Can leaving out bromide give a bit more speed with ID-68?

Discussion in 'B&W: Film, Paper, Chemistry' started by john_s, May 6, 2012.

  1. john_s

    john_s Member

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    I notice on the web site

    http://www.lostlabours.co.uk/photogr...rs/devID68.htm

    the formula for ID-68 contains no bromide although the replenisher does. Other sites show some KBr. I have used Pyrocat-HD without bromide (as suggested for some uses by Sandy King who invented it) which is supposed to give marginally more speed at the expense of a little fog. Is the bromide essential for the ID-68?
     
  2. Athiril

    Athiril Subscriber

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    Link is broken.
     
  3. jochen

    jochen Member

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    Hello,
    some developer substances give more fog and some less. Phenidone has a certain tendency to give more fog and Phenidone developers need more KBr or even Benzotriazole. D-76 (a hydroquinone-metol developer) does not contain KBr as it works clear without too much fog. If you leave out some KBr, you'll get more fog, the useable sensitivity will increase a little bit. I'm wondering why the replenisher does contain KBr and the developer not as the developer is enriched with KBr with every roll of film which was developed in the solution. Therefore I would not put in KBr in a replenisher.
     
  4. john_s

    john_s Member

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  5. Keith Tapscott.

    Keith Tapscott. Member

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    The link shows that the developer does contain potassium bromide.

    It is the replenisher that doesn't have it.

    IDK how much more noticeable the base fog will be if you omit the restrainer in the developer.
     
  6. michael_r

    michael_r Subscriber

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    Hi John,

    ID-68 is a balanced formula. If leaving out the restrainer was a net improvement (ie more speed without unfavourable impacts on other image characteristics outweighing the speed increase), Ilford's chemists probably would have left out the restrainer.

    Why would you want to do this though? What real benefit is there to a small speed increase? It's not the type of thing that will make the difference between say needing a tripod or not. Suppose you got an extra 1/3 stop? So what? Why not just give more exposure?
     
  7. albada

    albada Subscriber

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    John, I suggest that you mix 1/4 litre of ID-68 with *no* bromide in it. And develop a test-strip.
    Now add 0.5/4 (0.125) grams of bromide to the soup. Dev a 2nd test-strip.
    And add 0.125 more grams of bromide. Dev a 3rd test-strip.

    Now you have strips showing the effects of 0, 0.5 and 1.0 g/L of bromide.
    Select the one you like most.

    Mark Overton
     
  8. Photo Engineer

    Photo Engineer Subscriber

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    Neither D76 nor D76R have bromide in my Kodak formula book. The same is true of the reference cited above.

    PE
     
  9. john_s

    john_s Member

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    I didn't ever think that the difference would be gigantic. All formulas are compromises. I think that newer films show less fog than the older ones. ID-68 is an old formula. If I were using a tripod then I probably wouldn't be using a speed-increasing formula like ID-68 or Microphen.

    However the main reason I thought about cutting the bromide is that Ian Grant's website shows the formula for ID-68 without bromide. Either it's an inadvertent omission, or he knows something that I don't know.

    I will try Mark's suggestion as soon as I have time.
     
  10. michael_r

    michael_r Subscriber

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    Interesting. Usually Ian Grant is a stickler for referencing correct formulae, so I'd be surprised if it was an inadvertant ommission.
     
  11. Athiril

    Athiril Subscriber

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    Other way around like I thought it would be.

    The recipe linked has Potassium Bromide in the working developer, and none in the replenisher.

    This is because bromide salt concentration will increase as you develop film with the developer. The replenisher containing none, will dilute this level back down again to a more normal level. Maintaining (or attmepting to maintain) the same bromide concentration level.


    Here is another copy of the ID-68 formula
    http://books.google.com.au/books?id...PA96#v=onepage&q=Ilford ID-68 formula&f=false

    And
    http://www.digitaltruth.com/data/ilford_id68.php


    I would suggest this version is correct, and a bromide-free version modified.
     
    Last edited by a moderator: May 7, 2012