Re: Van Dyke Toning

Tom Ferguson (tomf2468@pppipeline.com)
Mon, 30 Jun 1997 18:37:34 -0700

In alt photo everything affect everything else. I too have noticed (and
measured) an increase in contrast ("snap") in prints exposed by sunlight
(about 1/6 to 1/3 stops or 0.05 to 0.1 density units in the plat/pallad and
cyanotype I tested). I doubt this is due to "the old point-source vs
diffused light situation", as we are contact printing. I would suggest
that the sun probably has a different spectral "makeup" than UV fluorescent
tubes. This difference seems (in my case) easily compensated for by
controlling film development.

tomf2468@pipeline.com

Jadlupp@aol.com wrote:
>Johnathan Russell commented on the differences in toning VD prints, and the
>apparent effect of the light sources. Just as an observation, I have noticed
>that the platinum and platinum/palladium prints, as well as cyanotypes, all
>seem tobe "crisper", for lack of a better term, when exposed via sunlight vs
>a uv light box. This is the old point-source vs diffused light situation, I
>would guess.
<SNIP>
>Don Upp
>Also in Michigan (where JR is )

Tom Ferguson (tomf2468@pipeline.com)
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