Speed increasing ascorbate/carbonate developer

Discussion in 'B&W: Film, Paper, Chemistry' started by Alan Johnson, Mar 3, 2014.

  1. Alan Johnson

    Alan Johnson Subscriber

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    This is based on my previous finding that a developer with high ascorbate and carbonate lasts a long time exposed to air in a half full bottle.My theory is that all the air only oxidizes a small proportion of the ascorbate and the high carbonate means the acid so produced does not cause a significant pH drop.
    I call the developer "3W" after the 3 witches in Shakespeare's Macbeth.

    3W developer
    Water.......................................850ml
    Dimezone-S..(stir till dissolved)........1g
    Sodium Sulfite..............................20g
    Ascorbic Acid (Vitamin C)...............20g
    Sodium Carbonate anhydrous.........40g
    filter through cotton wool.
    Water to........................................1L
    pH~9.8
    Develop about 10% less than for Xtol 1+0

    I have not measured the speed increase compared to D-76 accurately but the attached pics on APX 100 exposed at EI=200 (average metering) show there is an increase.
    Phenidone may be used in place of Dimezone-S but the developer may then be less resistant to hydrolysis if it is left unused for a long time.
    Previously Gainer formulated various ascorbate developers but unlike them the present brew contains sulfite to uncover latent image specks and provide an increase in EI.
    Thanks for comment.
     

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  2. michael_r

    michael_r Subscriber

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    My first thoughts are I'd be concerned about graininess and fog given the various aspects of this formulation. The development time is interesting, as I would have expected a formula with that much Dimezone and Carbonate at that high a pH to work much faster than XTOL. It seems closer to a print developer in formulation but without a restrainer.

    Interesting work. How did you arrive at the 20:1 ascorbate/Dimezone ratio?
     
  3. Rudeofus

    Rudeofus Subscriber

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    +1 to that. I'm very surprised to see such a long dev time for that much Phenidone plus strong secondary dev plus pH close to 10 ...

    And I'm also surprised to see that 40 g/l Sodium Carbonate plus 20 g/l Ascorbic Acid gave you pH 9.8 ....
     
  4. michael_r

    michael_r Subscriber

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    Would you have expected the pH to be higher or lower than 9.8?

    Regarding the development time, I guess what what don't know is the contrast obtained in the test images.
     
  5. David Allen

    David Allen Member

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    Very strange tonality - kind of reminds me of reproductions in magazine from the late 40s and 50s.

    Not my cup of tea!

    Bests,

    David
    www.dsallen.de
     
  6. Rudeofus

    Rudeofus Subscriber

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    Initially I would have thought pH should be lower. But given Ascorbic Acids high molecular weight I may be wrong.

    What still amazes me is the dev time Alan claims to need. E6 FD with 1 g/l Phenidone, 20 g/l HQMS and pH 9.5 develops Tri-X in less than a minute. When I developed Tri-X for 5 minutes at 30°C (which should equal 10-15 minutes at RT) with E6 FD diluted 1+1, I got a four stop push judging from the characteristic curve. And yes, such intense overdevelopment will raise shadow detail.
     
  7. pdeeh

    pdeeh Member

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    Interesting.
    I played with an Metol/Ascorbic Acid developer (ratio Metol 1:4 Ascorbic Acid) a few months ago, using Sodium Carbonate as the alkali, (although the original formula called for metaborate) and got some rather good results, excellent tone and sharpness, and nowhere near as much grain as I see in the attachments above. The formula was I believe a Kodak "lab developer" used for testing emulsions. it was pretty "hot" though, development times were stupidly short. I never pursued trying to tame it as I'm no chemist, just a fiddler.
     
  8. Alan Johnson

    Alan Johnson Subscriber

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    I forgot to mention that the developer is hoped to be re-useable but rather than wait it is convenient to write it up in bite-size chunks.I hope to report future results on the same glass bottle of W3.
    The ratio ascorbate:dimezone-s is within limits suggested by Gainer, dimezone-s is a bit heavier than phenidone per mole:
    http://unblinkingeye.com/Articles/Synergism/synergism.html

    I too expected a shorter development time.I have no densitometer but the contrast looks slightly less than what I get with Xtol and was a surprise and hard to explain.
    Perhaps dimezone-s is adsorbed on silver bromide crystals and once it covers the surface adding more does not make much difference. This aspect of chemistry is not my thing.
    Measuring the pH again gave 9.8, meter calibrated 6.9, 9.2 and checked afterwards with 5g/L Na2CO3 measured pH=11.1. I'm not entirely happy with this cheap meter.

    The pics were taken with an orange filter and I had to increase the contrast after scanning to get blacks. I doubt there is anything particularly unusual about the tonality of W3.

    Yes it is grainy and unless this is wanted Xtol pushing would probably be better. There are occasions where it is convenient to shoot 100 box speed film at EI=200.
     
  9. BradS

    BradS Subscriber

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    The results seem very good to me. I like the tonality....but, I think the effect due to the orange filter is the much larger than any effect due to the developer.

    I am very curious about the fog levels. Based upon my experiments with similar concoctions (yes, Gainer influenced many of us), I would expect considerable fog.
    What do you observe with respect to fog levels compared to D76?
     
  10. Alan Johnson

    Alan Johnson Subscriber

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    Hi Brad,
    Hope you can get an idea of the fog levels with D-76d EI=100 and W3 EI=200 from the attached pics on a lightbox.
     

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  11. nworth

    nworth Subscriber

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    It is, indeed, a very grainy developer. Some may be interested in it just for that reason. I'm not real fond of its rather brooding tonality, but that may be an exposure issue.
     
  12. BradS

    BradS Subscriber

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    Interesting....and about what I expected. There is noticibly more fog than with D76 but, it does seem manageable. It might be interesting to see what effect the addition of some benzotriazole (spelling?) or KBr has on the fog level.
    Thanks for the scan and the thread.
     
  13. Gerald C Koch

    Gerald C Koch Member

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    The ratio of dimzone to ascorbate that I have seen is usually 1 to 40 or even higher. All the phenidone derivatives tend to produce fog in highly alkaline solutions without a restrainer. For any super-additive combination there is an optimum ratio for the two developing agents. This ratio is dependent on the composition of the developing. You must take into account the sulfite content. alkalinity, restrainer, etc. Formulating a developer is NOT an easy task. Mason discusses this and shows a graph of effective speed versus the ratio of the developing agents. The curve is U-shaped showing that an optimum ratio exists.
     
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  15. Alan Johnson

    Alan Johnson Subscriber

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    Thanks for the suggestions re KBr/Benzotriazole and Dimezone-S.
    But first, to see if the developer has a reasonable shelf life,I am keeping 700 ml of it in a sealed glass bottle with 350 ml airspace and hope to monitor its activity.
     
  16. michael_r

    michael_r Subscriber

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    Before reaching for a restrainer consider Haist's advice: "if you've got too much fog, you've got too much alkali". This may be a better way to imrove overall characteristics as a starting point. You've got a relatively huge amount of carbonate in there for a film developer (and a high pH for any film developer let alone Phenidones). I'd try rebalancing first before adding a restrainer since your goal is a speed increasing developer. All things being equal, a restrainer will tend to reduce speed and increase contrast.

    Another important thing to consider is at this pH Phenidones are not effectively restrained by bromide so you're essentially limited to either Benzotriazole or other more exotic compounds.

    The first thing I think we need here is some sensitometric data. We need to quantify the speed increase, toe contrast/shape and overall contrast relative to the chosen reference developer (D-76). That will help determine the next steps. For example, depending on how much higher the speed is relative to D-76, we may find the "robustness" of this formula can be substantially reduced without a speed penalty, but with improvements in image structure. For a 1 stop speed increase at a high pH, it may also be possible to use Metol instead of Dimezone, which could help with fog, improve keeping properties etc.
     
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  17. Alan Johnson

    Alan Johnson Subscriber

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    Michael,
    Thanks for those ideas.
    I think there are some relatively simple things not known (or not published) about ascorbate developers and worth looking at,though it is a slow process.
    (1) In absence of sulfite oxidation gives an orange compound which may be dehydrosacorbate and first indications with another developer made from p-aminophenol and ascorbate are that the pH tends to drift lower.
    (2) In presence of sulfite,as in the present W3 developer, I expect oxidation to give a yellow compound, relatively colorless, and it is of interest to find out if the pH still drifts lower or if the sulfite stabilises it.
    For years people have said "Oh ascorbate developer working solution does't keep throw it out after a day"
    I'm not convinced that this is always true but it has to be found by experiment.
     
  18. michael_r

    michael_r Subscriber

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    I think the reported issues with ascorbate developers (the valid reports, at least) may have more to do with Iron ion impurities in the solution, leading to the well documented Fenton reaction which can destroy ascorbate quite quickly. This would tend to be more of a problem with home-mixed developers with tap water, ingredients of unknown purity, and the lack of a sequestering agent. These problems can largely be worked around.

    What is more difficult is the preservation of Phenidones in aqueous solutions, particularly solutions of relatively high alkalinity, as is the case with W3. On the other hand the presence of ascorbate (or other Phenidone-regenerating agents) helps. In Haist there is some interesting information on preparing concentrates with Phenidones with some proposed formulas (mostly based on the work of Axford/Kendall at Ilford), but they are typically two-part formulas.
     
  19. Alan Johnson

    Alan Johnson Subscriber

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    I am concerned with the case of many days/weeks exposure of developer to air in a part full container where the Fenton/ordinary oxidation of ascorbate is probably complete.
    The final products of the Fenton reaction are possibly oxalic and threonic acids:
    http://informahealthcare.com/doi/abs/10.1080/10715760410001700497?journalCode=fra
    The color of threonic acid is probably beige:
    http://www.hmdb.ca/system/metabolites/msds/000/000/849/original/HMDB00943.pdf?1358463319
    I just note this for reference,not claiming this is what happens to oxidized ascorbate.
     
  20. ntenny

    ntenny Member

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    For shelf life, it might be interesting to try to develop a version in an organic base, a la PC-Glycol/PC-TEA/HC-110. Keep the ratios of active ingredients, with some reduction in the carbonate to compensate for the base, and mix in however much glycol or TEA it takes to dissolve them, then dilute at time of use...

    I just did a little bit of googling and found a thread on APUG from 2006, in which a guy named Alan Johnson had a nice discussion with Pat Gainer about adding sulfite to PC-TEA. So you're probably way ahead of me on this line of thought already. :smile:

    -NT
     
  21. michael_r

    michael_r Subscriber

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    I still think we need to quantify the speed and contrast relative to the chosen reference developer D-76. Otherwise we don't really know what the formula is doing or what direction to move in for optimization.
     
  22. Rudeofus

    Rudeofus Subscriber

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    Out of sheer curiosity I tested this developer with a test clip contact exposed through a Stouffer wedge. I have not scanned in the clip, but from looking at it I'd say that with 5 Minutes development at 30°C the clip is seriously overdeveloped. We have every reason to believe that the alleged speed increase is an effect of this overdevelopment.

    Alan, can you confirm that you used anhydrous form of Sodium Sulfite and Sodium Carbonate for your test? I did and seem to get significantly higher b+f density than what you showed here.
     
  23. Alan Johnson

    Alan Johnson Subscriber

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  24. Rudeofus

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    I do my test charts at 30°C in order to speed up testing. Yes, if 7 minutes at 20°C is indeed the correct processing time for Xtol stock and Tri-X, then I should repeat this test either with 6 minutes at 20°C or 2 minutes at 30°C. But looking at the contrast of this neg, I think the threefold increase in dev time alone doesn't explain the huge contrast I got.
     
  25. michael_r

    michael_r Subscriber

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    I can try a test this weekend and plot the results if it would help. Unfortunately I don't have the film Alan used though. I could maybe use something non-exotic like FP4 since I have other reference curves for that film in XTOL and DDX. But I'm not sure what development time to try here. Based on the quantities of developing agent in W3, and its pH, I would expect it to behave more like a print developer in terms of activity and with high fog since it definitely (my opinion based on the formula) needs a restrainer. W3 contains the kinds of quantities we'd normally see in a stock print developer before dilution to working strength.

    I'm still wondering why it is so strongly formulated. Perhaps I need to better understand the goal of W3. Is the intention to make a long lasting concentrate, or is it just to increase speed over D-76? Etc. Some thoughts:

    -Phenidone film developers with superadditive secondary agents typically only contain a fraction of the amount in W3, even developers formulated for speed increases.

    -There is a lot of ascorbic acid present, and at a pH of 9.8 it might be doing more than regenerating the Dimezone-S. For a speed increasing developer, it is usually desirable to try to keep contrast under control, but the formula as-is seems like it would produce high contrast.

    -There is a lot of carbonate present, which would tend to make W3 highly buffered, which would tend to further promote contrast.

    -To control fog, I suspect a significant quantity of BZT would be required in W3, which would tend to reduce speed and further promote contrast.
     
  26. Alan Johnson

    Alan Johnson Subscriber

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    Yes, thanks for noting.

    10% less than Xtol 1+0 time is not correct for all films.

    It seems about right for APX100 but some Acros I developed in W3 for this time was somewhat contrasty and overdeveloped.
    I would expect about EI=80 for Acros with D-76, attached pics of a cable duct and some silver birch trees were taken at EI=125, have plenty of shadow detail overdeveloped in this way (in error).
    The fact that Acros was overdeveloped does not mean that there is no speed increase with correct development. Chemically it is similar in composition to the former Paterson FX-50 but more concentrated in the working solution:
    http://www.photomemorabilia.co.uk/Paterson/Chemistry/fx50testreport.pdf

    Michael,
    My theory is that these phenidone/ascorbate type developers kept in half full bottles usually fail because all the ascorbate is oxidized and/or the pH drops.
    To get round this I use a lot of ascorbate that can cope with a lot more air and a lot of carbonate as there is a lot more acidic decomposition products to be buffered against.
    Yes, if you get around to doing the test you mention it certainly would help to clear up the matter of the film EI vs some other developer.
     

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