Joseph Nicéphore Niépce made the first photographic image in 1826 or 1827. He then worked together with Louis Daguerre to improve the process. After Niépce's sudden death in 1833, Daguerre continued to work on the development that would eventually lead to the invention of photography in 1839. He named the process after himself and it got the name daguerreotype.
A daguerreotype consists of polished silver that is applied to a copper plate. The silver becomes light sensitive by treatment with iodine fumes, which produces silver iodide. After the plate was exposed in the camera, the image was developed by treatment with mercury fumes. The developed plate resulted in a positive image. There was no negative which could be used to reproduce the image. Each daguerreotype is therefore unique.
The French government acquired the rights from Daguerre and presented the process "free to the world" as a gift in 1839. Every photographer could now produce daguerreotypes and the process became very popular from 1840 to 1860, after it was replaced by the wet collodion process.
The first daguerreotypes required long exposure times and were only suitable for still lifes. The process was optimized by using other chemicals, such as bromine and chlorine fumes, allowing shorter exposure times. The daguerreotype could now be used for making portraits.
It was a major invention, but not everybody was immediately pleased by the results. The image was in black and white and could therefore not compete with the colourful paintings of the time. Daguerreotypes were sometimes hand tinted to add color to the image to satisfy customers.
This hand tinted stereo daguerreotype of a woman has a size of 17 x 8,5 cm and is made by an unknown photographer. The copper plate with polished silver is covered by a glass plate and both are bound together by tape. The image shows some decay, which is not uncommon for daguerreotypes. They are extremely sensitive to abrasion and exposure to air and pollutants and require good preservation.
This stereo daguerreotype is very impressive when viewed with a stereoscope. I think that the photo was captured by a stereo camera or with a pair of two mono cameras because both images together provide a good stereo effect. The hand colouring of the image is very well done and the artist who did this was very skilful. Both images had to be colored in the same way in order not to reduce the stereo effect.
Viewing a daguerreotype is somewhat challenging. The image is on a mirror-like silver surface and will appear either positive or negative, depending on the angle at which it's viewed, how it's lit and whether a light or dark background is being reflected in the metal. The darkest areas of the image are simply bare silver and the lighter areas have a fine light-scattering texture.