PMK dilution

Discussion in 'B&W: Film, Paper, Chemistry' started by noseoil, Oct 4, 2004.

  1. noseoil

    noseoil Member

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    I want to change the activity level of PMK for an experiment on film development. Contrast is too high and times are getting short (5:15 at this point and I'm concerned about dropping below 5:00). Has anyone done any work with dilutions and PMK?

    I'm thinking I should reduce the concentration from 1:2:100 down to about 1:2:125 to increase development times but maintain the same contrast level of the working solution. How does this sound, any suggestions?
     
  2. Loose Gravel

    Loose Gravel Member

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    I don't think extra water is the answer. If you are doing sub-normal developements, try reducing the B-part 25%. I haven't tried this, but I hear it is what Hutchings recommends. If you are trying to maintain contrast in the low end with sunglints coming into the picture, such as a church interior, or with some other scene that might have been exposed in a condition of reciprocity failure, then try splitting the A and B parts completely. Let me explain, as I've done this.

    When I have a scene that might call for normal minus 4 or 3, such as an interior with highlights or a deep woods picture, I use a PMK in a split form. These sometimes have exposures of many minutes, but have highlights that might blow out if developed in a normal way. In this case I soak the film in A-part concentrate. NO DILUTION. This soak probably takes 4 minutes. Then this is drained off completely (SAVE IT, IT IS STILL OKAY as A-part) and develop with the B-part diluted as usual. You will have to experiment for times. This is a split developer with PMK and it works great, just be sure to save the A.

    I do this in a Jobo 3000 series drum with 5x7 or 4x5 film. If gives good scale in the shadow details, and saves the highlights from being bulletproof.
     
  3. Ed Sukach

    Ed Sukach Member

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    Just as a "sidebar" ...

    I consider this proscription against developing times of less than five minutes to be a myth.

    I know.. I've read it carved in stone, but color negative film, with the C41 process is regularly develeped for 3' 15"; three minutes and fifteen seconds... without "pre-wetting" (specifically says NOT to prewet in the instructions!!), without uneveness ... and color is thought to be more sensitive than black and white. Irving Penn in "Worlds in a Small Room" wrote that he "mostly" used Tri-X; ".. development was usually in Ethol UFG, 3 to 5 minutes at 68 degrees F.", so apparently he wasn't an adherent of the "not less than five minute" rule either.

    I will admit that I do not use times less than five minutes (eight, actually) but that is only because I am too cheap to use strong developing solutions ... 1:50 (Rodinal) is very good in my opinion.

    Only a comment...
     
  4. Greg Rust

    Greg Rust Member

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    Loose Gravel,

    Thats a great idea. I'm going to try it. Do you presoak in water before the part A bath? If not, does the part A bath turn a color from the film backing?

    Thanks,
    Greg
     
  5. Loose Gravel

    Loose Gravel Member

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    Don't soak in water, or the film won't take up any developer. The only developer is what stays behind in the film.

    Mine has never shown the color of the backing. Don't know what happens there.

    I use HP5+.
     
  6. noseoil

    noseoil Member

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    1:2:120 helped tame things a bit last night. This seems to be the correct direction so I will continue. Thanks, tim