Thornton 2 baths developer

Discussion in 'B&W: Film, Paper, Chemistry' started by Marc ., Apr 11, 2006.

  1. Marc .

    Marc . Member

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    Hello,

    I am about to test the 'Thornton 2 baths' formula.
    I will develop 35mm FP4+ and HP5+ films for a condenser enlarger in a paterson tank.

    For those who do not know it, see :
    http://www.barrythornton.com/
    http://www.awh-imaging.co.uk/barrythornton/2bath.htm

    Can you share your experience on :
    - processing time/temp/agitation
    - which films you use
    - results speed/grain/acutance
    - contrast control
    - any changes to the original formula... ?

    Thank you !

    Marc
     
  2. davekarp

    davekarp Member

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    Marc, Thornton revised his published formula and included it in his book "The Edge of Darkness." He increased the metol to 6.5g/L. I am going from memory, but I think he reduced the sodium sulfite in the A bath to 80g/L. I e-mailed Mr. Thornton before his death, and he confirmed that the formula in his book was more current than the one on his website. I have used it with good results as refined in his book, plus I have made one change from time to time. I have used it with 40g/L sodium sulfite in Bath A and 40g/L in bath B. This works, and does not seem to be materially different than the results I receive when putting all of the sodium sulfite in Bath A.

    I have used this formula with FP4+, HP5+, Fortepan 400 (Arista.Edu 400), and Delta 100 in 4x5, and HP5+ in 120. IEs are 64-80 with F54+, 200 with HP5+ and Fortepan 400, 50 with Delta 100. Temperature varies from approximately 68-75 degrees F. I process 4x5 for 5 minutes in each bath, 120 for 4 minutes in each bath. I think Thornton recommeded these times at 70 degrees F, but I have seen little if any difference in the temperature range I have used.

    For contrast control, I have followed Thornton's suggestion of 12g/L of sodium metaborate in bath B for N, and 20g/L in bath B for N+1 development. I have not had to try N-1 development due to the automatic compensating nature of this 2 bath, but Thornton recommended trying 8g/L in bath B for an N-1 effect.

    I like the results very much, but have not yet tried it with 35mm film. Others often state that the 2 bath developers are inadequate in comparison to modern single bath developers used with modern films. I have not seen the problem using this formula.
     
  3. Marc .

    Marc . Member

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    Davekarp, I have read 'Edge of Darkness', and I confirm his modified formula :
    Bath A water 750 ml / Metol 6.5 g / Sodium sulfite 80 g / Water to 1 L
    Bath B Water 750 ml / Sodium metaborate 12 g / Water to 1 L

    What is the idea behind splitting the 80 g sodium sulfite beteween bath A and bath B ?
    Marc
     
  4. davekarp

    davekarp Member

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    Marc,

    I split the sodium sulfite between the two baths due Anchell's and Troop's comment that staining, streaking, and/or film swelling are potential problems when using a plain alkali B bath. They suggest adding 50g/L of sodium sulfite to the B Bath to avoid these problems. In addition, they discuss Vestal's divided D-76, in which he divided the sodium sulfite 50/50 in the two baths. I sort of combined the ideas, and split the sodium sulfite between the two baths.

    I suppose that I could have split the sodium sulfite 30/50 in the two baths, but the 40/40 split seemed to work fine so I never tried it. Later, I mixed the two baths as Thornton recommended, and never had a problem with streaking, staining, or swelling. I did not see any real difference in results, so I have not used my variation for a while now.
     
  5. skahde

    skahde Member

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    With respect to two-bath developers of this type it's more than worth while to read http://www.largeformatphotography.info/twobath/ which, instead of repeating the traditional conception actually did test how to achieve N, N-, N+ and came to some very surprising conclusions.

    Having used and testet the Stoeckler formula as well as Thorntons recipe back and forth I can I tell you from my own experience that you will get a decent picture even if you skip bath B alltogether. All you loose is a bit of speed whereas contrast doesn't change by a margin worth mentioning. Ups, that's in contradiction to what you find in the literature about two bath developers including Anchell/Troop, Adams and Thornton, right? Well, if you wan't to know how things work: As I said, the article above is worth reading and provides reproducible, real world test results instead of broad generalizations about two baths.

    With the Thornton formula I found 3.5 mins at 20 °C/68 °F to be a good starting point for Agfa APX as well as Fuji Neopan 400 and Kodak Tri-X new. Speed is about 1/3 to 1/2 stop lower than ISO-speed.

    Grain is low, accutance adequate (I take Pyrocat for if I want sharp edges), Contrast control is ok (did I say you should read the article?).

    I liked to use the formula for its ease of use, tolerant behaviour and relatively good speed. You can have a soft negative and not loose the shaddows which is great if you need it. But contrast is lowered a bit more in the low zones relative to the highlights which makes the shaddows less crisp. Good process control and a standard-developer can give you about the same result with slightly less speed but a more linear curve.

    Stefan
     
    Last edited by a moderator: Apr 12, 2006
  6. Marc .

    Marc . Member

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    Davekarp,
    Can you compare acutance and grain size between the two methods (standard vs modified baths) ?

    Stefan,
    Thornton describes a contrast control method, modifying concentration in bath B :
    Bath B N- Water 750 ml / Sodium metaborate 7 g / Water to 1 L
    Bath B N+ Water 750 ml / Sodium metaborate 20 g / Water to 1 L

    Thank you for the link. So, Kates describes another approach to contrast control for Stoeckler's 2 baths, based on time in bath A.

    If Thornton's formula behaves the same way as Stoeckler's (it should as they are very close), we have 2 methods for contrast control :
    - time in bath A
    - concentration in bath B
    That's quite interesting !

    Has anyone already compared ?

    Marc
     
  7. dancqu

    dancqu Member

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    Three and likely more. #3; presoak in B then into
    A then back to B. One-shot usage.

    A starting point could be: A bath, 1 gram metol and 5 of
    sulfite; B bath, 5 grams of sulfite or borax or bicarbonate
    or carbonate or a blend of two or three of those. All 1
    liter. I've not any metaborate so will not mention it.

    As was suggested development is usually well under way
    in the A bath by times up. S. sulfite is a medium strength
    alkali. Anchell, in some of his formulas, includes bisulfite
    which reduces the ph. A baths are usually very
    D-23 in character. Dan
     
  8. fhovie

    fhovie Subscriber

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    I have beenusing Barry's formula (version) for years - as published in Edge of Darkness. Works great. Compensating - a little soft. Not gritty like high definition developers. 3 to 4 minutes in each bath - no worries on temp - don't wash between baths. Shelf life is better than 2 years. Better than 15 rolls per liter on bath A - Bath B can be replaced that often or so, it is the one that takes the beating.
     
  9. Marc .

    Marc . Member

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    Dan,
    Is your #3 method is for N- ?
    Can you describe the results ?

    Fhovie,
    Did you try the N+ and N- baths B decribed by Thornton ?

    Marc
     
  10. davekarp

    davekarp Member

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    Marc,

    I have detected no difference in acutance or grain between Thornton's standard formula and my modification.
     
  11. dancqu

    dancqu Member

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    I've not tried the method. The method derives from a
    technique described by Steve Anchell in Camera and
    Darkroom. The usual A and B processing is used but
    the film is cycled through two or more times.

    Twixt the B and return to A, IIRC, a weak stop and
    rinse or rinses were required. Required because of the
    multiple use of the solutions. I gave the matter some
    thought. It came to mind that two cycles could be
    had with one pass through the developer.

    Cycle one, the film is loaded with activator then placed
    in the developer where the activator is expended.
    Cycle two, the film loads with developer then is placed
    back in the activator where the developer is expended.

    I may have pulled out another plum! If you know
    what I mean. Dan
     
  12. dancqu

    dancqu Member

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    [QUOTES=dancqu]
    "Three and likely more. #3; presoak in B then into
    A then back to B. One-shot usage."

    "A starting point could be: A bath, 1 gram metol and 5 of
    sulfite; B bath, 5 grams of sulfite or borax or bicarbonate
    or carbonate or a blend of two or three of those. All 1
    liter. I've not any metaborate so will not mention it."



    I'm going to amend that starting point suggestion.
    Because the film is twice developed it likely better if the
    A bath be inactive. That would make the A bath ph neutral
    or close. A correct blend of S. sulfite and S. bisufite will do it.
    Then again metol is an acid. If 2 grams of sulfite alone be
    added to 1 gram of metol that may be enough near
    neutral. Use soon after mixing.

    A blend of bicarbonate and carbonate will have a ph
    some where twixt the extremes of the two. I'd likely
    start with carbonate alone.

    To process give three minutes in each solution; B then
    A then B. Perhaps the N minus group will not take the speed
    hit they now take with conventional processing.



    "As was suggested development is usually well under way
    in the A bath by times up. S. sulfite is a medium strength
    alkali. Anchell, in some of his formulas, includes bisulfite
    which reduces the ph. A baths are usually very
    D-23 in character." Dan