From: Judy Seigel (jseigel@panix.com)
Date: 03/20/03-12:33:33 AM Z
On Tue, 18 Mar 2003, Katharine Thayer wrote:
> ... my experience has been that humidity affects exposure, but not
> staining per se.
I find it hard to separate humidity from heat-and-humidity, as in NYC
summer. When it's not hot, humidity is rarely over 45 in the studio, and
often in the 20s, and though the difference will affect drying time of the
emulsion, it doesn't affect much else -- but then again the absolute
amount of moisture in the air is much less than when it's hot.
Liam says that his studio is generally about 65 RH year round, which may
be more like upper west coast of US. When it is hot, I mean HOT, in NYC,
humidity is usually high, so it's not only more moisture relatively, it's
more absolutely -- and that's when I get staining if I don't expose
promptly.
But if ordinary humidity doesn't affect staining, it definitely affects
re-register, at least in a print larger than 8x10... or does around here.
If I want to re-register a large print and it's sat around in the heated
studio ... I have to wet it and let it dry to whatever point it was at
when I made the first coat.
As for "light sensitive when wet"... I believe all these emulsions are
(mixed cyanotype A & B goes off if you leave it out in room light, but
lasts for several weeks in brown bottle), though wet takes much more
exposure. Years ago Mike Ware tested it... though I don't recall which
medium, and got a print -- with much longer exposure. I myself exposed
cyano wet. It made a black print. Interesting color (you cover paper with
mylar or saran wrap to protect negative), but blotchy/uneven because it
gets dry in spots ... Getting it EVENLY wet is just another pain.
I didn't test a gum print wet because --- yuck, what a mess, & didn't see
much point.
As for the question about coating by which light -- I believe Keith. I
know from testing that coating gum by room light, or window light, even
the verboten fluorescent light, makes absolutely no difference in the
print from coating in the dark -- if the paper is dried in the dark. And
even drying the paper in the light, right out on the table, makes
surprisingly little difference -- just somewhat more dichromate stain...
(not pigment stain).
So when a book says coat by safelight, which a surprising number do, you
know they're just saluting the flag -- haven't tested -- and probably in
much else as well... Which is to say NOTHING in a book is to be taken on
faith... (or nothing anywhere else either for that matter).
I myself don't see how you can coat a gum print LET ALONE A VDB OR CYANO
that's yellow to begin with, by "bug light" and get a good coat. Of course
if your work space is in the darkroom, with water, counters, sink, etc.,
it makes sense to do alt there --- but no need. In fact many alt photogs
say "working in the light room" is one of the advantages. But even in the
darkroom, you get a better coat by white light.
J.
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