From: Judy Seigel (jseigel@panix.com)
Date: 10/01/01-04:34:23 PM Z
On Mon, 1 Oct 2001, lva wrote:
> > Have you tested change in color with grind in pigment?
>
> I have. In some cases the change in color is stunning. For example, the
> finer I grind the real Caput Mortuum powder pigment, the more colorful
> and violet it gets.
Brahma, was it you rhapsodized about the burnt sienna? Someone on this
list did... The LAST thing I wanted was to mess around with dry pigment
(having tried it in a limited way previously & found it lacking). But
whoever was so enthusiastic, and I DID have this jar of burnt sienna, and
it WAS a dandy color, so I tried it...
Actually it was interesting, promising even... but I found it sooooo
different from printing with tube paints I didn't really get a handle on
it -- and also erred in not making organized tests (do as I say, not as I
do) in my impatience. So far, I've tried the burnt sienna and Kremer
furnace black, but what I've found (again empirically, not methodically
tested) is that the GREATEST difference comes not from degree of mulling
(and OHHHHH, what a mess... spill just a puff of that black, you think
the chimney exploded)... but from the paper.
That is, a coarse paper (Merten Spiesse) looked like a coarse grind,
attractive but more like gravure than the usual gum, while a smooth paper
(uno) looked almost too smooth, yet both had been mulled about the same.
As near as I could tell that is, the mulling is so far out of control. How
do you keep it from creeping onto the table, across the floor and out to
the street? I mean trying with a palette knife to keep folding it in on
itself spreads rather than confines, and mulling in mortar and pestle
spreads clumps around. I used a knife to scrape off the pestle and scrape
down the mortar, very imperfectly, & another mess.
You say you add a lot of water for the mulling ... in what? Then pour it
off... that also involves a lot of wasted pigment, doesn't it?
> Dr Kremer has his own explanation for this. He thinks--and he points out
> that this is his personal opinion and not scientifically proven--that
> the human eye can perceive individual particles down to 10 micron. If
> you have ever seen a 10 micron line field (there's a test strip for the
> Cromalin process, for example), it looks grey and you cannot make out
> the lines. Kremer says while you cannot see them, you 'perceive' them.
> I'm not sure. But the possibility is there.
I don't see *any* individual pigment particle, so I don't follow that in
relation to brightness.
> Moist watercolor in tubes often consists of pigment particles between 0
> and 1 micron. That is VERY fine. Powder pigments usable for the gum
> process have particles between 0 and 20 or 30 micron. Kremer says the
> light effect these pigment "mountains" or rather pigment "rocks" create
> on the paper give life to the color. He may be right.
It's also possible that dry pigment from other sources has a different
grind... Grumbacher, et al, may sell same as their tubes. And to
complicate matters, my burnt sienna coating looked coarser, it was bought
in Switzerland 40 years ago. My Kremer Furnace Black was much finer
(seeming) tho you say Kremer pigments are coarser. I suspect the Furnace
black, however, is more like smoke (also called lamp black) than pigment,
which could explain (something).
What paper do you use?
> > How do you figure "fine grind" anyway? Are there absolute measures for
> > pigment particle size?
>
> Yes. In micron. There are technical sieves with known hole sizes.
> Sieving pigment through such a filter gives one a pretty clear
> indication of the coarseness of the filtered pigment.
I don't want to do it, you don't want to do it -- but have you done it?
Ie, sieved pigment to measure before and after "grinding"? Which is to
say, your enthusiasm is contagious, but I'm not sure how much of any of it
is established. That probably matters less than empirical experience
anyway (as in the rest of gum printing, where theory is useless), but
still I wonder....
Incidentally, the wet burnt sienna smelled like -- surprise !! -- mud.
Rather overpoweringly, maybe its age. But I for one have NO interest in
digging my own pigments, or growing my own vegetables either. I have
hundreds and hundreds of gum prints I haven't made yet & life is short.
Judy
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