What would restraining do for D-76...is it the same as replenishing?

Discussion in 'B&W: Film, Paper, Chemistry' started by streetshot, Sep 18, 2011.

  1. streetshot

    streetshot Member

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    Are these processes different or are they the same? Currently I'm replenishing D-76 for Tri-X (and HP5+) and recently heard about restraining. Is it the same as replenishing or is it different. If different how does one restrain D-76?

    With thanks for an amazing forum.

    Michael
     
  2. Monito

    Monito Member

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    Not the same as replenishing. It means to restrain or hold back an active or over active developer. (Replenishing means to add new developing agent to exhausted developer as an economical alternative to making fresh developer.) I think restraining is done with bromide sometimes added to the mix. I'm sure there are other restrainers too. I think it is for less acutance (edge sharpness due to Mackie lines) and finer grain, but I'd have to look it up. Bump for you because I'm interested to hear what others more knowledgeable have to say.
     
  3. panchro-press

    panchro-press Member

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    NO!
     
  4. johnielvis

    johnielvis Member

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    well----could be---when you replenish, the existing restrainers in the developer may "build up" over time....so you effectively end up with a different developer recipe with more of a percentage of the restrainer remaning....

    very difficult to determine the outcome without the specifics.
     
  5. streetshot

    streetshot Member

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    Thanks John. You open an interesting question about how much restrainer builds up through the replenishment cycle(s).

    The specifics - or as specific as I can be are this...I add .75 oz of D76R (now L76R) for each roll developed to the D76. Thats the process...in other words, when I develop 8 rolls in an 8 roll tank I pour the D76 back into its bottle and add 5-6 oz. of the replenisher to the bottle. I generally get between 90 and 100 rolls from a gallon of stock developer with replenishment.

    Am I effectively restraining the developer...or some other/similar effect?

    With thanks,

    Michael
     
  6. Monito

    Monito Member

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    Shoot two short rolls with some test shots of a target you make, including a step wedge, gray card, colour chart, and some colourful items that you can set aside. Use very repeatable lighting, such as high noon outdoors, or flash with fresh batteries, waiting double the recycle time between flashes, or incandescent light, either one at an accurately measured distance. Include a note in the shot saying whether it is roll #1 or #2.

    Develop one roll at the beginning of a batch. Run your 90 or so rolls through and develop the second roll as the last one.

    Compare, perhaps by printing the two (35mm?) strips side by side in a 6x7 negative carrier onto the same piece of paper.
     
  7. Photo Engineer

    Photo Engineer Subscriber

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    Ideally, a fresh developer should equal a seasoned developer. This is why in color you add a "starter" to make this outcome take place. In B&W, the seasoning effect is much less pronounced and the build up in halides in the developer have far less impact on the resulting image.

    Generally though, Iodide salts and Bromide salts are restrainers and also can repress edge effects. Included in this list are PMT (Phenyl Mercapto Tetrazole) and BTAZ (Benzotriazole). There are many many more. The initial effect is lower fog, then lower speed and contrast.

    PE
     
  8. streetshot

    streetshot Member

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    Well that was helpful. Why did you bother?
     
  9. Gerald C Koch

    Gerald C Koch Subscriber

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    For developers the bromide and iodide buildup does depress fog AND development. However as eluded to things are really never simple. For D-76, as it is poorly buffered, the pH tends to increase with use. This partially counteracts the development repression. For PQ developers like Microphen the phenidone is less susceptible to restrainers in comparison to metol.
     
  10. Bill Burk

    Bill Burk Subscriber

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    You've got Photo Engineer's and Gerald C Koch's answers... those are what I would consider the real answers...

    It looks like there isn't a restrainer like Potassium Bromide in D-76 or D-76R so you aren't restraining it when you add replenisher.

    I haven't added restrainer such as Benzotriazole or Potassium Bromide to D-76, though I have them handy and could if I wanted to. I just never did. And I rarely get measurable fog, unless I develop severely expired film. So maybe you won't need to restrain D-76.

    If you do add one of these chemicals, be prepared to test the film speed because you will probably turn that Tri-X into an EI 64 film. Would be worth it to try with expired film if you had a roll... I've got one I might try it with.
     
  11. MattKing

    MattKing Subscriber

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    Folks - this is a 5+ year old thread.
     
  12. Kevin Caulfield

    Kevin Caulfield Subscriber

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    Yes, but the OP replied to his own old thread today.
     
  13. Doremus Scudder

    Doremus Scudder Member

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    That's what I call restraint; waiting 5 years to take a poster to task!

    Maybe the OP has learned a thing or two about the difference between replenishment and restraining in the meantime. :smile:

    Doremus
     
  14. RPC

    RPC Member

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    And the poster he replied to has not been on the site for almost 4 years!
     
  15. Bill Burk

    Bill Burk Subscriber

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    Well that flew past my old thread detector. Hey I learned D-76 doesn't have a restrainer. Always thought it had some potassium bromide.
     
  16. RPC

    RPC Member

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    It seems D-76 is soft-working enough that it needs no bromide (restrainer) in the formula. The bromide produced during development is apparently enough to do the job of restraining.
     
  17. Photo Engineer

    Photo Engineer Subscriber

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    The bromide release plus the sulfite act together to give the sharpness and aid in reducing grain.

    PE