U of S | Mailing List Archive | alt-photo-process-l | RE: pt/pd stops

RE: pt/pd stops

Bob (whom I really wish would STOP SHOUTING in his posts) wrote:

You really should consider Pyro developers if you want negs that print well in both alt processes and silver gelatin. My 8X10 negs that print wonderfully in palladium with just a little platinum also print very well with a contrast #1 filter with most variable contrast fiber base silver gelatin papers.
If that is true at all, it is only true for multicontrast papers, which I do not use. Further, my guess is that you are not making 3.2 DR negatives for your Pd/Pt process -- even stained-pyro negatives with a total (silver + stain) actinic density range of 3.2 (which would typically have a silver-only DR of 2.8-3.0) will not print acceptably on MC SG paper with a #1 or even #0 filter.

Finally, as I posted in the past in the course of describing extensive testing I did on staining pyro developers:

I discovered that the resolution of the stain image was lower than the
silver image, by a fair amount.  A bit of reflection suggested that this
was due to lateral diffusion of the stain in the gelatin, which I later
found was known in the literature.  I also found that the stain density was
directly proportional to the silver density at all total densities under
the rather wide range of processing variables I tried (with an added
overall fog density when stain conditions were maximum).

(Another sidenote:  Because one can achieve HD curves identical to the pyro
silver + stain curves with other developing agents, I concluded that the
"look" of pyro is not due to its mass staining properties.  The main
difference I see is in the edge effects.  One often hears that pyro
negatives have especially high acutance and edge effects.  This is true of
the pyro *silver* image, and was a truism in the days of *non-staining* pyro
developers.  However, the *stain* image with its diffusion contributes a
softening, "reverse" edge effect.  The resulting edges have both a
[geographically] very-small-scale edge acutance, and a somewhat-larger-
scale softening of the edges -- a rather complex look.)
This can be a cool look, but the overall effect is certainly not what I would call "high acutance" (or if it is, it is because the stain is not contributing much of the actinic density and you have, for practical purposes, an un-stained pyro negative). Rather, I would describe the overall edge effect of an image made from a stained-pyro negative as a bloom or soft glow.

While I'm taken by the charm of this complex "reverse edge" effect for certain images, I'm sick to death of seeing it used for everything -- like putting mustard or caramel sauce on everything one eats. And because my personal vision runs to extreme detail, the overall loss of resolution due to the stain image is generally not a plus for my work.

The fact that the ancient non-staining pyro "high acutance" truism survived into the present staining-pyro era is another testament to the ability of writers to ignore their eyes and repeat the received wisdom.

Well, enough about pyro. I don't expect to talk anyone out of it, but perhaps someone will look carefully at his or her prints and see that -- whatever pyro's virtues -- they are not what many proselytes claim.

Best regards,