RE: Test for Silver Metal in Print?

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From: Peter Marshall (petermarshall@cix.co.uk)
Date: 10/29/03-04:37:17 AM Z


Sandy,

The suggestion that many kallitypes are in collections and dealers as
platinum prints is one that has been debated on this list several times in
the past, and I remember it was one of the things I talked to Mike Ware
about at Bath some years back. I don't recall if any of the previous posts
came up with good non-destructive method for testing, but it could be
worth a search in the archives.

> So the question is, of what does a Pt/Pd toned silver-iron print
> consist. Does it contain any free silver metal? And if not, has the
> silver been entirely replaced during toning, or has it been partially
> replaced and partially plated, or entirely plated.

I understood that most toning processes largely involve replacement on the
surface of metal crystals, and so would expect there to be residual silver
in toned kallitypes.

There were also a number of silver/platinum processes, which came into
their own when platinum prices rose, with commercial papers being
produced. The best known name is Satista. There were also published
recipes for those coating their own papers. I tried some of these in the
1990s. The prints were difficult to tell apart, although the print colour
differs.

Most of the old platinum printers used commercial platinum papers, and
certainly towards the end of the era may well have continued to make
platinum prints with papers that also contained silver.

As for inkjet prints, some of those that use carbon pigment inks are
already sold and labelled as carbon prints. Many have the look and feel of
platinum prints, and certainly some have been sold as 'digital platinum',
if not as platinum. Given we are now often seeing platinum prints with
many of the faults of inkjet printers faithfully reproduced from the
negatives, I'm not sure it matters.

One of the best ink sets I've seen is an attempt to recreate the look of
selenium toned black and white prints (the late Arnold Gassan advised Jon
Cone on producing these.)

> The answer to these questions would be important in evaluating the
> potential archival quality of kallitypes toned with the noble metals
> gold, palladium and platinum, and would also give guidance as to
> correct labeling. This would also have important economic
> considerations, especially for platinum printing, because if you
> could produce a print that consisted of 100% platinum metal with the
> iron-silver sensitizing method rather than with the iron-platinum
> method you would clearly save a lot of money. It takes about 1/5 as
> much of Pt/Pd to tone as kallitype as it takes to make a straight
> Pt/Pd print, and the difference is due to the fact that about 80% of
> the Pt/Pd used in coating is removed during processing.

Is it possible to recover the 80% of Pt/Pd lost from the processing
solution? This might be a more useful area to explore, along with methods
that use Pt in the developer rather than (or as well as) in the paper
coat, which could lead to more efficient use of the metal.

Regards,

Peter Marshall
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email: photography.guide@about.com
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