From: Bill Marsh (redcloud54@earthlink.net)
Date: 07/24/03-05:18:50 PM Z
You know Ansel used to do alot of work on Tri-x Ortho.
Would that be easier to make?
Bill
Ryuji Suzuki wrote:
> From: Scott Walker <walker@sympatico.ca>
> Subject: RE: Bromo-iodide Silver Gelatin Emulsion as an Alternative process
> Date: Thu, 24 Jul 2003 14:37:41 -0400
>
>
>>I was going to say that the dyes themselves are not mysterious, but
>>the way there used and the recipes and concentrations are.
>
>
> That's what I said. But we can't complain for the lack of published
> recipe for full spec modern emulsions as it would be a silly idea to
> think about making one in your basement two decades ago. To me, only
> now the idea of making silver gelatin material sounds very appealing.
> All but a few favorite enlarging papers and films disappeared from the
> market. Now we are betting on which is the next one to be gone. Plus
> we want to be creative about the material.
>
> The use and effect of dyes are affected by the other specs of the
> emulsion like the crystal shape, the method of chemical sensitization,
> etc. and because there is a great degree of variability in everything,
> I wouldn't be surprised by the lack of specifics in publications. Like
> anything else, you gotta try! Think about the range of pAg and pBr in
> your kettle while precipitating and ripening, and the range of mixture
> of crystal sizes and shapes. I think it would be unreasonable to
> expect an one-fits-all dosage recommendation.
>
>
>>In fact most of the sensitizer dyes can be de-sensitizers used at
>>the wrong time or in the wrong quantity.
>
>
> I think fogging problems are more likely.
>
>
>>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...
>
>
> I don't know Orthochrome T is still in use or available, or
> corresponds to what name in modern nomenclature. It is a primarily
> green sensitizer but posses high orange and red sensitivity, so it is
> considered a panchromatic dye in old literature.
>
> Modern literature goes with more systematic names. I recommend the
> article written by David Sturmer of Eastman Kodak, and Roderich Raue
> of Bayer AG. Raue's article covers methine dyes among others.
>
> Other starting points are articles by people like Gilman or Tani in
> Photographic Science and Engineering, Journal of Imaging Science, etc.
> A big leap in dye sensitization was in mid 60's, so I'd consider
> literature newer than that date.
>
> I still think the biggest challange is to work under total darkness
> with no automation. I would appreciate anyone's insight about this
> issue.
> --
> Ryuji Suzuki
> "Reality has always had too many heads." (Bob Dylan, Cold Irons Bound, 1997)
>
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