Hardness of Paint Test

Principle

Hardness of Paint Test

This test method covers a procedure for rapid, inexpensive determination of paint film hardness of an organic coating on a substrate in terms of drawing leads or pencil leads known as hardness.

One of the most common methods of determining coating hardness is the pencil hardness test, also known as the Wolff-Wilborn method, where a pencil of a known hardness is pushed across the coating at a specified angle, under a constant force. The pencil hardness is increased from B (soft), though HB (medium) to H (hard), until the coating is scratched. Alternatively, depending on the test method, you may start with the hardest pencil, and then decrease the pencil hardness until the coating isn’t scratched.