Permanganate reversal baths
Curiosity; a bit of a rambling question...
Simple question: does anyone know of a reason not to use a permanganate reversal bath after a first developer that contains thiocyanate/-ide/sulphocyanate/thiocyanic acid/rhodanide/KSCN/whatever-you-want-to-call-it? There's a good wash inbetween of course.
Back in the thirties the Dufaycolor process (B&W emulsion and chemistry despite the name) did exactly that (thiocyanate followed by permanganate), but I've found no recent reference. Example: Kodak specifically say (publication H24, module 15, page 25) that D-94 (which contains thiocyanate) should not be used as a first developer with R-10, which is a permanganate reversal bath. D-94 was designed for use with R-9, which is a bichromate reversal bath - now unacceptable for environmental reasons. As far as I can tell, it isn't because of the acidity of R-10, because R-9 also had a low pH. Is this one of those blindingly obvious reasons that I miss?
It's just curiosity - there are plenty of good alternatives for the first developer that don't use thiocyanate.
While I'm rambling about reversal processes: I'm also looking at fogging developers as second developers - with or without a reversal exposure (no reason not to do both). Good old T-19 sulphide toner seems to work quite well, giving sharp images with low graininess and lovely tonality (at least to my taste). Next on the list to try is KRST, then my next thought is colour developers (the colour of the film image is not important to me). Any other suggestions? I don't think that I'll be trying FD-70a or FD-72.
The only thing I can think of is the effect of the different bleaches. Permanganate being more of a proportional developer and dichromate more of an overall bleach. It most like has to do with the quality of the results rather than the possibility of any chemical reaction.
Actually in the book "Developing, a focal manual of Photo-Technique," Jacobson & Jacobson list several formulas with thiocyanate followed by a permanganate bleach. Of course this is an old book, so I am sure there might be another reasons for more modern processes.
The iron stain remover, trade name "Iron Out", is a good fogging agent. I haven't played with it for a while, but I think it works well with a little added carbonate. I don't have the bottle before me, but IIRC it is sodium hydrosulfite.
If you use a good stop bath after the first dev you should be okay. I can't think of an adverse reaction that permanganate in acid would cause but dichromate in acid wouldn't.
For fogging agents -- Pat Gainer's advice sounds really interesting -- otherwise there is stannous chloride or sepia toner. KRST in itself is not going to be enough to reduce un-exposed silver AFAIK, although if you did a conventional light re-exposure followed by re-development, you could tone the resulting silver positive image with KRST and get a nice archival B&W positive. I have read speculation that one of the final steps in the (proprietary) Agfa Scala process is a selenium-toning step.
With a sepia toner fogging agent, I noticed some pretty strong film effects. I used a thiocarbamide-based toner mixed up in a proportion that would give pretty cold browns in regular paper toning. I tried reversal processing some TMX and PanF at the same time in the same soup -- the PanF gave a beautiful cold brown tone while the TMX gave sickly yellows. This must have to do with grain size and shape etc.
I've given much thought over the years to B&W reversal, trying to get it to work with regular B&W chemistry as much as I can. I have a workable first developer recipe based on HC-110B. Send me an e-mail if you want more info.
Thanks Jorge, Patrick and Jordan.
I found 'Super Iron Out' which is sodium bisulphite and hydrosulphite according to the MSDS.
Some notes I made ages ago include this as a fogging developer. I have no idea where I got the formula from:
Propionic acid 15 ml
Stannous chloride 2 g
Sodium hydroxide 5 g
Water to make 1 litre
Have you tried any paper developers, with or without added thiocyanate or thiosulphate?
Once again, thanks for your contributions.
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When you have settled on a reversal process that seems to work well, would you mind sharing detailed instructions/formulae? I have long been interested in using reversal to enlarge negs.
If you are interested in making enlarged negatives by reversal look at the article at http://unblinkingeye.com/Articles/NbyR/nbyr.html and at links to Liam Lawless.
Originally Posted by mobtown_4x5
I have personally switched to digital enlarged negatives but I used Liam's reversal processing method for a number of years and can assure anyone interested in wet processing that it gives outstanding results.
Matt asked 'would you mind sharing detailed instructions/formulae?
I like sharing... but I doubt that I'd come up with anything that hasn't been published already. None the less I'm happy to post my results. Don't hold your breath though - I have to sneak all this kind of stuff in edgeways.
Thanks for the link. I think that I've read everything on unblinkingeye, but it's good to be reminded of what's there, and to read your experience of Liam's method.
BTW, I see that the link to Liam's article is dead. The original information by Liam, which is quite detailed, was published in two articles in Judy Seigel's Post-Factory Photography some years ago. It is the best information I have seen anywhere on reversal processing and although Ed Buffaloe's article follows Liam's method rather closely, the original articles are still well worth reading.
Originally Posted by Helen B
I downloaded Liam's original article a while ago, but I have no idea which country my copy is in, never mind which disk it is on.
I hope that people change from a bichromate bleach to a permanganate bleach (and a compatible clearing bath - the clearing bath should be chosen according to which bleach is used).