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  1. #1

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    Proper Agitation for Metal Spiral Tanks

    I have always used toroidal agitation for my small tanks. I have the Paterson system and that seems to work just fine. I have recently started to use the old school metal tanks. I like them for dev. economy and ease of controlling temperature. However, the film on the inner part of the roll does not receive the same amount of agitation as the film on the outermost part of the spiral. That is --- the last frames of the roll. I posted this problem on the Film Photography Podcast forum on Flickr, but I would like to hear more weigh in on whether I should just give up the metal tanks all together. I have heard that it is best just to invert the tank with out the twist. This makes sense as it would seem that agitation would be more even as long as the axis of inversion is varied. What are your experiences and/or impressions?

    Thanks,
    Chris Maness

  2. #2
    MattKing's Avatar
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    If you are having trouble with uneven agitation, check that you are not over-filling the tank. You need to have some air in there - and there is less extra space in the metal tanks.

    I would suggest a mix of inversion and toroidal agitation.
    Matt

    “Photography is a complex and fluid medium, and its many factors are not applied in simple sequence. Rather, the process may be likened to the art of the juggler in keeping many balls in the air at one time!”

    Ansel Adams, from the introduction to The Negative - The New Ansel Adams Photography Series / Book 2

  3. #3
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    I always invert the tank upside down, and then give it a slight rotation as I turn it back right side up. Three of these takes about five seconds, so that's my routine, although the thought went through my head the other day that maybe I've been doing it wrong for 20 years.
    Parker Smith Photography, Inc.
    Atlanta, GA

    Commercial & Fine Art Photography
    Portrait Photography

  4. #4
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    What Matt said. 8 fl oz for single 35mm and 14 fl oz for single 120. It covers the reel (Hewes) and leaves the space needed.

  5. #5

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    Quote Originally Posted by MattKing View Post
    If you are having trouble with uneven agitation, check that you are not over-filling the tank. You need to have some air in there - and there is less extra space in the metal tanks.

    I would suggest a mix of inversion and toroidal agitation.
    I use exactly 236ml (8oz). That leaves the perfect air pocket that they were designed for.

    Chris

  6. #6

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    The periodic twisting motion is purpotedly to help break up laminar flow when combined with a quick inversion (gives a similar effect to nitrogen burst). I don't think it is necessary and never had problems without it. Too much twisting motion will indeed cause more development further away from the center of the reel. I suggest simple inversions. Just make sure each time you agitate you are inverting in a different direction.

    Regarding solution volume, more is always better. You don't need more than 1/4" or so of air space. Some people fill to the top without problems. I use a two-reel Kindermann Stainless steel tank. I do one roll at a time. The loaded reel is on the bottom, an empty reel on top as a spacer so the reels don't move, and I use 400ml solution. That leaves me about 1/4" to 1/2" air space.
    Last edited by Michael R 1974; 11-29-2011 at 02:43 PM. Click to view previous post history.

  7. #7

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    Quote Originally Posted by ParkerSmithPhoto View Post
    I always invert the tank upside down, and then give it a slight rotation as I turn it back right side up. Three of these takes about five seconds, so that's my routine, although the thought went through my head the other day that maybe I've been doing it wrong for 20 years.
    I am thinking that the twist causes the fluid to rotate faster around the outside of the spiral. Thus causing a slight but noticeable differential development.

    Chris

  8. #8

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    Quote Originally Posted by Michael R 1974 View Post
    The periodic twisting motion is purpotedly to help break up laminar flow when combined with a quick inversion (gives a similar effect to nitrogen burst when). I don't think it is necessary and never had problems without it. Too much twisting motion will indeed cause more development further away from the center of the reel. I suggest simple inversions. Just make sure each time you agitate you are inverting in a different direction.

    Regarding solution volume, more is always better. You don't need more than 1/4" or so of air space. Some people fill to the top without problems. I use a two-reel Kindermann Stainless steel tank. I do one roll at a time. The loaded reel is on the bottom, an empty reel on top as a spacer so the reels don't move, and I use 400ml solution. That leaves me about 1/4" to 1/2" air space.
    Thanks Michael, that is the best reply I have gotten so far. I have also thought of changing the axis of the flip by 90 degrees every other flip without rotating at all. I think this should cure the problem -- as I have been twisting the crap out of the tank ever inversion. I guess I am finding out that was a bad idea. Do you think I need to add a little time if I am not twisting?

    Thanks,
    Chris Maness

  9. #9

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    This is one of those topics that is easy to overthink. Just use Kodak's recommended method as given in the following citation. It has worked for me for all the decades that I have used it!

    http://www.kodak.com/global/en/profe...4027/j4027.pdf
    A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral.

    ~Antoine de Saint-Exupery

  10. #10

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    Chris: The only way to know is try the different agitation scheme with the same development time and see if an adjustment is required.

    The key to good agitation in any tank or tray, in any film format, is to try to keep the flow relatively random. Hence the changing of directions etc. But it doesn't have to be overly vigourous.

    Another thing to keep in mind - metal tanks transfer heat from your hands much more efficiently than plastic tanks, particularly during initial agitation, when you've got the tank in your hands for 30-60 seconds. And the first minute of development is when uneven development usually gets started. It might be overkill, but I keep some balled up paper towel between my hand and the metal (whichever hand is grabbing the metal tank - the other hand grasps the rubber top of the tank in my case, but if you have a metal top, try some paper towel in both hands). A tempering bath is good for when the tank is at rest.

    I would agree with Gerald in general though, don't get carried away with all this. Keep it simple.

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