid to the regulation of temperature and humidity control box in the whole process of each test, so as to avoid affecting the test results.