From: clay (wcharmon@wt.net)
Date: 01/28/02-10:35:56 AM Z
Jeffrey et al:
Believe me, I know that this is way short of any sort of universal truth. I
was just curious about the different metal salts and how they react and look
under my lab conditions (69 degrees, 45 % RH, platine paper that was dried
with no heat under a fan to ambient humidity). The linearity I referred to
was simply my observation that the LiPd seemed to plot as a straighter line
than the NaPd. Nothing profoundly different though. It also seemed to be
about 1/3-1/2 a stop faster. As far as coating technique goes, I used a
glass rod so I was sure there would be no contamination and a generous
amount of sensitizer and metal. I've never believed in trying to save 4
drops of solution and ending up with a weak print. The color differences
were subtle at best on the single sheet of paper I used for a test. Just for
grins, I made a few prints with the LiPd for comparison, and the color
difference is more noticeable in actual prints.
Best,
Clay
----------
>From: "Jeffrey D. Mathias" <jeffrey.d.mathias@worldnet.att.net>
>To: alt-photo-process-l@skyway.usask.ca
>Subject: Re: LiPd / NaPd for the idle or curious
>Date: Mon, Jan 28, 2002, 7:18 AM
>
>clay wrote:
>> After Carl's comments about using LiPd in DOP, I ran a quick step
>> wedge
>> comparison test yesterday of the different metal salts and their
>> response at
>> the beginning of my printing session. ... I've plotted the results
>> of the test on
>> a excel spreadsheet for anyone bored or curious. ....
>> The bottom line is that the LiPd seems to have a
>> slightly
>> different speed and have a more linear response than NaPd.
>> There also is a very
>> slight color difference that is harder to see on the step wedge
>> than on an actual print.
>
>It would be interesting to see all the results. You may privately
>E-mail me the spread sheet as an attachment.
>
>I would recommend to be very cautious of these conclusions. Ambient
>Temperature and Relative Humidity, and the paper used can impact these
>results greatly. For example, DOP with LiPd on Bienfang 360 paper at
>65F and 35% RH can produce a very warm orangish brown color (not
>necessarily cooler than the other salts and warmer than NaPd).
>
>I have found the color differences to be quite distinguishable. There
>are some speed differences, but speed is also influenced by many other
>things.
>
>I am not sure what you mean by a "more linear response", as any of the
>metal salts can provide a very straight response and provide remarkable
>tones and tonal discrimination throughout the total dynamic range (white
>to black). It is very important that each metal salt be optimized in
>solution strength to match the appropriate strength sensitizer. If
>"weak" prints are produced (not enough metal), these results can easily
>be skewed. Also coating technique must be perfected or results could be
>easily skewed. Even a most experienced printer must coat carefully and
>accurately for a fair comparison.
>
>--
>Jeffrey D. Mathias
>http://home.att.net/~jeffrey.d.mathias/
>
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