Is there such an animal? Does anyone have a formula?
Please note PYROGALLOL.
Requirements:
Reuseable part "A"
Stain not important. So can have higher content of Sodium Sulphite.
Phenidone available to combine with the Pyrogallol.
Bath "B" to probably be Sodium Carbonate as a cheaper disposable solution can be made up. Or Sodium or Potassium Hydroxide?
Any takers??
It would be easy enough to substitute pyrogallol for the metol in Stoeckler's 2-bath, but why pyro if not for the tanning/staining?
I've played with two-bath PMK for extreme contractions. Here's what I tried.
Soak film in undiluted Part A for about 4 minutes. Then develop the film in Part B diluted as normal for 4-5 min. (to completion). Don't presoak film before the A. The A solution is fine and won't be discolored unless by the anti-halation dye and can be reused. This gives an N-3 or 4. I used an exposure compensation of about 1 stop.
Haven't pursued this much since I use SLIMTs with less loss in film speed.
Best,
Doremus
Thanks for the followup. I think Sandy King mentioned at one stage or it may have been Jay that Pyro gives many benifits even when not used as a staining developer. The Sodium sulphite reduces the stain but doesn't impact too much on the tanning. Still it was just a thought it is now winter here and while we don't have snow I do have time on my hands. Your practical experiment is basically how I was going to approach the idea Doremus.
Jay you have a good handle on alkalinity of second bath developers, can you theorise the impact using a stronger bath "B" with the scenario outlined by Doremus?
Steve
Steve
Steve,
If tanning is the goal, sulfite should be kept to a minimum, which impacts keeping. I think the best approach would be to use metabisulfite in the first bath, with the pyro, and carbonate in the second. Phenidone and high pH is a recipe for fog. You cold mitigate the fog with a restrainer, or use a different secondary developing agent -- if you think a secondary developing agent is absolutely necessary ( I do not).
I have to run, but I'll write more later.
Ok, I'm back. It should also be noted that any developing agent ( except glycin) used with low sulfite will tan. Back to pyro:
Making a 2-bath developer is different than just dividing a normal developer into two parts, and using them successively, which is more accurately referred to as a divided developer. A 2-bath developer should be considered as complete in the second bath. So, even if we have 100g/liter of sulfite in the first bath, the working developer will only contain a tiny fraction of a gram of sulfite per liter-- what can be absorbed into the emulsion during the first bath. So, it's not the absolute quantities of compounds in the first bath that's important, but the concentrations and ratios.
The above suggests it's possible to make a two bath pyro developer that keeps well, is re-useable, and both stains and tans. As long as the preservative does not significantly outweigh the developer, it will stain and tan. So what needs to be determined is how much developer needs to be present in the first bath for the emulsion to absorb and allow for complete development in the second bath. By considering 2-bath formulas known to work, we can extrapolate a formula for another developing agent. Something like 10g/liter is a reasonable concentration of developer, and that implies the concentration of preservative. For staining, the preservative should be kept to 1/2 the concentration of the developer. For keeping, metabisulfite is better than sulfite, and when combined with carbonate in the second bath converts to sulfite to control oxidation/stain formation in the second bath. So, the first bath might look like:
Pyro 10g
Sodium metabisulfite 5g
If staining is not important, the metabisulfite could be doubled to equal the concentration of pyro.
Now the second bath needs to be active enough to develop nearly instantaneously, before the developing agent absorbed in the emulsion diffuses out into the solution to make an extremely dilute developer. So, while 2-5g/ liter of carbonate is enough to develop in a single bath developer, a 2-bath developer needs much more activity, and an increase by a factor of ten is a good place to start, for a second bath of about 2% carbonate.
The second bath should be replaced occasionally, as developer products will build up there.
The above developer will work, but how well? I'm not convinced it will work as well as single bath developers.
Excellent information Jay. As soon as I have free time I will mix something similar and report back.
last week I was play with some phenidone+pyrogallol formulas. if you need 2 bath - here is the working formula
RD-201 developer
Bath A
Sodium sulfite 50g
Phenidone 0.2g
Pyrogallol 6g
Sodium metabisulphite 6g
Water 1l
pH=6.6
Bath B
Sodium carbonate anh. 15g
Sodium bicarbonate 6g
Sodium sulfite 35g
Water 1l
pH=9.8
process 3+3min like Diafine. you can vary 2nd bath with different pH (borax, sodium carbonate), but sodium sulfite is important part of bath B, otherwise you loss ~1stop
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