Drawing Techniques: a Guide
Dry Media: Metalpoint  

A metal stylus, when drawn over an abrasive surface, leaves sparse fragments, which produce a faint grayish line. This becomes more visible as the particles oxidize. Using a stylus of lead, bismuth, silver, or gold, the draftsman could draw on paper coated with bone-dust or chalk (calcite), which was usually tinted. Since it is difficult to distinguish the metals by simple examination, metalpoint is the most satisfactory term. However, reliable scientific methods of identifying the metal have been developed in recent years.

The technique enjoyed a limited revival in the late nineteenth and early twentieth centuries. For example, Alphonse Legros was especially partial to it for portraits and for studies of works by the old masters.

  South German, 1460-70. A Standing Knight in Full Armor. Worcester Art Museum.