Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 70,966   Posts: 1,558,413   Online: 895
      
Page 4 of 4 FirstFirst 1234
Results 31 to 37 of 37
  1. #31
    wogster's Avatar
    Join Date
    Nov 2008
    Location
    Bruce Peninsula, ON, Canada
    Shooter
    35mm
    Posts
    1,266
    Quote Originally Posted by octofish View Post
    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.
    I think that an insulated tank would be so that you would pour in developer at 39C and expect it to stay above 38C long enough to process a roll of film. One of the issues, the developing tanks we know and love, were designed for B&W film, where you usually used room temperature, measured the temperature of the chems, and used a time that matched. If you were to design a tank today for colour use, it would be designed quite differently.

    1) It would be able to maintain temperature for the duration of the process.
    2) It would not leak, for a steel tank with a steel lid, this is actually easy, put a neoprene ring in the lid, so that when the lid and top of the tank meet, the neoprene fills any voids.
    3) Would have a plastic top cap, on a spring over the filler hole. When filling and emptying the tank, you hold the cap open, otherwise the spring holds it closed. If pressure builds, the pressure pushes the cap up, and releases the pressure. We add a small weighted latch, so that when the tank is not sitting flat, the cap is held closed. You can still use inversion agitation, during the 5-10 seconds your agitating the tank, pressure isn't going to build enough, that during the 50 seconds it's sitting flat, it can't be released. Of course when pressure is released, you might burp a little chemical, but you can wipe that off with some paper towel.

    The fixing process, could change the temperature slightly, fixing, is not that critical temperature wise, it's development where temperatures are critical.
    Paul Schmidt
    See my Blog at http://clickandspin.blogspot.com

    The greatest advance in photography in the last 100 years is not digital, it's odourless stop bath....

  2. #32
    hoffy's Avatar
    Join Date
    Jan 2009
    Location
    Adelaide, Australia
    Shooter
    Multi Format
    Posts
    1,921
    Blog Entries
    1
    Images
    57
    So, after developing some film last night and then cleaning up the fix stains on the laundry floor this morning, I too have been wondering about leaky patterson tanks.

    So, this morning, I am going to try 3 wraps of teflon thread tape on the threads and see how that goes.

    The other though (& I am kind of suprised that one has mentioned it) is to use a standard industrial variety O ring in the lid of the tank. Surely, that will help with sealing, or am I missing something?

  3. #33

    Join Date
    Jun 2007
    Shooter
    35mm
    Posts
    984
    I think this may be the reason that some of us are surprised that so many have problems with Paterson tanks. The screw top versions (System III) were replaced far more than 25 years ago with the tupperware-lid style (System-IV). The sealing washers on the ancient tanks stand very little chance of still being pliable enough to work, if indeed they are still present - it was a grey, slide-in sort of ring if I remember rightly.

    My advice would be to find the newer tank version, but don't forget to keep the reel(s) from the old one as a spare because they are the same size. The new reels have mouldings to grip the central-core of the light trap so if the old reels slide around use an elastic band, or an original plastic clip from the old tank, to keep them in place.

  4. #34
    hoffy's Avatar
    Join Date
    Jan 2009
    Location
    Adelaide, Australia
    Shooter
    Multi Format
    Posts
    1,921
    Blog Entries
    1
    Images
    57
    Buy replacement tanks? You jest

    Actually, I have some relatively new tanks that are like the old Patterson ones. I also have a lot of older tanks that were given to me. I am sure its not going to be that difficult to stop the leaks. (its only been recently that they have leaked more then usual).

    My thread tape trick worked fine. Yes, I got a bit of leakage from the top cover during the stop and fix stage, but that was more residual fluid from the pour out then from agitation.
    Last edited by hoffy; 11-03-2012 at 07:48 PM. Click to view previous post history.

  5. #35
    Diapositivo's Avatar
    Join Date
    Nov 2009
    Location
    Rome, Italy
    Shooter
    35mm
    Posts
    1,844
    Quote Originally Posted by hoffy View Post
    The other though (& I am kind of suprised that one has mentioned it) is to use a standard industrial variety O ring in the lid of the tank. Surely, that will help with sealing, or am I missing something?
    I suppose O-ring gaskets would not work without a proper groove on the lid and on the tank.
    Fabrizio Ruggeri fine art photography site: http://fabrizio-ruggeri.artistwebsites.com
    Stock images at Imagebroker: http://www.imagebroker.com/#/search/ib_fbr

  6. #36
    Brian C. Miller's Avatar
    Join Date
    Dec 2010
    Location
    Everett, WA
    Shooter
    Large Format
    Posts
    495
    Blog Entries
    2
    Images
    13
    Quote Originally Posted by David Lyga View Post
    Coca-Cola can make a leak proof bottle for about 2 cents. So can multitudes of other manufacturers. Why cannot there be a film tank that absolutely, really and truly does not leak even one drop?

    And one that holds temperature like a Thermos?
    Let's see:
    Stainless steel tanks with steel lid: leaks. Why? No gasket. Not much, but it does. No big deal.
    Stainless steel tank with rubber lid: No leak.
    Patterson tank, plastic/rubber lid: No leak.
    Jobo tanks, using plastic/rubber lid: No leak.
    Jobo tanks, using cog lids: No leaks when attached to lift unit.

    Heat:
    Tanks go into tempered water bath. No problems.

    If you want to develop your film in a Coca-Cola bottle, remember to keep the lights off. If you want to develop your film in an insulated jug, which is just fine IMHO, you'll need to switch off the lights when changing chemicals.

    And remember, the Combiplan is far superior to the Yankee tank, which isn't sealable at all.

  7. #37

    Join Date
    Jul 2012
    Location
    North Yorkshire, England
    Shooter
    35mm
    Posts
    722
    A bit of a daft question really. Coke cans don't leak because they are for a one off task. Just try try-sealing one!!!!

    The only Dev tank I ever had leak was an ancient one 40-50 yrs ago where the only agitation was by a rotary process with a rod through the top and when it was upright. All my current tanks I use, ( 4 x Jobo [35mm & 120] 2 x Durst 35mm and 1 stainless 35mm) never leak provided the lids are put on properly. All it takes is a bit of care.

    As for losing temperiture, ANYTHING will cool down if left in a cooler place than where it was when it was first heated up

Page 4 of 4 FirstFirst 1234


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



Contact Us  |  Support Us!  |  Advertise  |  Site Terms  |  Archive  —   Search  |  Mobile Device Access  |  RSS  |  Facebook  |  Linkedin