His link includes procedures, which suggest he was testing the hardness of some surface coating or similar:

> For the pencil hardness test, reference ASTM D3363, pencils of increasing hardness values are moved over the surface in a precisely defined way until one lead damages the surface. Surface Hardness is defined by the hardest pencil grade which just fails to damage the surface.

> Observe the pencil track. Sufficient pressure must have been applied either to cut or damage the coating or to crush the lead pencil point.

> If neither coating damage or pencil point crushing is observed, repeat the test until a definite observation is made.

> If scratching or damage of the surface occurs, proceed with the next softer pencil grade and repeat the testing process until a pencil lead grade is found which crushes and does not damage the coating.

> If crushing of the hardest lead should occur, the coating is therefore extremely hard and is beyond the measuring range of this test