[pure-silver] Re: Iodide in emulsions...
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Fri, 27 Nov 2009 20:57:49 -0800
----- Original Message -----
From: "Ray Rogers" <earthsoda@xxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Friday, November 27, 2009 2:43 PM
Subject: [pure-silver] Re: Iodide in emulsions...
Richard,
Yes in the first volume, Haist does mention iodide at
length, but in terms of characteristics other than variable
contrast. Even, strangely, in the context of image
permanence.
Ray
There is an article somewhere, right at the edge of my
memory, about iodide and permanence. After a while I will
remember it.
I don't think iodide is important for contrast but
probably more for increasing emulsion speed or getting the
right color sensitivity. My understanding is that the
emulsions of variable contrast paper are all the same
contrast but have different threshold sensitivities. I have
yet to find a really clear explanation. Some early VC papers
seem to have been combinations of a high and a low contast
emulsion.
--
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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