Albumen print

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The albumen print, invented in 1850 by Louis Désiré Blanquart-Evrard, was the first commercially exploitable method of producing a print on a paper base from a negative. It used the albumen found in egg whites to bind the photographic chemicals to the paper and became the dominant form of photographic positives from 1855 to the turn of the century, with a peak in the 1860-90 period. During the mid-1800's, the Carte de visite (also known as CdV) was one of the most popular forms of this type of printing process.

The process is as follows:

1. a piece of paper is coated with an emulsion of egg white (albumen) and table salt (sodium chloride). The albumen seals the paper and create a slightly glossy surface.
2. the paper is then dipped in a solution of silver nitrate and water which makes the paper light-sensitive.
3. the paper is then dried in total darkness.
4. the dried prepared paper is then placed in a frame under a glass negative and exposed to light. Often, it is a glass negative with a collodion emulsion. This is exposed to direct sunlight until the image achieves the proper level of darkness.

Albumen prints are placed in direct contact with the negative. Since the image emerges as a direct result of exposure to light and without the aid of a developing solution, the albumen print is a printed rather than developed photograph.

A bath of Sodium thiosulfate then fixes the print’s exposure and prevents further darkening. Finally, gold toning improves the photograph’s tone and helps protect it from fading.

[edit] Why does it work ?

The table salt (sodium chloride) in the albumen emulsion forms silver chloride when in contact with silver nitrate. Silver nitrate is unstable when exposed to light, decomposing and leaving silver and chlorine. The silver is oxidized during the development process and the remaining silver chloride is washed out during fixing. The black parts of the image are formed by silver oxide.

[edit] See also

Albumen Photographs: history, science and preservation

[edit] References

Make Albumen Paper [1]

• Marshall, F. A. S. Photography: the importance of its applications in preserving pictorial records. Containing a practical description of the Talbotype process (London: Hering & Remington; Peterborough, T Chadwell & J Clarke, 1855).