From: Linas Kudzma (lkudzma@earthlink.net)
Date: 01/13/03-08:10:13 AM Z
Dick,
Interesting that Arentz is using sodium chloroplatinate (Na2PtCl6). I have been using it as my exclusive contrast agent for DOP for almost 2 years. I know just what you mean by the subtle "pop" it gives a print.
I know that this is a nit-pick, but I never liked the nickname "Na2" you gave the platinate. The salient chemical point is the oxidation state of the Pt metal ion (Pt+4 vs Pt+2), rather than the sodium counter ion. In my personal notes I refer to it as Pt(IV) vs the normal Pt(II). But I guess the train has left the station, product name wise...
Linas
-------Original Message-------
From: Richard Sullivan <richsul@earthlink.net>
Sent: 01/13/03 10:49 AM
To: alt-photo-process-l@sask.usask.ca
Subject: Re: getting more contrast out of pt/pd developer
>
> NA2 can cause graininess if used to excess. As you state many other factors
can contribute to graininess. Dick Arentz brought some sample prints to
Platypus in July and it was impressive. He showed a 12 x 20 that was made
using the standard techniques and it had some faint graininess in the sky.
Most people would not even see the problem but most trained pt printers
would. He then showed a print made with Na2. Not only was the graininess
in
the sky gone but there was more "pop" to the print. Dicks prints are
always
exquisite and few would have faulted the "before" print unless they had
seen the "after" one.
Now Dick Arentz is an accomplished platinum printer and the author of one
of the best books on the subject. Dick's mentor was Phil Davis and he
approaches Pt from a sensitometric angle. This was a case where Na2
"saved"
a neg. True it is best to get it in the neg but even the best miss on
occasion. Perhaps in this case it was just one of making a good print
better.
Dick will be doing a chapter on Na2 in the next edition of his book and is
doing a segment at this July's APIS in Santa Fe and I expect he will be
discussing with Na2 as well. Anyone who knows Dick knows he is a skeptic
and a hard sell when it comes to anything pretending to be a magic bullet.
Many other top notch printers have switched over to Na2 use as well.
Na2 or sodium chloroplatinate (Na2PtCl6) was basically a rediscovery of
mine. In 2000 I found a bottle with about 25 ml that I had made in the
late
70's. At that time I was doing a lot of research into platinum printing
and
as I recall I tried making a print with it and all I got was black smudges
as it was way too contrasty. That was about it at the time. When I found
it
again in 2000 I again tried making a print and got the same result though
when I first made the print I had forgotten about my earlier experience,
but when I got the super high contrast image I remembered, but this time
there was an "Aha!"
I made another print and only used a few drops. Still too much contrast
but
a much more recognizable image. Reducing the ratio further I got very nice
images. (See, some people do get smarter with age! In my case, not always
though. I used to have senior moments now it is senior days.)
After some further testing B+S sent samples to a handful of top printers
and from there we cautiously introduced it to the market where it has now
become the contrast agent of choice among the best printers.
Dr Howard Efner PhD, a retired chemist, has done a serious chemical study
on how it works and this is available at:
http://www.bostick-sullivan.com/Technical_papers/NA2/NA2%20papers.htm
There is also a practical paper by me there.
As it turns out the chemical was known to the classical printers at the
turn of the century but seems for the most part to be neglected as
"contrast" was not something they were looking for with ortho glass plate
negs. It was noted to be "too contrasty" by some authorities at the time.
Thus essentially what I thought to have been a discovery was in fact a
rediscovery. Needless to say, it extends the pallet of the platinum
printer
and that is what is important. B+S costs it out at the same price as
K2PtCl4 and Na2 is substituted for this in making the prints so the cost
factor of making a print is the same.
--Dick Sullivan
At 09:15 PM 1/12/2003 -0600, you wrote:
>>The way to get the right contrast is in the negative. And it ain't even
>>difficult to do.
>
>No argument there. I rarely use any contrast agent myself. But every now
>and then, a screw up occurs, and I'm happy to have the Na2. I haven't had
>the tonality problems you mentioned, but I use Na2 diluted to 10%, and as
>sparingly as I can. I have found graininess to be as much due to paper
>type and drying methods as anything else. But your point is certainly
>true: if you can get a good negative in the first place, life is good.
>
>Speaking of good negatives, I want to chime in on one of Sandy's
>recommendations vis a vis the BTZS palm pilot program. For grins,
recently
>I did duplicate exposures and development of some TMY
>negatives in D-76 1:1 according to its recommendations, and they were
>exactly right: shadow densities of .25, highlights densities of 2.1. This
>was not based on any personal testing. I just blindly followed its
>exposure and development recommendations and used the incident metering
>method that Phil Davis recommends, and I got perfect negatives on a very
>high contrast scene. I was impressed.
>
>Clay
>
Linas Kudzma
lkudzma@earthlink.net
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