The pencil hardness test, also known as the "Wolff-Wilborn" test, uses graphite pencils with different hardness values to evaluate the hardness of a coating.
The design of the Elcometer 501 ensures that the cylindrical pencil lead can be maintained at a constant 45° angle and a force of 7.5N (1.68lbF).
The pencil lead is pre-prepared with a special pencil sharpener and matte paper and placed in the Elcometer 501 main unit on a smooth, flat surface. A pencil with the minimum hardness value that can leave a mark on the coating determines the hardness level of the coating.

| Part number | Description |
| H501----1 | Elcometer 501 Pencil Hardness Tester |
| Size (with pencil) | 130 x 130 x 50mm (5 x 5 x 2”) |
| weight | 2.1kg (4lb) |
The following standards are complied with:
ASTM D 3363, BS 3900-E19, ECCA T4, EN 13523-4, ISO 15184, JIS K 5600-5-4
Scribing is a standard that has been superseded but is still recognized in some industries.