Liam Lawless (lawless@vignette.freeserve.co.uk)
Fri, 29 Jan 1999 22:02:04 +0000
Hi Judy,
The dichromate I get is not as soluble as it I think ought to be, but I've
seen many different figures quoted. You say 15%, but the 1956 BJ Almanac
says 1 in 14 in cold water, or soluble in its own weight of
hot water. What I think is that some chemicals are not what they used to be
(sod. sulphite, for example, once used to come as crystals, but contemporary
recipes would not necessarily have explicitly stated "crystalline");
similarly, I think things like solubilities are sometimes simply copied from
old texts and can be out of date. My guess is that modern dichromate
crystals probably contain less water than they would once have done.
Anyway, you've got the idea about the "inverted" harmonising: Steve said
that his shadows were about right, but that the highlights were thin because
of
exhausted developer. However, I forgot to mention the most important point,
that redeveloping in amdol will not increase density unless in conjunction
with something like chrome intensifier... hopefully he'll read this.
I have a suggestion re. your problem anticipating how much density will be
removed by fixing a partly-redeveloped neg. As I'm sure you've observed,
silver iodide is relatively inert and takes ages to tone or redevelop. It's
also pretty light stable as long as it doesn't get too much exposure to
sunshine. I have read that putting an unfixed print or neg into pot. iodide
solution converts any silver chloride or bromide into silver iodide; I've
done this in different contexts and am sure it's true; indeed I remember
reading in a very old book that some commercial desensitiser (German, I
think it was) was thought to be a 4% solution of pot. iodide,
My idea is basically that if, instead of fixing your neg when it appears
right you stick it in pot. iodide, no significant density change will occur,
and the result will be sufficiently stable on camera negs that are filed
away in cabinets or ring binders. If necessary, they can always be fully
redeveloped at a later date, to bring you back where you started. Worth a
try if you have negs that are unprintable anyway.
Liam
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