The Russell Effect and its Use in Non-Destructive Testing

The Russell effect was discovered in 1897 when it was found that some types of photographic plate could form an image in the dark when placed in contact with certain organic materials or freshly abraded metals. The technique was largely forgotten for several decades. It is now thought that image formation is due to hydrogen peroxide evolution caused by the autooxidation of the objects under examination. The peroxide reduces the silver halide in the photographic emulsion. Several interesting results have been obtained in the non-destructive testing of materials including the detection of recent abrasions of watermarks, areas of objects exposed to daylight, cracks in paint films and the enhancement of writing. A method for studying the Russell effect with modern materials is described.