Gelatin silver print
As such, films and printing papers available for analog photography rarely rely on any other chemical process to record an image.
These light-sensitive materials are stable under normal keeping conditions and are able to be exposed and processed even many years after their manufacture.
[2][3] In the 1860s, the dry plate collodion process (with gelatin or albumen) was described as advantageous for outdoor photography, especially when a large amount of shots in different places were required, or when there was little time.
[4] The introduction of the gelatin silver process is commonly attributed to Richard Leach Maddox, author of the 1871 article An Experiment with Gelatino-Bromide.
William de Wiveleslie Abney and Josef Maria Eder improved the formula with silver chloride.
Coating machines for the production of continuous rolls of sensitized paper were in use by the mid-1880s, though widespread adoption of gelatin silver print materials did not occur until the 1890s.
[citation needed] Research over the last 125 years has led to current materials that exhibit low grain and high sensitivity to light.
The image is then made permanent by treatment in a photographic fixer, which removes the remaining light sensitive silver halides.
Paper is in many ways an ideal support: it is lightweight, flexible, and strong enough to withstand both wet processing and regular handling.
In order to obtain this purity, the paper was originally made from cotton rags, though after World War I there was a transition to purified wood pulp, which has been used ever since.
Before a paper is exposed, the image layer is a clear gelatin matrix holding the light-sensitive silver halides.
Exposure to a negative is typically done with an enlarger, although contact printing was also popular, particularly among amateurs in the early twentieth century and among users of large format cameras.
The fixer, typically sodium thiosulfate, is able to remove the unexposed silver halide by forming a water-soluble complex with it.
Ilford, in collaboration with Metro Imaging, London adapted their FB Galerie emulsion paper and its light sensitivity so that it would be receptive to full spectrum RGB laser channels.
An essentially identical procedure called "silver staining" is utilized in molecular biology to visualize DNA or proteins after gel electrophoresis, usually SDS-PAGE.
