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  1. #1
    Dave Miller's Avatar
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    Fixers: acid vie alkaline

    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.
    Regards Dave.

    An English Eye


  2. #2

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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. #3
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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. #4

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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. #5
    Snapshot's Avatar
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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.
    "The secret to life is to keep your mind full and your bowels empty. Unfortunately, the converse is true for most people."

  6. #6

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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. #7
    Photo Engineer's Avatar
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    Quote Originally Posted by BobNewYork View Post
    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.
    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. #8

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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. #9

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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. #10
    Photo Engineer's Avatar
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    Quote Originally Posted by Snapshot View Post
    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.
    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

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