From: Judy Seigel (jseigel@panix.com)
Date: 04/02/03-02:27:58 AM Z
On Mon, 31 Mar 2003, Katharine Thayer wrote:
>
> I agree that the "staining" pigments don't stain in gum printing if
> used in proper proportions, but I find the assertion that these
> pigments (specifically thalo (PB15) and quinacridone red (PR 209)) are
> nonstaining pigments in and of themselves, to be a curious assertion.
> All my sources as well as my personal experience say that these pigments
> by themselves have a strong tendency to stain. They are so concentrated
> as they come, that they need to be diluted even when used very
> intensely.
Winsor Newton "Quinacridone red" is indeed PR 209, It is given as
non-staining by both Winsor Newton and Hilary Page, which was also my own
finding. It simply did not stain, even applied so thickly it flaked and
blocked up.
At present I'm using a Daniel Smith watercolor called Quinacridone red...
The DS catalog lists it as level 3, or medium staining, although Hilary
Page says this Quinacridone red is PV19. Whichever, it does not stain.
I've used it in fact as a single coat --very strong, no stain.
Hilary Page says that Daniel Smith Quinacridone Coral is PR 209. The DS
catalog gives it a "2" or low staining rating. Hilary considers it
non-staining also. I've never used it.
> ... Thalo (PB 15) depending on the paint brand can be very
> intense even at surprisingly low concentrations compared to other
> pigments.
Daniel Smith lists thalo blue, PB15-3 as staining, Hilary does not, nor do
I. In fact I have found that even using it so thick it flakes & is very
short scale, it doesn't stain. (Though I showed in P-F 2 that the thicker
the pigment, the less it stained.)
But again, my point is that the so-called "staining" in watercolors isn't
related or only vaguely related to pigment stain in a gum print. Or not
in any way I've found. Certainly the *process* is extremely different. To
get light tones in a watercolor, the paint is thinned with water so
drastically that there's little if any gum arabic left. In a gum print the
entire coat has the same amount of gum arabic -- it's spread evenly over
the paper. The depth of tone is determined by how much of it washes away
-- but the emulsion washes away as one body -- the pigment and the gum
arabic together.Whatever is left has the same ratio of gum to pigment.
For another example of the vagaries of these categories, Daniel Smith,
Winsor Newton and Holbein all list lamp black as non staining. Hillary
lists them all as strongly staining -- and as it happens I've found it
among the strongest stainers, depending on paper and size.
> There seems to be some confusion about how size of granule and the
> nature of the compound (organic or inorganic) relate to staining. My
> understanding is that the organic pigments (including thalo and
> quinacridone red) tend to stain more and also tend to be very fine. T
Actually David Aldera had an explanation of difference among paint brands
that seemed plausible and jibed with my own experience that some colors in
some makes DO stain but not in others. This is incomplete because it was
some time ago & details have faded, but essentially the synthetic colors
are made by soaking bulk synthetic material in dye, then grinding it
up,then mixing with gum, & whatever else to spreading consistency. But
the colors don't all mix wonderfully with each other, some tend to
separate. For purposes of mixing, and the manufacturer's idea of desirable
behavior, x amount of dispersion material is added. That is probably what
causes staining in gum printing. Or I'd say that when i tested a sample of
Golden pigment co's "Universal Dispersant" --- given me by Golden pigment
co, it stained like gangbusters.
The ingredients are (reading the fellow's handwriting as well as
possible): Octylphenoxy polyethoxy ethanol. The printed label says, "Used
to easily disperse dry pigments for use in waterborne systems. It
contains surfactants which are capable of wetting and stabilizing pigment
surfaces, allowing ease of mixing and greater color development." Of
course this particular company is geared to acrylics, but dispersal agents
are used in watercolors too -- by some companies with some colors.
In any event, I found the list of "staining-non-staining' in both Hilary
Page and the catalogs irrelevant to my experience. In fact checking back
through some conservation material and Hillary Page's own description, I
find the definition of "staining" vague and unconvincing. Flaky almost.
In fact Hilary lists "the ability to stain your paper" as one of the
*desirable* qualities of paint. My recollection is that that's her entire
definition... I think BTW that's what Mayer called "covering power,"
which is much more to the point. When a pigment has high covering power
you can use only a little & get good color without having the emulsion get
too thick.
Judy
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