From: Alan Bucknam (alan@notchcode.com)
Date: 01/13/03-10:13:56 AM Z
Thanks for the overview of Na2....I'll definitely try and "save" this
neg with Na2 in the future, as I think the bottom line is it was
underdeveloped (and as I mentioned before intensification has done all
it can at this point). If I wasn't rushing to beat a grad school
application deadline, I'd try it out immediately, but unfortunately
I'll have to substitute another image in the portfolio for the time
being.
-Alan Bucknam
On Monday, January 13, 2003, at 08:49 AM, Richard Sullivan wrote:
>
> 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
>
>
>
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