Pencil Film Hardness Test


Coating hardness is the capacity of a coating to resist scratching, marring or gouging of foreign objects. The pencil hardness test, also commonly known as the Wolff-Wilborn test, uses the varying hardness of standardized pencil sets to determine a coating’s overall hardness and scratch resiliency. The chosen pencil with a corresponding hardness level is placed on a tool to be run across the coating surface with a standardized force. If the coating resists permanent scratching, the pencil with the next hardness level is used and the procedure repeated until permanent scratching occurs, thereby determining the coating's hardness.

Standardized coating hardness & scratch resistance test

ASTM Specifications

ASTM D3363
ASTM Title
Standard Test Method for Film Hardness by Pencil Test
This test method covers a procedure for rapid, inexpensive determination of the film hardness of an organic coating on a metal or similarly hard substrate in terms of drawing leads or pencil leads of known hardness.

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