Portrait of a Man and a Portrait of a Woman. To make a daguerreotype, a copperplate, coated with silver, was polished and sensitized to light with iodine vapour. The plate was placed in the camera and exposed for 30-90 seconds. It was then removed from the camera in the dark and placed above a heated mercury bath. As the mercury vapour reacted with the plates surface, an image appeared, which was subsequentlyfixed.