Sulfite, used as preservative is mainly an Oxygene scavenger, have I learned then. The ammount of Oxygene in water is always very small, sulfite should be added, I think, like it is done for wine, one gramm is more than enough and should be added first to the water alone where a parte of it will oxidize to sulfate and then we can add coffee and Vit. C in this water previously de-oxygenated with sulfite. And we may also boil the water for some 10 minutes to free the air in it. I have done this and the content is now in a closed bottle that I will control for gas formation, if any. I don't think so.
But then, another fellow in Flickr suggested too that, instead of Caffenol we should try with Parodinal because it is a developer that is active in very small ammounts. Coffee and Vit C too, like my developer Caffenol Strong shows. Only 1 g/l of coffee + 1 g/l Vit. C can produce developement in just 15 minutes. But I accepted the challenge too, of experimenting the recipe suggested by Giorgio. I introduced some changes in the original suggestion:
Bath A: Parodinal 20cc + vit.C 6g (in 1 lt. water)Instead, and after having tried the suggestion without good results, I doubled the quantities in bath A and used Sodium Carbonate 5% as second bath with 1g/l Potassium Bromide. This worked very well, like a 2-bath should work. I soaked the film during 30 minutes in Bath A to ensure that the film absorbs enough developing agents. Modern B&W films have a thin layer that does not work very well with 2-bath developers. The film I used was a Ilford FP4 125 ISO and I shot very nice photos with a Holga GN 120 adapted with a mask to shoot 28 photos in size 24x36mm.
Bath B: metaborate (don't know how much - 10g/l?)