Stop bath for printing - water or something else?

Discussion in 'B&W: Film, Paper, Chemistry' started by pauldc, Aug 31, 2005.

  1. pauldc

    pauldc Member

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    When developing film I use a water stop bath and this works well. Is there any reason not to use a water stop bath for paper (both RC and fibre based) when printing?

    I did a search of the archives looking for an answer but nothing came up. Any thoughts gratefully received.

    Paul
     
  2. Donald Miller

    Donald Miller Member

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    Prints have the potential of carrying much more developer to the stop bath. Since you are planning on using water, you will quickly contaminate the water bath and then transfer developer to the fixer. This will lead to rapid deterioration of the fixer.
     
  3. Monophoto

    Monophoto Member

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    I also tend to use water as a stop in dveloping film, but an indicating acid stop when printing. There are several reasons for this.

    First, one of the main reasons for a stop is to provide a means of adjusting the pH of the film between developer and fix. Developer is a base, while fix is acid. If you use a plain water stop, it will quickly become a weak base. Then, when you move the print to the fix, the collision between base and acid results in the fix being neutralized. Using an acid stop minimizes this effect and makes the fix last longer. Fixer life is very important when printing because it's so easy to lose track of how many sheets of paper have gone through the bath.

    For this reason, the stop that I use in printing is also an indicator stop that changes color when it approaches a neutral pH. That way I know when it's nearing the end of its useful life.

    Another reason for an acid stop is that it brings the development action to a rapid conclusions. A plain water stop cause the development action to "coast" to a stop - that's fine when developing film, and may actually be advantageous. Paper is much more foregiving that film and can put up with the "abuse". But more importantly, stopping the development action abruptly makes it easier to tone the finished print - if you use a plain water stop, toned prints may have a mottled appearance since the duration of development will affect the visual appearance of the toned finished product.

    Louie
     
  4. Ole

    Ole Moderator Staff Member

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    The only time I use an acid stop is when lith printing. In that one case it is important to stop development immediately at the right point, and nothing does that as well as an acid stop.

    For everything else I use plain water. Paper is developed to conclusion (which it should be in all cases except lith prints), so any developer action in the "stop" - or even the fix - is irrelevant.

    I also use alkaline fix (again: For everything except lith printing), so there is no reason to change the pH from alkaline to acid before the fixer.

    Furthermore: pH has very little influence on the activity of the fixer. Adding alkali to an acid fix will neutralise the pH, but not the thiosulfate!
    If you are really worried about damaging the fixer I will suggest doing without the stop altogether, and replace the fixer as soon as it is visibly brown. That way you will never overuse it.

    In the one case where I do use a stop, I use about 10g citric acid (supermarket grade) in one liter of water. The cost is so low that I make a new one for every session.
     
  5. psvensson

    psvensson Member

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    I'm with Ole here. The fix doesn't stop working if it's neutralized, or even if it turns alkaline, as evidenced by the alkaline and neutral fixers out there. It the fix has hardener that may stop working when the ph rises, but you only need hardening in a few circumstances anyway. I use a water tray that I replace every few hours and a neutral fix.
     
  6. seadrive

    seadrive Member

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    Okay guys, I need some enlightenment here. Why should today be any different, right? :smile:

    Other than the smell, what's so terrible about using an acetic acid stop bath?
     
  7. Ole

    Ole Moderator Staff Member

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    The smell isn't enough for you? :surprised: :surprised:

    Acetic acid drops the pH lower than it should be, increasing the risk of damaging the emulsion due to differential contraction (leading to reticulation). Acetic acid without additives is also poorly buffered: It stops working suddenly.

    Citric acid is "self-buffering" to a certain extent, and also smells much nicer. Gram for gram, the capacity is greater. And I also find it much easier to avoid spilling the little citric acid crystals than to avoid spilling corrosive liquids. But that may be just me...
     
  8. MurrayMinchin

    MurrayMinchin Membership Council

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    I use a water stop for both FB paper and film, with TF-3 (an alkaline fix) for both. No problems with fast fixer exhaustion, or smell :smile:

    Murray
     
  9. Don Mills

    Don Mills Member

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    Yes Murray. It's effective and cheap. I love cheap!!
     
  10. jim appleyard

    jim appleyard Member

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    What Ole and Murray have said!
     
  11. esanford

    esanford Member

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    This may be a scientific truth, but I have been using 2% acetic stop bath for 20 years and I have not reticulated a film or damaged an emulsion... I don't use indicator stop bath because I don't trust it. The key is dilution. I dilute stop bath for films 1:31 with 2% acetic acid. Stop bath for prints is diluted 1.5:31. I am very careful to make sure that the stop bath and fixer are all +- 3 degrees from the developer. Stop Bath is discarded after every film or print developing session. Reticulation is caused more by the difference in the temperatures then any other source. I only use FB paper so I don't know the impact on platic resin coated papers.

    Getting to the question, I use a stop bath because it halts the developer. If I develop something for 2 minutes, I want 2 minutes... not 2 minutes and 10 seconds or 20 seconds. That level of precision lets me isolate other problems. Finally, the stop bath extends the life of the fixer... especially for prints. With films I develop no more than 7 rolls of film in one quart of fixer. With prints, I process no more then 75 prints in 1 gallon of fixer. I got this routine from Fred Picker's Zone VI workshop... A 30+ year old text that is still worth having....
     
  12. seadrive

    seadrive Member

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    Here's what it says on the bottle of "Sprint BLOCK Stop Bath (buffered, vanilla-scented, with indicator)", the stuff I use:

    "In conventional stop baths, the acid ingredient which stops development is hazardous and unpleasant to use, and can damage prints. Acid can break down print sizing which normally protects fibers from fixer thiosulfate contamination, a major cause of deterioration. Plain water stop baths eliminate the side-effects of acid, but do not stop development as effectively, and can cause stains, emulsion swelling and reticulation.

    BLOCK is an acid solution, but the acids are buffered to minimize the side-effects. Buffering protects print filbers for greater permanence, reduces emulsion swelling, staining, reticulation, and eliminates odors. BLOCK will also prevent carbonate gas ruptures of films (pinholes) when used as directed."

    Whaddya think, guys and gals?

    Steve
     
  13. Ole

    Ole Moderator Staff Member

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    Apart from the alleged "can cause stains, emulsion swelling and reticulation" from water bath, that's about what I think about acetic acid stop baths too. Well - I have my doubts about the deletorious effects of stop bath on sizing too...

    Block seems good - buffered, moderate pH (about 5.5 to 6?) - they've even added vanilla scent (to camouflage the characteristic smell of the main ingredient?)!

    But I still think I'll stick to my citric acid when I need a stop bath - a 25g pack lasts a very long time!

    As to short developing times: This is really the same thing as my lith printing, a need to stop immediately. But paper should be developed to completion (usually at about 2 minutes), and all the film/developer combinations I use are a lot slower.

    I'll round this off with a little "alternative stop procedure": Don't.
    I developed Maco IR 820/400 in Neofin Blau for 20 minutes, then ended the processing by pouring in a tot of 60% ammonium thiosulfate. Negatives were just great - no "stains" or "reticulation" or problems with "emulsion swelling" either! And no pinholes - which is a danger when using carbonate developers and acid stop baths!
     
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  15. Ed Sukach

    Ed Sukach Member

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    I think a great deal of the "troubles" usually connected with an acetic acid stop bath are a result of using too strong an acid concentration. However, I do NOT use any acidic or otherwise stop bath in film OR print processing, with one great exception: I've found it necessary between color development and bleach-fix in RA-4 Color Print processing - otherwise uneven development, streaking, and assorted other miseries seem to occur. In that case, I use 1% acetic acid -- made by diluting common 5% "strength" white vinegar 1:4 with water for a 1% acetic acid solution. All my work is "one-shot" anyway, in a JOBO processor.
    Diluting white vinegar with water - now we are talking CHEAP!!. As for the smell of diluted white vinegar - is there a smell? Certainly, I`ve used far stronger concentrations on my salads, and I've encountered stronger in one of my favorite foods - sill/i - pickled herring.
     
  16. Photo Engineer

    Photo Engineer Subscriber

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    There should be no problem with todays modern films if you use an acid stop bath. In fact, the acidity reduces the severe swell induced by the developer. Modern films have their minimum swell at about pH 4.5, the isoelectric point of gelatin. Swell is high on the alkaline side, and high below about pH 3.5.

    Swell is optimum and moderate in neutral and alkaline fixes, allowing faster fix and wash times. (see for example, specs for TF-4 and RA C41 fix)

    Acidification before an acid or neutral fix is said to reduce the potential for fixer stain and formation of dichroic fog in some fixers.

    If you use an acid hardener fix, you can precipitate the alum out of the fixer onto your film or paper by going from developer to water to fix. The alum is difficult if not impossible to remove and can be seen as a white crust or sheen on negatives or prints. So, a stop bath is really a good idea with acid hardening fixes.

    It has also been shown that uniformity in negatives and prints is somewhat better when a stop bath is used after the developer. The best example illustrating that is with the RA paper example above. Uniformity is best with a stop after development and before the blix. On large prints and LF or MF negatives, you can often see nonuniformities, streaks or mottle in large areas of uniform density.

    The only exception I have seen to this is in the C41 process where the development is slow (considering temperature) and the bleach is very rapid compared to development. A stop is not needed in C41.

    PE
     
  17. dancqu

    dancqu Member

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    Have you tried a sodium sulfite stop? You know how
    incompatible is the lith process with more than a
    trace of sulfite.

    The little lith printing I've done has had no "snatch"
    point; no suddenly done. So, as with any printing done,
    it's from developer and into the VERY dilute one-shot
    fix I use. A. or S. Thiosulfates, unadulterated, are
    ph near neutral.
     
  18. Bob Carnie

    Bob Carnie Subscriber

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    I print a lot of lith prints, and as Ole suggests I require an immediate stop of development . I get this with an acid stop bath and this would be my main concern with the stop stage.
     
  19. dancqu

    dancqu Member

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    I process as Ed processes save for my one tray being the
    one tube he uses. We both one-shot all chemistry and
    have no use for any sort of stop.

    The sodium sulfite stop may be faster than an acid stop.
    Faster still I'd think would be a sodium bisulfite stop.
    A 50/50 blend of the two may be acid enough.

    Actually I don't credit any chemical in a stop with
    more than a trace of involvement. After all, stop baths
    run, comparatively, about 49 parts small, light weight,
    swift moving H2O molecules and 1 part large, heavy,
    slow moving something else. An immediate dilution
    AND sudden drop in ph can be expected from
    water alone.

    BTW, I've gotten swamped with indoor and outdoor
    upgrades this summer and not been able to do the lab
    work I thought I'd be doing. I'll be less interrupted for
    having that work out of the way. Dan
     
  20. Bob Carnie

    Bob Carnie Subscriber

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    Dancqu
    With one shot I would imagine you would be ok for not using a stop bath, for me I use a lot of chemicals per printing session. 12 litres lith dev, 10 litres stop, fix a- 8 litres, fix b -8 litres, I suspect by using a stop I am helping out my fix a . I have found that without the acid the lith print will indeed travel more than I would like. ( I know this because I forgot the acid in my stop tray one session and I could not figure out why I was getting streaking until I checked the Stop.
     
  21. dancqu

    dancqu Member

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    Your lith processing vs a Jobo type one-shot conventional
    print processing; it's an apples and oranges sort of thing; a
    few ounces of chemistry used one shot and a two or three liters
    used repeatedly. Also, on one hand development to completion
    and on the other development which is speeding onward.

    Then there is the higher ph of the usual lith developer and
    the hyper-active quinone which actually does the lith. The
    quinone levels build up and the print takes off. How low a
    ph to stop that hyper-active agent?

    I didn't mean to get involved in a lith review. Ole mentioned
    needing acid stop and I suggested sodium sulfite or bisulfite
    or a combination of the two. Sulfite should shut down the
    explosive increase of the hyper-active quinone agent. Dan
     
  22. Donald Miller

    Donald Miller Member

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    I have used acetic acid based stop bath for over twenty years and I have had none of the effects that some seem to indicate.

    Furthermore noted photographers, by that I mean those who can hang work on the walls, seem to consistantly indicate that they use stop bath. I am more inclined to accept their advice based in their direct experience then I would someone's hypothesis without direct experience.
     
  23. MurrayMinchin

    MurrayMinchin Membership Council

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    "Noted photographers", generally speaking, have been around for a long time and probably don't feel a need to change after all those years :smile:

    All I know is that because I'm using an all alkaline processing sequence I can go: 3 minutes development, 30 seconds water stop, 1 minute first TF-3, 1 minute second TF-3, then straight into the selenium toner. A HUGE savings in both time and materials. This has past the residual silver test and the residual hypo test after only a 20 minute wash.

    Murray

    (added later) I still wash fine prints for an hour anyways.
     
    Last edited by a moderator: Sep 3, 2005
  24. Bob Carnie

    Bob Carnie Subscriber

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    Murray
    I am glad you added that little bit about the 1hr wash, I was wondering.

    ques, Why the all alkaline stages? with no acid stop
    are you using the hypoclear step?

    I as Don have been using an acid stop and was confinced it was a critical step in the sequence.

    my steps are 3min dev-30 second stop- non hardining fix one min-non harding fix one min- wash 1 min- hypoclear five min-selenium tone - wash 20-40 min standing washer.

    I believe this is close to the Ilford recommondations.
     
  25. MurrayMinchin

    MurrayMinchin Membership Council

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    Good morning Bob :smile:

    It was a couple months BIGI (before I got Internet) while reading the instruction label on a bottle of TF-4 (Photographer's Formulary Archival Rapid Fixer) that I had a revelation...I remembered Ansel saying in The Print that selenium toner requires an alkaline environment. So I began to wonder - why go: 3 minutes developer, 30 second acid stop bath, 3 minutes acid first fixer, a thorough wash, 3 minutes (alkaline) plain hypo, 3(ish) minutes selenium toner, 3 minutes hypo clearing agent, 1 hour wash? Why do acid at all?

    The old way, without even considering the first thorough wash, took 15 minutes...staying alkaline allows me to have a toned print (or test strip) in 8 minutes and 30 seconds.

    I found TF-3 at www.jackspcs.com and it was from The Film Developing Cookbook by Anchell and Troop where they state a hypo clearing agent is not required.

    Who knows...maybe in 99 years all my prints will spontaneously burst into flames :wink: but for now this is working for me.

    Murray
     
    Last edited by a moderator: Sep 3, 2005
  26. Bob Carnie

    Bob Carnie Subscriber

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    Murray
    Thanks for the link, I know other workers in town who use the all alkaline route I will think about this further.
    As I stated earlier , I print a lot of lith and the acid stops the explosive development , basically you have a 5-10 second period to pull and stop the print or nfg.