From: Scott Walker (walker@sympatico.ca)
Date: 07/24/03-12:37:41 PM Z
I was going to say that the dyes themselves are not mysterious, but the way
there used and the recipes and concentrations are. In fact most of the
sensitizer dyes can be de-sensitizers used at the wrong time or in the wrong
quantity.
But I take that back, the dyes are mysterious! I have spent about 6 months
on a Dye called Orthochrome T mentioned in Wall's book. So if you want a
challenge we can compare notes...
Please find:
Atomic Formula
Spectral absorbancy
Structural formula
Real name
Color in solution
Recommended concentration in emulsion.
Everybody has references or has read on spectral sensitization. Anyone have
anything they are willing to share?
Thanks to everyone for all their input,
Scott.
-----Original Message-----
From: Ryuji Suzuki [mailto:rs@silvergrain.org]
Sent: Thursday, July 24, 2003 2:21 PM
To: walker@sympatico.ca; alt-photo-process-l@sask.usask.ca
Subject: Re: Bromo-iodide Silver Gelatin Emulsion as an Alternative
process - response to Yu Rei
Umm...
About the chemical nature of classes of dyes suitable for silver
gelatin photography, there are papers on this topic published in last
decade or two in English (you can of course go older than that). I
know at least book chapters written by AGFA people and also another
chapters written by a Kodak retiree. Chemical nature of these dye is
well studied and reasonably documented. So, don't make dyes sound
mysterious.
What's unknown is method of using them in homemade emulsions. But this
won't be much of a problem once I get pure dyes from reliable source.
How do you make *panchromatic* emulsion and coat them?
Infrared dyes are rather easier to apply, because one can't apply too
much of it, the immersion of coated unsensitized plates seem to give
enough amount of dye. This, I can do in total darkness. But I think
panchromatic dyes should be added in the digestion stage. I don't know
what to do if I have to turn all lights off at that stage and on.
-- Ryuji Suzuki "Reality has always had too many heads." (Bob Dylan, Cold Irons Bound, 1997)
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