Seen from below, the imposing figure of Vulcan shows off his solid muscularity as he prepares to strike a blow on his anvil. The background figure, possibly an assistant or another version of Vulcan, reinforces the dramatic sense of impending movement. A broken, twisting outline artfully defines the figures and reveals an abstract beauty. Primaticcio may have intended to emphasize only the main lines of the design, for he barely noted the figures' interior modeling: short, expressive pen lines suffice, combined with subtle shadows and highlights.
Primaticcio made this drawing as a preparatory study for the Ulysses Gallery at Fontainebleau, which he designed and Nicolò dell'Abate and others executed. The Ulysses Gallery was entirely destroyed in 1739, and knowledge of it today depends on such preparatory drawings, copies, and written descriptions. Vulcan sat in one of the corners of the ceiling's second bay, making armor for Ulysses. The black chalk grid lines show that Primaticcio made this drawing late in the design process, just before his assistants used the squaring to transfer the design to the wall.