Daguerrotypes
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 Early photography: making daguerreotypes, J. Paul Getty Museum with Khan Academy
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The Daguerreotype (/dəˈɡɛrəˌtaɪp, -roʊ-, -riə-, -rioʊ-/;French: daguerréotype) process, or daguerreotypy, was the first publicly available photographic process, and for nearly twenty years it was the one most commonly used.
Invented by Louis-Jacques-Mandé Daguerre and introduced worldwide in 1839, daguerreotypy was almost completely superseded by 1860 with new, less expensive processes yielding more readily viewable images. During the past few decades, there has been a small revival of daguerreotypy among photographers interested in making artistic use of early photographic processes.
To make the image, a daguerreotypist would polish a sheet of silver-plated copper to a mirror finish, treat it with fumes that made its surface light sensitive, expose it in a camera for as long as was judged to be necessary, which could be as little as a few seconds for brightly sunlit subjects or much longer with less intense lighting; make the resulting latent image on it visible by fuming it with mercury vapor; remove its sensitivity to light by liquid chemical treatment, rinse and dry it, then seal the easily marred result behind glass in a protective enclosure.
The image is on a mirror-like silver surface, normally kept under glass, and will appear either positive or negative, depending on the angle at which it is viewed, how it is lit and whether a light or dark background is being reflected in the metal. The darkest areas of the image are simply bare silver; lighter areas have a microscopically fine light-scattering texture. The surface is very delicate, and even the lightest wiping can permanently scuff it. Some tarnish around the edges is normal.
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