MEETING Report

At the March Guild Meeting, Don Hutchinson described
his work in Summer 1983 in B.C. locating natural glaze
materials and testing them. He plans to produce a map of
the province showing where these materials soeeur. He will
provide each area with glaze tests made from materials
available locally. So far he has covered the Okanagan and
the Nelson area,

The materials are free, easy to get at, and can be
processed without expensive equipment. Any crystalline
rock, once bisque fire? {esleined), gan be broken up by
hand to pea-size. You-twen 2498.3, bell mill to break it
down to pass through a 60 to 60 mesh sereen. Don pointed
out that the 12th century Chinese potters obtained beau-
tiful, subtle variations of colour in their glazes by
using their local materials contalnlug impuribles.

Don is trying to simplify testing by using only three
ingredients in a glaze, or four at the most. He makes
10 gram samples (just enough to paint a test tile) as
follows:-

Sample 1 Sample 2 Sample 3 Sample
Rock ee 6.2 T9 Ts gr.
Flux 0.5 0.8 1.1 1.4 gr.
Olay 1.0 1.0 1.0 1.0 gr.

The flux may be, for example, lime, talc, dolomite, etc.
The clay he used was Kentucky Ball OM4 or China Clay.

In the first series you are looking for the character of
the glaze, ignoring the colour. Assuming that Sample ¢£
gives the character you want, but not the colour, you can
change the flux to get a different colour:-

Rock 7.6 7.6 7.6 7.6 gr.
Flux 0.5 Lad iacet 200 oR
Clay 1.0 1.9 1.0 1.0 gr.

Tale improves the feel of the glaze, dolomite has nore
character than lime, but too much makes it runny. Increased
lime make for crazing. Dolomite rock is a problem to crush
as it cannot 3e calcined.

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