solarization, sabattier and other effects

Discussion in 'Darkroom Developing and Printing' started by gr, Jan 13, 2006.

  1. gr

    gr Guest

    Some questions have been asked recently about various effects. Here are
    some of the ones you may want to play with;

    Solarization; Pump a whole lot of light at an emulsion and you will go
    past the d-max point to get partial reversal of the image. This is not
    done during development (see Sabattier ). Results are dependent on the
    emulsion type, developer type , and length of development.

    Sabattier effect: (often wrongly called Solarization) Produces black
    line and edge effects. Typical process;
    -use somewhat less than normal exposure
    -less than normal first development
    -a fogging reexposure
    -a second development
    -followed by the rest of conventional processing.
    I think a whole lot of light is not needed for this effect.

    Some other effects I mention in passing (not real useful ones):
    Herschel effect; First exposure with short wavelength (blue), second
    exposure with long (red), results in less density and contrast than for
    the blue exposure alone.

    Clayden effect; Short exposure with much light, followed by long
    exposure with low light causes partial reversal.

    Albert effect: Extreme exposure followed by bleach then fogging then
    redevelopment yields complete reversal (I don't know if this is
    different from conventional reversal processing).

    gr





    references; Photographic Sensitometry;The Study of Tone Reproduction
    (Todd and Zakia)
    SPSE Handbook of Photographic Science and Engineering
     
    gr, Jan 13, 2006
    #1
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  2. Conventional reversal processing requires only a normal
    exposure followed by development in an active developer. The
    silver negative image produced is then removed with a bleach
    that leaves the undeveloped halide in place. This is then
    fogged by either a second exposure or a fogging agent, and
    developed into a positive image.
    In color reversal the silver image from the first
    developement does not have to be removed before the second
    development. The first developer is one which does not react
    with the color couplers to produce dyes. The second
    developer does react so that only the postive developemt
    produces the dyes. The silver from both developers is
    removed as a last step. In the past some color reversal
    processes have used a second or fogging exposure but current
    processes have a fogging agent in the second developer or in
    a separate "reversing" bath.
     
    Richard Knoppow, Jan 13, 2006
    #2
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  3. I sent a previous reply which I canceled by accident.
    However. I found a somewhat fuller version of the Albert
    effect in Neblette [1]. Its only a paragraph, which I quote
    in its entirety here.

    The Albert Effect. In 1899 Albert found that if a
    wet-collodion plate is over-exposed adn then placed in
    nitric acid, a positive image may be obtained by exposing
    the plate to white light and developing. This is termed the
    Albert effect. Gelatin emulsions behave the same way, and
    chromic acid, ammonium persulfate, and acid potassium
    bichromate are effective.

    1,_Photography: Its Materials and Processes_ Sixth Edition,
    D.B Neblette, (1962,Princeton, D. Van Nostrand Company.
     
    Richard Knoppow, Jan 13, 2006
    #3
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