Re: Beginner Density Questions & Digital Negs

Gu,
Loris is right--that a 1.9 refers to density "range". Some processes
require a huge density range such as platinum. Some, such as gum and
cyanotype require a more compressed density range. A lot of the books will
describe it as a negative that prints on a grade 0 paper or a grade 2 paper
to differentiate between those processes that need a greater to a lesser or
a more normal density range.

I will add my two cents about the 2400 since that is now my printer. I
think originally, Gu, you asked a question about colorized negatives. I
have found in using the 2400 that the black ink is less dense than the
colored inks in that printer and by comparison to the Epson 2200, the black
is not as dense as the black ink in the Epson 2200 which I used to use, but
the colored inks are more dense than the Epson 2200 colored inks by a bit.
This is fine, because I don't use black ink in my negatives. The 2400
prints beautiful color-only negatives that work for all processes.

Depending on the process you are doing, you have to be aware that with alt
processes, it is the UV density of the digital negative that comes into
play, not just the blocking density. Hence, a color may look pale in
comparison with black ink, but actually hold back lots of UV light in
contact printing processes. I don't have a transmission UV densitometer,
and therefore can only find this information out by printing step wedges and
scanning and measuring reflective values on a flatbed scanner.

There are a number of ways to go with digital negatives, in my mind. For
one, go to Dan Burkholder's website and download a curve (plus his myriad
other tiny tutorials which are worth every penny--I had students this
semester using his platinum over pigment process and producing gorgeous
work).

Two, go to Mark Nelson's precisiondigitalnegatives.com site and purchase his
software system which enables you to create custom curves for every
process--more work to do but in the long run it is a necessary tool to
understand how digital negatives work in all processes with all different
printers. If I can teach it to 16 students who produced perfect platinum
prints in their first try, you know it works. Not one of them complained
about the $75 cost after they saw the results.

In fact, I have seniors waiting to take their last allowable junior level
class for a year just so they can be assured of getting into the alt process
class next spring (we have waiting lists on all classes and that class in
particular only accomodates one section of 16)! And I don't think it is for
my scintillating personality.

There are also a couple other people who have developed a personal method of
digital negative making--Clay Harmon on this list is one, and google his
name. I heard of one other person coming up with a system that you could
also try, but I forget at the moment his name.

The bottom line is that not only do you have to find the correct ink to
hold back light, but you also have to use the correct curve that is smooth
and fully tonal so you don't get steps/jumps/posterization. You don't want
bumps in your curve.

You know, is everyone on vacation or WHAT? Get those fingers moving you
people!
Chris

From: "Loris Medici" <mail@loris.medici.name>
Michael, I don't agree with you on the fact that the cited 1.9 density
range figure is referring to the reflective density of the print. In my
understanding the 1.9 figure refers to the density range of the
negative. And when one talks about density range this means the absolute
dmax of the negative should be even higher: For instance, if the
negative material's base + fog density is log 0.3, then the absolute
dmax of the negative should be 0.3 + 1.9 = 2.2 - that is for being able
to print a full tonal image by using the specific process (and/or
coating solution/emulsion mix) which requires a negative density range
of 1.9. IME, it is impossible to get a printed density range of 1.9 with
palladium - this is closer to what you can get from air dryed fiber
based glossy silver-gelatine paper! I can't get such a printed density
range even after coating my palladium prints with glossy polyurethane
wood finish... (which improves dmax by log 0.3 - 0.4 / over regular
uncoated prints).
On the other hand, with print-out palladium (ammonium iron(III) oxalate
sensitizer + Li2PdCl4 - that is Ziatype w/o any contrast agent) the
negative density range requirement is considerably higher than 1.9.
(This is probably true for develop-out palladium also...)
Received on 05/16/06-07:49:16 AM Z