Zinc Silicate Crystalline Glaze Pottery

Friends' Work

Graeme Anderson    Gemopal Pottery

May 10, 2008

Hi Phil.

Here's a pic of the key ring pot. 
Cheers.  Graeme

These pots are stuck on a tongue depressor, 3/4" wide.  They range from 9/16"  to  1 " high.  The toothpicks are to show that the pots are hollow.  I weighed one on my old opal scales, and it went 35 carats  weight.  At 5 carats per gram, that's about 7 grams for the pot.
Don't hold your breath for a pic of me actually making one.  I used a particular mix of clay, and it had to be just the right consistency for these mini pots.  Clay too soft or too hard was useless.  And I had to be in the right mood, too, with a happy crowd watching the demo.
Anyhow, I'll climb down into the bowels of the earth to my underground storage room, and see if I have any of that clay left from years past.  It's probably been ten or more years since the last lot went through the pugmill.  If I mix a new batch, I like to let it age for at least 3 months to gain plasticity before use on the wheel.


All my pots are handcrafted of clay dug from the world-famous black opal fields of Lightning Ridge. No other clay, or any colourant, has been added to the clay. I use lead-free stoneware glazes. The clay is reduced to a slurry with rain water, sieved through 60 mesh to extract coarse material, and hopefully, an opal or two. This fine grained clay has a high silica content, which causes problems with glazes, so a colourless flux is added to the clay to counteract the silica. The slurry is dried on plaster slabs to a plasticine state, put through a pug mill, wrapped in plastic to stay moist, and stored underground to age and sour (to gain plasticity) for at least three months before use on the potter's wheel. The clay varies from field to field in colour, silica and mineral content, and shrinkage rates.

 Other problems associated with using the opal clay are a high (2%) soluble salt content, and a high shrinkage rate, which can be up to 20%. The salts can cause unsightly scumming on the pot's surface. Flat plates and tiles have a tendency to warp. The clay is the silt from an ancient inland sea, which explains why there are so many salts and minerals present. I fire different kilns, using electricity, gas, and wood. I still experiment with local materials for glazes, and clays from different fields. At present, most of my pots are made of clay from Canfells, 3 Mile and 4 Mile fields, the 15-10 survey area, and "Anderson's Folly". (My old claim, 32km - 20 miles away by road and bush track.)

You may be interested in this shot of my pottery - the place looks almost tidy from a great height.  The green roofs next door belong to friends who run the Goondee - Aboriginal Keeping Centre.  Some fascinating insights into the history, and  collections of artifacts, tools and weapons. Roy Barker, who just turned 80, still makes stone axes, spears, boomerangs, and so on.  But he does use white man technology - such as saws, grinders, and sanders, etc.


(02) 6829 0375.

65207andon@ceinternet.com.au http://www.members.ceinternet.com.au/gemopaladsl/





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Phil Hamling