The collodion process, also called the wet plate process, was an early way of making photographic negatives on glass. Collodion is a sticky solution of cellulose nitrate in ether and alcohol. It was used to hold light-sensitive silver salts on a glass plate.
Frederick Scott Archer (1813-1857) published the method in 1851. The plate had to be coated, exposed and developed while it was still wet, so photographers needed a portable darkroom. It gave very sharp images and much shorter exposures than earlier methods. It was widely used until about 1880, when dry gelatin plates replaced it.
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