From: lva (lva@pamho.net)
Date: 10/02/01-09:32:26 AM Z
Judy Seigel wrote:
> 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.
The size of the particles of most powder pigments cannot be reduced in a
mortar.
> 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.
Put the gum in the mortar. Add the powder pigment. Grind until it's a
smooth paste. Add the dichromate. Coat.
> I used a knife to scrape off the
> pestle and scrape down the mortar, very imperfectly, & another mess.
If you insist on grinding the dry powder (I don't see any reason) and it
sticks to the mortar, put the mortar on a stove just so that the mortar
gets a warm. The moisture disappears and the pigment won't stick to the
wall of the mortar any longer.
> 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?
That's when I mine for pigments myself. No pigment wasted, only gained
;)
> I suspect the
> Furnace black, however, is more like smoke (also called lamp black)
> than pigment, which could explain (something).
Yes, a gas flame touches a sheet of metal and produces soot. No mulling
involved. You can make your own lampblack. Take a cigarette lighter and
hold it under a piece of aluminum foil. I have made some the other day
but haven't tried printing with it.
> What paper do you use?
Fabriano Uno Soft Pressed.
> > > 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"?
Of course I don't measure the particle size of my pigments. What for?
You wanted to know whether there ARE absolute measures. And yes, there
are. One can sieve a watery dispersion of pigment through a sive with a
known hole size. One can also use a microscope. But that is lab stuff.
It's not a production technique or for home use. The sieving or
measuring under a microscope is for analytical purposes only. What's the
problem?
> But I for one have NO interest in digging my own pigments, or growing
> my own vegetables either.
Haha! Can one grow vegetables in NYC?
Hey, but you know what you could do? As one of the greatest admirers of
the WTC, you could print a photo of the towers in airborne pigment
that's available in abundance right now all over Lower Manhattan. Maybe
on black paper. I'll buy one if you make them.
Take care.
Brahma
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