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Hello folks,
I can't tell you what fun I have had since subscribing to this list
(which began sadly enough with the Klaus Hendricks Obit). It is good
to be among others who feel so passionately about "our little patch of
the elephant".
Some observations about the procedure that is currenlty causing many
sleepless nights: ball milling pigments.
First, as someone said, we are not actually reducing the absolute size
of the pigments when they are ball milled, but we are reducing clumps
of pigments known as "agglomerates". It is actually quite difficult
to reduce the pigment particle size (measured on a Hegmann Scale)
smaller that when it was originally manufactured.
We are also dispersing the pigments in some sort of medium (water,
oil,etc). And this is exactly why ball milling your own pigments
makes sense. Because you can control what stuff is added to the
pigment to make it flow or glisten or whatever. That is why a W/N
watercolor pigment in a tube is not the same (for the purposes of
emulsion formulation) as its dry powder ("pan') equivalent.
Efficiently grinding pigments in a ball mill is a serious pursuit.
Typically, ceramic "stones", (usually 1/2" rods) are loaded into the
mill and occupy 30% of the volume. The pigment(s) are premixed in the
chosen medium and the poured into the grinding jar, covering the
stones and filling half the mill. After grinding 18-24 hours, add
water to fill the mill to 80%, grind a few more hours (this is called
"let down"), and pour off the grind thru a cheese cloth. Like so many
things, there are many ways to do this, but this technique has worked
well for me. I hope it works for some of you.
Regards to all,
Charles Berger
cb@ultrastable.com