Two part developer - A+B blend!

Discussion in 'B&W: Film, Paper, Chemistry' started by boy scout, Jan 4, 2008.

  1. boy scout

    boy scout Guest

    If there is a dilution of Pyrocat-HD I prefer using, is it alright to mix both parts A and B with X amount of water in one jug?

    I don't foresee any variation in temperature for the working solution, so to me - it seems okay!

    Any thoughts are greatly appreciated!

    Thank you! :smile:
     
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  2. Andrew Moxom

    Andrew Moxom Subscriber

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    What specific pyro developer are you using?
     
  3. boy scout

    boy scout Guest

    Pyrocat-HD.

    In theory, I suppose it'd work just fine - but will it not keep very well? :surprised:
     
  4. JBrunner

    JBrunner Moderator Staff Member

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    If you are talking about making a working solution to store, the answer is, in general, NO. Once mixed, the A+B solutions of "normal" Pyro developers begin to oxidize fairly rapidly. You will be left with spent developer in short order, no matter if you use it or not. The normal tray life of Pyro is an hour or less, depending on formula, agitation, quantity, etc. Activated solution in a bottle would last longer I suppose, but would not last long enough, and not be stable enough, to be of any real use in most practical situations.

    If you are making a working solution to use in short order, sure, you gotta mix it in something. Curious what the alternative (other than a pitcher or graduate) would be.
     
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  5. Snapshot

    Snapshot Member

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    I found that when I mixed pyro solutions A & B together, oxidation began almost immediately. Do you plan to store your developer for a period of time? If so, then you'll find it exhausted in short order.
     
  6. JBrunner

    JBrunner Moderator Staff Member

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    I see you amended your post to include that you are using Pyrocat. Pyrocat is more stable and lasts a bit longer than Pyrogallol, and can be used more easily in rolling development, but it my earlier post still applies. These are rapidly oxidizing developers, once activated.

    In the two part solution, they keep very well.
     
  7. boy scout

    boy scout Guest

    It's only a one gallon jug and I plan to blow through it in less than a week!

    When Pyro oxidizes, I don't suppose it'll change colors or viscosity? Haha...

    Guess I'll just have to separate the two solutions then! :tongue:
     
  8. JBrunner

    JBrunner Moderator Staff Member

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    Pyro turns brown when oxidized, although it may take on the color of your film backing when you use it, especially if you don't pre wet. Also, you will need to blow through it in a couple of hours.
    You ain't gonna get a day, let alone a week. Also developer activity, and thus your negatives, over the few hours, will be very inconsistent as activity falls off.

    Pyro needs to be mixed fresh, for each tank or tray development, and used one shot.

    It ain't hc110.
     
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  9. JBrunner

    JBrunner Moderator Staff Member

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    ".....and that's the photo news for today. Now lets take a look at tomorrows processing forecast with J Brunner, J?

    "Thanks Phil, tomorrow's forecast is for the thin negs of this evening to be followed by blank ones, with a pinkish tinge, in the morning. Afternoon gnashings may occur. Back to you, Phil.