Application of Pendula Hardness Tester in determination of automobile coating Hardness

 The hardness of the coating is one of the important properties to characterize the mechanical strength of the coating. At present, the pendulum hardness test method is commonly used to determine the hardness of automotive coatings. Pendulum hardness can be divided into two types: single pendulum type and double pendulum type. The measured value of the former is expressed in seconds, while the latter is expressed in percentage relative to the hardness of the glass.

Single pendulum is also known as Koenig and Berthazi pendulum hardness. These two kinds of Hardness Testers are mostly used by some large-scale automobile coating , and the hardness indexes of their automobile coatings, especially topcoats, are mostly expressed by these two hardnesses, such as BASF, Stolak, Aksu etc. , The working principles of several pendulum damping tests are basically the same, that is, when the pendulum in contact with the coating surface swings in a certain period, the softer the surface, the faster the swing amplitude of the pendulum decays, and vice versa. Usually the Koenig hardness value is about half . Because the structure, weight, size, period and swing amplitude of various pendulums are different , the interaction between the pendulum and the coating also depends on the elasticity and viscoelasticity of the coating itself . The measurement results of the pendulum cannot establish a mutual conversion relationship, so when listing the pendulum hardness value of the coating in the product standard, it is necessary to indicate the type of the pendulum used at the same time.

The double pendulum Hardness Tester is commonly used in CHINA, and its result is expressed by the ratio of the damping time of the swing attenuation within the specified swing range to the damping time of the swing attenuation on the glass plate within the same swing angle range . The double pendulum Hardness Tester needs to calibrate the glass .