Re: Paper negatives- Ink Selection
P.S. I don't disagree that a negative with a density range of
somewhere around 1.0 tends to work best for gum in general, but then
this is common knowledge among gum printers, so I'd assume most of us
are printing with negatives of similar density range.
On Oct 14, 2008, at 9:18 AM, Katharine Thayer wrote:
On Oct 12, 2008, at 11:23 AM, Loris Medici wrote:
I use the grayscale using all inks (not black and gray - if
present - inks
only), plus, I choose plain paper as the media. Fortunately, with
my inks
the printer lays just enough ink giving an almost perfect negative in
terms of density range (something around log 1.0), and the curve I
use for
gum prints are is the least drastic and most smooth one among my
curves
collection for many processes and paper. In fact, I think that's
why other
people's exposure times are considerably longer compared to
mines...(!?
Loris, I'm wondering what data you're basing this last bit on, that
other people's exposure times are longer than yours. It's
generally not useful to try to compare exposure times because there
are so many variables involved, but putting that aside for a
moment, I've looked back through this thread, and the only
reference to exposure times I can find is Guido's comparison
between oiled and unoiled Epson PQ paper, 8 vs 48 minutes, with
cyanotype. Since it was cyanotype, and since the paper is a
heavier paper (27 pounds) than yours, it's not surprising that his
exposure time for unoiled paper would be longer than yours, and we
haven't even got to light source yet; to reach immediately to
curves to account for a difference in exposure times seems rather a
long stretch to me.
Perhaps I've missed other posts that included exposure times for
gum and paper negatives (my server doesn't accept some of the alt-
photo mail, so I don't always see all the posts). At any rate, my
times with oiled paper negatives run close to my times with inkjet
transparencies, about 3 minutes, to add to your database on
exposure times. I don't have any comparison with unoiled paper to
offer, because that's not an option that makes any particular sense
to me.
But be that as it may, I can't see any reason why curves would
account for a difference in exposure time. After all, the exposure
time is determined before curves are even calculated, at least
that's how it is with the system I use, and I assume it's the same
with all systems; the curve doesn't change the exposure time.
Besides, curves simply redistribute the tones within the print
tonal range that particular emulsion can print under that
particular protocol; they don't extend it, so there's no logical
reason curves would have any effect on exposure time.
Katharine
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