On Fri, 12 Aug 2005, Ryuji Suzuki wrote:
> From: "Weber, Scott" <sweber@mail.barry.edu>
> Subject: blue vandykes
> Date: Fri, 12 Aug 2005 15:01:59 -0400
>
>> Does anyone have advice for combining cyanotypes and van dyke printing? I
>> have seen a few examples and like the combination of colors. I tried a few
>> the other day and found that the cyan on top of the vdb bleaches out the
>> brown image. Any help is appreciated.
>
> When this was brought up a few weeks ago, I suggested two possible
> methods to overcome this problem. One is to use polysulfide treatment
> after Van Dyke before cyano. Another is to use Fuji Ag Guard
> treatment, similarly after VDB before cyano.
>
> This bleaching is most likely due to oxidation of the metallic
> silver. Unlike silver gelatin, silver is not protected by gelatin,
> which makes the VDB silver image more susceptible to all sorts of
> oxidative attacks. The two methods I suggested are known to make
> silver more resistant to oxidation.
One of the ingredients in cyanotype, potassiium ferricyanide, is a silver
bleach. So a more common approach is to coat, expose & develop the
cyanotype first, which doesn't entirely eliminate, but definitely
mitigates the bleaching problem -- see for instance Donna Hamil Talman's
item on what she calls "Cyanodyke," Post-Factory #7, page 17.
Control is not perfect -- but in return, colors may be marvelous -- and
unexpected.
J.
Received on Fri Aug 12 15:06:49 2005
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