From: Judy Seigel (jseigel@panix.com)
Date: 04/16/03-12:01:40 PM Z
On Tue, 15 Apr 2003, Jack Brubaker wrote:
> I have thought on why some pigments stain when machine ground for tube paint
> and don't when used as powder mixed by hand into our gum solution. Someone
> was commenting last month about having read about grinding pigment into the
> gum until it no longer clumps. I think the clumping refered to is the
> tendancy of the finely powdered pigment to not easily disperse in the mix.
> At first the powder will "clump" together with many particals of pigment
> cemented together but dry inside the clump. The goal when grinding pigment
> into any medium be it oil or gum or what have you is to wet each grain
> seperatly. This can only be done by grinding very aggressivly with a solid
> muller on a hard surface like glass of steel. However I doubt that anyone is
> doing that for gum printing. So we are in effect printing with small clumps
> of pigment not super finely ground pigment. I believe the finer the pigment
> the more likely it is to sink deep into the surface of the paper or size and
> not wash out during developement. Hand ground (or brush mixed) pigment will
> be more likely to sit on top of the paper surface and be easy to develope.
> In purely economic terms we are wasteing pigment doing this since the
> pigment reaches its maximum tinting strength by being fully wetted out in
> the solution (the grains are all visable not stacked behind oneanother).
Jack... I'm not fully convinced about "wasting pigment" -- and if it
theoretically does, I find powdered pigment so extremely economical that
(unless it's something environmentally harmful, which I'd hope not to use
anyway) the point seems moot. What I'm TRYING not to waste is my own time
and energy (both on the wane) -- I find that long long grinding/mulling of
dry pigment doesn't make any perceivable difference in the print -- or not
that I detect. I brush with a stiff round bristle brush to combine the
gum and the powder only a bit longer than if it were tube paint -- it
seems to work the same as when I mull forever.
Judy
> Tube paint is finely ground to maximize the pigment and to keep it in
> suspension. But, pigment conservation is not as important as getting a
> print with clear whites. For reasons we can only guess at paint
> manufacturers add other ingredients to their paints some of these may
> further conflict with our goals. Most of my printing has been with tube
> color but I am beginning to wonder about it...
>
> The above is my guess as to what is happening. Does anyone have any thoughts
> or experience that would shed more light on the subject?
>
> Jack
>
> > From: "Christina Z. Anderson" <zphoto@montana.net>
> > Reply-To: alt-photo-process-l@skyway.usask.ca
> > Date: Mon, 14 Apr 2003 21:50:26 -0600
> > To: alt-photo-process-l@skyway.usask.ca
> > Subject: Re: Mixing a light pigment for gum
> >
> > Dave,
> > Do you notice a difference between ivory and lamp black? And
> > quinacridone what? Cobalt what? Cadmium what? I have cobalt blue and
> > violet but man, are they weak. In tube form, anyway. I did use a powdered
> > q. violet the other day and it was incredible how it did not stain and yet
> > was really bright, vs. the tube pigment which did. I can't figure out why
> > that would be the case.
> > Chris
> > ----- Original Message -----
> > From: "Dave Rose" <cactuscowboy@attbi.com>
> > To: <alt-photo-process-l@sask.usask.ca>
> > Sent: Monday, April 14, 2003 8:32 PM
> > Subject: Re: Mixing a light pigment for gum
> >
> >
> >> As others have noted, reducing the amount of pigment will produce a more
> >> subtle effect.
> >>
> >> My favorites? Umbers, siennas, ochres, phthalo blues & greens,
> >> quinacridone, cadmium, cobalt, ivory and carbon blacks. I prefer powder
> >> pigment to watercolor paint.
> >>
> >> Dave in Wyoming
> >>
> >>> And maybe I can ask this--what are people's favorite
> >>> colors--specifically paints? So far, for instance, in testing raw
> > sienna
> >>> against gamboge, similar colors (gamboge is yellower and more brilliant
> >> and
> >>> more transparent) I would choose raw sienna because it clears very well.
> >>> Chris
> >>
> >>
> >
>
>
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