APPLICATIONS DEVELOPING BLACK & WHITE FILMS
Reversal processing is used to produce positive transparencies from conventional black and white negative films. It may also be used for copying negatives.
The method starts with conventional exposure of the film and development of the negative image as usual. At this stage, the residual unexposed and undeveloped silver halide in the film represents the positive image that is the desired end point: therefore the remaining stages in the process involve removal (bleaching) of the original negative image, fogging the film to expose the remaining silver halide, and conventional development and fixing of this second, reversal, image.