How to clear dichroic fog?

Discussion in 'B&W: Film, Paper, Chemistry' started by MurrayMinchin, Oct 11, 2005.

  1. MurrayMinchin

    MurrayMinchin Membership Council Council

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    Ahhh, the pleasures of working in a vacuum with nobody to answer questions...blindly barging ahead making assumptions based on near zero experience and half remembered bug splats of technical data on the cracked windshield of my memory. An arduous, tangential path to discovery. Then again, NO GUTS - NO GLORY!

    So, anyways...I've recently experienced what I think is dichroic fog. After 20+ years of Tri-X & HC-110 complacency I've started using HP5+ in a glycin/metol developer of my own concoction.

    The dichroic fog (?) entered the scene just as I started testing minus development using SLIMT, so I assumed it was the stronger SLIMT dilutions I was trying. That theory got shot out of the saddle yesterday when my normal negatives caught the ghastly yellowish brown fog.

    I usually toss my TF-3 fixer after doing 40 negatives (it's supposed to be able to handle 20 8x10's per litre) but decided to try the "use your fix until it takes twice the time to clear" method. My new theory is that my fix was WAY over used. Make sense? (I mixed up a fresh batch of TF-3 last night and will fire off a negative today after work to be sure).

    I took a couple negatives yesterday I wouldn't mind keeping. Hence the question - how do you clear dichroic fog? I found a site where Richard Knoppow states that adding 15 grams of Citric Acid to 1 litre of fresh ammonium thiosulfate fixer is will do the trick. What do you think? Any other suggestions? Am I now actually on the right path?

    Murray
     
  2. Tom Hoskinson

    Tom Hoskinson Member

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    Hi Murray, are you seeing dichroic fog or image stain? Metol is a staining developer in a low sufite developing solution environment.
     
  3. psvensson

    psvensson Member

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    It sounds like exhausted fixer, which is not the same as dichroic fog. Forty rolls for a liter of fixer is a lot. Just try dipping it in fresh fix.
     
  4. fhovie

    fhovie Subscriber

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    My understanding is that BZT and Potassium Bromide are used as restrainers to pull back development of unexposed areas
     
  5. photomc

    photomc Member

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    Boy do I know this one...have had a round or two with dichroic fog. Best way I found to get rid of it was a weak Farmers solution and it did the job, just have to watch not to bleach the negative. I did a google for dichroic (or dichronic) fog and found a few places that metioned how to get rid of it...don't recall what they were though (sorry)
     
  6. MurrayMinchin

    MurrayMinchin Membership Council Council

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    (I usually did 40 4x5's per litre)

    Congratulations psvensson for giving the right answer! Please pick your prize from behind doors 1, 2, or 3 :smile:

    The good news is; that I've gone over 20 years without having exhausted film fix. The bad news is; that the first time it happened coincided with new film, in new developer, as the first SLIMT experiments began. The good news is; that just as psvensson suggested the negatives cleared right up in fresh fix.

    Thanks all for trying to help, I really appreciate it.

    Murray
     
  7. jnanian

    jnanian Advertiser Advertiser

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    if it is dichroic fog, it will be like a green metalic shiny film on your film.

    farmers reducer worked for me too...