The Romantic painter, showman, and entrepreneur Louis-Jacques-Mandé Daguerre first showed his newly invented art in January 1839 and revealed the steps in his process that August. Each daguerreotype—as he dubbed these first photographs—was a one-of-a-kind image on a highly polished, silver-plated sheet of copper, sensitized with iodine, exposed in a camera, and developed in mercury fumes. In the following decade and a half, the craze for daguerreotypes spread around the world like wildfire, with countless artists and artisans producing millions of portraits for a clientele that had never dreamt of leaving their likenesses for posterity.