Cloudy Chemistry

Discussion in 'Darkroom Developing and Printing' started by A R, Mar 10, 2008.

  1. A R

    A R Guest

    I have two litres of Bromophen stock solution. It was made a fortnight
    ago but has since developed a white sediment at the bottom. Shaking the
    bottle causes the stock to go cloudy.

    This weekend I mixed Barry Thornton's two-bath developer. Having never
    mixed my own chemistry from scratch, I wasn't sure what to expect. The
    metol proved difficult to dissolve despite warming the water and shaking
    the bottle quite vigorously -- the metol formed a suspension in the
    sodium sulphite/water solution and had a tendency to clump.

    A sediment forms at the bottom of Bath A, when left, and turns cloudy
    when shaken.

    I have developed two rolls of 35mm in the two bath. The first roll
    turned out okay, but the second turned out thin to the point of being
    almost clear.

    The Bromophen has turned out good prints thus far.

    The solutions have been stored in a dim room at room temperature in
    clear, plastic drinks bottles with the air squashed out.

    Are these sediments a good sign? Are they normal? How should I deal with
    them? Could the thin negs be a result of the sediment (the second reel
    was left in Bath A a minute less than the first)? Should the metol
    dissolve fully?
     
    A R, Mar 10, 2008
    #1
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  2. message
    About Metol, I has difficulty dissolving in a solution
    of sodium sulfite. You will notice that most formulas using
    it have you dissolve the metol first, then the sulfite.
    While the sulfite is there partly to protect the Metol and
    other developing agents from oxidation it really isn't
    necessary for the few minutes it takes to dissolve the
    Metol. To minimize the amount of oxidation boil the water to
    be used for about three minutes and let it sit and cool
    before use. The boiling will drive off most of the dissolved
    gasses.
    I am not sure about the sediment. It may be undissolved
    chemicals or it may be something in the water. Most packaged
    chemistry has sequestering agents in it to deal wtih the
    salts in hard water and to some degree with dissolved metals
    such as traces of iron compounds. It may be that your tap
    water has an unusual amount of something in it. You can use
    distilled water but grocery store distilled water is
    expensive and not always very pure. Another way is to use an
    activated charcoal filter, like a Brita filter, and then
    boil the water. This will eliminate most hardness and
    metallic ions. The water may also just be dirty, if so, the
    filter and boiling will remove most of it.
    If the developers work normally I would just filter
    them. Coffee filters work fine.
    Sometimes a little rubbing alcohol dissolved in the
    water will help the chemistry to dissolve. Perhaps 30ml (an
    ounce) in a liter (quart) of water.
    When mixing from scratch it sometimes helps to dissolve
    the separate ingredients in a portion of water and then add
    together the liquids.
     
    Richard Knoppow, Mar 10, 2008
    #2
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