information:extraction
Hardness test

Graded pencils can be used for a rapid test that provides relative ratings for a series of coated panels but cannot be used to compare the pencil hardness of different coatings. This test defines a "pencil hardness" of a coating as the grade of the hardest pencil that does not permanently mark the coating when pressed firmly against it at a 45 degree angle. For standardized measurements, there are Mohs hardness testing pencils on the market.