Introduced in 1851, by Frederick Scott Archer, the wet collodion process was a fairly simple, if somewhat cumbersome photographic process. A 2% solution of collodion, bearing a very small percentage of potassium iodide, was poured over a plate of glass, leaving a thin, clear film containing the halide. The plate was then placed in a solution of silver nitrate. When removed from the silver, the collodion film contained a translucent yellow compound of light-sensitive silver iodide. The plate was exposed still wet and then developed by inspection under red light. Once the plate was washed and dried, it was coated with a protective varnish. The collodion process replaced the daguerreotype as the predominant photographic process by the end of the 1850’s. It was eventually replaced in the 1880’s with the introduction of the gelatin silver process.
Video from the George Eastman Museum