pH Effect on Film Development

Discussion in 'B&W: Film, Paper, Chemistry' started by craigclu, Jul 24, 2005.

  1. craigclu

    craigclu Subscriber

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    I'm having a hard time getting a true grasp on the effects of pH in film developers. It seems that with traditional (non-staining) developers, moving, for instance from 8.00 to 8.20 has a rather distinct effect on developer activity. When working with catechol concoctions recently, it seems that one needs to be at 10.5 to 11.0 ranges to achieve reasonable activity. Could someone who is versed in this help put some sense to this for me? I assume it must be related to surface development/staining issues but I'm just guessing at best.

    Somewhat related: Has anyone done any work on staining monobath concentrates (TEA/PG based) that can create required alkaline levels without relying on a second component for this duty?
     
  2. df cardwell

    df cardwell Subscriber

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    Every developing agent needs a particular pH range in order to function.

    Metol, for example, works in a low pH environment, Rodinal (paraminophenol hydrochloride), high. At low pH, Rodinal doesn't work. At high pH, metol fogs. That's it. There really isn't any magic to pH.

    Of course every good developer has it's own character; all are magic.

    As we learn from Harry Potter, the trick is in learning how to make the magic work.

    Don

    "The purpose of Art is to transform the Artist."
     
  3. gainer

    gainer Subscriber

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    Different agents require different pH levels for different levels of activity. If that is not simple for you, join the crowd. You can add different combinations of developing agents to the mystery.

    It is really a matter of experimentation. Reading a lot of technical journals and books helps. Some think that it all should be predictable, and it may be when the proper axioms are available.

    A very simple staining developer that works quite well is as follows:

    9 or 10 grams pyrogallol
    100 ml TEA

    Heat till it dissolves. Shouldn't take more than about 160 F. It will stay in solution when it cools.

    Dilute with water just before use. 1 part concentrate to 25 or more parts of water. You'll have to play with developing times. At 1+25 it should act about like D-76 where time is concerned.

    The only problem with this formula is that TEA freezes at about 70 F. The stock has a very long life and need not be refrigerated. I keep mine in a brisker oven (used by bread makers for rising dough) at about 104 F. You could also thin out the stock with some propylene glycol and just use more in the working solution. While you're at it, you can add a tiny bit of amidol or phenidone just to see what happens.
     
  4. Tom Hoskinson

    Tom Hoskinson Member

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    Craig, in answer to the first part of your question, Sandy King has done a lot of experimentation with staining catechol developers and the most effective pH level for them. Much of this information is published on Unblinking Eye and additional information can be found by searching APUG and the Azo Forum.

    For the second part of your question, Monobath implies the incorporation of a fixing agent into the recipe. I have not yet compounded (or attempted to compound) a staining monobath.

    I have used triethanolamine (TEA) as the solvent in several concentrated developer stock solutions. With the addition of water, the TEA becomes the alkali (with pH in the 9.5 - 10 range).
     
  5. sanking

    sanking Member

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    As others have indicated, all reducers have a pH threshhold level of activity and a higher level of pH for full activity. This varies quite a bit, from a very low threshold for amidol to a very high one for hydroquinone and pyrocatechin. When you throw another reducer into the mix and get synergism between the two the absolute figure for any single reducer may change.

    My experience with TEA, at least the version that I have purchased, is that the working pH is almost ideal for pyrogallol, about pH 9.2, but a bit too low for full energy with pyrocatechin and hydroquinone, which have a threshold of activity over pH 10. That is not to say that these reducers will not work if mixed in TEA, only that they will have more energy when the activator has a higher pH, as is the case with the carbonates, TSP and hydroxides. ON the other hand, adding one or two other reducers, such as phenidoine and ascorbic acid, throws all of this into a land where only experimentation can answer the question.

    Sandy
     
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  6. craigclu

    craigclu Subscriber

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    I carelessly used the term "monobath", thinking of a single mix concentrate and not self-fixing. I was curious as to possible reducers (I guess that's the term to use) that could be incorporated into the single solution concentrate. Are the potassium family likely to be more soluble in TEA/PG as they are in water? I've got some things doing most of what I want them to with a blend of TEA and PG but require a pH boost with sodium carbonate or sodium hydroxide secondary additions and had a curiosity about what possibly could be used in a single solution concentrate. I like how my catechol, ascorbic acid, Dimezone-S (or phenidone, too) and BZT go into suspension at lower temps in the PG. I then top off with TEA and get blends that don't give viscosity/freezing battles in my cold basement darkroom.

    I'm feeling re-energized about photography in the last couple of years by getting more involved in tuning developers/curves to my tastes and needs. I feel like I'm 95% of the way to what I want at this point so I'm at the point where it gets harder! I might be wishing for too much to incorporate this all into a single solution developer.
     
  7. Alan Johnson

    Alan Johnson Subscriber

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    Re the second part of the question,I recently made up a basic formula attributed to Patrick Gainer which I call PCQ-TEA staining developer.The formula is 10g Hydroquinone,1g Ascorbic acid, 0.2g Phenidone, TEA to 100ml. I hope to report results in due course.
     
  8. sanking

    sanking Member

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    Pat Gainer has stated that there is a commercial version of TEA that has a higher pH than the stuff we get from the Chemistry Store. That might be worth looking into if your goal is to make a very energetic one solution developer with pyrocatechin.

    Sandy
     
  9. craigclu

    craigclu Subscriber

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    Sandy, I recall that you used sodium bisulfite in your Rollo TEA experiments. I realize that this used pyrogallol but was this for pH adjustment or ??? Thanks for you patience and information! BTW, I've had some very nice results with the Rollo TEA and only went pursuing catechol concoctions to get the easier VC compatible negs with catechol's stain color.
     
  10. Tom Hoskinson

    Tom Hoskinson Member

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    I'd try it with TEA as the only alkali first (I use TEA from The Chemistry Store).

    If you feel the need to boost the pH, stir a tablespoon of carbonate into the working developer.
     
  11. sanking

    sanking Member

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    I used sodium bisulfite in the Rollo-TEA formula because, 1) the original Rollo Pyro formula contained sodium bisulfite and part of my purpose in suggesting the Rollo-TEA formula was simply to show that some existing formulas, if mixed in TEA, would give essentially the same results as some of the TEA-based formulas being hyped at the time, and 2) I knew from my own testing that a small amount of sulfite is important in the synergism between pyrogallol and phenidone.

    BTW, I recently developed about fifteeen 12X20 negatives from a recent trip out west in the original Rollo-TEA solution that I mixed sometime in the spring of 2004, and the results were outstanding. Which points out one of the advantages of mixing solutions in TEA (and glycol), in that you know that they will be good for years and years.

    Sandy
     
  12. sanking

    sanking Member

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    Well, all this talk has made me want to do some developer experiments that have been on the back burner for a few months. So I decided to pull out my electronic balance that measures down to 0.01 accuracy since some of the tests will require very accurate measurments.

    Guess what. The scale is gone from where I always keep it, and I know that it was stolen by this thieving, lying SOB that my wife hired to do some renovation work in the house. Later she found that he forged a check on her account and speculated that if he would do that he probably stole other things from the house. She decided to not press charges, because she knows his mother, but now I am so angry that this piece of s*&t loser ripped off my scale (which I assume he took cause he wants to make some kind of drug) I feel like putting a bullet in his sorry ass.

    Yeah, it could have been worse. Fortunately he was not into large format equipment because he could have made a bundle by ripping off my collection of lenses and cameras.

    The only relevance of this to the topic is that I seriously wanted to run a couple of tests and now am here stewing because the equiment I need was stolen.

    Sandy
     
  13. phfitz

    phfitz Member

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    not being funny but; anything based on the following is to be PUBLIC DOMAIN, FREE FOR ALL USE.

    craigclu, in reply to the first question about pH levels, I hope the attched jpeg is of use. It is from 'the American Annual of Photography, 1951(Reinders and Beukers ; Ber. VIII intern. Kongr. Phot.; Dresden, 1931). The only variable in the tests is the pH level of the solutions.

    As you can see the inherent contrast of a metol only developer is perfectly predictable and repeatable. It can run from very soft to hotter than lith developer. By adjusting the pH level you can achieve any development from N-4, N, N+4 without changing time, temp, dilution, aggitation or film speed.

    By eliminating variables you increase the rate of success, fewer goof-ups in the chain. By keeping the same film speed, you reduce the risk of over-exposure or reciprocal failure. By keeping the same dev. time you give maximum advantage to the shadows. By not diluting the devloper you reduce the risk of blocking the highlights thru exhaustion. By keeping the same developer mix you keep the same base-fog and grain pattern, no suprises. By keeping everything but the pH level the same you can set this up for machine processing, set it and forget it.

    A fine starting point is:

    4.0g metol
    75g sodium sulfite
    3.0g borax
    0.4g potassium bromide
    1 liter water
    start times at HC-110, this is a little hotter
    (leave out the bromide with TMX)

    If you like the look, have fun working it up. When I get the time I will play with this more. I have tried this formula with Plus-X, FP4, TMX and TMY so far it works well with all and adjusting the pH does make the expected difference.

    Good luck with it and always have fun.
     

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  14. gainer

    gainer Subscriber

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    The commercial grade of TEA has some diethanolamine and perhaps some mono, which both have somewhat higher pH. The pH of each of these varies quite a bit with concentration. You don't want to mess with MEA. I doubt that you could get it shipped to you anyway. See the Dow Chemical web site for more data than you thought was possible in PDF form.

    I have found it useful, especially when experimenting, to have stock solutions of phenidone, amidol, pyrogallol, catechol, hydroquinone and ascorbic or erythorbic acid in glycol. Sandy mentioned the effect of ascorbic acid on Pyrocat and relatives, and the same effect can be had in pyrogallol developers, with the same limitations. Too much ascorbic acid will diminish the stain image.

    10% solutions in glycol of all but phenidone and amidol can be made with some heating. A little of each of those goes a long way when they are used as the activator in a superadditive combination, so no more than a 1% solution will be required.

    Using glycol for the solvent allows trying various alkalis that are not soluble in glycol a la PMK and Pyrocat. If you find that TEA has sufficient pH, which is true for pyrogallol, you can find a solution of your developing agents in TEA that will allow a single stock solution, or just add the TEA to the stock and change your dilution accordingly.

    The formula I gave in a previous post on this thread becomes quite active with the addition of a little of the ascorbic acid stock. About 1/10 the amount of the pyro stock should do.
     
  15. gainer

    gainer Subscriber

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    I read my own writing and as often happens found I couldn't understand it. Specifically, the 1% solutions are of phenidone and amidol. The others are 10%.
     
  16. Kirk Keyes

    Kirk Keyes Member

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    Sandy - File the charges - don't let the bastard off with no consequesnces. If you don't, you are giving him your blessing that it is acceptable to you that he rip you off. And then he may come back your the rest of your gear.

    kirk
     
  17. gainer

    gainer Subscriber

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    I second the motion.
     
  18. dancqu

    dancqu Member

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    As the ph increases the developing agent-agents activity
    increases; shorter developing times.

    As the ph increases the gelatin swells and so takes on
    more fluid. The silver halids gain in mobility and grain
    size increases. Fine grain developers are of low ph.

    Surface development is a characteristic of compensating
    developers. FX-1, Beutler's, and even Rodinal, all are
    examples; high ph very dilute developers. Dan