FIXER - ammonium or sodium thiosulfate?

Discussion in 'B&W: Film, Paper, Chemistry' started by Lukas_87, Jun 3, 2009.

  1. Lukas_87

    Lukas_87 Member

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    Hello,
    can anyone tell me what's the difference between ammonium thiosulfate and sodium thiosulfate fixers?
    I know that sodium thiosulfate works slower and doesn't tend to bleach the image during prolonged fixing time.

    Someone says that Ilford has stopped producing sodium thiosulfate fixers since introduction of the Delta films because sodium thio. wouldn't fix these films "completely" so a ammonium thio. rapid fixers are need for safe fixing of these film - this doesn't make sense to me but I'm being scared of any non-archival processing (I'm young so I suppose my films just have to last long time before I die) because Ilford really writes in every datasheet of its fixers that they doesn't contain any sodium thiosulfate (hypo) at all.

    Can somebody help me about that before I finally order 25 kg sack of hypo? :smile:
    Thanks.

    ...please excuse my bad english, I'm still learning...
     
  2. nworth

    nworth Subscriber

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    Ammonium thiosulfate fixers are much faster, and they may wash out more easily. If you overfix (fix for too long a time), there is a chance they will bleach your prints (but not a big chance).
     
  3. Ian Grant

    Ian Grant Subscriber

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    You summed it up. Sodium Thiosulphate isn't as good with Tmax/Delta type films.

    Most people use Ammonium Thiosulphate fixers these days, at one time Rapid fixers used Sodium Thiosulphate and Ammonium Chloride but this is less efficient.

    Ammonium Thiosulphate or Sodium Thiosulphate are fine for archival processing of papers, you should do a test with a Sodium Thiosulphate fixer and the films you use. You can always add Ammonium Chloride to the film fixer.

    Commercial fixer like Hypam/Ilford Rapid fixer is reasonably economic.

    Ian
     
  4. Ian Grant

    Ian Grant Subscriber

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    Actually with some warm-tone papers it happens within 5 minutes.

    Ian
     
  5. sidearm613

    sidearm613 Member

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    Hi Lukas,
    I'm not that much of a chemist (I'm not much of a photographer either), but FWIW, they seem to smell a bit differently, if thats of any matter. The fact is though, that if you give ANY fixer long enough, it will bleach the image. Simple fact of life, there. Sodium thiosulfate will fix Delta, but the fixer time is long. I usually fix for 10 minutes, which is a good long time. So there you have it, any fixer will fix any type of film, except for films developed in pyro, which need an alkaline fix like TF-4. Buy whatever fixer you want, and if you are worried about your negatives with Delta, over fix by several minutes, because a few minutes won't bleach the film
     
  6. sidearm613

    sidearm613 Member

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    Ian, please tell me, because it is killing me, what is the difference between Hypam and Rapid Fix. I know Hypam can take a hardener, but aren't they both just ammonium thiosulfate?

    thanks
     
  7. Ian Grant

    Ian Grant Subscriber

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    It'll be the type of buffering, but for all practical purposes they are the same, an aluminium sulphate/chloride hardener needs a more acidic pH to work.

    Boric acid and Sodium Acetate are two typical pH buffers used in Fixers.

    Ian
     
  8. Dana Sullivan

    Dana Sullivan Advertiser

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    When I develop film, I use our in-house Rollo Pyro developer and fix in plain sodium thiosulfate, without any issues. What lead you to believe you needed a specially forumlated fixer?
     
  9. sidearm613

    sidearm613 Member

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    I can't speak for Rollo Pyro, but I can speak for PMK, which will vanish to nothingness unless an alkaline fix is used. Also, it isn't particularly specialized fixer, as it will work just fine as a standard rapid fix, albiet a non-hardening one. I am by no means a pyro wizard, I have never used Rollo, Tanol, or Pyrocat, or any bizarro dev (ABC comes to mind...), but I can tell you with fair convictions that most pyro developed negatives will not take kindly to ammonium thiosulfate.
     
  10. Ian Grant

    Ian Grant Subscriber

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    Fixers like Hypam/Ilford rapid fixer are fine with Pyrocat and some other staining developers the pH at 5.2/5.4 isn't that acidic so it's not a problem. But some acid fixers go to pH 3.

    Plain hypo fixers are fine for one off or very small volumes but they aren't efficient or robust for use where there is greater volumes and work-flow simply due to their lack of buffering.

    David, you're very wrong about Ammonium Thiosulphate as it's the basis of TF-3 & TF-4 and also thealkali colour fixers some people use for B&W work with staining developers & just as a general film or paper fixer.

    BTW Hypam uses additional Boric acid as it needs greater buffering capacity to prevent possible sludging (and reduction in hardening) caused by the Aluminium Sulphate if the pH goes past 5.5

    Ian
     
    Last edited by a moderator: Jun 3, 2009
  11. dancqu

    dancqu Member

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    The OP mentioned the Delta films. IIRC, the Delta films
    are thought of as being iodized. It is common knowledge
    that Rapid fixers Slow way down with such emulsions.
    Rapid fixers, with such films, become little faster
    than a sodium fixer.

    Fixer capacity is much reduced, Sodium or
    Ammonium. Dan
     
  12. Lukas_87

    Lukas_87 Member

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    so using TF-2 (alkaline sodium thiosulfate fixer) with Delta (or T-Max or Neopan) films should be OK and archivally stable?
    measured clearing time with Delta 400 is about 2 mins 15 sec and fixing for 10 minutes aren't problem for me (and it doesn't hurt film - everything looks good).
    the whole question is only about archival stability of modern films fixed by sodium thiosulfate, nothing else.
     
  13. mikebarger

    mikebarger Member

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    I started using TF-4 with 510 Pyro, but have since switched to Kodak fixer wilth no problems. Shipping water is just too expensive.


    Mike
     
  14. RalphLambrecht

    RalphLambrecht Subscriber

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    I tested this with Ilford MGIV and it was measurable after 8 minutes.
     
  15. dancqu

    dancqu Member

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    Look at it this way, for ourselves there is no substitute
    for thiosulfate. And it's been that way since the 1850s
    when it was discovered that thiosulfate will complex
    with silver and hold it in solution: that is, will make
    soluble non-image silver.

    Ammonia is the RAPID part of Rapid fixers. It alone
    will make soluble the chlorides of silver but does
    poorly with the bromide. It has very little effect
    on the iodide of silver. So, Rapid fixers are
    slowed in the presence of silver iodide.

    Sodium or ammonium, it is the thiosulfate which
    carries the load. Thiosulfate along with cyanide
    are two compounds which have great affinity
    for the silver ion.

    Rapid fixers became popular in the latter
    50s and 60s. Now days I use fresh brewed
    unadulterated S. Thiosulfate and use it very
    dilute one-shot, film and paper. Dan
     
  16. Lukas_87

    Lukas_87 Member

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    Thank you a lot, Dan!
     
  17. Philip Jackson

    Philip Jackson Member

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    In The Film Developing Cookbook, p. 105, Bill Troop says that “current research indicates that sodium thiosulfate … cannot adequately fix modern films or papers”, and in a footnote cites Haist, Modern Photographic Processing, and the following article:

    Lee, W. E.; Drago, F. J.; Ram, A. T. “New procedures for processing and storage of Kodak spectroscopic plates, type IIIa-J”, Journal of Imaging Technology, Vol. 10, No. 1 (Feb. 1984), pp. 22-28.

    This investigation into microspot formation on astronomical plates led to a new processing procedure and storage recommendations for enhanced image stability for these materials.

    Lee reports that the densitometric characteristics of plates images processed in Kodak fixing bath F-5 (sodium thiosulphate) and Kodak rapid fixer were virtually identical; however F-5 left significantly more silver halide in the emulsion layer, “indicating less fixing action” even with a total of 12 minutes in two baths of F-5 compared to 4 minutes for complete fixation with rapid fixer. Lee also found that the density loss with inadvertent prolonged fixation was proportionally worse with F-5, contrary to long held assumptions, and on the basis of these findings recommends that rapid fixer replace F-5 for this application.

    Lee does not conclude that fixing with sodium thiosulphate is “inadequate”, just that rapid fixer is better for this application. More research might be desirable before generalising the recommendations arising from this study to all modern photographic materials.

    Incidentally, Lee also found that hypo clearing agent had an adverse influence on permanence, as indicated by his accelerated peroxide microspot test. Later research demonstrated the benefits of a very small amount of residual hypo. Thus, current recommendations are not to use Hypo Clearing Agent for film, which should not be over-washed, and should definitely not be subjected to the HE-1 hydrogen peroxide-ammonia hypo eliminator.

    Lee also recommends a postprocess treatment of Kodak rapid selenium toner, although later research demonstrated that sulfiding treatments are superior (See for example the Image Permanence Institute study at http://cool-palimpsest.stanford.edu/byorg/abbey/an/an12/an12-5/an12-507.html).

    From a behavioral point of view, it might also be worth commenting that over-fixing is less likely if the process takes a relatively short amount of time; i.e. you're more likely to forget your film in a sodium thiosulphate fixer while you go off and do something else for the next ten or twelve minutes (even though you should be agitating the film in the fixing bath!), on the other hand, you're more likely to wait around for the precise time if you know the film needs to come out in three or four minutes!

    -Philip Jackson