Transparency v semi-transparency

Hi,
It occurred to me that I didn't need to wait til I do the tricolor tests
to do this; I could just print some yellows on black paper. So I did
that; I printed the following colors:

PY 175 (benzimidazolone yellow) -- semitransparent
PY110-(isoindoline) -- transparent
PY 151 (benzimidazolone lemon)--semitransparent
PY 3 (Arylide (hansa) yellow light)--semitransparent
and PY 35 (cadmium yellow) --semiopaque

I'm looking at the finished and dried results now. None of the
semitransparents printed as transparently as the PY110; they all exhibit
a definite mist of opacity over the black, but there's some variation
among them. Arranging the semitransparents in order from most to least
transparent, it's 151, then 175, then PY3, which is almost as opaque as
the cadmium. The cadmium is, as one would expect, the most opaque of the
lot, covering the black with a veil of definite yellow. The effect is
green, looking through the opaque cadmium to the black, and that is also
true of the PY3. With the PY 175 and PY 151, the veil is so light it
appears white rather than yellow, but it's still definitely there. Where
the PY 110 is on the paper, it just looks like a blank spot, until you
turn the paper at an angle to the light catch the sheen of the gum.
(Another example of this pigment printed over black can be seen in the
image on my home page, on which I added another layer of yellow after
the tricolor was printed, because I thought the apricots needed a little
more yellow)

http://www.pacifier.com/~kthayer/

Caveats: (1) There's possibly a loose variable in that while I've tried
to mix each of the pigments to color saturation, there is probably some
variation in how well I've achieved that. So I wouldn't put too much
faith in the ranking of the semitransparents. But there's no doubt that
the PY 110 is well saturated; I mix it to orange, though it prints as a
deep yellow. (This is one counterexample to what I said the other day
about the printed color usually looking the same as the mixed color.)
(2) I'm not so sure about the PY3; I grabbed it in Grumbacher because I
didn't have it in my usual brands, and I don't trust Grumbacher to be an
accurate representation of the pigment. So I wouldn't say as a general
rule that PY 3 is almost as opaque as cadmium.

I scanned this but the scan doesn't accurately represent the subleties
of the differences, and I don't have time to mess with it and try to get
it more right.
Katharine

Katharine Thayer wrote:
>
> Christina Z. Anderson wrote:
> >
> > (Katharine said) The PY 139 is only
> > > semitransparent, and the "new gamboge" by which I assume you mean the
> > > new paint that M. Graham now markets under the name "gamboge" can't
> > > possibly be as transparent as the PY110, since both of the pigments it
> > > contains are only semi- transparent.
> >
> > Katharine,
> > How much difference do you think going from a transparent to a semi
> > transparent pigment would actually make, when the pigment is mixed in gum
> > and applied thinly? I suppose I could test this by just brushing the two
> > over a dark layer and seeing the effect, but if you've already done a side
> > by side test that'd save me some time. The reason why I ask this is because
> > the cad colors and nickel titanate are realllly opaque, but in thin layers
> > you can still see through them.
>
> Sure, you can see through them, like a veil, but it's not the same as
> being truly transparent. I like being able to put yellow over black
> (as in adding an extra layer of yellow as a fourth layer over a
> tricolor) without there being any evidence of the yellow as a separate
> layer over the black. PY110 is the only yellow I know that can do that.
>
> One of the things I plan to do this week is print a bunch of different
> yellows as the last layer on a tricolor, to show the difference.
>
> My point earlier was that each pigment has its own unique character,
> that's what's so cool about pigments: no two are the same, and they
> aren't interchangeable.
>
> Katharine
Received on Tue Jun 7 12:52:32 2005