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  1. #1

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    Anti fogging agents- effects and developer types

    I'm using a lot of older film these days for my panoramic photography. Some is aerial film. I want to understand anti fogging agents and their effects in order to minimize the base plus fog build up with these older films.I thought I would start with benzotriazole. How does this affect contrast and speed when you use it. Any other problems I need to know about? I usually use roll pyro for development. Is it compatible. Anyone have any good reading material they could recommend on this?
    Thanks! Jamie Young

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    While we are at it Jamie, perhaps you wouldn't mind me asking something relevant. Given the fact that benzotriazole is used in cool tone print developers and that cool tone is a result of large grain, would it be a good choice for film developer antifoggant? Would KBr, which gives warmer tone (finer grain) in prints be a better choice?

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    It's known to be and excellent antifoggant, hence my mention in this post. That being said, I've never used any anti fogging agent and am asking for advice on the subject. I'm using it for film and not interested in tone changes.

  4. #4
    Axle's Avatar
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    Benzotriazole is the only anti-fog agent I know, and one I've used myself, add that to a strong developer (Xtol or D-76 stock) and you'll have little issue with fog.
    Canadian Correspondent for the Film Photography Podcast
    A bi-monthly podcast for people who love to shoot film!

  5. #5
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    Quote Originally Posted by Anon Ymous View Post
    While we are at it Jamie, perhaps you wouldn't mind me asking something relevant. Given the fact that benzotriazole is used in cool tone print developers and that cool tone is a result of large grain, would it be a good choice for film developer antifoggant? Would KBr, which gives warmer tone (finer grain) in prints be a better choice?
    Why do you think benzotriazole is used only in cool tone print developers? This is not the case.

    “The contemplation of things as they are, without error or confusion, without substitution or imposture, is in itself a nobler thing than a whole harvest of invention”

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    The BZT and KBr will slow the development their effectiveness is dependent on developer ie the agent eg metol and pH but they are not magic bullets.

    If the film fogs uniformly you need to print through it.

    Reduce ISO a stop and time in dev by 20% may be best gambits while you experiment.

  7. #7
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    You can add anti-foggants/restrainers, and increase developing time to cut fog effectively.

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    Quote Originally Posted by cliveh View Post
    Why do you think benzotriazole is used only in cool tone print developers? This is not the case.
    I don't. I'm only asking if it is a good choice, regarding the granularity of the processed film. Still if it's the only reliable option, that would be an acceptable compromise.

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    I dont think it is simple eg if you dose DK76 with KBr it will really slow it down whereas the same amount in Microphen may not make any detectable difference to negative at all. the base fog level might not change, in either case!

    If you have lots of negative material you are going to need to experiment Id start with a low fog dev and dose it with both KBr and BZT and soup a test shot

    Sweep the ISO from box to slower in 1stop steps meter for zone 1 you need to know the speed over fog at an acceptable fog level. If you develop for longer in my experience you get more fog...

    if you are lucky you will get a slower film with less range and fog you can print or scan through. BZT is toxic take care.

  10. #10
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    In order of strength and effect on speed and contrast:

    BTAZ (Benso Tri AZole - thus the abbreviation), 5-Nitro Benzimidazole Nitrate, and Phenyl Mercapto Tetrazole (PMT).

    The first and last are available from the Formulary and last practically forever on the shelf and in solution.

    PE

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