Pencil hardness pencilhardness, also known as film hardness pencil measurement. It is a test method and measurement system for calibrating the hardness of a film. According to industry standards, the hardness of pencil refills is divided into 13 grades. From the hardest 6H step by step through 5H, 4H, 3H, 2H, H, then through the moderately soft HB, then from B, 2B to the softest 6B. Where H represents hardness and B represents black. The hardness from 6H to 6B decreases in turn, and the color of the pencil becomes darker. The color depth is related to the graphite content. The darker the color, the higher the graphite content and the softer the pencil.

This is a scientific hardness system with a defined hardness value. In the coatings industry, this series of different hardness pencils is used to test the hardness of the coating film, and the test result is called the pencil hardness of the coating film. The tester for determining the pencil hardness of the coating film is composed of a pencil holder and a coating plate moving table. The sample film to be tested is fixed on the mobile table with the front side facing up, and the pencil is clamped on the pencil holder at an angle of 45° to the plane of the coating film. The upper end of the clamp has a weight, so that the nib is pressed against the coating film. . Shake the handle, move the table forward with the template, let the pencil make a push-plow on the film, change each time, change a pencil, start from the hardest pencil, order from hard to soft, test one by one. Until the pencil whose coating film is not scratched is found, the hardness of the pencil is the hardness of the film to be tested.