Re: Help with gum pritns on black paper with white Gouache.

From: Dave Soemarko ^lt;[email protected]>
Date: 01/18/05-10:00:49 PM Z
Message-id: <00d901c4fddb$767dfd50$0502a8c0@wds>

> darker background. For example, the apricots on my index page (I am so
> glad I've finally got a website so I can use it for examples to
> illustrate what I'm talking about here):

Isn't that nice? :-)

> the sample print of PY110 at the bottom of my page on pigments. So it's
> not that the yellow is printed less concentrated that makes it
> transparent, it's its *transparency* that makes it transparent. To check
> the concentration that was printed,
> But if you printed an opaque yellow on top of the black, you would see
> it as a thin veil or a thicker more opaque layer of yellow over the
> black, depending on the concentration of the pigment in your mix.

Yes, but you are really talking about relative transparency. One yellow
pigment can be much more transparent than another yellow pigment. That I
agree completely.

> To summarize this point, transparent pigments are transparent and will
> be invisible over a darker background no matter how concentrated they
> are printed; opaque pigments are opaque and will be visible over a
> darker background no matter how thinly they are printed.

This might be true on particular watercolor pigment, but the description is
not technically correct. There is nothing as pure transparency. I am afraid
we are getting a little too technical again, but think about this, when you
paint some yellow paint on white paper, why does the paper look yellow?
Because the pigment block up the total reflection of the white of the paper.
It doesn't block up all colors, so you see yellow, but something obviously
is blocked, otherwise the paper would still be white if the paint is
completely transparent and every spectrum of light still passes through the
film, reaches the paper, and gets reflected black. It is relatively more
transparent in a sense that you can lay down a relatively thick layer and
can still see the color beneath it.

On whether you can have enough concentration or thickness to make it opaque,
just think of it this way. If I buy some dry pigment of your transparent
yellow, and I pour two teaspoon over of a small black patch covering it, do
you think you will still see the black patch under the pigment? How about if
put even more and make a small hill of yellow pigment. Will you still see
the black under it? Now imagine that we add just enough gum to hold the
pigment there, it become a yellow cake covering the black. This is an
exegeration, but it shows that with enough concentration and thickness the
so called "transparent" pigment can be made opaque.

>> As for additive, however, W&N literature specifically said that they
>> don't
>> add additive to increase the opacity and that they use more pigment
>> instead.
> I read this differently than you do; I read it to mean that they don't
> add fillers like white chalk like the makers of cheaper gouaches do. But
> of course they add other ingredients; all paints add some other
> ingredients, as Judy taught me.

Yes, of course they add other ingredients. I didn't mean to say that the
ingredients for watercolor are exactly the same as those for gouache. What I
was saying was that they didn't add other filler in order to make it opaque.
We can probably agree that we read their description differently; but I
didn't just read one line of description. This has been many years ago, but
I remember the description also said that they didn't add filler so that the
color saturation was not affected (or degraded). If one adds filler to the
color pigment, the saturation is going to be decreased because you don't
have that much color pigment. But at least W&N said they didn't add filler
but used more concentration of pigment so that saturation was not affected.
All together, it sounded more like no filler was added.

> No, a transparent pigment is transparent no matter how thickly you lay
> it on; at least in gum printing you can never make a transparent pigment
> heavy enough to completely block the light, because if you printed it
> that thickly it would just flake off in development.

But here you are talking about the *process* of gum that cannot (or is
difficult) to print infinitely thick. That I agree. But I was talking about
the pigment itself.

!!! And I didn't intend to get this technical either. It's just that someone
asked something
!!! (actually I forgot what exactly the question was but it had something to
do with whether
!!! it was possible to print full range with gouache or that it is
impossible because gouache was
!!! inherently transparent). So my answer was simply that it was possible,
and I gave some
!!! explanation of my reasoning as well as showing my works done with
!!! Just that simple.

Received on Tue Jan 18 22:01:03 2005

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