~~~~~~~~ Excerpt from the Guide to Platinum Palladium Photographic Printmaking by Jeffrey D. Mathias ~~~~~~~~
No part of this document may be reproduced in whole or in part without the express written permission of the Author.
updated December 2000
 
Exposing Direct sunlight
Indirect sunlight
Artificial UV light

Exposure may be accomplished by illumination with sunlight or an artificial Ultra Violet light source.  Different illuminations can produce a variety of results.  The sharpest prints will be made by direct sun illumination.  The softest prints will be made by shaded or diffuse illumination.  Both shade and most artificial illumination may not cast a hard shadow.  This gives a soft transition when burning or dodging without even shaking the tools (The wire handles of dodging tools may not even shadow the print).  It is also thought that various spectrums of light may produce differing results.

Note: Any humidity in a DOP coating during exposure could add graininess or
           diminish the blacks in the print.
Note: The printout should only be checked with safelight illumination.

Exposure has some other effects on the print. As exposure occurs, development takes place and the coating "prints out" (forms an image).  The darker areas will become quite dark and in turn block light form further exposing the coating ("self-masking").  This can allow much exposure to be given to the coating with out a loss of shadow detail (of course, the negative should be properly made, with plenty of detail in the shadow areas).  This also causes the contrast of the print to change.  More exposure will produce less contrast, and less exposure will produce more contrast.  These effects can be useful when fine tuning a print.

The importance of a negative of sufficient contrast should be understood from these effects.  If a negative has insufficient contrast, more contrast agent is used; the printing time becomes longer; the contrast is thus lessened; so more contrast agent is required. Eventually the printing time becomes very lengthy, and print quality may diminish.

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EXPOSURE BY DIRECT SUNLIGHT:

  • Cover printing frame and take outside.
  • Set on the printing stand.

    •      Note: Stand should be aimed directly at the sun. A pencil or stick
                    perpendicular to the frame face will have no shadow when the
                    frame is aimed properly.
  • Uncover and start timer simultaneously.
  • Do any burning or dodging that may be needed.
  • At end of exposure cover and take back to darkroom.
  • Record printing information in the notebook.
  • Check printout and add exposure (optional).


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    EXPOSURE BY SUNLIGHT, BUT IN SHADE:

  • Cover printing frame and take outside.
  • Set in the shade (no shadows). Make sure illumination is even (spatially and temporally).
  • Uncover and start timer simultaneously.
  • Do any burning or dodging that may be needed.
  • At end of exposure cover and take back to darkroom.
  • Record printing information in the notebook.
  • Check printout and add exposure (optional).


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    EXPOSURE BY AN ARTIFICIAL UV SOURCE:

  • Place printing frame under the UV source (OFF).
  • Set then start timer, which switches on and off the UV source.
  • Do any burning or dodging that may be needed.

    •      Note: It is important to wear eye and skin protection when using an UV
                    source (see section on safety).
  • Record printing information in the notebook.
  • Check printout and add exposure (optional).
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