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  1. #11
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    Michael, your experiment seems fine to me, but remember that the overall content of the developer may be critical in getting good results. Even dilution matters as is seen with many developers.

    And, BTW, the pH change in D76 is well known and commented on by Haist. I most always keep my D76 for 1 day before using it.

    PE

  2. #12

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    Thanks for the feedback, everyone. I think I will try to set up the test I outlined and see if I can come up with any meaningful data for a Metol developer. I don't know that it will be possible, but worth a try.

  3. #13
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    Michael, I think we can not and should not generalize "low pH" and "high pH" developers. There is a profound difference whether you change pH of a single development agent formula or a formula where two development agents work together. And we know that even the interaction between two development agents can be different, remember PEs thread about electron transfer agents vs. superadditivity. For that reason I do not think that an experiment with divided D-23 will tell you much about Phenidone+Ascorbate developers.

    Another issue I would like to raise is the effect of Sulfite on granularity. I keep reading that it "etches into the grain" which is a gross misrepresentation of what's going on. Sulfite will not etch away any Silver, the grain you see in enlargements is not the individual Silver particles, and etching away part of the Silver particles (e.g. with a Ferricyanide bleach) won't change the granularity of your image. From what I have understood, Sulfite ions can bind Silver ions which then allows for physical development, which puts tiny Silver particles between the regularly developed Silver. If my understanding is correct, this action should reduce sharpness, and I wonder whether the effect is much different from a slightly defocussed enlarger lens.
    Trying to be the best of whatever I am, even if what I am is no good.

  4. #14
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    The most important thing og pH is that it lowers or rises the activity of the developping substance. There is less value of changing the pH largely with a given reduction substance. This lead to uncomfortable short or long developping times.
    ---
    Uwe Pilz

  5. #15

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    Quote Originally Posted by Rudeofus View Post
    Michael, I think we can not and should not generalize "low pH" and "high pH" developers. There is a profound difference whether you change pH of a single development agent formula or a formula where two development agents work together. And we know that even the interaction between two development agents can be different, remember PEs thread about electron transfer agents vs. superadditivity. For that reason I do not think that an experiment with divided D-23 will tell you much about Phenidone+Ascorbate developers.

    Another issue I would like to raise is the effect of Sulfite on granularity. I keep reading that it "etches into the grain" which is a gross misrepresentation of what's going on. Sulfite will not etch away any Silver, the grain you see in enlargements is not the individual Silver particles, and etching away part of the Silver particles (e.g. with a Ferricyanide bleach) won't change the granularity of your image. From what I have understood, Sulfite ions can bind Silver ions which then allows for physical development, which puts tiny Silver particles between the regularly developed Silver. If my understanding is correct, this action should reduce sharpness, and I wonder whether the effect is much different from a slightly defocussed enlarger lens.
    Rudi, I agree I would not generalize about the effect of pH, and indeed developers with superadditive combinations are quite different than single agent formulas. So I would like to reiterate/clarify some things:

    1. The experiment I propose has nothing to do with divided/two-bath development. I don't think an experiment with different alkalis in a divided process would necessarily tell us enough about the direct effect of pH on granularity because the sensitometric/densitometric characteristics can change. Too many variables. In addition, D-23 contains a lot of sulfite, further complicating the situation.

    2. The experiment I'd like to try would involve alkali substitution in a Beutler-type developer. Metol, very low sulfite, and alkali. The idea would be to try (if posssible with extended developing time) to duplicate, as closely as possible, the characteristic curve of the carbonate developer with a milder alkali. The low sulfite level would take solvent/physical development effects out of the equation. And no superadditivity would be involved.

    Regarding "etching", this is a complex topic as you know, and indeed the way many people describe the effects and what we see, is a misrepresentation - particularly regarding edge sharpness of image detail. This was something I tried to challenge in another thread regarding traditional acutance and solvent effects. What we perceive as "grains" in a developed image are aggregations of developed silver (filamentary, compact etc.), and in most cases no matter what the magnification there is little if any remnant of the actual shape, borders, or clean edges of the original grains.

    We do know that sulfite (as well as other agents) dissolves the silver halide grain, etching and pitting it. If enough of this action can take place before the latent image centers are chemically reduced to metallic silver filaments, as is the case in relatively slow working, high sulfite developers, the filamentary silver is indeed forming from slightly smaller grains, potentially increasing the space between aggregations of developed silver, which may lead to less overlap and therefore decreased non-homogeneity as measured by microdensitometry (ie granularity).

    But this is only one aspect of solution physical development. Chemically developed filamentary silver can become thickened by the "plating" of dissolved silver. Or a highly solvent developer can cause the formation of "compact" rather than filamentary silver. Etc. The various combinations and their effects on image structure - particularly traditional acutance, are still not very clear to me. Myths abound, and this extends into tanning/staining developers as well.

    I had a thread going on all this some time ago. It would make for a fascinating discussion with PE etc. And actually it's too bad we couldn't find a way to get people like Silvia Zawadzki and others in on things like this. But they'd probably quickly tire of it.

    All that to say, in order to try to come up with any meaningful experimental conclusions regarding the direct effect of alkalinity on granularity, it seems to me I need to focus on chemical development, meaning eliminate the complications of solvent effects as much as possible.
    Last edited by Michael R 1974; 04-16-2014 at 07:50 AM. Click to view previous post history.

  6. #16

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    Michael,
    I made a somewhat similar experiment:
    http://www.apug.org/forums/forum37/5...developer.html
    To an extent the smaller grain expected at lower pH seems to be negated by the longer development time required.
    Await your results with interest.

  7. #17
    Rudeofus's Avatar
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    Quote Originally Posted by Michael R 1974 View Post
    2. The experiment I'd like to try would involve alkali substitution in a Beutler-type developer. Metol, very low sulfite, and alkali. The idea would be to try (if posssible with extended developing time) to duplicate, as closely as possible, the characteristic curve of the carbonate developer with a milder alkali. The low sulfite level would take solvent/physical development effects out of the equation. And no superadditivity would be involved.
    The question remains why you would bang on that dead horse Metol. If you look at Kodak's and Ilford's more modern commercial B&W developers, they all use Phenidone/Dimezone-S and a secondary developer, which is usually Hydroquinone (HC-110, TMAX, DD-X, Ilfosol, ...) or Ascorbate (Xtol). PE has made it quite clear that the combination of development agents dictates the results (speed, grain, sharpness) you can achieve, so chances are pretty low that you will find a spectacular new developer based on Metol or Metol and a second dev agent.

    Quote Originally Posted by Michael R 1974 View Post
    We do know that sulfite (as well as other agents) dissolves the silver halide grain, etching and pitting it. If enough of this action can take place before the latent image centers are chemically reduced to metallic silver filaments, as is the case in relatively slow working, high sulfite developers, the filamentary silver is indeed forming from slightly smaller grains, potentially increasing the space between aggregations of developed silver, which may lead to less overlap and therefore decreased non-homogeneity as measured by microdensitometry (ie granularity).
    Since Sulfite shows no fixing action, I don't think that its grain reducing action comes from Silver Halide grains that are reduced in size. In the early days of photography there were several attempts to first fix away the Silver Halide, then use Silver Nitrate plus developer to create the image from the undissolved latent image centers. The result were abysmal and the resulting film speed was many stops below what could be reached via regular development. I think Haist's books have a chapter about these attempts.

    Another example are monobathes, where Silver Halide is fixed away while the film develops, and again, these are not known to be ultra low grain developers despite the fact that they likely etch away a significant amount of the exposed Silver Halide grains.

    The key to fine grain with solvent developers seems to be the deposition of tiny Silver specks nearby the larger developed Silver grains which sort of blends the density between these Silver grains, thereby reducing density ripple. This reduced density ripple will translate into smaller visible granularity and at the same time reduced sharpness, that's why I tried to compare it to a defocussed enlarger lens.
    Quote Originally Posted by Michael R 1974 View Post
    But this is only one aspect of solution physical development. Chemically developed filamentary silver can become thickened by the "plating" of dissolved silver. Or a highly solvent developer can cause the formation of "compact" rather than filamentary silver. Etc. The various combinations and their effects on image structure - particularly traditional acutance, are still not very clear to me. Myths abound, and this extends into tanning/staining developers as well.
    I am still not convinced whether solvents are the best way towards small grain. If you look at PC-TEA, there is general agreement that it is a very fine grain developer, yet it is completely free of a solvent. What I personally like to compare grain to is amplifier noise. You start with a few Silver atoms and create whole Silver grains with your developer, which corresponds to a gazillion fold amplification. Different amplifiers (dev agents) will create different noise levels, you can reduce apparent noise by reducing spatial resolution (solvents), and you can increase higher spatial frequencies (e.g. by weak buffering) but will obviously also increase noise at these spatial frequencies. Since the latter two measures tŕade grain for sharpness, I's strictly focus on the first (choice of dev agents) before wasting my effort on trade off optimizations.
    Trying to be the best of whatever I am, even if what I am is no good.

  8. #18

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    Quote Originally Posted by Rudeofus View Post
    The question remains why you would bang on that dead horse Metol. If you look at Kodak's and Ilford's more modern commercial B&W developers, they all use Phenidone/Dimezone-S and a secondary developer, which is usually Hydroquinone (HC-110, TMAX, DD-X, Ilfosol, ...) or Ascorbate (Xtol). PE has made it quite clear that the combination of development agents dictates the results (speed, grain, sharpness) you can achieve, so chances are pretty low that you will find a spectacular new developer based on Metol or Metol and a second dev agent.
    Agreed. I'm not trying to re-invent any wheels here, or formulate a developer. Not only for the reasons you cite, but PE has also repeatedly hinted to us that at the point when research at Kodak stopped things were going in new directions we probably wouldn't recognize at all by now. My proposed experiment is strictly an attempt to evaluate and/or learn something (as are all my ventures down technical rat holes).

    Quote Originally Posted by Rudeofus View Post
    Since Sulfite shows no fixing action, I don't think that its grain reducing action comes from Silver Halide grains that are reduced in size. In the early days of photography there were several attempts to first fix away the Silver Halide, then use Silver Nitrate plus developer to create the image from the undissolved latent image centers. The result were abysmal and the resulting film speed was many stops below what could be reached via regular development. I think Haist's books have a chapter about these attempts.

    Another example are monobathes, where Silver Halide is fixed away while the film develops, and again, these are not known to be ultra low grain developers despite the fact that they likely etch away a significant amount of the exposed Silver Halide grains.
    Regarding sulfite etching, here I have to disagree with you. Sulfite is a silver solvent and fixer, albeit a fairly poor one in comparison to thiosulfates etc. If we use Haist as a source, the grain etching action of sulfite is documented all over the place. It's in several chapters including The Function of Developer Constituents, Fine Grain Developers, The Fixing Process, etc.

    I can't say much about monobaths other than they are based on the competitive actions of strong developing and strong fixing. Physical development plays a role, but based on my reading of Haist, image structure characteristics are quite complex with all sorts of interesting things about silver mass, covering power, etc.

    Quote Originally Posted by Rudeofus View Post
    I am still not convinced whether solvents are the best way towards small grain. If you look at PC-TEA, there is general agreement that it is a very fine grain developer, yet it is completely free of a solvent.
    I'm not knowledgeable enough when it comes to formulas containing compounds like Ammonia-based alkalis. I've never worked with them. Is this one of Patrick Gainer's things? My understanding is organic Amines do solublize silver halides (at least chloride and bromide).

    But again - I'm trying to get at possible effects of pH exclusive of solvent effects. Hence my choice of a Beutler-type developer as a control.
    Last edited by Michael R 1974; 04-16-2014 at 02:05 PM. Click to view previous post history.

  9. #19
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    Quote Originally Posted by Michael R 1974 View Post
    Agreed. I'm not trying to re-invent any wheels here, or formulate a developer. Not only for the reasons you cite, but PE has also repeatedly hinted to us that at the point when research at Kodak stopped things were going in new directions we probably wouldn't recognize at all by now. My proposed experiment is strictly an attempt to evaluate and/or learn something (as are all my ventures down technical rat holes).
    Kodak may have walked new ways with their research, but Xtol isn't exactly an old formula, so why not base your experiments on the Phenidone-Ascorbate combo? Mark Overton (aka albada) did a great job finding out a formula replicating Xtol, and all your modifications (solvent, alkali, buffering, ...) could start from that formula.

    As I have mentioned, different dev agents and combinations respond differently to pH changes. DD-X/TMAX work at much higher pH than Xtol, and we can safely assume that each has been optimized for best overall performance.

    Quote Originally Posted by Michael R 1974 View Post
    Regarding sulfite etching, here I have to disagree with you. Sulfite is a silver solvent and fixer, albeit a fairly poor one in comparison to thiosulfates etc. If we use Haist as a source, the grain etching action of sulfite is documented all over the place. It's in several chapters including The Function of Developer Constituents, Fine Grain Developers, The Fixing Process, etc.
    We both agree that developed Silver grains are not being etched by Sulfite, so the term "grain etching" can only refer to Silver Halide grains. If you dissolve a small part of Silver Halide grains, you create two effects: first, you make these Silver Halide grains a tiny bit smaller. Second, you suddenly have Silver ions in solution that can be physically developed. The term "grain etching", even if applied to Silver Halide grains, suggests to me that the first effect is the dominant one for reducing grain, while I am quite convinced that the second effect is the only one producing visible results.


    Quote Originally Posted by Michael R 1974 View Post
    I can't say much about monobaths other than they are based on the competitive actions of strong developing and strong fixing. Physical development plays a role, but based on my reading of Haist, image structure characteristics are quite complex with all sorts of interesting things about silver mass, covering power, etc.
    Fact is these monobathes contain about as much solvent and etch about as much Silver Halide as you possibly can, but they are still not "costs two stops but gives the finest grain imaginable" kind of developers. This whole theory of solvents and grain must be flawed.

    Quote Originally Posted by Michael R 1974 View Post
    I'm not knowledgeable enough when it comes to formulas containing compounds like Amonia-based alkalis. I've never worked with them. Is this one of Patrick Gainer's things? My understanding is organic Amines do solublize silver halides (at least chloride and bromide).
    TEA is a tertiary amine which has no Silver Halide solvent power to speak off. It is an alkali that can dissolve a range of organic compounds and mixes freely with water, which makes it great for developer concentrates. Water free concentrates is what the Ascorbate developer crowd yearned for, because it kept their Ascorbate stable without special, hard to get sequestering agents. It gives pH values around 9, which is a bit lower than Carbonate/Metaborate and therefore quite suitable for developers which want the lower pH.
    Trying to be the best of whatever I am, even if what I am is no good.

  10. #20
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    great thread, cleared up a few grey areas I had in my own notes.
    "The real work was thinking, just thinking." - Charles Chaplin

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