The wet plate photography process was a manner of taking photographs which used panes of glass, coated with a chemical solution, as the negative. It was the method of photography in use at the time of the Civil War, and it was a fairly complicated procedure.

The wet plate method was invented by Frederick Scott Archer, an amateur photographer in Britain, in 1851.

Frustrated by the difficult photography technology of the time, a method known as calotype, Scott Archer sought to develop a simplified process for preparing a photographic negative.

His discovery was the wet plate method, which was generally known as the “collodion process.” The word collodion refers to the syrupy chemical mixture which was used to coat the glass plate.

The wet plate process required considerable skill. The required steps:

•  A glass or aluminium sheet was coated with chemicals, known as collodion.
• The coated plate was immersed in a bath of silver nitrate, which made it sensitive to light.
• The wet plate, which would be the negative used in the camera, was then placed in a light-proof box.
• The negative, in its special light-proof holder, would be placed inside the camera.
• A panel in the light-proof holder, known as the “dark slide,” along with the lens cap of the camera, would be removed for several seconds, thereby taking the photograph.
• The “dark slide” of the light-proof box was replaced, sealing the negative up in darkness again.
• The  plate was then taken to the darkroom and developed in chemicals and “fixed,” making the image on it permanent. (For a photographer working in the field during the Civil War, the darkroom would be an improvised space in a horse-drawn wagon.)
• The plate could be coated with a varnish to ensure the permanence of the image.