Metalpoint
A metalpoint drawing is made by applying a stylus—a thin metal rod inserted into a holder—to a prepared surface. Generally, the preparation involves coating a gesso-like ground on paper of medium thickness or a wood panel. As the stylus moves across the textured ground, it deposits miniscule particles of metal and creates a mark.
Traditionally, the ground consists of a mixture of calcium carbonate (or a similar inert mineral) to give body, pigment to impart color, and a binder, such as rabbit skin glue, to hold the ingredients together. The resulting mixture is then brushed or rolled onto paper and allowed to dry. Today, artists can buy pre-made grounds and metalpoint papers.
Until the twentieth century, these drawings were generically called silverpoint. But a variety of metals have been used to produce them, including gold compounds, tin, antimony, bronze, and lead, as well as silver. Each metal oxidizes and darkens to a subtle grey-brown hue. The type of metal is difficult to recognize by eye alone and requires technical analysis, such as X-ray fluorescence, to establish its identity.
The fine metal wire traditionally used for these drawings lends itself to a precise linear technique, with forms built up from elongated strokes. The medium has neither great darkness nor tonal range, but both can be achieved by layering strokes and varying their spacing.
Artists can also create areas of mass with closely-spaced parallel hatches and cross-hatching.
Metalpoint drawing was common throughout Europe during the Renaissance, then waned in popularity before experiencing a revival in the nineteenth century that continues to this day, with many traditional techniques still being practiced. In the fifteenth century, the use of brilliantly colored, prepared papers was distinctive at a time when only natural white, off-white, and blue sheets were available. Drawings rendered on prepared papers were often highlighted with white gouache.
Metalpoint is mostly associated with highly refined, finished drawings. However, artists have used it in a light summary manner for preliminary sketches, often further developed with pen and ink, such as in this sketch by Leonardo.