RE: Digital Negs - RGB vs CMYK

From: Judy Seigel ^lt;[email protected]>
Date: 12/02/04-11:32:47 PM Z
Message-id: <>

On Thu, 2 Dec 2004, Don Bryant wrote:

> Judy,
>> Let me suggest that that depends on your printer.
> And your inkset and kind of ink. As I remember you are using the inexpensive
> non OEM inks and they are dye based not pigments.

All the inks for the 1160 are dye based... pigment inks arrived later. I
tested extensively, by the way, and found no difference in color,
performance, exposure times or archivality (insofar as I could test for
that, meaning a daylong exposure under UV) and found NO difference between
the non-OEM inks ($3 to $5/cartridge) and the OEM inks at $25/cartridge.

> Additionally the media
> setting in the Print Quality setting found in the Epson Driver dialog box
> will affect the opacity too, not to mention the printer DPI setting. Of
> course since you are using OS something or another with your G4 (or is now a
> G5) the exact settings may be described differently.

Yes, that's what I said.

> If you choose black only in the printer driver then only black ink will be
> used. Also it is usually best to turn off any color management in the driver
> and have the color management set to Same As Source.

Yes, Don... Understood.

>> Not to mention that the process
>> itself is so extraordinarily, infinitely flexible -- in coats, mixes,
>> choice of colors, development, repeats, additions, etc. etc. -- that the
>> negative is in a sense academic -- in the sense of being theoretical
>> rather than definitive.

> strive to eliminate the variable of the ink jet negative even for creative
> reasons, otherwise you end up shooting in the dark, especially for beginning
> gum printers like myself. However I am not suggesting that gum is an exact
> science nor should it be but having one less thing to worry with is a
> relief.

There's a difference between establishing a protocol for printing one's
own negatives and attempting to establish some theoretically "correct"
system for making "real" color negatives. The former is probably useful,
especially for beginners, but my point was that the latter, attempting
"correct" (dare I say "perfect"?) color negatives is, in gum anyway,
attempting to square the circle...or eff the ineffable, or obsess about
trivia, or barking up the wrong tree.

>> And, for what it's worth I'll add that I printed my negatives by CMYK in
>> black, because (a) at the time I didn't know there were alternatives & my
>> laser printer didn't speak RGB, and (b), I was familiar with CMYK from dye
>> transfer, but that (c), the prints were, if anything, TOO realistically
>> "photographic," which was one reason I lost interest in that particular
>> project.

>.... but the question does arise,
> how to create and apply the required adjustment curve or curves. Apply a
> curve to the image before separation or separate and apply curves
> individually?

I found that, given the givens about variability in development described
by all right-thinking gummists, the only meaningful "adjustment curve" for
gum negatives is in the density range. That is, depending on the kind of
printing I was doing, making the negative to be the number of steps on the
21-step that paper/emulsion combo printed *if I wanted full range of the
neg in one coat.* But more frequently, as I gained experience, making a
more contrasty negative (about a range of 1.0) and filling in the image
with 3 coats or so in different exposures. This was especially useful in
making "fake" color prints -- using cyan, magenta & yellow to print 3 or
more coats from a single negative, with some brushing out & filling in

In other words, essentially the method with the white cards & the negative
on the light table, described in P-F #1... We did that for beginners in
class so they got the principle, but one soon gets the general range for
one's own materials.

Otherwise, due to the variables previously mentioned, a "curve" for gum
printing seems, um, delusional? Or self-defeating? To make it work, you'd
have to follow the same protocol for every coat and/or every print. The
thrill of gum printing is the discovery. The unexpected and unplanned.
Otherwise, why bother?

Received on Thu Dec 2 23:33:03 2004

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