Photographic Processes: 1839 - 1889


Silver-based, one-of-a-kind image on silver/copper plate

A silver-plated copper plate is polished on the silver side to a mirror-like sheen and exposed to iodine vapor, creating a layer of light sensitive silver iodide. A latent image forms after exposure to light in the camera, and the image is developed with heated mercury vapor, fixed in hypo (sodium thiosulfate) and rinsed. Several subsequent developments improved this process, including the addition of bromine fumes and gilding with gold chloride solution.

A daguerreotype is one-of-a-kind photograph, meaning that the process produces only a single image. It can appear as a negative or a positive view of the subject depending on the viewing angle and the lighting conditions. A daguerreotype is subject to tarnish and usually is encased to protect the image.

Unidentified. Daguerreotype, ca. 1850. [zoom]
Quarter plate
Parts of the Daguerreotype, ca. 1854. From left to right: Glass, Mat, Daguerreotype, Preserver, Case [zoom]

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