Kodak F8 Rapid fixer

Discussion in 'Kodak' started by Ken Smith, Dec 23, 2003.

  1. Ken Smith

    Ken Smith Guest

    The Kodak Rapid Fixer Formula F8 (sans hardener) calls for 360 grams
    of thiosulfate, and 50 grams of ammonium chloride per liter. What then
    is the dilution for film and paper? Are the times just like the liquid
    Rapid Fix by Kodak?

    I can't believe I was asleep at the wheel for so long and missed this
    formula, or the money I spent shipping water. Thanks.
     
    Ken Smith, Dec 23, 2003
    #1
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  2. Ken Smith

    Jorge Omar Guest

    I use F9 (almost the same) straight for films.

    Jorge

    (Ken Smith) wrote in @posting.google.com:
     
    Jorge Omar, Dec 23, 2003
    #2
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  3. Kodak F-7, F-8, and F-9 should be used full strength. They
    are not as rapid as fixers made with Ammonium thiosulfate
    but are about twice as fast as Sodium thiosulfate fixers
    without the sodium chloride. Note that grocery store table
    salt usually has Iodide added as a dietary supplement and
    often has silicates added to promote free-flowing. Kosher
    salt is usually chemically pure sodium chloride. I don't
    know how much Iodide is in table salt but Iodide even in
    small amounts slows down fixing significantly.
    F-9 is a modified formula for reducing the corrosion of
    stainless steel containers.
     
    Richard Knoppow, Dec 24, 2003
    #3
  4. Ken Smith

    Jorge Omar Guest

    Sodium choride???
    Isn't it ammonium chloride?

    Jorge
     
    Jorge Omar, Dec 24, 2003
    #4
  5. Worse, it also contains ferricyanide ("yellow prussiate of soda") as an
    anti-caking agent.

    I recently learned that "pickling salt" (sold with canning supplies) is pure
    salt, granulated to the same size as table salt but without the additives.
    It dissolves a *lot* faster.
     
    Michael A. Covington, Dec 24, 2003
    #5
  6. Yes it is. I don't know what I was thinking about when I wrote this,
    must have been in a hurry. :-(
     
    Richard Knoppow, Dec 24, 2003
    #6
  7. I believe "Kosher" salt has potassium ferricyanide added
    to it for 'free flowing' and contains no iodine.

    Regular salt uses dextrose as a free-flowing agent and
    comes with or without iodine.

    I think I will stick to my Goy diet ... and so will my
    darkroom.

    Both salts are mined from fossilized sea-salt and contain
    the usual admixture of sea minerals, neither are chemical
    grade sodium chloride.
     
    Nicholas O. Lindan, Dec 24, 2003
    #7
  8. Ken Smith

    Ken Smith Guest

    So time wise, double the clearing time for film. Paper I gather
    if F8 works twice as fast as Sodium Thiosulfate by itself, would
    mean 2 min.each in two baths. Capacity? Discard and mix fresh for each
    printing session, or reuse bath two?
     
    Ken Smith, Dec 24, 2003
    #8
  9. Ken Smith

    Jorge Omar Guest

    (Ken Smith) wrote in
    Pasting from an earlier posting from Michael Gudzinowicz in RPD:

    "The following are Grant Haist's recommendations for paper fixer
    capacities:

    One-bath fixation: Commercial Archival

    Paper:

    Max. Ag conc.: 0.3 g/l 0.05 g/l
    Max. sheets/gal: 30 8x10 5 8x10
    Non-image Ag in paper: 0.005 mg/in^2 0

    Two bath fixation: Commercial Archival

    Paper:

    Bath 1:Max. Ag conc.: 2 g/l 0.8 g/l
    Max. sheets/gal: 200 8x10 70 8x10

    Bath 2:
    Max. Ag conc.: 0.3 g/l 0.05 g/l
    after 200 after 70

    Non-image Ag in paper: 0.005 mg/in^2 0 "

    Jorge
     
    Jorge Omar, Dec 24, 2003
    #9
  10. Ken Smith

    Dan Quinn Guest

    I've studied Dr. M. G's treatise. He has done much research in
    some areas and little in others.
    When he writes of fixers and fixeing he relies on sources other
    than himself. The above table is one example.
    I don't consider the above table to be of any value. Dealing with
    trivial matters; 2, .8, .3, .05 g Ag/l of what? That alone makes the
    above, one table, worthless. What is he talking about; liters of
    what. I suppose we are just to suppose. We are to suppose it
    is the same old concentrated, and I mean working strength,
    mix of sodium thiosulfate and what and how much of
    something else, who knows?
    Now to be very precise. Kodak tells us that one liter of Kodafix
    concentrate is good for 208 8x10s. Ilford claims 160 8x10s from
    a liter of one of their popular fixers.
    Now, what if the fixer is fresh each print or roll of film and
    less than 1/10th the concentration of those above at working
    strengh? Not Dr. Gudzinowicz nor Dr. G. Haist have shed any
    light. Dan
     
    Dan Quinn, Dec 25, 2003
    #10
  11. Dan

    Grant Haist was with Kodak Research Laboratories and did
    research in many areas. One in particular is monobath
    processsing.
    Diluted fixer is not a good idea. The ability of a fixer
    to solubilze halide is dependent on the amount of free
    thiosulfate ions. When halide is dissolved it becomes bound
    to the thiosulfate. The amount of thiosufatw must be much in
    excess of the amount of halide or some halide will be left
    in an insoluble or only partially soluble condition.
    The capacity of a fresh fixing bath of either sodium or
    ammonium thiosulfate, to completely fix out printing paper
    is only about 10 8x10 sheet per _gallon_ (agreed on by both
    Ilford and Kodak). By using a two bath system the capacity
    for _complete_ fixing is from four to ten times that of a
    single bath.
    Remember that capacity numbers are given for both archival
    and "commercial" use. The commercial capacity is
    considerably greater but the prints are not expected to last
    for more than about 20 years. Also, the criteria for
    residual silver in the emulsion has changed a couple of
    times so that capacity numbers also change.
    Any fixer diluted as much as you suggest is likely not to
    provide complete fixing even if used only once. Its
    reasonably easy to check silver contend of fixing baths by
    either the clearing time test or by using an Iodide test
    solution. The Iodide test should be diluted differently for
    single baths or for a two bath system. Kodak gives
    instructions in several publications, for instance, _The
    Kodak Black-and-White Darkroom Dataguide_ I perfer this to
    Edwal Hypocheck because Hypocheck is of unknown strength.
    Cleating time is easy to check with film, harder for
    paper. For film test the clearing time for the fresh hypo
    using a film sample which has been soaked in water for a few
    minutes. The normal criteria is to discard the fixing bath
    when this time doubles. This is proabably OK for commercial
    fixing with a single bath but is excessive for archival
    fixing. Its OK for the first bath of a two bath system.
    The use of a sulfite wash aid, such as Kodak Hypo Clearing
    Agent, will extend the capacity of the fixing bath because
    it makes soluble some otherwise insoluble, or tightly bound,
    fixer reaction products.
     
    Richard Knoppow, Dec 25, 2003
    #11
  12. Ken Smith

    Ken Smith Guest


    The Hypo Clearing aid is used between the two fixers? I always
    used it after the second fixer, and prior to toning. Then I used it
    again after the toner, then wash. I know many people will tone right
    after the fix, but I don't mind a cautionary few minutes with a
    valuable print.
    I don't understand the idea of extending the fixer with hypo
    clear, when it is meant to clear the last hypo solution.
     
    Ken Smith, Dec 25, 2003
    #12
  13. Lots of snipping....
    NO NO NO the wash aid is used _after_ fixing, preferably
    after a short wash (30 seconds to a couple of minutes) to
    reduce the carryover of fixer into the wash aid. The reason
    sulfite wash aid extends fixer life is that it is capable of
    removing some of the reaction products that somewhat
    exhausted fixer leaves. I would still not push the capacity
    of the fixing bath or baths.
    If you are doing work which you expect to be long lived
    you should be testing for residual silver _and_ residual
    fixer. Residual silver is tested for using a 2% solution of
    Sodium Sulfide or a 1:9 dilution of Kodak Rapid Selenium
    Toner. The toner test should be made only on well washed
    prints or film since it fails where there is a large excess
    of hypo.
    Put a couple of drops of either solution on a clear area
    of the print or negative and allow to stand for 2 minutes.
    Blot off. There should be NO visible stain. A yellow or
    brown stain indicates incomplete fixing.
    The test for excessive hypo is a solution of Siver Nitrate
    and Acetic acid. It is used similarly to the above. A couple
    of drops is placed on the film or paper in a clear spot and
    allowed to stand, then blotted or rinsed off. Depending on
    the paper or film it should leave only the faintest stain or
    no stain. Directions for both tests can be found in many
    Kodak publications, for instance, the Kodak Black-and-White
    Darkroom Dataguide. The Dataguide also describes how to use
    two bath fixers.
    Sulfite wash aids work in a couple of ways. I specify
    sulfite because there are some other forms of wash aids
    using detergents. I am unaware of any published testing to
    show their effectiveness although they may be effective.
    Sulfite wash aid was developed at Kodak Research
    Laboratories nearly fifty years ago. There has been
    extensive testing of its effectiveness. It was developed as
    a result of research into sea water washing. The fact that
    photographic materials wash in about half the time in sea
    water has been known for more than a century. The sea water
    wash must be followed by a short fresh water wash because
    the halides in sea water will destroy images very quickly if
    left in the emulsion. Sea water washing was done extensively
    during WW-2 on board ship and in other locations where fresh
    water was at a premium.
    Kodak found that a 2% Sodium Sulfite solution was even
    more effective than sea water. They further found that
    buffering the solution to neutral pH improved its
    effectiveness. Sulfite works in two ways: 1, it adjusts the
    emulsion to a pH above the isoelectric point of the gelatin.
    At this pH the gelatin will not bind thiosulfate or
    thiosulfate-silver complexes. Also, when a white alum
    (postassium aluminum sulfate) hardener is used it acts as a
    mordant binding thiosulfate and its reaction products
    tightly to the image silver and to the gelatin. This is in
    addition to the binding effect of gelatin on the acid side
    of its isoelectric point. While any alkali will increase the
    pH sufficiently to eliminate both effects a bath of 1% or 2%
    Sodium carbonate, or Sodium Metaborate, as often
    recommended, will also undo the hardening action and causes
    gelatin swelling. A sulfite bath buffered to neutral pH will
    also eliminate the binding due to both gelatin pH and
    mordanting by the aluminum without destroying the hardening
    effect. Also, its close to the isoelectric point so that the
    gelatin is at its minimum swelling point. Kodak points out
    that minimum swelling is a desirable condition for rapid
    washing because the diffusion path the thiosulfate ions must
    follow is shortest at this point.
    The other effect of sulfite, and the most important as a
    wash aid, is that the sulfite ions displace thiosulfate
    ions, an ion exchange effect. Since sulfite is easily washed
    out of the emulsion and paper support wash times are
    shortened by a factor of at least five. Kodak Hypo Clearing
    Agent is a buffered sulfite solution with the addition of
    two sequestering agents to prevent the deposition of
    aluminum sludge or carbonates from the water when the
    solution is re-used.
    Sulfite is also a mild fixing agent. In combination with
    its ability to disable the bonding effect silver-thiosulfate
    complex ions to the gelatin and image silver, it acts to
    clean up after somewhat exhausted fixer. I would not count
    on this for archival fixing but its a back up safety factor.
    The kind of cation of the sulfite does not seem to matter,
    some commercial wash aids use Ammonium Sulfite rather than
    sodium sulfite, it probably makes no difference. However,
    the buffering does make a difference. AFAIK, Kodak's product
    is the only one which is buffered which is why I often
    recommend it by name.
    For long print life (I hate the term "archival") do the
    following:

    Fix in a two bath fixer which is kept reasonably fresh.
    Treat with wash aid as directed.
    Wash for the times recommended by the wash aid. (see note
    below)
    Treat prints with either a sulfiding toner (like Kodak Brown
    Toner or Agfa Viradon)or with a Gold toner, or with Kodak
    Rapid Selium Toner at no more than 1:9 dilution, or with a
    stabilizer like Agfa Sistan or Fuji Ag-Guard. While the
    stabilizers are not as effective as toning they do not
    change the image color or density. It is especially
    important that prints which are to be displayed receive some
    sort of toner or stabilizer treatment since they are
    subjected to much more exposure to oxidizers in the air than
    a stored print.
    Generally, film does not need toning although either
    toning or a stabilizer will increase resistance to oxidation
    of the image.
    Note: I use the wash times recommended for Kodak wash aid.
    Some wash aids have what appear to be very optimistic times.
    Longer wash times than the Kodak recommendations will not
    result in longer life.
    Finally, the effectiveness of both fixing and washing
    should be checked occasionall by processing a scrap print
    along with the regular run of prints and using the test
    solutions described above on it. Film usually has a
    sufficient clear border to test without taking the chance of
    ruining a negative, but a film srip can be processed in the
    same way as a disposible test subject.
     
    Richard Knoppow, Dec 25, 2003
    #13
  14. Ken Smith

    Dan Quinn Guest

    One hell of a lot. Dr. M. G's treatise, refered to earlier, delves
    into the subject in some detail. Ilford's rapid fix capacity is lifted
    from 10 to 40 8x10s per liter of working strength solution.
    One catch though, Ilford specifies the use of their HCA. Are we to
    suppose it is the same as Kodak's. Perhaps it's more like Edwal's
    4 in 1. Edwal's HCA is quite a different blend. Dan
     
    Dan Quinn, Dec 26, 2003
    #14
  15. Dan

    The MSDS for Ilford Wash Aid is on their web site. The
    ingredients are:

    EDTA 60-00-4 1-5 %
    SODIUM ALKYL ETHOXY SULFATE 9004-82-4 0-1 %
    POLYMETHYLSILOXANE 63148-62-9 0-1 %
    WATER 60-100 %
    SODIUM SULPHITE 7757-83-7 5-10 %


    The main ingredient is Sodium sulfite as in KHCA, the EDTA
    is also in both for the purpose of preventing deposits of
    soluble carbonates on the film or paper. I think
    Polymethylsilozane is an anti-foaming agent. I am not sure
    of Sodium Alkyl Ethoxy Sulfate but think its a surfactant
    (wetting agent or detergent).
    Kodak Hypo Claring Agent is a powder consisting of Sodium
    Sulfite, Sodium Metabisulfite, EDTA tetra sodium salt, and
    Sodium Citrate.
    The Meta bisulfite is the buffering agent, the other two
    are sequestering agents for soluble minerals.
    The two solutions should perform about the same way.
     
    Richard Knoppow, Dec 26, 2003
    #15
  16. Ken Smith

    Ken Smith Guest

    I may be a bit myopic sometimes, and miss the obvious, but I
    still don't see how wash aid extends the life of fixer when the fix is
    a prior step. What does the amount of prints passing throught the
    fixer have to do with a hypo clearing step that comes after this has
    happened?
     
    Ken Smith, Dec 26, 2003
    #16
  17. Ken Smith

    Dan Quinn Guest

    RE: (Ken Smith) wrote
    In effect the WA is acting as a bath two of a two bath fix routine.
    Bath one working capacity can thereby be increased. That "second" HCA
    bath can not, though, be promoted to bath one. Used thusly, I've no
    idea of the capacity of the HCA bath. Dan
     
    Dan Quinn, Dec 26, 2003
    #17
  18. Ken Smith

    Guest Guest

    sodium thiosulfate + ammonium chloride -> ammonium thiosulfate + sodium
    chloride
     
    Guest, Dec 26, 2003
    #18
  19. Ken Smith

    Dan Quinn Guest

    wrote
    In solution the two compounds on the left in the above equation
    dissolve. Sodium, thiosulfate, ammonium, and chloride exist as ions
    in solution. There is no chemical reaction.
    By evaporation I'd expect a mix of all four of the above. Dan
     
    Dan Quinn, Dec 27, 2003
    #19
  20. Because the fixer can be allowed to become more exhausted.
    The same thing puzzled me until I re-read the paper
    describing wash aids. Besides displacing thiosulfate the
    wash aid _also_ displaces some imcompletely reacted silver
    thiosulfate reaction products which are either not fully
    soluble or are tightly bound to the image silver. Silver
    halide as in emulsions _must_ be insoluble. It if were
    soluble it would simply wash out in the developer. Once
    developed it must be removed from the emulsion. If left it
    will eventually blacken from exposure to light. In order to
    remove it the halide must be converted to a water soluble
    compound. Hypo does this by a complex reaction. The halide
    is transformed into successively more soluble forms until it
    reaches a fully soluble form which mostly comes out in the
    hypo. In order for this reaction, or rather chain of
    reactions, to become complete a large excess of thiosulfate
    ions must be available in the fixing bath. As it works the
    free thiosulfate ions become bound up with the reacted
    halide which is dissolved in the hypo bath. At some point
    there are no longer enough free thiosulfate ions to complete
    the process so some insoluble complexes remain. These are
    bound up in the emulsion and don't wash out. If left there
    they will eventually decompose into materials which will
    attack the image and also cause staining of the highlights.
    The best way of insuring that all the halide is transformed
    to a soluble form is to use a two bath fixer and to limit
    the amount of material processed in it. The first bath may
    not be able to complete the transformation but the second
    bath will remain fresh enough so that it does complete it.
    The use of sulfite wash aid further insures removal of these
    insoluble reaction products by displacing them from the
    image silver to which they are bound. The use of KHCA or
    other sulfite wash aid is not a subsititute for good fixing
    but will allow more material to be processed before some
    thiosulfate-silver complexes are left in the emulsion to do
    damage.
     
    Richard Knoppow, Dec 27, 2003
    #20
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