Proper Agitation for Metal Spiral Tanks

Discussion in 'B&W: Film, Paper, Chemistry' started by kq6up, Nov 29, 2011.

  1. kq6up

    kq6up Member

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    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. MattKing

    MattKing Subscriber

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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.
     
  3. ParkerSmithPhoto

    ParkerSmithPhoto Subscriber

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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.
     
  4. MaximusM3

    MaximusM3 Member

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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. kq6up

    kq6up Member

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    I use exactly 236ml (8oz). That leaves the perfect air pocket that they were designed for.

    Chris
     
  6. michael_r

    michael_r Subscriber

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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 a moderator: Nov 29, 2011
  7. kq6up

    kq6up Member

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    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. kq6up

    kq6up Member

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    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. Gerald C Koch

    Gerald C Koch Member

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  10. michael_r

    michael_r Subscriber

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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.
     
  11. kq6up

    kq6up Member

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    @Michael This sounds good. I will have to shoot, soup a roll and report back.

    Chris
     
  12. Gerald C Koch

    Gerald C Koch Member

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    An excellent point to remember.
     
  13. ParkerSmithPhoto

    ParkerSmithPhoto Subscriber

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    I bought a white two gallon plastic paint pail ($4 at Home Depot) that I fill with water for a water bath. After processing, I use the water to wash the film, then when empty, I use it to store all the graduates, etc.
     
  14. kq6up

    kq6up Member

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    Well everyone. After testing -- simply inverting the tank (metal reel tank) and alternating the axis of rotation every 90 degrees every other flip worked MUCH better than torodial agitation. The negs looked indistinguishable from beginning to end.

    Thanks for the Help,
    Chris Maness
     
  15. jvo

    jvo Subscriber

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    used this method - 20 years+, may be wrong but works for me too!!!

    someone else said, "don't overthink" - good advice.
     
  16. JBrunner

    JBrunner Moderator Staff Member Moderator

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    Invert-de-invert-turn-invert-de-invert-turn-invert-de-invert-turn...that's how I roll.
     
  17. jnanian

    jnanian Advertiser Advertiser

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    i always agitate in the shape of a figure 8 ...
     
  18. JBrunner

    JBrunner Moderator Staff Member Moderator

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    Everybody knows my method is the best! Anybody who does it differently and gets good results is just plain lucky. Sure, a figure eight might work good for you, but that's only because you are probably swirling it fast enough to generate random Von Karman vortices. Not everyone has your forearm strength, you know, and studies have shown that Von Karman vortices, while setting up sufficient agitation, can in fact introduce micro-reticulation in certain maniform sections of carbon based films, particularly if one does not consider the weak anthropic principle. Fool! I can't believe I even hang around here!


    Oh wait, were talking about agitation, not agitating. Sorry John. I've been monitoring some threads that are pretty much like that. :smile:



    ...Seriously, I think there are probably as many ways to agitate as there are agitated analog photographers. The one that you find works for you, is the right one. Probably because everybody is different. A unique snowflake.
     
  19. michaelbsc

    michaelbsc Member

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    Jeez, now Jason is calling me a snowflake. (I'm sure it was a personal attack even though I haven't posted in the thread. I can just tell these things.)

    Damn, where are the moderators when you need them.

    Oh wait, he is one.
     
  20. kq6up

    kq6up Member

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    Well, my purpose for posting the original question was met. How do I agitate a spiral tank to get even development. I now know.

    Chris
     
  21. jnanian

    jnanian Advertiser Advertiser

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    yeah i know what you mean i sometimes get micro reticulation and hear the voices when i process my film,
    ... the voices are usually telling me to --- Invert-de-invert-turn-invert-de-invert-turn-invert-de-invert-turn,
    and do the hokey pokey, but i tend to ignore the voices just the same
     
  22. michael_r

    michael_r Subscriber

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    I saw a guy once doing that rolling thing, but then the tank rolled off the counter, so it ended up being burst agitation.