From: Sandy King (sanking@CLEMSON.EDU)
Date: 10/28/03-12:13:52 PM Z
Hi Philippe,
Thank you for your clear analysis of the possibilities and how to proceed.
As to why I want to know this it relates to a comment made a few
weeks ago by Judy Seigel regarding Pt/Pd toned kallitypes versus
straight Pt/Pd. What Judy wrote was this:
Most casual photo purchasers probably never heard of kallitype, and even
the "savvy" ones would probably confuse it with calotype.... Including the
dealers. (If they actually know the difference they're probably
photographers or historians and not in the market.) In any event, you
might finesse the point by doing what the ancients apparently did... I
doubt there is a non-destructive test to distinguish between the pd print
& pd-toned kalli.... there may not even be a "destructive" test (???).
Which is to say, the medium is what you say it is.
This got me to wondering if there are any actual essential physical
differences in a Pt/Pd toned kallitype and a straight Pt/Pd print. If
there are not such differences, that is if they both consist of
nothing but palladium and/or palladium metal on a paper surface, then
my thinking is that it would indeed be appropriate to label a Pt/Pd
toned kallitype as simply a Pt/PD print. In other words, if the two
printing processes produce an image with identical tonal
characteristics, identical physical properties, and identical
archival properties there would appear to be no functional difference
and we would merely have two paths to reach the same end.
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.
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.
Let me make it clear that I am not making claims here, just trying to
find answers. But at least I think I now understand how to find the
answers.
Sandy
>Sandy,
>
>Your question is interesting.
>
>OK, first, you should probably describe your toning formulation so
>that we chemists could foresee what is likely to happen. This way we
>could probably discard one of the 3 possibilities. Anyway the 3
>possibilities here are:
>
>1/ There is no silver left
>2/ You have platinum/gold/palladium plated silver particles
>3/ Both silver and platinum/gold/palladium are present and show
>free surface
>
>First you can check for hypothesis #3:
>
>Take your reflection density on a given spot in a uniform density
>spot on your toned print.
>Process your print with rehalogenating bleach (ferri +bromide), as
>Judy suggests.
>Fix and rinse and dry.
>Measure the density again.
>If you have a density loss, hypothesis 3 is the right one
>
>If not, hypothesis 3 is wrong. You then have to check for hypothesis 1 or 2.
>Therefore, the most straight forward method is indeed X-Ray
>fluorescence (very close to EDS but more easy to find closeby I
>think). You just send high energy X Rays on a sample, and it reemits
>low energy X-Rays with an energy depending on the reflecting
>material.
>Just go in the chemistry of physics departement with a part of your
>print to analyse. Ask a 3d year student who's the
>professor/assistant in charge of basic training on this technique
>(also called Coolidge tube experiment), or a PhD student (they like
>to play). You will most likely find it in the Physics departement.
>Student often try this simple technique during the first or second
>year. Just ask to submit your print to the test. We did it with
>everything we had at hand.
>You will have the Palladium or Platinum or Gold peak, and maybe the
>silver peak. If you have the silver peak, hypothesis 2 is true.
>If you don't, basecally I would say hypothesis 1 is true with some
>assumptions.
>
>My question: why do you want to know it ?
>
>Hope this might help,
>
>Philippe
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