Someone posted the alleged Fuji E6 formulas
here. Stefan Lange posted his formulas
here.
Stefan's formulas work great and consist of compounds you can order from Fototechnik Suvatlar, who ships internationally. Stefan's formulas, however, only cover first developer and color developer, that's where the Fuji formulas come in.
Here is a summary of my personal experience with reexposure bathes:
The work, they are simple to mix, but they are said to suffer from the same "sudden death syndrome" as some well known B&W developer product. In theory, it takes tiny traces of SnCl
2 to render a whole roll of film fully developable. In practice SnCl
2 is a powerful reducer, which happily reacts with aerial oxygen and shows no sign of deterioration until it's gone. The other challenge is that many tin salts are quite insoluble, most notably Tin Carbonate.
So your reexp bath must stay somewhere around neutral in pH, it should be somewhat buffered, and it should contain a sequestering agent to keep the Sn
2+ in solution. Pretty much any sequestering agent will work here: EDTA, Dequest 2010, Dequest 2000, I have even tried Citric Acid and it worked. You start with 1 g/l SnCl
2 and 20 ml/l Acetic Acid 80%, then add 3-5 g/l sequestering agent, then add Sodium Hydroxide until you reach around neutral pH. EDTA is a good indicator for this, because it won't dissolve until pH is close to neutral. Process with this soup for about a minute, then go directly into color developer (no rinse between reexp and CD).
PS: Some people here have reported success with Super Iron Out or Sodium Dithionite, which may be easier for you to obtain. Note, however, that Sodium Dithionite will develop
all the silver if you process for too long, which means color developer can't develop colors. Maybe run a few tests before you commit important work.