Lily Krakowski on sun 25 may 03
The other day there was a question by someone who wanted to build a glaze
from scratch.
Ok. I see NO point in it unless you are some kind of survivalist and want
to start from some point zero. Every glaze known to mankind is known and
its recipe available somewhere. The reason knowing glaze calculation is
VITAL is that recipes are deceptive. A glaze can contain Whiting, Dolomite,
Frit X, China Clay, Flint, and be exactly the same as one containing
Wollastonite, Talc, Frit Y, Ball Clay. (No I have not figured that
out...it just IS. Because what we really are dealing with is calcium,
magnesium, soda, potash, aluminum, silica.)
But if an angel (wearing a mask and a lab coat!) appeared on top of your
Ohaus and said: "Go forth etc...." do this:
1. Buy a pack of those alphabet looseleaf binder dividers that allow you to
turn a regular looseleaf notebook into an address book. Except here you
will use it to make notes.
2. Read every book you can on glaze. That means RonJohn's (that sounds so
Japanese!) Fraser, Rhodes, Cardew, Cooper, Bailey, Hopper, and then some...
Follow each ingredient through to the end...if there is something in Hopper
on Calcium on page 11, and something on page 76, and so on, read it all and
make notes. Put down who said what....Do this in the alphabetized notebook
so you have a SECTION for alumina, one for boron, one for bentonite, and can
put all the information you gather on each all together under that heading.
Next decide what you want the glaze to be like. Put together the fluxes in
what you think are proper amounts, and then add increments of alumina and
silica according to the usual limit formulae. So that you have maybe 20
tests for one prospective glaze.
Because frits contain both fluxes and boron alumina and silica (not all do,
but that is how it works in essence) treat them as BOTH flux AND
alumina/silica sources.
Test these combinations in small thick cups. See what you get. Evaluate
the results. Make straight line and triaxial blends. Test and retest.
ALL THIS TAKES TIME. Be firm with yourself. Set aside a 3 hour plus time
slot each week, or whatever to do the practical work. The reading you can
do at odd times. I do all my glaze mixing and testing on Thursday
afternoon, the end of my work week, so that by Sunday when I get back to the
studio unavoidable dust has settled, and a wash down of tables and floor is
easy. And--pace, Vince-- after I have finished the mixing and testing I get
out of my dusty clothes which head straight for a water/bucket or the
washing machine, and I head straight for the shower. (My studio
shoes--rubbler clogs, live outdoors, get hosed down)
Lili Krakowski
P.O. Box #1
Constableville, N.Y.
(315) 942-5916/ 397-2389
Be of good courage....
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