Role of Sodium thiosulfate in Farmer's reducer

Alex Benjamin

Subscriber
Joined
Aug 8, 2018
Messages
2,712
Location
Montreal
Format
Multi Format
Found many answers to my questions regarding bleach in various Phototrio threads, except those regarding sodium thiosulfate.

I do understand the role of the potassium ferricyanide, of course, and also understand that the addition of potassium bromide makes the bleach a rehalogenating bleach, meaning I can re-develop the print.

What I'm not sure I understand is the role played by sodium thiosulfate in Farmer's reducer. What, exactly is its impact? Can I still re-develop if my solution contains both potassium bromide and sodium thiosulfate, or is that cancelled because of the sodium thiosulfate? Do I still need to fix the print afterwards?

I use this formula from the latest edition of The Darkroom Cookbook:

 
Cookies are required to use this site. You must accept them to continue using the site. Learn more…