Temperature range to avoid mosaic effect?

Discussion in 'B&W: Film, Paper, Chemistry' started by Marco Gilardetti, Jan 5, 2009.

  1. Marco Gilardetti

    Marco Gilardetti Member

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    Good evening fellows.

    Tap water here during winter flows at mean temperatures of 4-6 Celsius degrees (near freezing point, that is). I usually avoid developing anything until April because I fear to cause mosaic effect on gelatin, not to mention the fact that the wash itself would be partly inefficient.

    However, this winter I have taken pictures of my sister, who's waiting a baby, so I'd like do develop the film immediately to make sure everything is OK and eventually take the pictures again. If I wait and - say - find out that the shutter was broken, I'll have no further chance to take these pictures once again. So this time I am compelled to deal with very cold water during wash.

    Let's suppose I start with a developer at 18 degrees (not the usual 20) and then wash at 4 degrees. Is this range enough already (with nowadays emulsions) to cause a mosaic effect?

    In case, what should I try? Would it be better to develop with a colder developer (say 14-15 degs.), or trying to rise the wash temperature with the heater (which usually causes cycles of cold and warm water around an avarage temperature, which may be worse for the mosaic effect)?

    Film is Ilford FP4 by the way. Thank you very much for reading.
     
  2. trexx

    trexx Member

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    Regardless of the temperature it is best to have all chemistry and wash be the same temperature. It is wide differences in temperature that cause reticulation, mosaic, to occur.

    So set aside several liters of water in a warm place. When it has come up to room temperature, at least 18C, use it to mix the chemistry and for wash. Using the Ilford wash method you only need 1.5 liters for a .5 liter tank. ( fill 5 inversions dump, fill 10 inversion dump, fill 20 inversions dump)
     
  3. nyoung

    nyoung Member

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    Marco, I would try to get my developer, fix and wash temperatures closer together than 14 degrees. Prehaps you could preheat 4 to 6 liters of wash water to 15 degrees or so. Washing under the running tap is not absolutely necessary. With 6 liters of wash water you could fill, agitate for a minute or so, pour out, and then refill 6 or more times for the typical developing can.

    The mosaic effect you are talking about is generally not a result of temperature so much as it is the result of a sudden large change in temperature.

    Many people don't realize this but you can "hold" film almost indefinitely by leaving it sitting in a tank of water.

    You could also develop in your 20 degree developer and fix then fill your tank with water near that temperature. Then let the whole tank sit until it has cooled down enough to wash under your running tap.
     
  4. Ian Grant

    Ian Grant Subscriber

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    Reticulation is difficult to achieve with modern films except Adox/EFKE. However micro reticulation is a problem this increases the apparent grain and is caused by the sudden change in temperature, why not use Ilfords wash technique it uses very little water. Keep the wash within 1 ir 2 degrees of the rest of the processing.

    Ian
     
  5. Marco Gilardetti

    Marco Gilardetti Member

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    Thanks a lot for your replies so far.

    Where did you read about the Ilford technique? On their papers I've seen only the one involving the Ilford Washaid, but that requires running water as usual.

    Otherwise the last paragraph written by nyoung seems the best road to travel...
     
  6. Bob F.

    Bob F. Member

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    Sorry - getting confused here - not sure if you mean film or paper...

    For prints, RC can be soaked in 3 changes of water after 2 mins in wash-aid - change water every 5 minutes.

    For fibre, a quick rinse followed by 10 mins in wash-aid followed by 3 soaks for 10 mins each in water will do the job.

    The Ilford technique for film is: fill tank with water, 5 slow inversions; dump water and refill and invert 10 times; dump water and refill and invert 20 times. Some people like to repeat the 20 inversions again. It is in all Ilford's film datasheets and here: http://www.ilfordphoto.com/applications/page.asp?n=31 in the downloadable PDF.
     
    Last edited by a moderator: Jan 5, 2009
  7. Ian Grant

    Ian Grant Subscriber

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    The Ilford wash technique is in all their data sheets for films etc. Ilford say + or - 5 degrees but really you should be more accurate than that, you can let the temperature drift down slowly.

    Like Bob suggests I give slightly longer wash than Ilford recommend but it doesn't use much water.

    Ian
     
  8. Marco Gilardetti

    Marco Gilardetti Member

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    Okay, thanks for clearing it up.

    I as well, on my side, do think that's not enough for washing (without even a hypo eliminator, gosh...). Nonetheless, I'm sure adopting this technique in this specific case as I understand that a wash at 4 degs. would however be too low to really solute all the hypo in the film.

    On the other hand, letting the water temperature in the tank cool down gently may be an idea I should keep in mind for mid-seasons. For some reason, I've never thought about it.

    Thank you very much for your hints!
     
  9. Nicholas Lindan

    Nicholas Lindan Advertiser

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    It only takes 4 or so changes of water to completely wash film. For a 250ml tank you would only need 1 liter of room temperature water. 5 minutes for each wash, with good agitation - as if you were developing - is all that is needed.

    Common sense might say the wash times should lengthen with each change, but in fact they should remain constant as a perusal of the equations governing diffusion processes will show. Prolongation of the wash times will have no benefit and can only harm the film. Overwashing to the extent of removing 100% of the hypo will shorten the stability of the image, a trace of hypo is desirable.

    There is a lot of hysteria about washing times - like a fish story, they get longer and longer with each re-telling.
     
  10. Steve Roberts

    Steve Roberts Member

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    I have this situation through much of the winter. (When developing a roll of FP4 last Sunday the temperature of the tap water was 7 degs C.) My technique is to develop and fix at my usual 20 degs, then several short washes at progressively lower temperatures (4 or 5 degs) until I'm at ambient tap water temp, then the usual flow wash. The film stays in the water at each stage for as long as it takes me to mix water of the next lower temperature - perhaps 30 - 45 secs. Never had any problems.

    Best wishes,

    Steve
     
  11. dancqu

    dancqu Member

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    I'll side with Common sense and Ilford. The Ilford
    Sequence allows for increases in wash time with each
    change of water. Much of the fixer is removed with the
    first rinse. The second and third rinses each need more
    time. The fixer to be removed is located deep within the
    emulsion and is slow to migrate to the surface. Also,
    the body of water as the medium of diffusion is
    more throughly used. Dan
     
  12. Martin Aislabie

    Martin Aislabie Subscriber

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    I tend to do my film processing infrequently but in large batches.

    I therefore would need a store of 20C wash water the size of a bath to do all the film washing

    So I use cold tap water which in winter is 5C (ish)

    Reticulation is caused by thermal shock to the emulsion and base of the film producing differential contraction rates

    I minimised the thermal shock by after fixing filling the tank with 20C water then dribble in to my Dev Tank tap water at its 5C (or what ever)

    I use a forced film washer - so the water goes in at the bottom and comes out at the top.

    When the water coming out of the tank approaches the tap water temperature, I increase the flow rate.

    Then after a few more minutes I turn up the wash water flow rate to allow my cascade washer to do its turbulent flow thing and leave it.

    Washing in very cold water is slow, I at least double the wash times recommended to account for the lower water temp.

    I have never yet had Reticulation issues - but as the saying goes - there is a first time for everything

    Martin
     
  13. tac

    tac Member

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    It was years ago, so probably won't apply to today's emulsions, but as for letting film sit in wash water for extended periods of time, I have had emulsions fray and wash off of the base support after sitting in room temp. soak water overnight. Not sure, but I think it was TX back in the early 80's.

    Modern emulsions probably won't do that, but some (Efke?) may.
     
  14. Ian Grant

    Ian Grant Subscriber

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    All modern emulsions suffer from micro reticulation it's not the same as thev classic old reticulation, you might not even realise you have it.

    But then ask yourself why your negatives are grainier than someone else's with the same film/developer/times/agitation/EI etc. The only thing they are probably doing different is keeping their temperatures stable from developer to stop bath then fixer & wash.

    Ian
     
  15. Kirk Keyes

    Kirk Keyes Member

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    Ian - can you point to some examples of micro-reticulation so I can see what to look for?
     
  16. Ian Grant

    Ian Grant Subscriber

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    Micro reticulation is grain clumping rather than a problem with the gelatin as in conventional reticulations so it just looks like more grain than usual.

    There were some articles written about 20 years ago I think in Darkroom Technique, I have a copy somewhere back in the UK. Helen Bach would be able to give you further references but she seems to have stopped posting on APUG.

    Ian
     
  17. Kirk Keyes

    Kirk Keyes Member

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    Ian - Can you give a more authoritative reference than DT for grain clumping? I guess I can dig out my old copies and see what they say.
     
  18. Ian Grant

    Ian Grant Subscriber

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    Most of my information etc is in storage back in the UK so I can't look up references etc. There were some research papers but most people took little notice because most good pro's & labs etc keep their temperatures fairly tight in any case so would never come across it at all.

    As I said Helen Bach also refers to it occurring and we discussed it here on APUG a few times some time ago, and she would most likely have references. I only had 3 or 4 copies of DT so it must be roughly 86'ish maybe 87.

    Ian