Re: Light sensitive compounds for alternative daguerreotypie

Jon-

The Pt/Pd aren't significantly light-sensitive salts.
They rely on the ferric ion mixed in the sensitizer to
render them light sensitive - in those cases they are
using iron instead of silver. My understanding is that
the paper could be exposed with just a ferric oxalate
coating and then developed in a platinic solution, but
it would be a flippin' *expensive* jug of developer. I
just got some ideas on how to do a Pt based dag, but
haven't had time to play with it yet.

The gilding of your dags - I assume (not having time
to dig in the books) that the gold plates the silver,
protecting it from atmospheric sulfides.

Tox

--- Jonathan Danforth <jonathan@danforthsource.com>
wrote:

> Ryuji,
>
> Thanks for your response.
>
> What I fail to understand is why things like
> platinum/palladium prints
> and chrysotypes work. None of those three processes
> use silver unless
> I'm missing something. If a piece of off-the-shelf
> B&W paper is just a
> silver slurry smeared on paper and a piece of
> handmade platinum paper is
> the same thing but substituting platinum for silver,
> what's the difference?
>
> I'm frankly not sure what the gold chloride step
> does chemically but it
> certainly makes the image on the dag plate more
> durable and enhances
> contrast. If you're not careful and heat the
> solution too long on the
> plate, solarization starts to occur in highlights.
> The whole gilding
> process is unrelated to the photosensitive part of
> what's going on with
> a daguerreotype though.
>
> -Jonathan
>
> Ryuji Suzuki wrote:
> > 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
> >>
> >>
> >
> >
> >
> >
>
>
> --
> http://photographs.danforthsource.com
>
>
Received on 07/28/06-02:18:14 PM Z