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One Introduction:
1. Hardness
The definition of hardness has some misunderstandings in the previous coating industry. Most coatings have sticky elasticity, so they cause sinking to some extent. Therefore, the DIN 55 945 is as follows: hardness is the resistance of coatings to stress, friction and scraping of mechanical forces such as mechanical forces.
2, the hardness of the string
This method evaluates the hardness by measuring the attenuation time of the swinging of the swing. The pole is supported by two stainless steel balls on the surface of the coating. There is a physical relationship between the oscillating time, amplitude and geometric size of the pole. The elasticity of coatings determines the hardness of the coating.
When the swing rod is placed on the surface, the ball rolls back and forth on the surface and puts pressure on the coating surface. According to the elasticity of the coating, the oscillating will be or weak. Without elasticity, the swing will vibrate ly. Highly elastic surfaces will cause attenuation to accelerate.
3, scratch hardness
This is an ideal method for quickly evaluating in painting products. The measurement result cannot be associated with any other hardness measurement method. The scratch test can be performed with a metal needle (DUR-O-TEST) or a pencil. Different hardness level pencils are scratched on the surface of 
coating to determine which pencil can cause indentation. This method is only suitable for smoother surfaces.
Testing two types of string is standard:
Trace hardness instrument
The instrument has a dual cone module, which placed it on the coating for 30 seconds. Use the precision microscope to observe the pressure marks, and then calculate the following formula
Hardness: Pressure marks (British) 100mm/indentation length
