Crucifixion with the Two Thieves

To make this drawing—which could be a ricordi (a visual record of a painting)—the artist first sketched part of the composition with charcoal before completing it with pen and ink. Charcoal was not regularly used as a drawing medium until the second half of the 1400s. Even then, it was usually a secondary medium, as seen here, meant to sketch or outline figures to be completed in other media. Charcoal and black chalk became more popular with later generations of artists, including Michelangelo, who found the supple qualities of the media ideal for rendering the human figure.