Tom Buck on wed 10 mar 99
Cheryl, others
Can we look foward to reading your devoutedly-to-be-wished-for
textbook on glaze calculation as the basis for glaze design for your
standard non-techie potter? Most unlikely; unless there is a change in
the way things are, I cannot see this happening in the near future. My
reasons:
1) The inventors of glazcalc programs are busy elsewhere, partly competing
against each other, partly revising the program, partly preoccupied with
their day jobs (teaching, consulting, potting, etc.).
There is no trend towards a single glazcalc program that would win
unanimous support among interested potters, although when computers change
-- when cross-platform systems/programs become universal -- then perhaps
the authors of glazcalc programs will adopt a standard approach to Raw
Materials Definition (that is, a common database of raw materials'
composition/analysis and conversion to a Seger Formula).
2) Without an acceptable, reliable set of Seger Formulas for raw
materials, the non-techie potter would be at a substantial disadvantage,
even if a someone wrote a companion book to Lawrence's "Ceramic Science
for The Potter" -- say, "Glaze Design ABCs".
Locally, our sources of Pottery Materials and Equipment, keep in
stock close to 100 materials, some high-grade chemicals, some
raw materials slightly upgraded (clays, feldspars, minerals). In some
cases, the dealer will obtain an analysis of some materials (clay
composition is often uncertain). You'd have to fill in the blanks
yourself, or revert to "grab & pitch" mixing/testing, tedious at best,
disappointing at worst. Which camp are you in? Try to obtain/derive a
Seger for the following materials:
Albany slip or Alberta slip
Barnard slip
Bone ash
Kentucky stone
Cornwall stone
Copper carbonate
Feldspar F-4 or NC-4
Frit RCG 3104
Nepheline syenite (Can. or S.Africa)
Petalite
Pyrophyllite
Spodumene
Talc (NY or ?)
Wollastonite
If you do this test you will see you cannot avoid some chemistry --
nomeclature, a peek at the Periodic Table of Elements, the notion of
hydrates, the basic structure of glass, and with time/experience you will
not wince when you read the words "eutectic", phase diagram, triaxial
diagram -- all part of predicting with enough precision to obtain a
successful glaze after a few tests.
So, Cheryl, there the project rests. I hope someone will undertake
to write/publish the book on glaze design for non-techies; it will be a
labour of love with little reward. As you hint, if it comes you will
welcome it and be prepared to learn enough chemistry to become a
successful glaze designer. Good calcs, good tests, good pots. BFN. Tom.
Tom Buck ) tel: 905-389-2339 & snailmail: 373 East
43rd St. Hamilton ON L8T 3E1 Canada (westend Lake Ontario, province of
Ontario, Canada).
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