Re: Light sensitive compounds for alternative daguerreotypie

From: Jonathan Danforth <jonathan@danforthsource.com>
Subject: Re: Light sensitive compounds for alternative daguerreotypie
Date: Fri, 28 Jul 2006 13:57:19 -0400

> What I fail to understand is why things like platinum/palladium
> prints and chrysotypes work.

They are iron-based, as already mentioned in the other response by
Scott and your reply.

> None of those three processes use silver unless I'm missing
> something.

Silver halide is not the only photosensitive compounds. There are
many. It's just that some are more successful than others.

> 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?

It's not silver slurry. Silver gelatin emulsion consists of crystals
that are highly controlled in its structure, location and amount of
impurities, deliberately created crystalline defects, etc. The
chemistry of silver halide and that of platinum are VERY
different. Material property of silver halides and platinum salts are
also VERY different. Indeed, even if you make silver bromide of same
gross composition, the property of this material varies a LOT
depending on the fine structure of the crystals.

Gold toning of daguerreotype should increase the longevity of the
plates, but if this is the greatest concern, I would say daguerreotype
is probably not the best process to begin with.

From: Richard Knoppow <dickburk@ix.netcom.com>
Subject: Re: Light sensitive compounds for alternative daguerreotypie
Date: Fri, 28 Jul 2006 14:17:31 -0700

> The use of a silver compound is not necessary to get sensitivity to
> light but they appear to be if the amplication is desired. While
> much research has been carried out over perhaps a century or more,
> nothing has been found to replace silver halides.

There are some other materials with this chemical amplification can be
used, but then those materials are not as stable as silver, so
practical image would have to be formed by dyes from a color developer
and couplers. This would be a PITA and also not a very good substitute
for our b&w photography.

> As far as light sensitive materials, your skin reacts to
> light in a complex and rather slow way by releasing melanins
> cause tanning. If you tape a negative to your skin and lay
> in the sun you will get a print on your very own body!
> Bathing suit marks are an example of this process, no silver
> involved. Again, this takes a lot of energy where a silver
> halide emulsion takes very little.

Speaking of alt-process and bikini, check this out:

http://www.solestrom.com/shop/index.php?main_page=product_info&cPath=73&products_id=288

You can get perfect exposure to print out your body!
Received on 07/28/06-04:51:12 PM Z