Safelights and paper developer?

Discussion in 'Darkroom Developing and Printing' started by Geoffrey S. Mendelson, Aug 20, 2007.

  1. Geoffrey S. Mendelson

    Rod Smith Guest

    Wash aids tend to deteriorate over time, so unless you've got a way for
    testing activity, I'd be a bit cautious with the wash aid. Fixer develops
    a spoiled-egg smell when it goes bad, although I suppose that might be
    masked by an ammonia odor with some fixers.

    As to sodium carbonate, that's a VERY common ingredient in household
    detergents. In the US, Arm and Hammer Washing Soda is pure sodium
    carbonate monohydrate; I use that in my formulas that call for it. You
    might be able to find sodium carbonate sold as a laundry booster in
    Israel, but I don't know your local brands, so you'll have to check box
    ingredients yourself.
     
    Rod Smith, Aug 23, 2007
    #21
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  2. Geoffrey S. Mendelson

    dan.c.quinn Guest

    All that's needed for film and paper developers is ascorbic acid,
    phenidone, and sodium carbonate and/or borax. For fixer all that is
    needed is sodium thiosulffate. Water is often used as a stop. All but
    the phenidone should be close at hand. Ten grams of phenidone will
    make 250 liters of developer. Likely that would be mail-order.
    If Graded paper is available a higher level of lighting can be had
    in
    the darkroom. I've a few orange-ish yellow safelights. Very easy to
    see and do in my darkroom. Dan
     
    dan.c.quinn, Aug 24, 2007
    #22
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  3. Speeaking of that has anyone tried to put a compact flourescent bulb in
    a safelight? I assume if it would work, the safelight would have
    much farther from the paper than with an icandescent one of the same
    wattage.

    Thanks.

    Geoff.
     
    Geoffrey S. Mendelson, Aug 24, 2007
    #23
  4. I'll have to look around for them. I have not seen them sold here,
    and have seen several questions, but never any answers about buying them.

    Thanks,

    Geoff.
     
    Geoffrey S. Mendelson, Aug 24, 2007
    #24
  5. It would likely work but the compact fluorescent lamps
    are all quite bright compared to low power incandescent
    lamps. Another possibility is to use an array of LED's.
    There has been a lot of discussion of LED safelights, do a
    google search for it.
     
    Richard Knoppow, Aug 24, 2007
    #25
  6. Both developers and fixers need an anti-oxidixing agent.
    In traditional powder formulas this is usually Sodium
    Sulfite but there are other agents that perform the same
    duty in liquid concentrates. While there is an ocassional
    flurry of enthusiasm for making developers without Sulfite
    they really have no advantage. Sulfite in fixing baths is
    necessary even when the bath is neutral to protect the
    Thiosulfate from oxidation from the air and to prevent
    staining from carried over developer. It is used in acid
    fixing baths in excess to prevent decomposition of the fixer
    by the acid.
    Sulfite performs several functions in developers. Beside
    protecting the developing agents from oxidation from the air
    the sulfite also acts to regenerate developer reaction
    products, to prevent staining from these products, and as a
    halide solvent. The action of a halide solvent is quite
    mis-understood, it does not "etch" the silver crystals,
    rather it changes the way the halide crystals develop into
    metallic and, in moderate amounts, removes a small amount of
    the crystal surface exposing more development centers and
    increasing effective film speed a little. In greater
    quantity, as in some fine grain developers, it can reduce
    film speed by destroying some of the development centers.
    The amount of Sulfite will not by itself tell you much about
    the solvent activity becuse that is a complex function of
    the Sulfite and the activity of the developing agents. For
    instance, D-23 and D-25, an exta-fine-grain developer, have
    exactly the same amount of Sulfite, but D-23 is buffered to
    neutral and is much less active than D-23. So, D-23 grain
    and film speed is about the same as D-76 but D-25 looses
    about one stop of speed while delivering about 1/2 the
    speed.
    Not much sulfite is needed in a neutral fixer, about 5
    grams per liter will do. More provides some reserve to take
    care of carried over developer. However, there are
    advantages to regular acid fixers even when they are not
    hardening fixers. Acid fixing baths usually have about 15
    grams per liter of Sulfite.
    Its certainly true that not much is needed to make up
    developers and fixing baths. Film can be developed with
    D-23, which contains only Metol and Sulfite. A more active
    developer is needed for paper but can be made up of the
    above with the addition of Sodium or Potassium Carbonate,
    hydroquinone (or ascorbic acid), and some Potassium bromide.
    Formulas for developers and fixing baths abound on the web.
     
    Richard Knoppow, Aug 24, 2007
    #26
  7. Fixer will eventualy decompose. When it does it has a
    strong sulfur odor but also usualy has a deposit of
    precipitated elemental Sulfur in it. It can be yellow or
    cream. It has to be pretty far gone for this.
    Acid fixer is much more likely to decompose than plain
    fixer but both have a limited life. Even rapid fixer
    concentrate has a limited life, perhaps because most of it
    comes in plastic containers which are permeable to air.
    The sulfite in wash aid will slowly oxidize to Sulfate.
    The sulfate does no harm but does not have the washing
    accelerating properties of Sulfite (or at least it has them
    in much reduced amount).
    Its hard to know how long the life of a wash aid
    concentrate is. The Kodak product is about 10% Sulfite and
    Kodak gives its shelf life in a filled, sealed, container as
    6 months. Kodak tends to be conservative about shelf life
    but, since wash aid gives no sign of being oxidized, its
    good practice not to keep it for too long. Working strength
    wash aid is strictly an expendible and should not be saved
    and re-used. Its life in a tray is several hours.
     
    Richard Knoppow, Aug 24, 2007
    #27
  8. The advantage of compact flourescents is that they are very common
    here and relatively cheap. I looked around the local shopping mall
    (the largest in the "middle east") and the local hardware store.

    At the mall I was unable to find anything, at the hardware store
    I found 15 watt bulbs with a small base (no adaptors available)
    for refigerators and sewing machines and 5-10 watt bulbs that fit
    it. The lamp base is part of the safelight, it's a Kodak cone
    shaped grey metal can with a lamp socket at one end and a filter
    at the other.

    Unfortunately I have no way of telling what their wattage really is, my
    AC ammeters don't go that low.

    I'm no longer sure who recommended the Kodak publication "How safe is
    your safelight" (I think it was you Richard), but I can not find
    it on line. A search of their web site shows several references to it,
    but not the document itself. :-(

    LED safelights are definitely a possibilty, I have many red LED's
    and the necessary skill to wire them togther.

    Yesterday, my youngest son came down and saw the enlarger and said
    "ooh a camera, let's do it", so there may be hope yet. :)

    Thanks,

    Geoff.
     
    Geoffrey S. Mendelson, Aug 24, 2007
    #28
  9. So did Kodak. This is the result of research carried out
    by Edith Wyde at Agfa labs in the 1930's. The alkali works
    because it changes the pH of the gelatin to a point above
    (more alkaline) than its "isoelectric" point. This changes
    the electrical charges on the molecules in a way that
    rejects Thiosulfate ions instead of attracting them.
    Unlike many other substances Gelatin has no definite pH.
    Rather it has the properties of both an alkali and an acid.
    This is called being Amphoretic. Gelatin tends to have the
    pH of the last bath it was treated in. Nonetheless, the
    molecular charges in Gelatin are dependent on whether the pH
    is higher or lower than its isoelectric point (where the net
    molecular charge is zero). When it is on the acid side the
    charges are opposite to fixer and its reaction products so
    their ions tend to be attracted to and held by the gelatin
    molecules. By adjusting the pH to a point on the alkaline
    side of the isoelectric point the charges are reversed and
    repel the unwanted ions, thus accelerating their washing
    out.
    The isoelectric point of gelatin depends on how it was
    manufactured. For most photographic gelatin the isoelectric
    point is just slightly on the acid side of neutral.u
    The alkaline condition also has an effect where a White
    Alum(Potassium Aluminum Sulfate) hardener has been used. The
    Alum tends to bind the Thiosulfate ions and the silver
    complex ions to the gelatin in a way similar to the mordant
    used to prevent the running of dye. Again, this effect is pH
    dependent. It is most effective in a fairly narrow pH window
    on the acid side of neutral. The alkali bath changes the pH
    of the gelatin to a point where this mordanting effect is no
    longer active. However, most alkalis, such as the
    Carbonates, or Borax, move the pH far enough to the alkaline
    side to break the cross-linking of the hardening so the
    hardening is also no longer effective.
    Sodium Sulfite is also a weak alkaline and has the above
    effects on Gelatin. However, most of its accelerating action
    on washing is due to another effect called ion exchange. The
    Sulfite ions are taken up the gelatin preferentially to the
    Thiosulfate ions and Thiosulfate-silver complex ions
    resulting from fixing so these are actively displaced. In
    Kodak's research no other substance tested had the
    ion-exchange property to the same extent as the sulfites.
    Other sulfites, such s Ammonium Sulfite, can be used, but
    the sodium salt is common and easy to obtain. Also, Ammonium
    salts tend to be unstable in solution.
    Kodak Hypo Clearing Agent is buffered to neutral. This is
    so that it will preserve the hardening action of white alum
    hardener but break its mordanting effect. Neutral pH is also
    far enough away from the isoelectric point of photographic
    gelatin to reverse the charges on the molecules and repel
    the Thiosulfate ions and fixer reaction products which may
    be bound up to the gelatin and image silver electrically.
    Another advantage of conditioning the Gelatin to neutral
    pH is that its swelling is minimised. The swelling of
    gelatin is dependant on its pH compared to its isoelectric
    point. The swelling is minimum at the isoelectric point.
    Kodak, in one of its reseach papers, states that the rate of
    diffusion of the unwanted ions is partly dependant on the
    swelling of the Gelatin. While it seems intuitive that the
    rate should increase with swelling in fact it is the
    opposite. The diffusion rate is dependant on the diffusion
    path, which is minimum when the Gelatin is _not_ swelled.
    Kodak Hypo Clearing Agent also contains two sequestering
    agents to prevent a deposit of Sulfite, Aluminum (from the
    hardener) and mineral salts from the water on the film or
    paper.
    The patent shows only one of the sequestering agents,
    EDTA Tetra-Sodium Salt, but the MSDS shows the commercial
    product also contains some Sodium Citrate. Otherwise an
    effective wash aid may be made from 2% Sodium Sulfite, or if
    he buffered version is desired, add some Sodium Bisulfite
    (or Sodium Metabisulfite). The patent formula shows:
    For one liter of concentrate:
    Sodium Sulfite 100.0 grams
    Sodium Bisulfite 15.0 grams
    EDTA Na4 5.0 grams
    Water to 1.0 liter


    Dilute 1 part concentrate to 4 parts water for use.

    The amount of Sodium Citrate in the commercial version is
    not known but is probably the same as the amount of EDTA.
     
    Richard Knoppow, Aug 24, 2007
    #29
  10. Claudio Bonavolta, Aug 24, 2007
    #30
  11. Actually, there is an error in the formula I gave,
    which was done from memory.
    The formula is from the patent USP 2,860,978. This
    gives an example of working solution as follows:

    Sodium Sulfite... 20 grams
    Sodium Bifulfite... 5 grams
    EDTA Na4... 0.5 grams
    Water to make 1.0 liter

    That would make the formula for a concentrate of the
    commercial strength:

    Sodium Sulfite, dessicated 100.0 grams
    Sodium Bisulfite 25.0 grams
    EDTA Na4 2.5 grams
    Water to make 1.0 liter

    Dilute 1 part concentrate to 4 parts water for use.

    Packaged KHCA also contains Sodium Citrate. The MSDS
    gives only the approximate amount, with a possible ratio of
    1 to 5 in quantity. However, its given as the same ratio as
    the EDTA so probably the amount is the same. Citrate is
    mentioned in the patent as a possible sequestering agent but
    is not included in the example.
    The other published formulas, including the ones I have
    posted at various times were worked out partly from the MSDS
    and partly from the amounts needed to buffer the solution to
    about neutral. The above formua, being from the patent, is
    more reliable and is probaby very close to the packaged
    version.
    I appologize for the errors in my original post, I
    should know by now not to trust my memory entirely.
     
    Richard Knoppow, Aug 24, 2007
    #31
  12. Well, that adds yet another formula ...

    I have accumulated several recipes over time. In grams/liter
    of working strength they are:

    Source
    ==================================
    Above Anchell Usenet Usenet Average
    #1 #2
    S. Sulfite 20.00 20.00 10.00 15.00 16.00
    S. (Meta)Bisulfite 3.00 5.00 2.00 5.00 4.00
    EDTA Na4 1.00 0.25 0.60
    S. Citrate 1.00(?) 0.25 0.60

    I am pretty sure the exact amounts do not matter, but any
    suggestions...

    I am using - just to add another variation - Usenet #2
    with .2gm EDTA/litre working.
     
    Nicholas O. Lindan, Aug 24, 2007
    #32
  13. Geoffrey S. Mendelson

    Rod Smith Guest

    The problem is that you're in Israel, whereas most people reading this
    newsgroup are in the United States or Europe, with perhaps a few more in
    other countries. We just don't know what specific sources of supply to
    recommend.

    You might consider checking out APUG (http://www.apug.org). My impression
    is that it's less US-dominated than this newsgroup. At the very least,
    there are lots of active European members. Although I don't recall any
    specific posters from Israel, there may be some lurkers or others who can
    recommend likely TYPES of places to look for stuff, or non-Israeli sources
    who'll ship to Israel for reasonable prices. (As I've posted before, JD
    Photochem in Canada [http://www.jdphotochem.com] ships internationally.)

    Among common developer and fixer ingredients, sodium sulfite, sodium
    carbonate, and either sodium thiosulfate or ammonium thiosulfate will be
    your heaviest items, and therefore the ones that are most important to
    locate locally to minimize shipping costs. Check Lloyd Erlick's site
    (http://www.heylloyd.com/technicl/bulkchem.htm) for one man's tale of
    locating a local source of bulk chemicals in Canada. Although his source
    is likely useless to you, his procedures for finding it might help.
    Another resource might be the Household Products Database
    (http://householdproducts.nlm.nih.gov). Click the "Ingredients" tab and
    type in a chemical name to see what sorts of products use it. For
    instance, I typed in "sodium thiosulfate" and found that it's used in
    ammonia remover for goldfish tanks, so checking pet stores might turn some
    up. (Chances are you'd pay ridiculous prices at a pet store, though.)
     
    Rod Smith, Aug 24, 2007
    #33
  14. Geoffrey S. Mendelson, Aug 25, 2007
    #34
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