Hi John,
--- John <ap@darkroompro.com> wrote:
> At 11:03 AM 3/10/2004 +0100, you wrote:
> >You should never use soap with silk, just soak it
> in water and change the
> >water many times. If your water is basic, add some
> drops of lemon acid.
>
> My apologies if this is simplistic but why
> would one want a acidic
> material ?
AFAIK, lemon acid (citric acid in other words)
dissolves Ferrous ions. The presence of Ferrous ions
in the support will cause fogging. I think that's why
Galina offered the idea of treating silk in citric
acid. In my experience another effect of citric acid
is reducing contrast (if not washed off from the
support before sensitizing) and changing the color(!)
of cyanotype (if gives a different hue of blue).
Anyway as I will be rinsing silk in mild potable water
(that incorporates no ferric or ferrous ions) after
treating in citric acid, I don't think the support
will remain too acidic - in fact, acidic environment
is good for cyanotype as it fades in alkali
conditions.
Hope this helps,
Loris.
(Please someone correct my if'm wrong in any of above
statements)
Received on Sun Mar 14 03:39:33 2004
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