Selenium Toner (KRST) update

Discussion in 'Darkroom Developing and Printing' started by Lloyd Erlick, Feb 4, 2006.

  1. Lloyd Erlick

    Lloyd Erlick Guest

    February 4, 2006
    Some observations of the behaviour of Kodak
    Rapid Selenium Toner (KRST) over a long time
    including periods of use and periods of

    Recently I made some prints for the first
    time in too long. I've been keeping records
    on my present jug of selenium toner (KRST),
    which I first mixed in 2001.

    It's diluted 1+5 in distilled water. I
    normally keep around 3000 ml in the jug, but
    the level was quite low. I had not used it
    since early 2003, and apparently I did not
    top it up before I put it in storage.

    Examination of the contents of the jug of
    KRST showed it was quite clear, no trace of
    the characteristic murkiness that often
    darkens KRST. Also, a large amount of white
    fungus was living in it -- sort of like a
    miniature aurora borealis hanging in space
    within the solution. It seemed to hold
    together like a jelly fish. I poured it
    through a coffee filter, scrubbed out the
    jug, and filtered it through a fresh coffee
    filter back into the jug. It smelled fairly
    prominently of ammonia. I expect future
    regular and frequent filtering will keep the
    fungus from proliferating again.

    The first print I made was toned in the KRST
    before I added a liter of fresh mix to top it
    up. It toned as it had always done. I
    couldn't see any change in the action of the

    The second print was made after I added 200
    ml KRST concentrate plus 1000 ml distilled
    water to top up the jug. The toning action
    was as usual. The smell of ammonia was quite

    So it seems to me a solution of KRST can last
    pretty much as long as one wants. As long as
    I'm active in the darkroom I don't see why I
    can't have this very jug or its descendents
    at work. Really, as a darkroom effluent, KRST
    need only dribble out in drainings from each
    sheet toned, not as a dumped container of

    The solution now has toned the equivalent of
    1098 8x10 sheets of FB material.

    I attribute the lack of precipitate in the
    used KRST to the absence of acid in my

    Lloyd Erlick Portraits, Toronto.
    voice: 416-686-0326
    Lloyd Erlick, Feb 4, 2006
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  2. Lloyd Erlick

    Tom Phillips Guest

    One would surmise diluted it would lose
    strength more readily. OTOH I mixed KRST
    1:9 yesterday from concentrate that must
    be at least 12-13 years old from a half full
    container (taken from the school lab I used
    to work at and stored in an old HC110 plastic
    bottle.) The strength seemed equal to the new
    KRST I bought last month.

    Kodak puts an expiration date on most of their
    packaged chems to cover their you know what.
    Either that or to get you to throw stuff out
    and buy new every couple of years.
    Tom Phillips, Feb 5, 2006
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