Hydroquinone stains

Discussion in 'Darkroom Developing and Printing' started by Elia Freddi, May 6, 2005.

  1. Elia Freddi

    Elia Freddi Guest

    Hi all,

    yesterday I made some experiment with hydroquinone as paper developer.
    The results are interesting - a kind of lith developer, but on few
    sheets some brown stains are left. I guess it's someway due to the
    exausted hydroquinone.
    Does anybody know how to remove them?
    No way with additional rinse...

    Thanks a lot!






    Elia Freddi
    ················································
    "Sii tecnico spietato con il mezzo e poeta con la mente" - il ratto
    "In ogni fotografia c'è sempre qualcosa di troppo, tranne quand'è riuscita" - Edouard Boubat

    MypagE at http://efreddi.altervista.org/
     
    Elia Freddi, May 6, 2005
    #1
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  2. Hydroquinone is a component of almost all paper developers. Are
    you using hQ as the sole agent in combination with sulfite, bromide,
    etc., or are you using hQ as the only chemical in the developer?

    You don't give enough information to determine the cause of the
    staining.

    Selenium toner is often the cause of permanent staining.
    If this is the case:

    Developer stains are, in general, impossible to remove.

    The most expedient solution may be to throw out the stained
    prints and make replacements.

    If don't want to do this then I would begin by making up a stack
    of hQ stained prints to sacrifice in the name of experimentation.
    In finding a way to consistently make stained prints you will find
    the cause of the staining.

    From a position of ignorance, mild reducing agent may work:
    s. sulfite, vitamin C ... A dash of carbonate may help to unstick
    the oxidized hQ. A re-fix in fresh fix is a good idea.

    Potassium permanganate and nitric acid make up a universal stain
    remover. However, permanganate can leave permanent brown stains
    on anything organic [paper and gelatin] and nitric acid if not
    very dilute will eat away the gelatin and turn the paper into
    highly flammable and unstable nitro-cellulose. OTOH, it might be
    worth a try ...

    Don't use chlorine bleach, it will remove the emulsion.
     
    Nicholas O. Lindan, May 6, 2005
    #2
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  3. What is the formula for the developer? Hydroquinone as
    a sole developing agent is a very high contrast developer
    when used at high pH, usually with hydroxide as the
    accelerator, but very warm tone developers can be made using
    carbonates.
    If there is not adequate sulfite in the developer stains
    can be produced as the result of the reaction products of
    Hydroquinone.
    An example of a warm tone developer using Hydroquinone as
    the sole developer is Ansco/Agfa 110

    Agfa 110 Brown Black Paper Developer Stock Solution

    Water (at 125F or 52C) 750.0 ml
    Hydroquinone 22.5 grams
    Sodium Sulfite, dessicated 57.0 grams
    Sodium Carbonate, monohydrated 75.0 grams
    Potassium Bromide 2.8 grams
    Water to make 1.0 liter

    For use dilute 1 part stock with 5 parts water. Expose
    prints 3 to 4 times normal and develop 5 to 7 minutes at 68F
    (20C).

    Although the above formula shows the Hydroquinone being
    dissolved first its probably better to dissolve the sulfite
    first. Hydroquinone will dissolve in Sulfite solutions,
    unlike Metol.

    I am copying this formula as an example. It may be
    practical but I've not tried it.
    Agfa also had a warm tone developer using Hydroquinone and
    Glycin (No.115). This does not require the overexposure
    and long development of the above. From the description it
    is not as warm as 110, which is supposed to produce brown
    images on warm tone paper, at least the warm tone paper of
    the time. No.115 dates from the late 1930's some time.
     
    Richard Knoppow, May 6, 2005
    #3
  4. Elia Freddi

    Elia Freddi Guest

    On Fri, 06 May 2005 07:02:06 +0200, Elia Freddi

    Thank both of you for your answers.

    Actually I forgot to put some more detail. The developer is self made,
    the formula as follow:

    NaOH: 7gr
    Ascorbic acid: 1 gr
    Hydroquinone: 2 gr
    Tap water: 1 liter

    it's woth to remember to any reader how is dangerous the NaOH - pay
    attention to protect yourself and use cold water.

    I added the ascorbic acid just to avoid a fast oxidation. I tried with
    some sodium sulfite (5 gr per liter) but there is no more the lith
    effect. It keeps for 1 hours more or less, I know too short, but
    enough to develope some paper. With Agfa MCC it works very fine, with
    a smooth infectious development. With Agfa MCP instead it's very fast,
    very high contrast and difficult to control, not recomended. The
    overall tone is just slightly warm.

    The staining I had I think it's due to exausted developer. As I
    understand, no way to remove it... Ok, not a big issue.

    Regards






    Elia Freddi
    ················································
    "Sii tecnico spietato con il mezzo e poeta con la mente" - il ratto
    "In ogni fotografia c'è sempre qualcosa di troppo, tranne quand'è riuscita" - Edouard Boubat

    MypagE at http://efreddi.altervista.org/
     
    Elia Freddi, May 7, 2005
    #4
  5. Elia Freddi

    dan.c.quinn Guest

    Interesting formula. That's all one needs for a lith developer;
    Alkali, preservative, and hydroquinone. I almost forgot, OXYGEN. A
    carbonate will do for the alkali and sulfite for the preservative
    and air for the OXYGEN.
    A year ago, with no intention, I compounded a lith developer. A
    protracted development gave interesting results. With some study and
    further tests I confirmed it was the lith phenomenon.
    If you care to, test some more with sulfite and carbonate. Put only a
    little developer in the tray; no more than 250ml on an 8 x 10 basis.
    Allow at least 8 minutes for the lith effect to generate. More or
    less time may be the case.
    There was an English site on the WWW with a lot of lith formulas. I
    see just now it has been droped. A German version still exists. Wall's
    Normal Hydroquinone lith developer may be of interest. Dan
     
    dan.c.quinn, May 7, 2005
    #5
  6. Hydroquinone used as in your formula is a tanning-staining developer in
    the class of catechol. A small amount of sulfite will eliminate the
    staining, but the staining is what gives it a warm tone effect. The
    stain is redder than pyrogallol's and not as resistant to sulfite. The
    stain is a dye formed when hydroquinone is oxidized, and it is quite
    permanent AFIK.

    I would suggest keeping the developing agents and NaOH or other alkali
    in separate solutions to be mixed just before use, as the oxidation
    begins soon after mixing.
     
    PATRICK GAINER, May 25, 2005
    #6
  7. Elia Freddi

    dan.c.quinn Guest

    I mentioned oxygen. I will expand on that. For the lith
    phenomena to take place oxygen is NOT needed BUT is always present.
    Some may not take that into account. I do because I use very dilute
    minimal volume solutions. That oxygen will destroy sulfite or A.
    acid more quickly where small volume, highly dilute solutions
    are used. Low preservative levels are needed with lith
    developers. Search this NG for, semiquinone .
    That site with a lot of lith formulas is back. From Google
    search for, "lith formulas" . I've perhaps half a dozen 'lith'
    formulas, not counting my own, which do not require a hydroxide
    or formaldehyde. Lith? I suppose so. I wonder if Dr. Gudzinowicz
    ever got around to working with Wall's Normal Hydroquinone? Dan
     
    dan.c.quinn, May 27, 2005
    #7
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