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Thread: Gas Burst Chemistry Oxidation Questions

  1. #51

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    Re: Gas Burst Chemistry Oxidation Questions

    Something else to consider is that Kodak were not terribly keen on gas burst deep tanks without significant additional manual agitation for either E-6 or C-41 - gas and manual agitation for C-41, gas was actively advised against for any roll format for E-6 - rack and tank dip/dunk are fine because they mechanically agitate and gas burst. While the non-uniformity might be less with BW, you might want to consider that the critical development stages in both processes are not that different from BW film. What worked OK for large batch, high throughput BW sheet film processing (with relatively low image quality standards demanded, owing to lack of enlargement/ purposes other than fine-art photographic quality) in the 1940s/50s with relatively much lower technology BW emulsions, may not work as well with more complex, modern structures. Development uniformity was well studied by Kodak etc - hence why they don't recommend stand processing either.

  2. #52
    Tin Can's Avatar
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    Re: Gas Burst Chemistry Oxidation Questions

    I have 3 questions

    What do you use?

    Do you own a JOBO system?

    Have you used Gas Burst?


    Quote Originally Posted by interneg View Post
    Something else to consider is that Kodak were not terribly keen on gas burst deep tanks without significant additional manual agitation for either E-6 or C-41 - gas and manual agitation for C-41, gas was actively advised against for any roll format for E-6 - rack and tank dip/dunk are fine because they mechanically agitate and gas burst. While the non-uniformity might be less with BW, you might want to consider that the critical development stages in both processes are not that different from BW film. What worked OK for large batch, high throughput BW sheet film processing (with relatively low image quality standards demanded, owing to lack of enlargement/ purposes other than fine-art photographic quality) in the 1940s/50s with relatively much lower technology BW emulsions, may not work as well with more complex, modern structures. Development uniformity was well studied by Kodak etc - hence why they don't recommend stand processing either.
    Tin Can

  3. #53

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    Re: Gas Burst Chemistry Oxidation Questions

    Of the methods I looked at, for B&W negative sheet films I found, to my surprise, classic hand shuffling in open trays to be one of the better methods when it comes to development uniformity. It was one of the ways Kodak often recommended, and really can work very well with some practice and care.

    Most of the high volume/commercial processes including dip/dunk and gas burst were compromises.

    As someone pointed out earlier, these systems had to be pretty carefully designed etc. I suppose back when these things were more commonplace, there were likely some pro labs that had well designed/engineered systems. In more recent times it would undoubtedly have been more sketchy, and I found this to be the case with two dip/dunk labs I sent B&W sheets to. Uniformity was horrendously bad.

    Another important thing to consider is how good does good need to be? I was using a very stringent test method - uniformly flashed film. This will obviously reveal even small artifacts which might not be visible or noticeable under photographic conditions. And the more “busy” the photograph, the more non-uniformity you can get away with. I think in many cases (as is often the case with photographic processing - particularly B&W), people just don’t notice non-uniformity unless it is really, really bad. Similar to other technical aspects of the photographic process such as EI, tonality/tone reproduction, developers etc., are we getting what we think we are getting? Often, the answer is no. However when it comes to B&W at least, there is enough flexibility in the end-to-end process that great prints can be made even under a variety of circumstances.

    Quote Originally Posted by interneg View Post
    Something else to consider is that Kodak were not terribly keen on gas burst deep tanks without significant additional manual agitation for either E-6 or C-41 - gas and manual agitation for C-41, gas was actively advised against for any roll format for E-6 - rack and tank dip/dunk are fine because they mechanically agitate and gas burst. While the non-uniformity might be less with BW, you might want to consider that the critical development stages in both processes are not that different from BW film. What worked OK for large batch, high throughput BW sheet film processing (with relatively low image quality standards demanded, owing to lack of enlargement/ purposes other than fine-art photographic quality) in the 1940s/50s with relatively much lower technology BW emulsions, may not work as well with more complex, modern structures. Development uniformity was well studied by Kodak etc - hence why they don't recommend stand processing either.

  4. #54

    Re: Gas Burst Chemistry Oxidation Questions

    Quote Originally Posted by interneg View Post
    Something else to consider is that Kodak were not terribly keen on gas burst deep tanks without significant additional manual agitation for either E-6 or C-41 - gas and manual agitation for C-41, gas was actively advised against for any roll format for E-6 - rack and tank dip/dunk are fine because they mechanically agitate and gas burst. While the non-uniformity might be less with BW, you might want to consider that the critical development stages in both processes are not that different from BW film. What worked OK for large batch, high throughput BW sheet film processing (with relatively low image quality standards demanded, owing to lack of enlargement/ purposes other than fine-art photographic quality) in the 1940s/50s with relatively much lower technology BW emulsions, may not work as well with more complex, modern structures. Development uniformity was well studied by Kodak etc - hence why they don't recommend stand processing either.
    As should be the case, factual first hand personal experience as it directly relates to processing results is the only thing that matters. My goodness how far we have come. I can very effectively do stand and semi stand development in gas burst tanks with multiple sheets of film in hangers which was the classic recipe for disaster from Kodak.

  5. #55

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    Re: Gas Burst Chemistry Oxidation Questions

    I've got a mountain of equipment I've accumulated over the last 40 years. I have old Jobo, I have new Jobo. The CPP3, is a very well built machine, with the lift it's pretty straight forward. No where in the very sparse instructions (literally a photocopied sheet) is there adequate discussion of understanding temperature in the tank throughout the process.
    The only way it stays at 100 +/- 1/2 °F is if the room and everything else is at 100 F. If I'm working in my darkroom @ 19°C or cooler in winter, even if I prewarm, prewet, have chemistry at temp. The lift is still cold, uncontrolled etc.
    The only way for a Jobo to be able to be dead on, would for there to be some sort of closed loop process. That would take instrumentation in the tank, in the lift chute and the appropriate software etc..
    I have a Arkay set-up that can handle E6 7 solutions in 2 gallon or C41 up to 4 3.5 gallon tanks. It's all heated, big circulation pump. It's deadly accurate, IF, you follow the Kodak gospel on using hangers, print baskets etc. The old Kodak had you use scrap paper and the hangers, baskets etc to understand what the environment of the darkroom had on temperature.
    Only huge masses of liquid can be held relatively constant. You need a water bath to develop roll film in Nikor stainless tanks. My Bearpaw hands will heat up a stainless tank.
    For me the biggest issue with big tanks is replenishment, which is impossible without the discipline of control strips and a densitometer.

    I don't have the volume of film to do much other than use oversize (larger than required) Jobo tanks, a water warm up presoak (even Jobo is recommending this now) I use 1 liter solution volume. Try to keep everything consistent.
    I think this is what Tin Can is doing with one shot, 2 gallon of Rodinal, which I'm going to try at sometime because I love Rodinal, I love XTOL too. With air for the gas in black and white, the Rodinal or something like D-23, seems to be a very workable solution.

    I like getting bargains on equipment. Otherwise I would be downstairs right now with my 4x5 hard rubber tanks developing film in, the old days, HC-110 Dilution B.
    Peace, stay well.

  6. #56

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    Re: Gas Burst Chemistry Oxidation Questions

    Quote Originally Posted by Michael Kadillak View Post
    As should be the case, factual first hand personal experience as it directly relates to processing results is the only thing that matters. My goodness how far we have come. I can very effectively do stand and semi stand development in gas burst tanks with multiple sheets of film in hangers which was the classic recipe for disaster from Kodak.
    Yeah, you must be doing something wrong if you're getting good results

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