dagerotypy

Dagerotypy, or the daguerreotype, is an early photographic process introduced by Louis Daguerre in 1839. The image is a direct positive on a highly polished silver-plated copper plate, producing an unusually sharp and detailed likeness that is typically viewed under reflective light from a glass protective layer.

The process involves several steps. A copper plate is coated with a thin layer of silver and meticulously polished to a mirror finish. The plate is sensitized by exposing it to iodine vapor, forming silver iodide on the surface. In a camera, light exposure creates a latent image. Development is carried out by exposing the plate to mercury vapors, which amalgamate with the silver to reveal the visible image. The image is then fixed with a solution such as sodium thiosulfate, washed, and often toned with gold chloride to brighten the whites. Finally, the plate is varnished or sealed under glass.

Characteristics of daguerreotypes include exceptional detail and tonal range, with a high-surfacial sheen and a need to view the image at a specific angle. Each daguerreotype is unique and not readily reproducible; images were typically mounted in cases with a protective cover glass.

History and impact: first publicly announced in 1839, the daguerreotype rapidly gained popularity across Europe and North America in the 1840s and 1850s, especially for portraiture. Improvements reduced exposure times, but the method required careful handling due to the use of mercury and silver. By the late 1850s, newer photographic processes such as the wet plate, albumen print, and other negatives largely supplanted daguerreotypes, though they remained valued for their clarity and historical significance.