Hardness refers to the resistance of a paint film to the intrusion of foreign objects into its surface. The hardness of the paint film is one of the important properties of its mechanical strength. Generally speaking, the hardness of the paint film is related to the materials and drying degree of the paint film. For example, the more effective the paint film dries, the higher the hardness will be. At present, there are four methods for measuring the hardness of paint film: pendulum hardness determination method, Swat hardness determination method, Kleeman hardness determination method and pencil hardness determination method. Hardness measurement generally needs to be operated on a Hardness Tester, and the pencil hardness measurement method can also be manually operated, the method is as follows:
(1) This method uses a set of pencils to measure the hardness of the paint film. The pencils are generally high-grade drawing pencils produced by the same manufacturer. The types of pencil cores are HB, H, 2H, 3H, etc.
(2) Hold the pencil with your hand, keep an angle of about 45° with the surface to be coated, try your best (but not break the pen lead), and push the pencil forward at a speed of about 3 mm/s. A pen core with a length of about 3 mm, after reciprocating five times on different parts, wipe off the pencil dust with an eraser or soft cloth, and check the scratches on the paint film. If the paint film remains intact, it is the hardness of the pencil. The pencil hardness test method is mostly used for the hardness test of electrophoretic paints and architectural coatings.
