Formulary's TF-4 Archival Rapid Fixer is excellent for use with PMK and other Pyro Film Developers.. TF-4 is an extraordinary fixer for both paper and some films. TF-4 works well in batch processing, fixing resin coated paper in 30 seconds and fiber based paper in 60 seconds. You can also use TF-4 on T-Max films, fixing for 6 minutes to remove the magenta stain. We recommend 20 rolls of film to 1 liter working solution. TF-4 does not require a stop bath nor a hypo clearing agent, and has little odor when mixed with distilled water. TF-4 is a non-hardening fixer which makes it excellent for prints that are to be toned or retouched. Most modern film emulsions have built-in hardener, eliminating the need for hardener in the fix. The stock solution which has a shelf life of 1 year is diluted 1:3 to make the working solution. The working solution has a shelf life of 6 months.