Fixers: acid vie alkaline

Discussion in 'B&W: Film, Paper, Chemistry' started by Dave Miller, Jan 4, 2008.

  1. Dave Miller

    Dave Miller Member

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    Following on from a resurrection of the debate regarding the best film washing regime I thought I would raise this issue.


    Since the majority seem to use acid fixers what are the perceived advantages of using acid fixers over the use of alkaline fixers.
     
  2. Tom A

    Tom A Member

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    For me, the greatest advantage in the shift from acid to alkaline fix, was the much shorter washing time for FB-papers. The washing time was roughly cut in half, without use of HCA.

    Tom
     
  3. 23mjm

    23mjm Member

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    I have used both---they both work---I now prefer a rapid fixer(Ilford which is alkaline I think but none the less could care less) as to shorten washing times. But I think the bottom line is settle on one use it learn it and make great pictures.
     
  4. BobNewYork

    BobNewYork Member

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    The Darkroom Cookbook and/or The Film Developing Cookbook indicate that sodium thio. may not adequately fix modern emulsions so ammonium thio is the way to go. Also, over-fixing in sodium thio will start to bleach the image - ammonium doesn't have these problems. The value of short wash times without the additional HCA bath cannot be over-estimated either! The less 'tedious' work in the darkroom leaves more time for image-making.
     
  5. Snapshot

    Snapshot Member

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    Shorter wash times and less film swelling are two advantages that I'm aware of for alkaline fixers. In addition, if you plan on using staining developers, having an alkaline fixer becomes vital in retaining image stain. As for the advantages of acid fixers, I'm not aware of any other than the chemistry is ubiquitous and perhaps less expensive.
     
  6. Rich Ullsmith

    Rich Ullsmith Subscriber

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    What about expense? Kodak Flexicolor is still available for anywhere from 6 to 8 dollars a gallon! Or if you can find a lab that's going completely digital, it's free. They'll be glad you saved them a trip to the hazmat dump.
     
  7. Photo Engineer

    Photo Engineer Subscriber

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    All thiosulfates bleach the silver image to a certain extent, but the rate is higher on the acid side than on the alkaline side.

    Alkaline fixers tend to keep better than acid fixers.

    PE
     
  8. BobNewYork

    BobNewYork Member

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    Thanks P.E. I'd never thought of that. Shoulda listened in high school chem classes! I've noticed the keeping properties as well. I tend to buy mini-lab C-41 fixer and use that. The container just lists ammonium thiosulphate - shouldn't be a problem; should it?

    Bob
     
  9. Trevor Crone

    Trevor Crone Member

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    Hi David,

    I've used both but simply prefer Fotospeed's FX30 odourless fixer diluted 1:4. I use this dilution for both film and paper. I also use their odourless stop bath.
    It's more economical then the alkaline fixer I used. It also has quite a high capacity.

    As I mostly use pyro developers I've not noticed any reduction in staining, re. acid vs. alkaline.

    regards,
    Trevor.
     
  10. Photo Engineer

    Photo Engineer Subscriber

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    Actually, alkaline fixers have shorter wash times due to greater film swelling. The chemistry diffuses out of the coating faster and the wash water diffuses in faster.

    Acid fixers can easily be made hardening fixers, and in any event leave films and papers less swollen and harder. So with softer film or paper products, an acid fixer is generally better than an alkaline fixer.

    PE
     
  11. Photo Engineer

    Photo Engineer Subscriber

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    It depends on which C-41 fixer you have. The RA Flexicolor fix has more ingredients than the plain C-41 fixer, but they both contain sulfites, EDTA or some sequestrant, and buffers. So it is not a simple solution of Ammonium Hypo.

    PE
     
  12. Ole

    Ole Moderator Staff Member Moderator

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    A simple experiment is to cut a piece of WT paper in half and fix one in a simple sodium thiosulfate fix, the other in a simple ammonium thiosulfate fix. I know that if you use a lith print, or even better POP, you will find that the ammonium thiosulfate bleaches the image much faster than the plain hypo.

    I use very very dilute ammonium thiosulfate as a bleach for clearing highlights in POP and VanDyke prints...
     
  13. Michel Hardy-Vallée

    Michel Hardy-Vallée Membership Council Council

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    As PE said, all thiosulfate fixers can bleach the image if used too strong (time, concentration), sodium being less active than ammonium.

    There are three two-place variables in currently available fixers: pH, thiosulfate type, and hardening agent. All variations exist, so that's a total of 2 at the power of 3 = 8 possible fixers.

    * pH: alkaline or acid. Acid is more readily available. Alkaline washes off more easily
    * Thiosulfate: Sodium or Ammonium.The differing uses between sodium and ammonium are based on the type of silver salts you need to fix away. Modern emulsions for both film and paper contain silver iodide, which really needs ammonium thio fixer.
    * Hardener: old emulsions were not much hardened, so an extra hardening step in the fixer was useful. Not necessary with modern films/papers.

    So you can have:

    • Acid sodium w/ hardener
    • Acid sodium w/out hardener
    • Acid ammonium w/ hardener
    • Acid ammonium w/out hardener
    • Alkaline sodium w/ hardener
    • Alkaline sodium w/out hardener
    • Alkaline ammonium w/ hardener
    • Alkaline ammonium w/out hardener

    I use Ilford rapid fix (non-hardening, ammonium thio, acid) simply because it's available at my corner photo store, and because it's the best for my purposes I can find on the shelves over here. The other choice is Kodak Kodafix (liquid hardening acid ammonium), and Kodak plain fixer (powder hardening sodium thio), none of which meet my needs: I don't need hardener or sodium thio (I use modern films and papers only).

    I'm just not that into buying liquid fixer by mail, so I stick with what I can find.
     
    Last edited by a moderator: Jan 4, 2008
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  15. Bruce Osgood

    Bruce Osgood Membership Council Council

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    I bought a jug formularys' TF-4 for fixing negs and prints. The fiber print time is listed as 1 minute to fix. I'd never heard of anything that short, usually in the 5-6 minute area. If 1 minute will do it there seems no need in a two bath fix regime.
     
  16. Rich Ullsmith

    Rich Ullsmith Subscriber

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    Well, a two-bath for fiber prints is still better. The idea is for the first bath to dissolve the silver, and the second is to remove it from the fiber base. The actual fixing happens pretty fast, and I have had no problem with 2 30-second baths. The Toning Book says a single bath fix can contain up to .5g silver before fixing is impaired; with two-baths it can contain 2g. With TF-4 or the Flexicolor, that sounds conservative because those baths seem to last forever.
     
  17. Photo Engineer

    Photo Engineer Subscriber

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    Michel;

    The alkaline ammonium fix with hardener is not practical. You cannot use alums on the alkaline side, and aldehydes tend to polymerize on the alkaline side in the presence of ammonium ion. Therefore, I know of no good alkaline hardening fix based on ammonium thiosufate.

    In regard to ammonium 'bleaching' silver faster than sodium, IDK. It depends mainly on pH AFAIK and activity, and so I would think that if bleaching were to take place it would be faster in acid and with ammonia present. I have not tested it personally. Textbooks show this but don't make all of the necessary comparisons to be able to properly define the rate of any fix in bleaching silver. I know that it is rather rapid! More so than most of us would expect.

    PE
     
  18. pentaxuser

    pentaxuser Subscriber

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    I have read all the posts and I am somewhat confused about the advantagesof alkaline over acid, specifically in respect of staining developers. One post says no effect on staining with pyro while another says there is an effect. In the case of no effect it is clearly based on pyro and actual experience while I wasn't sure if the other poster was talking from experience of trying both alkaline and acid or was taking the use of alkaline as being better as perceived wisdom.

    Closer to home i.e. the U.K. a popular staining developer is Prescysol which may or may not be similar to pyro in terms of the effect of acid fixer and the maker most certainly recommends an alkaline fixer. Has anyone done an experiment of trying a roll in Prescysol with acid then one with an alkaline fixer to see if there is an effect on stain. Clearly if there is an adverse effect on stain from acid fixer then not to use alkaline negates the benefit of using Prescysol in the first place and the case for an alkaline fixer is proven - at least in the case of Prescysol.

    pentaxuser
     
  19. Michel Hardy-Vallée

    Michel Hardy-Vallée Membership Council Council

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    Ron, thanks for the correction about hardener, I was unaware of that detail. My only reference for sodium v. ammonium thio bleaching is Haist, so I guess you must have a more up to date one?
     
  20. Photo Engineer

    Photo Engineer Subscriber

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    It is just experience Michel and the knowledge that formalin reacts with ammonia, especially on the alkaline side.

    Kodak alkaline hardener fixes used sodium thiosufate + formalin not ammonium.

    PE
     
  21. Dave Miller

    Dave Miller Member

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    I await the result of your experimentation with anticipation. :smile:
     
  22. Trevor Crone

    Trevor Crone Member

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    Just to clarify from a personal point of view I've only carried out a visual comparison with Peter Hogan's alkaline and Fotospeed's acid fixers with 4x5 T-max 100 developed in PMK pyro and I could not see a visual difference as to the amount of stain. They looked the same to me.

    While I have used Peter's excellent Prescysol developer I have never done a comparison with this developer. Peter clearly states on his website that his alkaline fixer preserves the staining effect.
    http://www.monochromephotography.com/fixer.htm
    The effect may indeed be apparent with different films/developers it would be nice if someone could carry out a comprehensive test with various films/staining developers.

    Regards,
    Trevor.
     
  23. Dave Miller

    Dave Miller Member

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    Sounds like the basis for an excellent article fro B&W Trevor!
     
  24. Trevor Crone

    Trevor Crone Member

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    Thanks for your support David but I've just not got the time at the moment. Perhaps Leon will if he's got the time. If he dosn't respond to this thread I'll drop him an email.

    Regards,
    Trevor.
     
  25. Baxter Bradford

    Baxter Bradford Member

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    I agree with Trevor regarding film.

    I was using Barry Thornton's Alkaline fix with his developers, then with PMK. The arrival of my Jobo coincided with me running out of the fixer. I did try Ole's alkaline fix listed here on APUG, but the clearing time was ages, so I swapped to Ilford Hypam and have seen no visual reduction in staining. Incidentally I use 1:4, then dilute this 1:1 with water. Makes it more economical as one shot with the Jobo. The choice of Hypam was simple - I had some in the garage!

    Thus to the photographer on the street, the staining developers work well with more commonly available fixers.
     
  26. bdial

    bdial Subscriber

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    No wish to hyjack the thread, but does the steel wool method of removing the silver from spent fixer work with alkaline fixers, such as TF-4?
    How about silver loading tests, such as Edwal Hypo check?
    Thanks