From: Andre Fuhrmann (andre.fuhrmann@uni-konstanz.de)
Date: 01/28/02-02:59:07 AM Z
>... I've done the T55 & the T56. The selenium isn't used alone, in the
>first it's with sodium sulfite, the second with sodium sulfide.
>
>I gather you're saying it *needs* the fixer or else why is it there? I
>could speculate on a number of reasons, such as to be ON THE SAFE SIDE..
>many old formulas say refix after toning ...
>
>In any event, in the old Brovira I was using, no color change with KRS,
>the T55 & T66 made lovely purply brown-blacks... and did not to my notice
>do anything bad, like fade, or bleach. Is that what we're talking about?
I'm afraid, I'll have to give up at this point, Judy. Not being a
chemist I have to admit that I don't really understand why selenium
is first dissolved with sodium sulfite to only release it again
during toning. I think your guess --being on the safe side -- is a
very good one. Could someone help please?
A bit off-topic: Interesting observation you made with respect to
Brovira. I observed exactly the same and was puzzled because before
I made the tests I used to believe that Brovira is the kind of
emulsion that would react strongly with selenium. And apparently it
does -- but not with KRS! But KRS was always the selenium toner with
which I got by far the best results on chlorobromide papers. I once
read somewhere that aged papers (and my stock of Brovira is
well-aged!) may be difficult to tone because the gelatine has become
very hard. In that case hot selenium may do the trick -- or some
agent X that unlocks the gelatine to let selenium in ;-)
André
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