D-76 waiting time after mixing stock

Discussion in 'B&W: Film, Paper, Chemistry' started by jensenhallstrom, Jul 6, 2013.

  1. jensenhallstrom

    jensenhallstrom Member

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    Hi, ive seen a thread or two on this subject, some people have explained they havent had any trouble with using their freshly mixed stock d-76 as soln as it cools, others say you have to wait 24 hours after mixing to use. Can i get a legitimate explanation why this 24 hour rule would help the developer in whatever aspect rather than using as soon as it cools? Thanks.
     
  2. MattKing

    MattKing Subscriber

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    When it is first mixed, D-76 is more active than normal. If you use it immediately, your negatives will be developed more than normal.

    After 24 hours, the activity will have stabilized, and thereafter will remain quite consistent for some time, until the developer starts to degrade due to age.

    I don't have quantitative information about how much over-development will occur because of using freshly mixed developer.
     
  3. jensenhallstrom

    jensenhallstrom Member

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    Thank you. That makes sense!
     
  4. Bill Burk

    Bill Burk Subscriber

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    One thing I like to do is maintain personal time-contrast index charts of TMY-2 and D-76.

    The fluctuation in activity of D-76 over time has been explained and I can accept the explanation.

    I would say, that using fresh D-76 while performing calibration lab tests would be a mistake. Just as exposing test wedges immediately before developing would be a mistake. Both of these mistakes would possibly lead you to believe your film speed is higher than you would really achieve in the field.

    But I do not believe using fresh D-76 would be harmful in day-to-day developing.
     
  5. Bill Burk

    Bill Burk Subscriber

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    MattKing's explanation is about perfect.
     
  6. tkamiya

    tkamiya Member

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    I wait over night before using any developer, not just D76. Reason being when freshly mixed, I always have something floating around and not completely dissolve into water. I'd hate to have them land on my film and create spots of over/under development. I guess I can filter them but I just mix mine the night before so that everything has time to fully dissolve. I don't necessary wait 24 hours. Sometimes, more like 12 hours.
     
  7. clayne

    clayne Member

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    D-76, I usually wait overnight as it's not going to cool any faster. XTOL I use immediately.
     
  8. markbarendt

    markbarendt Subscriber

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    I'd say as soon as the powder has fully dissolved and it has cooled down to the temp you plan to use it at, you are ready.

    I can't see how chemically it would make any difference beyond that.
     
  9. mfohl

    mfohl Subscriber

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    I just mixed a batch a week or so ago. I mixed it in the afternoon, then used it in the evening after it cooled. The negatives seem OK to me; I don't notice anything different from negatives developed after waiting.

    -- Mark
     
  10. Iluvmycam

    Iluvmycam Member

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    Will it stil mix OK with tap temp water? Or does the water have to be heated?
     
  11. markbarendt

    markbarendt Subscriber

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    D-76 requires hot water, forget the exact temp. It will say on the package.

    Ilford's ID-11, a D-76 look alike, needs 40C / 104F so hot tap water depending on your set up at home may work.
     
  12. jensenhallstrom

    jensenhallstrom Member

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    The temp needed to be heated to is 122F to 131F, somewere in that range, also distilled water is a hell lot better than tap water for mixing any chemistry, especially developer. Tap water has many minerals in it, whereas distilled has none.
     
  13. Hatchetman

    Hatchetman Subscriber

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    Can you mix a stronger solution and then cool it off quickly with cooler water to reach the proper concentration?
     
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  15. Ian Grant

    Ian Grant Subscriber

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    You could, however it's not really an advantage.

    When I used deep tanks and ID-11/D76 we always noticed the first few films in a new batch lacked the quality of the later films, first fresh D76 hasn't had time to equilibilise which takes a few hours, and second later films benefit from the slight build up in bromide and other pocessing by-products once a few films have been processed. The Highest quality from full strength ID-11/D76 is when used replenished, followed by using at 1+2.

    Remember these developers were designed for replenishment from the outset.

    Ian
     
  16. michael_r

    michael_r Subscriber

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    Since you used the word "legitimate", I'd say Kodak and Ilford are probably the most legitimate sources for D-76/ID-11. Follow their mixing/processing directions. I don't think either company indicates any kind of "stabilization" period is needed after mixing.
     
  17. MattKing

    MattKing Subscriber

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    Michael:

    IIRC, the package directions themselves on D-76 recommend waiting 24 hours after mixing.
     
  18. markbarendt

    markbarendt Subscriber

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    The problem you describe here is typical of replenished systems, but not one shot systems, there is no build up of anything with one shot.

    As to equalizing, what reactions are going on?
     
  19. markbarendt

    markbarendt Subscriber

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    Ilford's info does not.

    I haven't been able to find a copy of the D76 mixing instructions.
     
  20. michael_r

    michael_r Subscriber

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    Hi Matt, I don't have a package handy but I'd be pretty surprised if it said that. It isn't in the tech publication either.
     
  21. selmslie

    selmslie Subscriber

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    It depends on your water supply, not all dissolved minerals are detrimental. Kodak designed their chemicals and development times for "normal" tap water whatever that is. They do not specifically recommend distilled water because it might actually change the developer's performance slightly. I would be more concerned with the water used with the Photo-Flo, which at least ought to be filtered - distilled might be even better.
     
  22. markbarendt

    markbarendt Subscriber

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    selmslie you are right that chemicals designed by the likes of Kodak and Ilford are designed to be used with tap water.

    The biggest advantage of me using distilled to mix the chemicals is that eliminates a variable.
     
  23. Sal Santamaura

    Sal Santamaura Member

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    I'm looking at a package of D-76. It has no such recommendation. The directions say (using graphics as well as words):

    "To Make 800ml (tap) water at 50-55C / 122 - 131F → Stir (contents of packet) Until Dissolved → add (tap) water to make 1 Liter"​
     
  24. MattKing

    MattKing Subscriber

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    Thanks Sal - I was hoping someone here would actually have a package to look at.

    I've obviously confused my sources.

    FWIW, there is no reference to this issue (or mixing in general) in any of the various Darkroom Dataguides I have here. And as Michael noted, there is no reference to mixing in the dataguide for D-76.

    EDIT: I'm sure though that somewhere there are or were instructions that specifically referred to allowing the developer to cool to room temperature.
     
  25. fotch

    fotch Member

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  26. DLawson

    DLawson Member

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    This is a frequently repeating question.

    As I recall explanations from PE and others with knowledge beyond mine, D-76 mixed from standard formulas is more active for several hours after initially mixing. D-76 from a Kodak package has added buffering agents to compensate for that.

    Since I do the perpetual gallon jug with replinishment, waiting 24 hours after the rare new batch is no big deal. I just mix stuff in that before-mode, when I'm clearing clutter and dust so I am ready to deal with film. (Maybe I need to improve my housekeeping in general.)