Albumen is a printing out process based on the light sensitivity of silver chloride, which is suspended in an albumen binder on a thin paper support.

Albumen prints were made by hand on both the commercial scale as well as by the individual photographer. Chloride (sodium or ammonium chloride) was added to egg white, which was then beaten to a froth. Once the mixture settled it was strained and sometimes allowed to ferment. Fermentation was introduced in the 1860s, but was not practiced regularly in commercial production until the 1880s. Very thin, good quality paper was then floated on the albumen mixture and dried; drying in a warm room allowed for a higher surface gloss. Double coating of albumen prints was popular in the 1880s and 1890s because it allowed for a glossier finish. The coated paper was then floated on a solution of silver nitrate rendering it light sensitive. Commercially coated paper could be purchased, but sensitizing had to be done by the photographer just prior to use. Like all printing out papers, there is an excess of silver nitrate. Once dried, the paper was contact printed under ultraviolet (sun) light. Printing was done entirely by eye and experience. The print was then washed, toned in a gold chloride solution, fixed with sodium thiosulfate (“hypo”), and washed. Prints were then usually trimmed and mounted. During the mounting process, prints could be burnished to obtain a glossy surface and to smooth the print. Burnishing is a finishing technique in which the mounted print was run through hot metal rollers. 

The albumen printing process was introduced in 1850 by Louis-Désiré Blanquart-Evrard as an improvement to the salted paper process. It allowed for good reproduction of detail, greater density and contrast, and was a good match for the collodion negative, which was introduced about the same time. Albumen was the major printing process of the nineteenth century until it began to be replaced by gelatin and collodion printing out papers in the mid-1880s. The last albumen papers disappeared from the market in 1929. Due to the dominance of the process, it was used for every application of photography and can be found in a wide variety of formats. Some of the most common formats include the carte-de-visite, cabinet card, stereo-view card, and professional photographic albums.