I have spent a few days testing the Standard Exposure time of Pt-Pd printing with my 4000 W Plate burner. I have made two different kinds of tests, by using the Stouffer 31 steps covered with Pictorico and also by making strips of different exposure values of a coated piece of paper with half of it covered with Pictorico. I have found some really puzzling results…
Basically, when I observe the print from above, under reflected light (or I scan), certain areas seem darker than the rest. So far, so good. Then, when I place the print on a big light table, under transmitted light the darker areas seem to be others! Is there any physical explanation for this?
Another weird thing was that when analyzing the test strips under transmitted light (lit from behind, in a dimly lit room), I seem to see the blacker blacks happening under exposure values of more than 16 minutes… which seem to me a bit exaggerated for a 4’000 W metal halide unit (lamp placed at around 1.20 m).
Should we only evaluate the reflective densities in order to analyze the blacks when calculating the exposure time? Is it normal the reflective and transmissive densities are different? (I would say almost contradictory!)
I will also take advantage and ask you another thing. I have seen most people out there calculate the exposure times by using Stouffer step tablets (31 steps for instance, in 0.10 steps), by placing a piece of Pictorico on top of it and seeing at which step the next one becomes indistinguishable. What I do not understand however is that this calculated exposure level would be the one providing Dmax when exposing a negative whose density is the addition of the density of the Pictorico film + the Stouffer negative. And so, if we use that exposure level when exposing only Pictorico, we will be giving too much light… Should not we take into account the subtraction of the Base+fog density of the Stouffer step wedge to reduce the exposure level accordingly?
Thanks and warm regards,