You must have a color densitometer to read the silver + stain of Pyro PMK
developed negatives (or at least one with sensitivity to the yellow/green
stain). I use the blue mode of a Macbeth color densitometer for this. What
you find, if you compare the curve of only the silver image (which can be
done with the B&W setting) with that of the silver + stain image (using the
blue setting) is that the two readings are about the same in the low values
just over B+F but as exposure increases the silver + stain increases with
reference to the silver. The printing density is of course that of the
silver + stain.
Richard Knoppow writes: "Unless alternative printing materials have much
different spectral characteristic then I think they do (sensitive to blue
and near UV, with no effect on contrast caused by the color of the exposing
light) a Pyro negative should print no differently than a somewhat higher
contrast negative made with a non-staining developer."
This statement is clearly at odds with my experience with carbon printing.
To the contrary, as Kerik comments with respect to platinum/palladium
printing, what I observe is that the range of highlights is greatly
extended. Perhaps the theory of Richard's reasoning is flawed because it
does not take into account the fact that the sensitivity of some of the
alternative process emulsions extends into the green portion of the
spectrum. From testing I did a couple of years ago I found that dichromated
gelatin has considerable sensitivity to light at 500-600 na, and even
beyond.
That aside, PMK has other good qualities. The stock solutions are rock
stable for years (if mixed with distilled water), tones are much smoother
because the stain serves to mask the grain, and acutance is very high. It
is true that some emulsions do not stain (or very little), T-Max 100 among
others. However, even without the stain PMK is still a very good devleoper
that gives results something like D-76.
Sandy King
I'm not sure how the stain
>density will affect densitometer readings, and haven't a densitometer
>handy right now to check. But it prints in platinum like a 2.0 neg. I
>haven't yet had a chance to see whether it will also print at a much
>lower contrast on standard silver paper, but it looks promising just
>eyeballing the negs.---Carl