Sabattier process, or pseudosolarization, has been re-discovered multiple times during the short history of photography — probably beginning as an accidental effect when the darkroom light was turned on while a print was in the developing bath. The introduction of light during this stage of print development produces unusual effects, such as reversal of tones and halos around figures. These effects are unique to each occasion, and cannot be replicated precisely; the uniqueness of each pseudosolarized print adds an autographic twist to an allographic art.