colors for colorizing digital negatives

Hi All,
I'm so glad to have a printer (Epson 1280) that will allow me to
print negatives on transparencies again. My 1280 prints great
negatives by simply choosing "color inks" and "inkjet transparencies"
to print a black negative that's dry almost as soon as it comes out
of the printer. The negative looks fairly thin when you hold it up to
the light, but it prints gum beautifully, and I don't see any reason
not to just keep doing this.

But last fall when Clay posted his ternary method for choosing a
color to use for colorizing, I was intrigued, and the other day I
downloaded the triangle (thanks, Clay!) and printed it on Pictorico
(by the above method) and printed that (twice) on gum, just out of
curiosity.

I found that six of the seven triangles that blocked radiation
completely were in the red corner of the larger triangle: (R: 255,
G: 0, B: 0) (R 190, G 0, B 0) (R190, G 0, B 64) (R 190, G 64, B 0)
(R 128 B 64 G 0) (R 128, G 128, B 0). The other one was (R 64, G
128, B 0). The other triangles in the red corner, and the other
triangles in the green corner, printed with various fairly light
tones. The triangles in the blue corner printed with heavy tone, with
one exception they printed as dark as the tone in the border outside
the triangle; in other words, for almost all mixtures containing more
than B: 64, the ink didn't add anything to the Pictorico in terms of
blocking radiation.

This is interesting to me in that when I tried printing colorized
negatives with my old printer (Photo Stylus EX) I didn't find that
colorizing with red-orange worked well at blocking radiation, and
in fact I just got rectangles of solidified gum, no image, by either
of Dan's colorizing methods. It's also interesting given that I
thought I'd been reading (this could be wrong, because I wasn't
paying too much attention to those discussions) that people were
finding a green or blue-green color to be best. But maybe that wasn't
for gum. Or maybe it was for inkjet printers that use pigmented inks
rather than traditional inks.

I do understand, as other folks have cautioned, that one shouldn't
make much of the color, because how well an ink blocks light probably
has more to do with other properties of the ink than with the color
per se, and besides it's probably one of the many issues with gum
that are best resolved individually since each printer will find a
different color that works, depending on the characteristics of the
printer, and it's what works that counts. But I'm stlll curious.

   I don't have a transmission densitometer, but just looking at the
negative against the light and laying it over newspaper text, I can't
see any noticeable difference in transparency between the different
colors (my hypothesis would have been that the blue ink is more
transparent than the others). And when I scanned the negative back in
as film and looked at the colors as printed (as opposed to the colors
in the original file) I didn't find that the blues were lighter than
the other colors, although I did find that the blues were in
general less saturated (many of the colors in the original file were
out of printing gamut, but the printer desaturated the blues more
than it desaturated the other colors to bring them into the printer
gamut).

Katharine
Received on Fri Mar 24 10:15:27 2006