Confusion bout stand development

In the developer manual, there is a calculation for the minimum developer solution required per unit area. For example, in the manual for Tetenal Paranol S it states that 250ml corresponds to 25 rolls of 135 film (one roll of 135 film equals 4 sheets of 4x5 film).
Each 4x5 sheet requires at least 2.5ml of developer solution for development.

My question is:
For instance, when performing stand development with a Jobo tank, testing can start from a minimum of 2.5ml. Once the developer solution amount is determined, let's say using 4ml of developer solution and 1000ml of water at a ratio of 1:250, when increasing the number of films processed from one sheet to two sheets in same jobo tank, the minimum developer solution requirement becomes 5ml. Since 4ml is no longer sufficient for developing two sheets of film, if I follow the logic of using 4ml of developer solution per sheet, I would need 8ml of developer solution, changing the ratio to 1:125.

My understanding is:
Once the ratio is established, increasing the number of films processed should involve maintaining the ratio of developer solution to water per sheet. Thus, it would be 8ml of developer solution plus 2000ml of water for two sheets.
However, I believe that since stand development involves minimal or almost no agitation, the effect of 1000ml of water and 4ml of developer solution on developing two sheets of film might not differ visibly from developing one sheet of film.
This is just my speculation, as I haven't started testing yet, and I would like to hear others' opinions

I have tried stand development with Rodinal in the past and I guess I can understand your point. Per each 35mm, you need 3ml Rodinal which works fine for 35 mm roll film, at1+100 300ml solution.

The issue is when it comes to sheet film and 120 film. The tank for sheet film requires 1 litre of solution and the required chemistry for 120 film is 500ml (Paterson tanks) so automatically I pass 3ml min required solution. I always stick to 1+100 dilution and try not think about the required min developer volume.

Fatih Ayoglu said:

I have tried stand development with Rodinal in the past and I guess I can understand your point. Per each 35mm, you need 3ml Rodinal which works fine for 35 mm roll film, at1+100 300ml solution.

The issue is when it comes to sheet film and 120 film. The tank for sheet film requires 1 litre of solution and the required chemistry for 120 film is 500ml (Paterson tanks) so automatically I pass 3ml min required solution. I always stick to 1+100 dilution and try not think about the required min developer volume.

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Thank you for your response. I believe you're correct - it's always about prioritizing ratios and disregarding the amount of developer needed per unit area. From my understanding of the developing principle, only the solution in direct contact with the film reacts with it. So, in a scenario where stand development is conducted without any agitation, regardless of the number of films, the concentration of the solution in contact with the film remains consistent. While exploring semi-stand development might require extensive experimentation to determine the optimal number of films and agitation cycles before a decrease in development capacity occurs, it may not hold significant value considering the already low cost of stand development. For 4x5 using a Jobo developing tank, single-sheet processing is feasible, albeit time-consuming.

Wouldn't the minimum developer solution actually needed depend on the average brightness level of your image? With images containing a lot of white, or being push processed, needing more and images like night shots that are almost all black needing less. So can we take the minimum recommendation as anything but a very general estimate? Could it also depend on other things like the amount of silver in the film? Rendering their recommendation no better than a rule of thumb.

loccdor said:

Wouldn't the minimum developer solution actually needed depend on the average brightness level of your image?

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Depends. If you follow manufacturer's recommendation, I would assume that their minimal amount will be sufficient to swamp the effects of image density etc. so that you'll get consistent results all the time, every time, regardless of lighting etc. Stand development is a different animal since you're willfully balancing on the edge of the abyss - you only want to supply just enough developer to get the job done and for it to deplete (and/or get loaded with restraining halides) locally in doing so. Of course (lack of) agitation plays a role in this as well.

This implies that effects may/will vary indeed if you're doing stand/semi-stand and you're skirting on the low side in terms of the amount of developer. Lots of things start to matter if you work that closely to the edges of the predictable. It'll make a difference whether a bright (high density) area is above a darker (lower density) area or below it on the film as it sits in the developer. Here's an example (positive; 100% crop from 1200dpi scan from negative and inverted):

Note how the developer was reduced in activity more so below the white area than above it. It's essentially bromide drag. Agitation wasn't even so infrequent here; once every 3-4 minutes, in Pyrocat HD1+1+100 (3ml to 300ml water in a Paterson tank, 1x 135/36). Film and chemistry manufacturers will generally recommend process conditions (dilution + agitation) to keep these kinds of effects out of the door. Stand development and reduced agitation willfully exploit the side effects. A degree of unpredictability is inherent to this; factors that usually don't matter (much) all of a sudden have a significant influence - such as the orientation of the film on the reel in this particular example.

koraks said:

Note how the developer was reduced in activity more so below the white area than above it. It's essentially bromide drag. Agitation wasn't even so infrequent here; once every 3-4 minutes, in Pyrocat HD1+1+100 (3ml to 300ml water in a Paterson tank, 1x 135/36). Film and chemistry manufacturers will generally recommend process conditions (dilution + agitation) to keep these kinds of effects out of the door. Stand development and reduced agitation willfully exploit the side effects. A degree of unpredictability is inherent to this; factors that usually don't matter (much) all of a sudden have a significant influence - such as the orientation of the film on the reel in this particular example.

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That was a very interesting post you made on your blog regarding these edge effects. In particular the idea of a sweet spot in agitation where this is maximized. I've done a lot of Rodinal stand development but never had edge effects as intense as yours. I always assumed longer development would maximize the effect but that must be wrong.

loccdor said:

I've done a lot of Rodinal stand development but never had edge effects as intense as yours.

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Well, I've done some stand development over the years as well, now and then, and never got anything as extreme as this either. In fact, part of this series of experiments was also some stand and semi-stand development and this produced rather (very!) dense negatives, but otherwise free of odd effects. Same film, same developer!

I've been stand developing 120 and 4x5 mostly with pyrocat HD for a few months at this point, and I tend to stick with the 1+1+100 ratio (or, sometimes, 1+2+100), despite the size of film and the so called "required developer for area". At least with a developer like pyrocat, which is definitely formulated for stand and semi-stand use, i've had no issues, although I use my B+W developer as a one-shot and rarely do more than 2 sheets of 4x5 film in a 3 reel peterson tank (1L of chemistry), 1 roll of 120 in a stainless steel tank (~450-500ml), or 2 rolls of 35mm in a 2 reel tank (~6-700ml). I do all my stand developing at 70 degrees, I'm not sure why because I was taught to agitate develop at 68, but I just decided on 70 the first time I tried and have been building my data off that since.

f/Alex said:

a developer like pyrocat, which is definitely formulated for stand and semi-stand use

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Not specifically as far as I know. I do think Sandy and others started experimenting with reduced agitation pretty soon after pyrocat came out. But one of the main aims of Sandy was pretty much the opposite: having a staining developer that would play nice with continuous rotary agitation.

koraks said:

Not specifically as far as I know. I do think Sandy and others started experimenting with reduced agitation pretty soon after pyrocat came out. But one of the main aims of Sandy was pretty much the opposite: having a staining developer that would play nice with continuous rotary agitation.

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Guess I misread something somewhere, but most of the developing data that comes with pyrocat is for semi stand I belive? I didn't RTFM tho so I actually don't know, that data sheet serves as a convenient piece of paper for me to write my own results over the text in sharpie (surprisingly, nothing is seriously over or under developed so far)

f/Alex said:

but most of the developing data that comes with pyrocat is for semi stand I belive?

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It's popular for this kind of application, but that's a different matter than whether it was made for it.

Keep in mind that popularity also propels itself. There are other developers that would work similarly, and yet, when it comes to stand and seni-stand, it's mostly pyrocat and rodinal. A lot of this has to do with people following each other's lead.