The autoxidation of organic materials and the oxidation of metals can be detected photographically. This phenomenon is called the Russell Effect after its discoverer. In conservation the technique can be used to compare the rate of oxidation of various materials. Three main applications are discussed: detection of watermarks, comparison of conservation treatments, and the testing of materials for photographic storage. The effect is thought to be caused by evolution of hydrogen peroxide by materials. See also AATA 21-123.