From: Sarah Van Keuren (svk@steuber.com)
Date: 02/18/01-07:47:35 PM Z
> If you're using digital neg it develops differently, so viscosity of coat
> works differently... but with contone neg I find that a *thick* coating
> doesn't develop as nicely as thinner... Thinner (I think, haven't done
> controlled test) dissolves more delicately. The gummier coat is thicker
> when wet -- unless very hard-exposed, thicker coat more easily damaged
> when attempting area development..
>
> Judy
Every once in a while a student of the gum process will apply the emulsion
with a sponge brush that is not entirely dry and the results have been
unpleasant surprises such as streakiness and pigment not releasing. This has
made me stick religiously with 14 baume gum but Judy's heretical deviation
from the norm opens my eyes to new possibilities.
Already I practice using perhaps 5 parts of ammonium dichromate to 4 parts
of pigmented gum for lower contrast, more continuous tone.
To get high contrast in another color from the same negative, I might use 5
parts gum and to 4 parts dichromate.
The highest contrast brush occurs by brushing pure dichromate on the paper,
letting it dry and then brushing the pigmented gum on top. But sometimes
the gum is too thick to brush down. If I stirred a few drops of water into
the pigmented gum, I might get the high contrast with smooth brushing.
Another way around the issue is to brush on the pigmented gum before the
dichromate has dried but that blends the two parts so much that some of the
high contrast is lost.
I have wondered how in the 19th century the right baume was made from gum
resin in cheesecloth submerged in water overnight. But of course they did it
by feel the way artists and cooks do ‹ about the consistency of syrup,
whatever that means.
Sarah
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