RE: Best CI for process

From: Sandy King ^lt;[email protected]>
Date: 10/03/05-03:11:14 PM Z
Message-id: <a0602041cbf674d3b59ae@[]>


I do indeed use a figure of 90% black when plotting with the
Winplotter program. This gives very close to the same value as when
measuring a step wedge print in the way I just described to Mark,
i.e. from the first step about pure paper white to the first shadow
step that merges visually with the next one.

What I have been trying to figure out from the beginning of this
thread is is, 1) are Eric and Emille using options which give a much
longer ES than I am used to in my work, or 2) are we simply using
terminology and practice that does not allow us to communicate
intelligently on the subject?

I still have not figured out which is the case, though some of the
recent communications are making me lean toward the second of the two


>Is this exposure scale derived by counting 21-step Stouffer tables discernable
>steps and multiplying by .15? The reason I ask is that I'm betting Sandy is
>using the BTZS plotter program, and the way it calculates exposure scale is
>predicated on picking a maxium black value. I know that Dick Arentz uses 90%
>black for his work....
>Quoting Eric Neilsen <>:
>> Sandy, I don't use or test a pure palladium. The smallest amount of platinum
>> that I add is 15% of total metal salt solution. I make my own ferric oxalate
>> and use a palladium solution that is mixed at 5 g NaPd with 3.5g NaCl to
>> make 40 ml. This makes a .7 M solution to match my .7 M ferric oxalate. The
>> Platinum is a .457M solution in potassium version and .7M when I can get the
>> ammonium version. The molarity may be off by +/- .015 as these are from
>> memory but I don't think so.
>> My exposure scale for the 1.0ml FO, .15ml K Pt, and .85ml Na Pd, is 2.45.
>> I make most of my exposures after a 10 minute dry@ 100F and a 30 minute
>> humidification @60% RH. I process in Potassium Oxalate at both room temp of
>> 70 and heated to 90F. The exposure test that produced the ES above was
>> processed at 70F.
>> These test were also performed with Starphire glass in the contacting
>> printing frame.
>> Eric Neilsen Photography
>> 4101 Commerce Street, Suite 9
>> Dallas, TX 75226
>> 214-827-8301
Received on Mon Oct 3 15:11:32 2005

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