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Thread: Developing tank advice

  1. #51

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    Re: Developing tank advice

    Bromide as a development restrainer/inhibitor is only one of several things that causes “drag” artifacts, and only one of several things that may or may not contribute to development non-uniformity (various forms) in general.

    Also note that even concerning bromide ion specifically, it is released by the silver halide crystals in the film emulsion itself during development as silver bromide is reduced to metallic silver. So, even if the developer formula contains no bromide, bromide will build up as development proceeds (unless of course the emulsion contained no silver bromide, which is never the case with film).

    Quote Originally Posted by tundra View Post
    OK so, to followup on this... Yesterday I mixed up a batch of Pyrocat-M and processed two sheets of exposed film using the Kodak frame hangers to suspend them in a 1/2 gal Kodak rubber tank.

    There are still definitely development byproducts visible along the edge of the film that was at the bottom of the tank. IOW, even removing the KBr from the developer does not fully solve the low agitation development artifact problem.

    It's worth noting that I Semistand developed this for an hour with an initial 2min of agitation and one midpoint agitation. I suspect that had I done EMA, this would not have been an issue.

    I think the term "bromide drag" really refers to all byproducts of the development process not just those attributable to the KBr in solution.

    I therefore will continue to use pinch/minimal contact support for all my low agitation development.

    As an aside, it was hard to come up with a canonical formula from Pyrocat-M. Some formulae call for 25g of Metol/liter (!) and some just 2.5g/l. Sandy King's original article called for 10 parts Metol for every part of the Phenidone it is replacing, which would put it at 20g/l. I went with 2.5g/l and got solid negatives a full film speed with Agfapan APX 100 sheet film. I'd love to know why there is such variability in the formula though ....

  2. #52

    Re: Developing tank advice

    Quote Originally Posted by Michael R View Post
    Bromide as a development restrainer/inhibitor is only one of several things that causes “drag” artifacts, and only one of several things that may or may not contribute to development non-uniformity (various forms) in general.

    Also note that even concerning bromide ion specifically, it is released by the silver halide crystals in the film emulsion itself during development as silver bromide is reduced to metallic silver. So, even if the developer formula contains no bromide, bromide will build up as development proceeds (unless of course the emulsion contained no silver bromide, which is never the case with film).
    Yes, this was my understanding as well. However, someone here suggested I try Pyrocat-M since it has no KBr to see if this reduced the propensity for drag. It did not, and I am unsurprised.
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  3. #53

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    Re: Developing tank advice

    If you ever developed a sheet of ortho film in a tray under safelight, you have seen a cloud of a fuzzy beard over heavily exposed areas... This "cloud" contains a combination of superaddivate components (that increase development) and bromide & by-products that inhibit development... Agitation moves these back into the solution to normally average out development...

    Now, a developing tank is a confined space with support ribs to hold film, and film near other film etc... The "clouds" can easily drift over to other film areas where their "effect" can be easily seen (like skies, edges etc), so normal ideal agitation involves getting these "clouds" away from the films back into the solution... Too little, and the clouds remain near film, too much, and the surging of solutions can band them together (like a river) over one area and leave trails...

    "Clouds" are more dense in less diluted developers due to more local development action, but less dense in more diluted solutions so in the confines of a tank, it will be easier to diffuse the thinner clouds more diluted...

    Stand and semi-stand processing depend on less clouding and usually vertical placement while processing, where gravity assists the clouds to roll off areas and diffuse back into solution (hopefully)... As mentioned, film and supports can impede this process, so design of the tank is important... And method of agitation (not too little/not too much) is crucial for success... Follow the daylight tank's manufacturers directions carefully for a starting point...

    As a general point, agitation methods that allow daylight tank to be inverted during agitation help a lot...

    Steve K

  4. #54

    Re: Developing tank advice

    Quote Originally Posted by LabRat View Post
    If you ever developed a sheet of ortho film in a tray under safelight, you have seen a cloud of a fuzzy beard over heavily exposed areas... This "cloud" contains a combination of superaddivate components (that increase development) and bromide & by-products that inhibit development... Agitation moves these back into the solution to normally average out development...

    Now, a developing tank is a confined space with support ribs to hold film, and film near other film etc... The "clouds" can easily drift over to other film areas where their "effect" can be easily seen (like skies, edges etc), so normal ideal agitation involves getting these "clouds" away from the films back into the solution... Too little, and the clouds remain near film, too much, and the surging of solutions can band them together (like a river) over one area and leave trails...

    "Clouds" are more dense in less diluted developers due to more local development action, but less dense in more diluted solutions so in the confines of a tank, it will be easier to diffuse the thinner clouds more diluted...

    Stand and semi-stand processing depend on less clouding and usually vertical placement while processing, where gravity assists the clouds to roll off areas and diffuse back into solution (hopefully)... As mentioned, film and supports can impede this process, so design of the tank is important... And method of agitation (not too little/not too much) is crucial for success... Follow the tank's manufacturers directions carefully for a starting point...

    As a general point, agitation methods that allow tank to be inverted during agitation help a lot...

    Steve K
    Interesting. In my case, I am using pinch support at the top of the film and nothing elsewhere in 1/2 gal open rubber tanks. This seems to eliminate drag effects completely in all films (except one very old batch of 2x3 Plus-X). I am presoaking for 3 mins, initially agitating for 2 mins continuously, and then agitating for 15 sec at the 31 min mark for a total development time of 60mins at 20C.
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  5. #55

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    Re: Developing tank advice

    I use dip & dunk tanks myself, and it works well... I was taught agitation takes a knack where the lift is not too fast, hangers are tilted over 45 with a slight pause, and re-inserted not too fast to prevent surging...

    Having a rack or something that holds hangers from going astray (or the right way to hold all together evenly) helps a lot!!!

    Works well!!!

    Steve K

  6. #56

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    Re: Developing tank advice

    Quote Originally Posted by Michael R View Post
    Here's one of mine. No laughing!Attachment 221862
    What's going here. Please show us more.

  7. #57

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    Re: Developing tank advice

    Quote Originally Posted by Duolab123 View Post
    What's going here. Please show us more.
    Hi Duolab123,

    It’s a rotary development device I made (4x5). Hand cranked.

  8. #58

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    Re: Developing tank advice

    Quote Originally Posted by Michael R View Post
    Hi Duolab123,

    It’s a rotary development device I made (4x5). Hand cranked.
    Very nice.

  9. #59

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    Re: Developing tank advice

    Quote Originally Posted by Duolab123 View Post
    Very nice.
    Thanks. It was lots of work designing and testing but this final prototype works wonderfully. Perfect development uniformity, no artifacts/risks, easy to use. It only does up to 4 sheets at a time, but that’s perfect for me. It is one of a few different types of things I came up with on a deep dive into agitation/uniformity recently.

  10. #60
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    Re: Developing tank advice

    Combi tanks hold 6 sheets. not made anymore. Yankee made some years ago. both are day light 4x5 tanks. a table top film tent would be needed to load film into tanks.

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