I haven't seen any notion of this process in literature but some photo chemist told me that he had read about it once. So I kind of reinvented it. The idea is simple: just use a toner right after the first development. It turns undeveloped silver halide directly into highly stable silver sulfide which allows you to use a rehalogenating bleach like in color processes. This way you are avoiding using of strong oxidising bleaches. Dichromate is not just toxic but it can be hard to obtain in some countries. The permanganate bleach in turn is prone to emulsion damage. I personally had success with it only if the stinky formaldehyde pre-hardening bath was involved.
The toner is 1% thiourea solution in 2% sodium hydroxide solution (Haist)
The bleach is a modified ECN-2 "alternative" bleach aka SR-29
Possible improvements:
As the toner is not meant to be stored it's concentration can likely be lowered for one-shot use.
The number of baths can be reduced to just three if blix is used.
Some sample images:
Update:
I found at least one related post: https://www.photrio.com/forum/threa...essing-using-sepia-toner.155754/#post-2018742
Also this: https://www.35mmc.com/02/07/2022/ma...ner-kit-by-andrew-smale/?utm_content=cmp-true
And the earliest mention I could find, dated back to early 2000s: http://www.profotos.com/education/promag/articles/monotrans/index.shtml
| Step | Time at 20ºC, min |
| First Developer | Depends on film and chemistry, for low ISO films and D-67 developer it's 7 min |
| Wash | 5 |
| Toner (see below) | 1 |
| Wash | 5 |
| Bleach (see below) | 5 (?) |
| Wash | 5 |
| Acid Fixer | 10 |
| Wash | 5 |
The toner is 1% thiourea solution in 2% sodium hydroxide solution (Haist)
The bleach is a modified ECN-2 "alternative" bleach aka SR-29
| Water | 900 mL |
| Potassium Ferricyanide anhydrous | 40 g |
| *or Potassium Ferricyanide trihydrate | 47 g |
| Sodium Bromide anhydrous | 25 g |
| *or Potassium Bromide | 30 g |
| Water to make | 1 L |
Possible improvements:
As the toner is not meant to be stored it's concentration can likely be lowered for one-shot use.
The number of baths can be reduced to just three if blix is used.
Some sample images:
Update:
I found at least one related post: https://www.photrio.com/forum/threa...essing-using-sepia-toner.155754/#post-2018742
Also this: https://www.35mmc.com/02/07/2022/ma...ner-kit-by-andrew-smale/?utm_content=cmp-true
And the earliest mention I could find, dated back to early 2000s: http://www.profotos.com/education/promag/articles/monotrans/index.shtml
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