If you have a copy of the Michael Ware article, An Investigation of
Platinum and Palladium Printing, you'll find that he did test on the
response of the different metals of platinum and palladium, and the
yields of metal created by exposure to different wave lengths. It
suggest that at 365nm both pt and pd are produced at about the same
amount, and that they are different up to that point. They also have a
different color and speed based on the humidity. But while both of them
drop off drastically between 365nm and 405nm, Users of Super actinic
tubes are making prints, and their output peaks around 420nm. This from
an area indicated by Ware research where very little should be
happening.
Are all users of super actinic tubes using traditional ferric or do
any use the ammonia based ferric? And what about the mercury vapor
lamps? There output is all over the place depending on which lamp you
use? Another important consideration when talking color and contrast of
the print is the humidity levels and how it effects the speed of the
sensitizer and it's component metals. And while ammonia based ferric
prints - Ziatypes and Ware's formulas, exhibit interesting printing
possibilities, but how do they differ for the traditional print
chemistry? I know that I've spent many hours on both of them already.
I have also used Rosco gels to try and match Pyro stain. It has
produced good affects. I didn't spend the time yet to test all the gels
that I got however. Green, Blue, different shades of yellow, etc....
And then Dick introduced the idea of different salts to replace sodium.
The possible outcomes are staggering.
The can of worms that can be opened by seeing what color you can make a
print is quite large. Print color and contrast are both effected by
many things.
1) light source output - curves and peaks
2) sensitizer used - what combination of metal salts and type of ferric
3) humidity of paper
4) pH of ferric - different pH gives different color print
5) type of paper used
6) stain of film or apparent stain by using a gel
7) type of developer - concentration, temperature, and additives
8) type of glass used in the contact frame
9) where were the chemicals purchased and how might that effect
reactions and who mixed them
Holy smokes Batman, there is a lot to the color and contrast of a
print. Which variable to test and in what order? While this color
manipulation and contrast control has a level of interest, it might to
better to spend time working on execution of "high quality" images than
to beat the process to death to see what can be done. I am however,
glad that I'm still young enough to play with all this for years to
come.
So back to the printing...
EJ Neilsen
Carl Weese wrote:
>
> Dick,
>
> <<<DuSel also says that blue
> gel has no contrast effect on the Ziatype but does change its color. >>>
>
> There seems to be a real correlation between light source (or filtration
> or negative color/stain) and print emulsion response, in color as well
> as contrast. My recent tests of pyro-developed negatives have shown that
> Ziatype prints give different color response to these negatives. Zia
> formula's that have just a touch of cesium and generally print just
> slightly warmer than neutral print a good deal more brown when the
> negative is a yellow/green pyro neg. Something about the color of the
> light is changing the paper sensitivity, but I don't know what. It would
> be intresting to see what other gel filters might do, strong yellow or
> green ones--what effect on contrast, and what effect on print color?
>
> ---Carl