The resident expert at Voltarc told me they found exposure times
just about the same with fluorescent bulbs at 415 and 360 nanometers,in
platinum and other "non-silver" processes, but whether this sameness
applies to plateburner bulbs I suppose depends on how much lower the
lower bulb is.
About the same? Meaning what, exactly. As you mentioned later, you desire to
tweak in the process by matching negative to print material, etc. so why not
tweak in the bulb, too? A good test would require that same wattage 360 and
420 bulbs be used in the same exposure unit so all the other poswsible
variables -- ballast amps, bulb to paper distance, # of bulbs, etc -- were
now constants.
When you say dodging and burning with rubylith, I take it you mean by
means of masks. I find cut-out masks leave a very unattractive hard
edge. As for "neanderthal," well, let's say I disagree.
Yes, I did mean masks, but mine, placed on the surface of the glass, are far
enough away from the image that a hard edge doesn't appear. Another trick is
that after cutting the rubylith I take a red fine point Sharpie pen and draw
a squiggly line if necessary to soften the edge. In fact, right now I'm
typing this while a Pt/Pd print gets a 100% burn on four small nails in an
image which take a teeny portion of the image and are obviously hard edged as
objects, but even with such a long burn you don't see the edges.
(Besides which, gum printing isn't exactly cutting edge.)
I was sort of joking with the neandrathal bit, but then just because gum
isn't "exactly cutting edge" we shouldn't necessarily use techniques which,
young or old, are potentially dangerous. When I made that comment, it was in
reference to an earlier post where someone talked abiout sticking his hands
in the light beam for dodging and burning and I still call that neandrathal.
Maybe cro-magnum (sp?) but pretty silly nonetheless given the potential harm.
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