How important is HCA?

Discussion in 'The Darkroom' started by rob91, Sep 15, 2008.

  1. rob91

    rob91 TPF Noob!

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    The process that I learned in school, and what I've been using since, is after the fixer 2 min water rinse, 2 min HCA, then a 5 minute water rinse. Is HCA necessary? If not, how would I alter my plan? Thanks.
     
  2. compur

    compur No longer a newbie, moving up!

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    My "bibles" for film developing are Steve Anchell's books, The Darkroom
    Cookbook
    and The Film Developing Cookbook.

    Most fixers are acidic but Steve recommends using an alkaline fixer and he
    states that when using an alkaline fixer no HCA is needed and film wash times
    are also greatly reduced. Photographer's Formulary sells an alkaline fixer
    called TF-4, also available from Freestyle. This is what I use. An alkaline fixer
    is also far less likely to cause pinholes then acid fixers.

    Steve also gives a simple formula for mixing your own alkaline fixer from
    scratch in his books.

    If using an acid fixer, though, you do need to use HCA for archival permanence.
     
  3. ann

    ann No longer a newbie, moving up!

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    are you talking about with film or papers?

    for film and RC papers there is no need for HCA

    for fiber papers it is very helpful for reducing the wash times
     
  4. rob91

    rob91 TPF Noob!

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    I'm talking about film. I use Kodak rapid fixer, btw.
     
  5. JC1220

    JC1220 TPF Noob!

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    The risk of pinholes comes with the use of acid stop baths that are not buffered well and with a pH higher than say 4. When the sodium carbonate, in most developers, hits the acid stop carbon dioxide gas is created in the emulsion causing the pinholes.

    Acid fixers are typically lower acid pH around 5.5 and are typically not the cause of pinholes. I suppose it is possible if you plunge the film right out of the developer into the fix it may happen, but the fix will most likely become quickly exhuasted without doing a water rinse prior.

    Also, if you skip the stop bath and go with a water "stop" know it does not actually stop development, so you will need to adjust your development time to account for this.
     
  6. compur

    compur No longer a newbie, moving up!

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    ^ Yes, that's true. I forgot to mention I also use a water stop bath as Anchell recommends, making it it all all non-acid process.
     
  7. rob91

    rob91 TPF Noob!

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    compur, do I need a non-alkaline fixer, or were you referring to something else?
     
  8. compur

    compur No longer a newbie, moving up!

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    I use a water bath stop and an alkaline fixer called TF-4.

    That makes the whole process non-acidic since developers are
    also alkaline and water is, of course, neutral.

    It's my belief that this is a very archival way to process and is
    also simpler & faster because no HCA is necessary and wash
    times are reduced when processing this way. There is also
    less chance of "PH shocking" emulsions by going from an alkaline
    developer to an acid stop and fix which can cause reticulation,
    pinholes, etc.

    However, regular acid fixers are much more plentiful and may
    be cheaper too. Most photographers use them and I don't
    mean to say they are doing anything wrong. I just like to
    treat my materials as gently as possible. But, there's nothing
    wrong with using an acid fixer -- just use HCA and wash
    thoroughly when you do if you want your negs and prints to
    last a long time.

    The preceding is purely my opinion and the way I like to do
    things. :)
     
    Last edited: Sep 17, 2008
  9. rob91

    rob91 TPF Noob!

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  10. Helen B

    Helen B TPF Noob!

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    There are also neutral fixers, often intended for use with C-41*.

    If you are using a rapid fixer and it has not been overused, you should be OK without HCA for film. You might want to consider switching to a set of water changes (say six, to be on the safe side) with constant agitation for one minute instead of your current wash method.

    Washing fixer out of film is easy. Washing intermediate silver complexes out of the emulsion after incomplete fixing is more of a problem, therefore it is important not to overuse fixer. One way of ensuring complete fixing while staying economical is to use a two-bath fixing process.Most of the fixing is done in the first bath, and the second does very little.

    The first bath may be discarded when the clearing time is double that of fresh fixer. What was the second bath then becomes the first bath, and a fresh second bath is made up.

    As an aside, The Film Developing Cookbook is attributed to Steve Anchell and Bill Troop. Many of the formulae are Bill Troop's. A formula beginning TD or TF is likely to be a Bill Troop formula (TD for Troop developer and TF for Troop fixer, such as TF-4).

    Best,
    Helen

    *Edit: An example is Kodak Flexicolor Fixer, a rapid fixer which has a pH of 6.5 at working strength - ie close to neutral. It is often easier to find such fixers than it is to find TF-4 if you don't want to pay for shipping liquids.
     
    Last edited: Sep 17, 2008
  11. Helen B

    Helen B TPF Noob!

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    That's a regular sodium thiosulphate fixer, with ammonium alum hardener. It has a pH of around 4.5 at working strength - ie it is an acid fixer.

    When I use TF-4 my fixing time is usually one minute in each fixing bath.

    Best,
    Helen
     
  12. rob91

    rob91 TPF Noob!

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    Thanks Helen.

    When you say "each fixing bath" are you referring to the two bath process you describe, or two separate fixers?

    Also, something interested I noticed while researching: http://www.usefilm.com/Photo_Forum/13/1012562/

    You're everywhere!
     

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