[pure-silver] Re: Here's one for the head scratchers
- From: Ryuji Suzuki <rs@xxxxxxxxxxxxxxx>
- To: pure-silver@xxxxxxxxxxxxx
- Date: Sun, 16 Jan 2005 18:21:41 -0500 (EST)
From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
Subject: [pure-silver] Re: Here's one for the head scratchers
Date: Sun, 16 Jan 2005 14:01:52 -0800
> Modern emulsions contain additives for the purpose of
> reducing or eliminating pressure effects.
What kinds of compounds are you talking about?
I add nothing to my emulsions for this purpose but I don't get
pressure effects. Of course I handle my materials carefully, but even
if I give some pressure with fingers and nails, the worst that happend
to me is blotting of processing solution to the paper base with some
paper stock, appearing darker while wet, or damage to the emulsion
before getting any developed area due to pressure.
A retired Kodak emulsion expert told me that some old products using
halide conversion were so highly pressure sensitive and the technology
was abandoned. This type of technology is also described in Keller,
but the sentence is written in past tense, though it doesn't say it
was abandoned. Some of my formulae use that technology, and they work
very well in my hand. I don't know why. The chloride paper print on
the pure-silver weblog (photolog) is made that way with 20% bromide in
the shell after precipitating 100% chloride core.
--
Ryuji Suzuki
"Keep a good head and always carry a light camera."
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