David Kachel's S.L.I.M.T. Bleach Kit from Photographers Formulary is for use with Selective Latent Image Manipulation Techniques. It makes two (2) 500ml Stock Solutions: Potassium Ferricyanide and Potassium Bromide.
SLIMTs are used for contrast reduction/contraction, while processing most materials used for photographic negatives or prints. Instead of altering an image by changing development, SLIMTs alter the latent image itself, after exposure and BEFORE development. SLIMTs can be done in place of a pre-soak, so no major steps are added to most darkroom workflows. The development that follows is normal. SLIMTs bleached images can be developed right along with “normal” negatives that have received no alteration to the latent image. It is not recommended to use SLIMTs with “exotic” developers or processing methods.
For more detailed information on SLIMTs and the appropriate starting formulations for film and paper, please find David Kachel’s Practical Applications for S.L.I.M.T., in the PDF Downloads tab.