William Laven (wmlaven@platinotype.com)
Mon, 18 Jan 1999 16:57:39 -0800 (PST)
>Every time you add extra water into the emulsion you are effectively lowering
>the amount of metal per sqare inch that actually stays on the paper. Using
>more sensitizer doesn't work - because the paper only takes so much
>(especially rod coated papers). So, if you can absolutely limit the amount of
>water by using very saturated metals and iron you theoretically achieve a
>coating with a richer emulsion, and ideally you get better blacks because of
>it.
I don't follow the logic of this. Unless one adds copious amounts of water
to the sensitizer which results in much of the sensitizer not soaking into
the paper and being "dried away" then the amount of metal per square inch
is identical without water or wit a little.
I commonly double coat on Arches Platine: 6 drops FeOx Sol.A, 5 drops metal
for each coat on a 4x5. I use dichromate in the devleoper for contrast
control. In an experiment to see if I could duplicate the results of double
coating (higher dmax most notably) with less sensitizer I made a mix of 9
drops of FeOx Sol. A and 8 drops of metal and 5 drops of water which I then
split into two portions which were used for double coating. The idea was to
have one and a half times the amount of sensitizer normally used for single
coats with the water added to make coating easier. That method results in a
print superior to a single coat and just a teeny tad weaker than a double
coat as I normally did it with double the amount of sensitizer. If there
were significantly less metal per square inchg as you claim, my 1 1/2
sensitizer-double-coat would have been much weaker. As long as the
sensitizer gets into the paper -- with whatever amount of water added to it
-- the same amount of metal is there.
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WILLIAM LAVEN PHOTOGRAPHY
Workshops and tutorials in Platinum/Palladium printing and Zone System.
1931 23rd Street, San Francisco, CA, 94107
415-647-9432 (voice) 415-647-9438 (fax)
wmlaven@platinotype.com
http://www.platinotype.com
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