Pencil hardness test

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A test used to evaluate the hardness of a soft material such as a coating. A set of pencils of varying grades of hardness are sharpened to a point. Starting with the softest, each pencil is drawn across the surface to be tested. The test results is hardness of the hardest pencil that does not scratch the surface. This test has many variable that cannot be easily controlled such as pressure and pencil angle. Thus it should just be used for a rough comparison of materials.