Yesterday escaped me entirely. When I logged on today, 30-plus exciting
messages from This List seemed more than computer girl could comprehend in
one sitting, much less respond to. But Terry's pertinent & provocative
points are like the call of the wild:
On Sat, 17 Feb 1996, TERRY KING wrote:
> > Will your test data for
palladium prints include details of the parameters under > which the tests
were made. Was the paper sized and with what, what light source > was
used, what was the peak UV output. All these factors can affect the
result. > I ask in the light of a previous academic analysis of papers for
gum printing >
Well might Terry say, "In the light of." After some initial tests that
showed great differences in cyanotype and gum prints made with different
exposure lights, I have continued testing gum with blacklight
fluorescents, daylight fluorescents and the NuArc Mercury bulb ....
The tests aren't random, tho I've set up my light table so I can do both
emulsions in BL and DL at the same time that I expose by the NuArc, but
the colors, mixes and papers are just what I happen to be making a "real"
print with at the time -- not a consistent, organized rundown of one
variable.
What I find -- SO FAR -- is virtually no organizing principle. That is,
different colors respond differently to the different lights. The DL
fluorescent is almost always a much SHORTER scale, but at the same time a
much denser COLOR. The scale is generally SO short that I couldn't or
wouldn't print with it, but the density is so seductive I expect to try to
find a way. (Phil Davis's sodium dichromate, with its much longer scale,
certainly calls. )
Why do I bring up gum in the middle of an exegesis on, what was it? Oh
yes, platinum/palladium. Because, despite the obvious differences in
media, Terry's question hits the alarm button right on the head: Will
these charts and curves change equally and consistently with changing
variables? For instances, would the "best" papers be the best with a
different exposure light? And if so, would they be the "best" in the same
way?
Let me add here, I found Keith's study, modus operandi and results
absolutely riveting (well, I don't watch TV, so I'm easily excited). As
excellent as his labor, was the proposition, the framing of the
problem(s). My hunch is that even were he to repeat all steps himself
results might vary, but no matter. We now have a, well the medical term
might be base line... or perhaps a bench mark. The framing of the issues
wouldn't translate to other media -- gum, for instance, has other criteria
-- but the approach should be a viable model across the board.
Congratulations to Keith.
That's the good news..... and here's the bad news:
Terry noted about earlier tests of his:
>Had the parameters been more
carefully drawn > in the light of the
basic principles of the process, such as absorbancy, PH, > freedom from
contaminants and so on. all the hard work put into the tests would > have
been of greater use. > >
Right. That of course is the bad news. One day Keith will probably set up
his parameters "more carefully." But that may be a truism, like saying
"youth is wasted on the young." Here again I refer to my own trials and
errors (especially errors). I have shoeboxes full of gum tests, which
certainly tell something, but NOT what I thought they told at the time,
because when I began I had no inkling of just how many and subtle and
far-ranging the variables were. And neither did anybody else, or if they
did they weren't publishing. (Which is one of the things that's so great
about this list, we can learn from other people's mistakes, too.)
Meanwhile, I'm glad, Terry, to see I'm not the only one!
Judy