Platinum/Paladium testing

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From: Nick Makris (nick@mcn.org)
Date: 11/02/01-10:39:03 AM Z


I am still testing inkjet negs - I actually have been doing other things in
my spare time, but I'm still finalizing the combination of paper, negative
substrate, PT, PD, PC, FO and time. I just can't seem to get the
combination just right.

I think this process has been confounded by an unexpected departure that
occurred during my tests of a few weeks ago. For no apparent reason, a
specific time I was using was no longer producing the same density. I never
got to the bottom of it and now I am somewhat skeptical of my current test
results. Not the reason for this post.

I would like to open a general discussion (PT/PD specific) on the subject of
Density VS Contrast Control. Specifically, my interest would be the group
consensus (to the extent that's possible) on the effects of including
specific components in a predominantly PD sensitiser.

The test image I am working with is a 4"X6" 21 step photoshop image and the
current sensitiser mix consists of:

7 drops of PD (Palladium)
7 drops of FO (Ferric Oxalate)
1 drop of PC (Potassium Chlorate 4%)
1 drop of PT (Potassium Chloroplatinate)

I may be expecting too much here, but let me continue. While the results do
appear quite qood, I am trying to zero in on the problem of definition in
the 1-5% and 95-99% areas of the scale. Consider that I have been able to
produce a negative that shows an even gradation in those areas, but that
gradation gets lost in the print.

My last test was 5min 15sec and the results are as follows:

Highly desirable black in the areas that were not affected by the negative
(ie, the sloppy part)

Very nearly desirable black in the area of base plus fog (ie, a
distinguishable difference from the above desireable black - less than 1/2
stop lighter and perhaps somewhat colder).

The dark and light areas are exactly the opposite - no density gradation in
the last 5% areas. Either all black or all white.

The question is where do you go from here. The subtleties are escaping me.
It seems that if I add time (which I am about to do) I will lose definition
in the 90-100 instead of 95 to 100. If I don't add time, I'll not be able
to get the blackest black.

All comments appreciated.

Many thanks,

Nick


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