From: Christina Z. Anderson (zphoto@montana.net)
Date: 02/27/03-12:41:19 AM Z
So, in gum research today, re: glyoxal yellowing, I came across the
statement Judy made that an alkali added to glyoxal turned it orange. Is it
possible that the yellow stain that happens sometime with glyoxal is a mild
alkali in the paper that has been sized with glyoxal and it affects it
sitting in the drawer, and this is this "orange" tint diluted by the paper
base white? Maybe buffered papers might yellow the glyoxal just sitting
there?
Also, since alkaline conditions make dichromates work more slowly (hence
adding ammonia to a dichromate to slow down printing, or slow down dark
reaction to enable storage of paper) is the reason different gelatins have
different printing speeds because some are more alkaline than others? Or is
it just the viscosity? I mean, it seems acid (lemon juice) speeds up
emulsion and ammonia slows it down so I was just wondering...
That's my musings for the day.
Chris
PS my white gouache on cyanotype printed with a positive worked fine, but it
was, as Keith said earlier, sort of anemic and grey. It did not seem to
bleach the cyano as much as I expected, either. The positive did much better
in white on cyano than the negative.
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