Benzotriazole in LPD with expired Brovira

Discussion in 'B&W: Film, Paper, Chemistry' started by pstake, Aug 22, 2013.

  1. pstake

    pstake Member

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    I stumbled upon some expired, unopened Brovira Grade 3 that I plan to use it in my ordinary developer, which is LPD.

    I generally use the LPD diluted 1:1.

    I am wondering if I add the benzotriazole (from Photo Formulary), how much I should add — and if I need to add it at the beginning of each session or if I can add it once and re-use the LPD as normal.

    On a separate note, would i have better luck using the Brovira for lith prints (is there less of a chance of a fog this way?)

    Cheers,
    Phil
     
  2. Jim Noel

    Jim Noel Member

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    I would process one image w/o the benzatriazole in order to evaluate the quantity necessary to be added, if any.
     
  3. Bruce Osgood

    Bruce Osgood Membership Council Council

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    I agree with Jim, try one and see if the paper is fogged.

    If you feel it is I would use 6 to 15 mL of 1% solution BZT per liter of working solution developer. Experiment with 6, 9, 12 and if 15 is needed maybe a new batch of paper is in order.
     
  4. Gerald C Koch

    Gerald C Koch Member

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    Use as little BZT as you can since it will tend to cool tones. You might also try using a 10% solution of KBr to limit fog. The concentrations are such that the two solutions can be used similarly.
     
  5. pstake

    pstake Member

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    Thanks for all the info. I ordered a 10g container of BZT from photo formulary. Do you know how much water i need to mix it with to make a 1 percent solution?

    EDIT: based on reading this on the b&h site, it seems like this will make 10 liters of .1 percent or five liters of .2 percent. My math isn't great but I think that's right.



    "Make a 0.2% solution of benzotriazole (2g benzotriazole in water at 125°f/52°c or higher to make 1 liter) then reduce the bromide to 1/10 or 1/6 strength and use just enough benzotriazole solution to prevent developer stain or fog. A little experimentation may be required."
     
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  6. Tony D

    Tony D Member

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  7. Gerald C Koch

    Gerald C Koch Member

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    You would dissolve the BZT in 1 liter of hot water. When the water cools check the volume and add water to make 1 liter . This will yield a 1% w/v (weight to volume) solution.
     
  8. pstake

    pstake Member

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    How much do I dissolve in the 1 liter (and later adding another liter for a total of 2 liters)? 2g?
     
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  9. pstake

    pstake Member

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  10. Gerald C Koch

    Gerald C Koch Member

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    For a 1% solution dissolve 10 g in 1 liter of water. Since you must use hot water to avoid doing a lot of stirring the volume will contract when it cools and you need to add a little additional to bring it up to 1 liter. Sorry if my post didn't make this completely clear.

    >>> BTW I found the PDF article very interesting and worthy of being posted on its own thread for access to a larger body of readers. <<<
     
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  11. Gerald C Koch

    Gerald C Koch Member

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    Benzotriazole is difficult to dissolve in water and its solubility is about 20 g/l. Therefore trying to dissolve 10 g in 500 ml of water may be a bit difficult. Solutions more concentrated than 1% may exhibit precipitation of the solid when stored at lower temperatures. Traditionally photographers have used a 1% solution for this reason.

    The object with any restrainer whether BZT or KBr is to use as little as possible to avoid speed loss and tonal changes. Therefore it is unwise to start with 30 ml/l. One needs to do a bit of testing first.
     
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  12. pstake

    pstake Member

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    Isn't 20g/l and 10g/500ml the same ratio?
     
  13. pstake

    pstake Member

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    Oh, okay — this makes sense. Thank you.

    By the way, I tested the Brovira tonight and there was no noticeable fog after 3.5 minutes in the dev, then stop and 2 minutes in the fix. It has a creamier base than I'm used to, and a different finish (that I like) ... "crystal."
     
  14. NB23

    NB23 Member

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    I dissolve my Benzo in Alcohol (the cheap 50% isopropyl works fine). It dissolves in seconds as opposed to water (Biiig pita!).
     
  15. K-G

    K-G Subscriber

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    Try without benzotriazole first. Last year I printed on my last remaining stack of Brovira. It did not show any fogging.

    Karl-Gustaf
     
  16. pstake

    pstake Member

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    Thanks, KG. Mine didn't show any fog either when I tried a cut piece last night.
     
  17. RattyMouse

    RattyMouse Subscriber

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    What's the function of BZT in developers? We use this chemical in my industry as a corrosion inhibitor.
     
  18. MattKing

    MattKing Subscriber

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    It slows down activity. This aids in reducing fog in old film and paper, and leads to a cooler tone in prints.
     
  19. Gerald C Koch

    Gerald C Koch Member

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    Benzotriazole is what is known as a restrainer. In its action it is similar to potassium bromide. It suppresses development of active centers which would result in fog. When used in excessive amounts active centers associated with an image are also suppressed resulting in a general loss of film speed.

    Organic restrainers are often called anti-foggants while inorganic ones like potassium bromide are just called restrainers. Developing agents differ in their ability to distinguish between image centers and fog centers. A developing agent like sodium dithionite has little ability to distinguish between these two centers. This is in contrast to the developing agents which are most often used like Metol. Therefore a restrainer may be required for a particular developer while not for another.
     
  20. Bruce Osgood

    Bruce Osgood Membership Council Council

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    Thank you Gerald,
    I needed this.
     
  21. pstake

    pstake Member

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    Gerald,

    How do you know so much? Are you a chemist or did they actually teach this at a photography school at some point?

    I'd love to have this understanding of photochemistry.

    Thanks, again for all the info/advice — everyone.

    Cheers,
    Phil
     
  22. Gerald C Koch

    Gerald C Koch Member

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    Hi Phil,

    Yes, I am a trained chemist but my interest in photography caused me to read and re-read many of the classic books on photochemistry like Mason and Glafkides. The most up to date book is the two volume set by Grant Haist. A course in solid state chemistry was helpful in understanding what happens when radiation impacts certain solids like glass and the silver halides.

    Jerry
     
  23. Thomas Bertilsson

    Thomas Bertilsson Subscriber

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    Instead of using restrainers, I have used Brovira and printed it with my standard LPD (replenished) chemistry. Whatever fog is there in the paper I have bleached back with dilute pot ferri. Refix and wash.
    It helped me, because I don't have any benzotriazole handy, but I have plenty of bleach.
     
  24. cliveh

    cliveh Subscriber

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    Thomas, just wondered how the pot ferri differentiates between fog and normal tonal values?
     
  25. Thomas Bertilsson

    Thomas Bertilsson Subscriber

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    It doesn't.

    You have to do a couple of test prints to figure out how to properly expose your print in order to come up with something that looks good once you're done.