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  1. #21
    David Lyga's Avatar
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    Bob D659 does, indeed, bring up a valid point in that the development process does release gas. But, so does carbonated soda. That is why there had to be a truly leak proof container made for soda. Enough did not 'complain' that the same should have been done for 'mere' darkroom nuts.

    And, Ken Nadvornick, there is a valid point here about the desirability of using a material such a stainless steel that AIDS in conducting temperature (ie, water bath). But, still, there are some who would like a truly leak free tank.

    And Gerald C Koch, I am not saying that you are wrong with your SS tank with plastic top being entirely leak free, but I would like to put it dry upon a towel, without your water bath, and see it stay dry. I have my doubts but it might be as you say. In a water bath you would never notice a leak. And you could not prove this by merely putting food coloring in water to see if any color came out into the water bath. As I just confirmed Bob D659: there is a pressure build up that 'forces' leaks in the development process. - David Lyga

  2. #22

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    Not sure that a well insulated tank would be that useful. Unless you temper it very accurately - which is a pain to do - you will get a temperature change when you put chems in anyway. Tempering will be impossible from the outside (it's not even all that feasible using a normal plastic tank - takes too long), which pretty much means you need to prewet whether you want to or not.

    The other option is estimating the expected temperature change, which is necessarily uncertain. You can always measure inside the tank with a thermometer to work out where you are, but then if you are wrong, how do you get the tank temperature to where it needs to be, if the tank is well insulated? A water bath will be ineffective.

    Also I believe some proceses (fixing?) result in a bit of a temperature change by their nature, in which case you're stuck where you end up as a result of that. Could be wrong about that though.

    Of course, this is all if you care about that level of precision. If you don't, then a plastic tank is pretty much good enough anyway.

  3. #23
    MattKing's Avatar
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    It occurs to me that very few in the beverage bottling industry see much need for a bottle that is both light tight and enables rapid dumping and filling of liquids.

    So I'm not sure that is a great source of comparison.
    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

  4. #24
    eddie's Avatar
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    Quote Originally Posted by MattKing View Post
    It occurs to me that very few in the beverage bottling industry see much need for a bottle that is both light tight and enables rapid dumping and filling of liquids.
    They also need to open and close only about 5-6 times. And, they only have one cap. A developing tank has two.

    I would like to see a stainless tank with deep screw top threads, on both lids. Kinda like my martini shaker...

  5. #25

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    Quote Originally Posted by paladin1420 View Post
    A Question:
    The plastic lid on my double reel SS tank has a crack in it and leaks, does anyone know if these can be replaced?
    Here's another brand sold by B&H:
    http://www.bhphotovideo.com/c/produc...h_Cap_for.html
    I don't know if this is really the same as the Samigon posted earlier.
    The price is $2 higher, so it must be better.

    Mark Overton

  6. #26
    Diapositivo's Avatar
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    Quote Originally Posted by bobwysiwyg View Post
    I use the much maligned Combiplan with no leaks. I have say though, initially I did until I figured out the issue. You press the lid on thinking it is tight and secure, dribbles persisted. Because the lid is softer rubber it "grabs" a bit and doesn't really secure, water tight unless you apply a good deal of pressure all the way around. I do it by pressing the tank bottom to my chest, then working my fingers around the rim firmly press the lid against the rim of the tank. No leaks since and I do inversion agitation.
    I do the same but I press the tank on a table and I press with my weight on it. I really press hard checking all the rim is well pressed. The "click" is not enough as experience shows.

    That work but a thermic flask design would probably be better for inversion use. I use open tanks (Jobo with "lift") so I don't think I would have a substantial advantage in using such a design.

    I would advice against trying with a thermic flask as developing produces gases and thermic flasks don't have a vent they could, who knows, "explode".
    Last edited by Diapositivo; 10-15-2012 at 05:01 AM. Click to view previous post history.
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  7. #27

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    The problem with JOBO tanks popping the lid off can be cured by using a red hot needle to piece the top cap. This allows the release of the gas pressure caused by mixing the developer and blix. If you use the inversion technique it is a simple matter of putting a small strip of adhesive tape over the hole, or even simpler, use your index finger. With the cap intact, I have never had a jobo tank leak. I also have a quite old 120/35mm Jobo tank with a screw top and the red top is of a different design but this has the hole already made.

    I also have tanks made by Durst (Centre loading plastic) and unnamed stainless and non of these leak , - I must be unique, but when they are in use, they stand in a bath of warm water. So if there was a leak it may go un-noticed, but mine don't anyway.

  8. #28
    David Lyga's Avatar
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    eddie said (concerning soda bottles): "They also need to open and close only about 5-6 times."

    I take issue with that inferred lack of durability. I regularly use these same bottles for storing developer, stop, and fixer and have used the same bottles for YEARS. The caps never wear out and the tightness of fit remains intact. - David Lyga

  9. #29
    Thomas Bertilsson's Avatar
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    I use SS tanks for the reason of being able to use Hewes reels, because they are unbelievably good. A pleasant side effect was/is what you're describing - thermal transfer from surrounding water bath to temper processing solutions to perfection. I use very little water by simply dipping my thermometer into the water bath, and pour in small amounts of warm water as the temperature drops more than a half degree below my 70 degree processing temp. Works swimmingly well.

    And, with the plastic lid my stainless steel tanks do not leak.

    Quote Originally Posted by Ken Nadvornick View Post
    Single-walled stainless steel tanks are preferred precisely because of that thermally conductive property. That very characteristic is what makes precision temperature control in a tightly maintained water bath possible. Very low thermal inertia. Contained liquids respond very quickly to changes in external water bath temperatures.

    In my own case I maintain water bath temperatures using a Hass Intellifaucet K250. Marvelous temperature control possible using this precision tool. In the winter I often set the Intellifaucet to, say, 68.4F to counteract the slight loss of solution temperatures resulting from the colder darkroom ambient air temperature. Single-walled stainless is what makes this possible.

    What needs to be insulated is not the stainless steel processing tank (or tanks). It's the container holding the water bath in which they sit. That's the common reference point that you don't want to drift. I would never use plastic processing tanks. Too difficult to precisely adjust. Especially for color.

    This particular behavior isn't a bug. It's a feature.

    Ken
    "Often moments come looking for us". - Robert Frank

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  10. #30

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    One note about the Jobo tank lids; for C41 processing where one expects some expansion from the tank the red lids are designed to be pushed, or popped, inwards before being put on the tank. The gas produced during processing then pops the centre of the lid back out again whether using rotation or inversion agitation.

    For the Paterson System-4 tanks with the one-piece "Tupperware" style lid I just fart the lid, in the same way that one does during putting it on initially, except in between the inversions. In that way the pressure is prevented from building up, note that nitrile gloves are a good idea for this as there can be splashes depending on the pressure released.

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