Re: Light sensitive compounds for alternative daguerreotypie

From: Ryuji Suzuki <rs_at_silvergrain.org>
Date: Thu, 27 Jul 2006 19:28:35 -0400 (EDT)
Message-id: <20060727.192835.98925597.lifebook-4234377@silvergrain.org>

I'm afraid that halogenating those metals won't make them
photosensitive like silver halides, even if you could afford to use
those metals. First of all, halides of those metals are generally
soluble in water and you don't want that.

Silver halides are not just some random combination. It has very
useful property as a photosensitive material. Silver halides (except
fluoride) are indirect bandgap semiconductor material (ask a solid
state physicist, material scientist or an electrical engineer with
semiconductor specialty for more details) and each grain of salted
paper and gelatin emulsions work sort of like a photodiode, except
that the response in AgX is roughly linear in log exposure, while
semiconductor devices respond roughly linearly to linear exposure
scale. (The latter is one of the difficulties in digital imaging
systems.) People tried to replace silver with other material for
various reasons (such as cost) but none was very successful.

I don't know the details of how you treat your dag plates in gold
chloride, but is there a specific reason to worry about the logevity
of the treated material?

From: Jonathan Danforth <jonathan@danforthsource.com>
Subject: Light sensitive compounds for alternative daguerreotypie
Date: Thu, 27 Jul 2006 12:59:09 -0400

> All,
>
> I've been worrying a great deal lately about the longevity of
> Daguerreotype on silver (despite the gold chloride gilding stage) so I
> was wondering what people thought about working with other compounds.
>
> I know that you can use iron, gold, uranium, etc. salts to make images
> but I'm wondering about the sensitization process. With Daguerreotypes,
> I expose a silver plate to Iodine vapor and BAM... light sensitive
> silver iodide. What I'm wondering is if I could do the same with 24kt
> gold (a la the Chrysotype) or rhodium plate and make an image using the
> same process using either UV or mercury as the developing agent.
>
> Ideas? Will it work using the same clearing and developing methods as
> the Daguerreotype?
>
> -Jonathan
>
> --
> http://photographs.danforthsource.com
>
Received on 07/27/06-05:28:58 PM Z

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