Craig Martell on thu 4 dec 97
At 02:41 PM 12/1/97 EST, David Mcbeth wrote:
>----------------------------Original message----------------------------
>Gibby's Wild Rose Tenmoku (altered from John Chalke) ^ 6 ox
>Lithium Carb 10.5
>Bone Ash 10.5
>Neph Sy 61.5
>EP Kaolin 17.5
>
>Add:
>Red Iron Oxide 10.5
>However, also where it is thick, the glaze shivers off.
>Fournier's Dictionary recommends replacing the china clay with feldspar
>or the china clay with ball. Since there is no feldspar to replace and
>only a little china clay to work with, I'll try that. Any other
>suggestions would be aprpeciated.
Hi David:
When looking at this glaze in the molecular state, the main flux, on the
molecular level is Lithium. It is just slightly more than the KNaO. Since
Lithium has almost no coefficient of expansion, this is a low expansion
glaze and will not fit all clays. Nepheline Syenite can be considered as
the spar in this glaze. It is considered to be a soft soda feldspar and
contributes soda, alumina, and silica to the glaze. It is the highest
expansion spar that potters use, but here, on your clay it is not enough to
offset the Lithium.
For this glaze to work on your claybody, you need to reduce the amount of
Lithium in the glaze. This glaze is a bit low in silica too but adding more
silica in its present state will only make the shivering worse.
regards, Craig Martell-Oregon
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