Sodium chloride as a restraniner - anyone used it?

Discussion in 'Darkroom Developing and Printing' started by Jorge Omar, Aug 14, 2003.

  1. Jorge Omar

    Jorge Omar Guest

    I mean besides Microdol-X.

    Are there advantages over sodium bromide (more salt=less emulsion swelling, etc)?


    Jorge Omar, Aug 14, 2003
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  2. It's not a restrainer, but a solvent, and yes I have used it.

    Never used sodium bromide in photography. KBr, yes.
    Michael Scarpitti, Aug 15, 2003
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  3. I don't have a definitive answer to this. Sodium chloride,
    in the presence of silver ions, is an effective silver
    solvent. Sodium or potassium bromide is also a solvent when
    present in large concentration. Sodium chloride probably has
    some advantage in reducing swelling but I don't think that
    is its main advantage.
    Bromide is a restraining agent in that it reduces the
    amount of fog. I don't think sodium chloride has this
    effect. In any case, its not effective enough to be listed
    as an antifoggant.
    Microdol-X is a low activity Metol developer with a high
    concentration of sodium chloride. Ilford Perceptol seems to
    have been identical for a long time. It now contains a large
    amount of bromide, which is also a good fine grain agent.
    So, it would appear that sodium chloride is not useful as
    an anti-foggant.
    This is covered so some degree in _Modern Photographic
    Processing_ Grant Haist, original publication 1979,
    Wiley-Interscience Books. Reprinted 2000 by the Author,
    available from the Haist Press, PO Box 805, Okemos, MI
    Richard Knoppow, Aug 15, 2003
  4. Jorge Omar

    friend Guest

    snipped all

    chlorides can be used, and are used as restratiner for emulsions with
    silver chloride (modern color papers processed in RA-4)

    chlorides are innefective for bromide emulsions, and in particular for
    films with mixed bromide/iodide emulsions.

    it has to do with Nernst equation and solubility of silver salts.
    friend, Aug 15, 2003
  5. Dr. Chapman in Photo Techniques said sodium chloride is about 1/200 as
    effective a restrainer for iodo-bromide emulsions as sodium bromide.
    Patrick Gainer, Aug 15, 2003
  6. Jorge Omar

    Jorge Omar Guest

    Thaks, guys

    The reason for the question is that since the chemist was without KBr
    I decided to try NaCl (salt, no iode) just to see what would happen.
    I used 2.5g per 300cc diluted dev - roughly the amount of Micrdol-X
    Developer was FX-37 without any restrainer.
    125PX negatives had a weak greenish cast when wet, good contrast and
    accutance, and grain is finer than FX-37 without KBr but with
    There wasn't any speed loss I could measure on Zone 1.
    The 2.5g of NaCl is about 100X KBr (re Pat Gainer posting) for FX-37

    That's why I thought finer grain could be related to less emulsion
    And, for sure, the neg does not have Microdol's look - lack of
    microcontrast IMHO.

    Jorge Omar, Aug 15, 2003
  7. What exactly do you mean by "microcontrast".
    Richard Knoppow, Aug 15, 2003
  8. I think what you are refering to are called border or edge
    effects. This is an exageration of the contrast at sharp
    demarcations of high and low density. The effect is to
    increase apparent sharpness, an effect called acutance.
    The increase in conrast at borders has several
    contributing causes. Principly it is the result of very
    localized effects of developer reaction products. Depending
    on the developer these reaction products can either restrain
    development or accelerate it.
    Generally, edge effects take place where there is little
    sulfite to prevent the developer reaction products from
    forming, or to convert them into something inactive.
    Metol and p-aminophenol (basis of Rodinal) are not very
    sensitive to bromide. Their reaction products tend to be
    restrainers. Hydroquinone is very sensitive to bromide but
    its reaction products are themselves very active reducing
    agents. Both will cause edge effects where there is low
    Infectious development does not take place in ordinary
    developers. It is rather specific to Hydroquinone when
    accelerated with formaldehyde. It is the development of
    unexposed silver particals in close proximity to developing
    ones. Infectious development is important in attaining very
    high contrast and density in lithographic developers. These
    usually rely on Hydroquinone as the sole reducing agent.
    They have lots of bromide so that developing action is
    confined to well-exposed halide particals. Other halide
    particals which are very close also develop, increasing the
    The purpose of bromide or other restrainer in ordinary
    developers is to suppress the formation of fog. In the case
    of developers which are to be replenished a fairly large
    amount of bromide may be included to reduce the effect of
    bromide accumulated from the film during the development
    process. This is why color developers are "seasoned". The
    addition of bromide stabilizes the activity of the
    developer. Seasoning is not necessary for one-use
    Microdol-X has a large amount of sulfite in it but also
    acts slowly so the sulfite has a long time to work. D-76 and
    D-23 have the same concentration of sulfite but act faster
    so that the effect of the sulfite, both as a silver halide
    solvent and as a preservative, is greater. These developers
    tend not to have much edge effect although their resolution
    may be pretty high. When these developers are diluted the
    development rate is not slowed down as much as the ratio of
    dilution so the relative effect of the sulfite is decreased.
    For instance, both Microdol-X and D-76 produce substantial
    edge or acutance effects when diluted 1 part stock to 3
    parts water.
    The extra fine grain property of Microdol-X is lost at
    this dilution and film speed becomes normal rather than the
    one stop loss it has when used full strength.
    The fact is that edge effects (high acutance) and fine
    grain are mutually exclusive. The reactions which produce
    one suppress the other. So, one must decide which is more
    important and choose an appropriate developer to achieve it.
    In general, adding bromide will not add edge effects,
    rather the opposite, plus it will tend to reduce shadow
    detail by suppressing the low exposure latent image.
    Since carbonate makes a developer more active adding it to
    a diluted developer will tend to increase edge effects.
    Richard Knoppow, Aug 16, 2003
  9. Jorge Omar

    Dr. Dagor Guest

    There was an article about this in one of the mags within the past
    couple of years -- Photo Techniques I think. I can't remember the
    conclusion, but I recall that the quantities of salt used were huge.
    I think that the fine grain you saw was also noticed, but me
    recollection is that the author concluded it wasn't as effective as
    other agents.

    Does anyone recall the article (or have a good index to PT)?
    Dr. Dagor, Aug 16, 2003
  10. Jorge Omar

    friend Guest

    solubility products for silver salts - at 25°C

    silver bromide 7.70x10^(-13)
    silver chloride 1.56x10^(-10)
    silver iodide 1.50x10^(-16)

    do your own math now.

    If sodium chloride is 1/200 of sodium bromide, then you would need 200
    g of common salt instead of 1 g of sodium bromide.
    Hardly practical.
    Further reading Chapter 1 - James - The Theory of the photographic
    friend, Aug 16, 2003
  11. Jorge Omar

    Jorge Omar Guest

    [Google groups is not updating this thread]?


    I saw this microcontrast term in some posting.
    Since, as I've stated, I have seen clearly only a few times (line)
    edge effects, and since dilluted Microdol even with carbonate did not
    give me the 'look' I wanted, I thought it could be something else.
    But, this could be just semantics.

    Anyhow, I obtain this effect only with highly active Beutler like
    developers - such as PQ, HC-110 but not by simply dilluting them.
    As I've stated, I've used HC-110 1+63 but added alkali; FX-37 I
    dillute P and Q to 1+11 but alkali and sulphite are kept at the level
    of 1+5.
    To this last soup I've added the sodium chloride.
    (note: after developing a roll, the used developer still darkens film

    So, there is very little developer, but the idea is to keep activity
    elevated, producing exaustion (and, who knows, microcontrast) effects.

    Jorge Omar, Aug 17, 2003
  12. (Jorge Omar) wrote in message
    Jorge: try getting your hands on some Acutol.
    Michael Scarpitti, Aug 17, 2003
  13. Jorge Omar

    Jorge Omar Guest

    No way; I do not live in the US and it's nearly impossible to purchase
    liquid developers through international mail order.


    Jorge Omar, Aug 17, 2003
  14. Jorge Omar

    Norman Worth Guest

    I did some very limited experiments recently. Sodium chloride does seems to
    act as a restrainer, if you use enough of it, but the effects are
    noticeably different than with potassium bromide. Its slight silver
    solvent action (it is quite slight) may account for this. The grain seems
    rather more point-like. You should compare results under a microscope (30X
    will do) to understand its action. I don't know how it affects fog, but
    there was no obvious difference vs. KBr in my limited tests.
    Norman Worth, Aug 19, 2003
  15. Jorge Omar

    muchan Guest

    Now I wonder, (without any scientific data), maybe KBr works as restrainer
    for AgBr halide reducing but not, (or much more than,) as the AgCl halide

    Somewhere (I think on "Darkroom cookbook") I read that Potassium Bromid
    used as restrainer tends to make the print warmer (where Benzotriazole
    makes print cooler). Is it, the warmer tone, is attributed that the
    AgBr in bromochloride paper is more restrained than AgCl, so more
    AgCl is reduced to silver, making smaller grain and warmer tone typical
    of chloride paper?

    If it's so, maybe using Sodium or potassium chloride as restrainer
    will restrain more AgCl reducing, thus making more reduced AgBr,
    thus making the print cooler? Can you control the fogs and tone
    sametime by changing the amount of KBr and NaCl in the print developer?

    But I don't know. Maybe the added iodide in the table salt has negative
    effect on print developer, or a little carry over may affect fixer?
    (somewhere I read "Kocher salt" doesn't have iodide, but here I don't
    see it in the store... NaCl in chemical shop is as expensive as KBr.)

    Let's try and see...

    muchan, Aug 19, 2003
  16. Jorge Omar

    Jorge Omar Guest

    Thanks, Norman

    I do not have a decent microscope, but as I've stated, grain was less
    visible with NaCl than without it, and photos were sharp.
    Now I have KBr and I intend to do a compare between the two (Ilford is
    using large ammounts of it in Perceptol nowadays).

    One note: I've purchased technical NaCl (aka Kosher salt) very cheap -
    $1 per Kg...

    Jorge Omar, Aug 19, 2003
  17. Where do you live?

    Michael Scarpitti, Aug 19, 2003
  18. Jorge Omar

    Jorge Omar Guest

    Brazil, where one finds only Kodak and Ilford (and some, only)
    prepackaged devs/fixers.
    Luckly my late father was a ChE and I had some (fun) lab training...

    Jorge Omar, Aug 19, 2003
  19. Jorge Omar

    friend Guest

    depending on country, you may get some iodide as well, plus some
    sodium silicate as well. It may have unexpected results.
    friend, Aug 20, 2003
  20. Rats!

    Well, anyway, try to get some somewhere. It's great stuff.
    Michael Scarpitti, Aug 20, 2003
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