U of S | Mailing List Archive | alt-photo-process-l | Pigments for neutral color balance in gum: (Re: Fish Eyes again)

Pigments for neutral color balance in gum: (Re: Fish Eyes again)

Hi Loris, sorry about taking off on a tangent. I'm just guessing
here, because I've not used that yellow (and would recommend using
handprint's mixing triangle as an initial screen, as I suggest on my
tricolor page) but I would definitely suggest a less blue magenta
with your combination. I've had good results with PR 175, a deep
scarlet, with ultramarine and PY110, and Marek recently reported
doing well with perylene maroon (PR179)-- which has a very similar
hue to PR175-- with PY 150, which is also kind of an off-the-beaten-
path yellow, and indanthrone, which like ultramarine, has more red in
it than a true cyan.

It's a casual observation (I haven't done a careful study of this)
that PV 19 is more likely to be implicated in those ugly purplish
brown "neutrals" than other pigments; I use it only with yellows and
blues that stay pretty close to the pure primary hue. Since the
ultramarine is redder than a true cyan, you need a yellower red
rather than a bluer red like PV19 to balance it, and so forth. The
way I think of it is that in order to produce neutrals you need your
three colors to be sort of equidistant on the color wheel, and if one
is hue-shifted in one direction, then the others need to be shifted
in the same direction. Which is an implication of Bruce McEvoy's
mixing triangle: the triangle needs to enclose the center of the
triangle in order to be able to produce a neutral black; if the
triangle is way skewed from equilateral, it may not contain the
center (black) and the three colors layered won't add to black. If
that doesn't make sense, then I need to find a way to write it better.

On Sep 17, 2008, at 12:08 AM, Loris Medici wrote:

"PV19 -> strong paint" is a side note, irrelevant to the main subject
fisheyes... I use very little of this when compared to the other
I'm currently testing/trying for tricolor (BTW, it occured to me
that it's
stronger than Ivory black). So far it gives me nice reds (when
with Schmincke Yellow Raw Ochre 656 - a mixture of PY42 and PY43) and
violets (when combined with PB29 Ultramarine Blue). But I can't get a
neutral black with this combination (but brown). What other pigment
you suggest for being able to get neutral black in tricolor printing?
(Tricolor -> Cyan from Red, Magenta from Green and Yellow from Blue.)


16 Eylül 2008, Salı, 7:12 pm tarihinde, Katharine Thayer yazmış:

On Sep 15, 2008, at 11:33 PM, Loris Medici wrote:

I have the same problem with the same pigment, Schmincke Ruby Red
PV19. BTW, it's a very very strong paint... Do you think that adding
alcohol to the coating mix can help?

Sorry, this doesn't make sense to me, Loris.  In the pigment lexicon
I understand, strength of pigment refers to its mixing power (or
layering power, in our case);   a  strong pigment needs to be used
sparingly in order to keep from overwhelming the other colors that it
is mixed or layered with.  In other words, with a strong pigment,
you need to use much less pigment to get the same color intensity
that takes more pigment to achieve with a weaker pigment.  (I'm not
the first person to notice this; I recently came across a paper where
Demachy was making the same point.)

So if the PV 19 is a  strong pigment (in my mind, PV 19 is, yes,
fairly strong as magentas go, but not as strong as lamp black or
pthalo)  then it stands to reason that you should be using less of it
to balance the other colors than you might use of a different pigment
(PR 209, for example, requires a much larger amount of pigment to
achieve the same effect) and I would think that it would be a mix
that had more pigment in it that would require smoothing out with the
Everclear, not one with less pigment.   Unless the purpose of the
Everclear is to smooth out a watery mix rather than a more heavily-
pigmented one.  Or unless you're meaning something entirely different
by the term.  glad you're back, by the way.