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  1. #1

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    Stand Developer Concentrations

    All this recent talk about stand developing has inspired me to ask a longstanding question that I've had about this technique - I notice that when making up the developer using a 2 part developer like Pyrocat-HD, practitioners seem to maintain the ratio of the A & B parts fairly close to what is used in the "normal", non-stand application. I often see suggestions for 1+1+200 or 1+1+250, or sometimes like Steve Sherman's View Camera article which mentions 1.5+1+233. All these developer concentrations require relatively long development times.

    So what I'm wondering, is has any one tried dilutions where the B part is at a higher conc than the A part, and still in proportions that are similar to the original formulation (1+1+100 or sometimes 1+2+100)?

    I'm curious to find out what happens when the pH of the developer remains similar to what it is in normal dilutions, or perhaps even higher? Using the developer at a higher pH should help push the kinetic balance of the development process, and this should result in shorter development times. But by keeping the A part limited, it should promote the exhaustion of the developer in the highlights.

    So has anyone tried dilutions like 1+4+200 maybe even 1+6+200?

    Kirk - www.keyesphoto.com

  2. #2
    gainer's Avatar
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    Increasing the pH should also increase the initial rate in both shadow and highlight. From there it's a race to see whether the shadows develop faster. Maybe it's a little like asking if a glass is half full or half empty. If anyone knows the answer, it is Sandy King. If no one knows, an experiment is called for.
    Gadget Gainer

  3. #3

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    I don't get the water glass analogy, Patrick, but I agree that the initial rate, and other development rates should increase at the higher pH. And granted, with a well buffered developer the pH may not change all that much, but it should increase some.

    And since the development is being pushed along at a faster development rate from the higher pH, that leaves us to the diffusion rate of the chemicals in and out of the film. So I would suspect that this approach may give higher edge effects than the weaker pH versions of the same developer - the exhaustion rate of the developing agents will increase, while the diffusion rate of these agents (and their by-products) should be very close to the same rate as at lower pH levels.

    Perhaps the diffusion rate will be the limiting factor in this type of development approach. But then the higher pH solutions may benefit from more frequent agitation than what is used with the "traditional stand" technique and therefore help lower the development times.

    Maybe this would lead to less "standing" around in the darkroom? Talk about kinetics!

  4. #4
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    Kirk, I'm rather amused at this thread.

    I can understand criticism of using a microdensitometer as being to expensive and 'technical' for common usage in the other thread, but here you are dragging pH into it.

    Now, even with pH meters being so inexpensive, how many times do we see people discussing the pH of their developer, or adjusting the pH in their experiments to insure batch to batch uniformity? Seldom, right?

    I think that your direction has merit, but as for quantifying it or getting repeatable results it will not happen until the pH and buffer capacity are documented for all of the conditions. This will probably draw a lot of criticism, I'm sure, but some of the effects of stand and dilute developers are due to halide edge effects, and others are due to pH effects (buffer exhaustion) and no one has gone to the trouble of distinguishing between them, even though they do different things and act different ways.

    In the other thread, you propose standards, but standards imply measurment and numeric values and this was negatively viewed for the most part.

    I think your suggestions here and earlier have great merit. Keep it up. Non illegitemati carborundum (just in case they try).

    PE

  5. #5

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    Quote Originally Posted by Kirk Keyes
    All this recent talk about stand developing has inspired me to ask a longstanding question that I've had about this technique - I notice that when making up the developer using a 2 part developer like Pyrocat-HD, practitioners seem to maintain the ratio of the A & B parts fairly close to what is used in the "normal", non-stand application. I often see suggestions for 1+1+200 or 1+1+250, or sometimes like Steve Sherman's View Camera article which mentions 1.5+1+233. All these developer concentrations require relatively long development times.

    So what I'm wondering, is has any one tried dilutions where the B part is at a higher conc than the A part, and still in proportions that are similar to the original formulation (1+1+100 or sometimes 1+2+100)?

    I'm curious to find out what happens when the pH of the developer remains similar to what it is in normal dilutions, or perhaps even higher? Using the developer at a higher pH should help push the kinetic balance of the development process, and this should result in shorter development times. But by keeping the A part limited, it should promote the exhaustion of the developer in the highlights.

    So has anyone tried dilutions like 1+4+200 maybe even 1+6+200?

    Kirk - www.keyesphoto.com

    Kirk,

    My experience is that the opposite is true, i.e. for stand dilution with long development times it is better to slightly incrase the proportion of A to B. Having more A in the working solution seems to slow down the rate of exhaustion and results in less general stain. If one increases the prorportion of B to A, the result (at least my result) is more general stain, even with slightly shorter times of develoment.

    This is my experience, though the observations are based on just a few, and perhaps incomplete, direct tests. It may well be that more extensive testing will prove me wrong.

    Sandy

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    Quote Originally Posted by Photo Engineer
    Kirk, I'm rather amused at this thread.

    I can understand criticism of using a microdensitometer as being to expensive and 'technical' for common usage in the other thread, but here you are dragging pH into it.

    Now, even with pH meters being so inexpensive, how many times do we see people discussing the pH of their developer, or adjusting the pH in their experiments to insure batch to batch uniformity? Seldom, right?


    PE
    I can not speak to the practice of others but I have always used pH meters in my work in comparing developers.

    I don't know about the relationship between dilution and pH with other developers sometimes used in stand developing, such as HC-110 and Rodian, but I do know it for Pyrocat-HD. This is virtually no difference in pH in Pyrocat-HD solutions ranging from 1:1:100 to 1:1:400.

    Sandy

  7. #7

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    Quote Originally Posted by Photo Engineer
    Now, even with pH meters being so inexpensive, how many times do we see people discussing the pH of their developer, or adjusting the pH in their experiments to insure batch to batch uniformity? Seldom, right?
    I don't mention pH and the use of my pH meter in every thread. Then again, I don't mention my microdensitometer either...
    Tom Hoskinson
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  8. #8
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    Sandy, the buffer capacity of a solution can decrease with dilution while the pH can stay the same. This is due to the buffering effect itself. As buffer capacity decreases, the production of hydrogen ion becomes gradually more and more significant in the overall reaction, and begins to have its own effect similar to bromide in edge effects. It does not 'drag' in the classical sense of 'bromide drag' due to the lighter nature of hydrogen ion, but rather it tends to diffuse further in all directions.

    Tom, I would love to see some data from your microdensitometer. Of course, to use it properly, you do have a microsensitometer, right? Oh, I suppose you also have a source of soft x-rays for it so you can separate out edge effects and turbidity.

    I, of course, have all of the above powered by a small 1.21 gigawatt Tokamak in the basement. It was given to me by a Vorlon named Kosh, but then aren't they all?

    PE

  9. #9
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    Quote Originally Posted by Kirk Keyes
    I don't get the water glass analogy, Patrick, but I agree that the initial rate, and other development rates should increase at the higher pH. And granted, with a well buffered developer the pH may not change all that much, but it should increase some.
    It's another way of saying that maybe it half a gross of one and six dozen of the other.
    Gadget Gainer

  10. #10
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    Quote Originally Posted by Photo Engineer
    Sandy, the buffer capacity of a solution can decrease with dilution while the pH can stay the same. This is due to the buffering effect itself. As buffer capacity decreases, the production of hydrogen ion becomes gradually more and more significant in the overall reaction, and begins to have its own effect similar to bromide in edge effects. It does not 'drag' in the classical sense of 'bromide drag' due to the lighter nature of hydrogen ion, but rather it tends to diffuse further in all directions.

    Tom, I would love to see some data from your microdensitometer. Of course, to use it properly, you do have a microsensitometer, right? Oh, I suppose you also have a source of soft x-rays for it so you can separate out edge effects and turbidity.

    I, of course, have all of the above powered by a small 1.21 gigawatt Tokamak in the basement. It was given to me by a Vorlon named Kosh, but then aren't they all?

    PE
    Does "carrying coal to Newcastle" mean anything to you?
    Gadget Gainer

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