Thursday, July 4, 2013

Shades of Clay

Recently I was lucky to get my hands on some very old clay and pottery materials, but unfortunately nobody remembers exactly what they are.  They were stored for thirty years underneath a pottery which is now closed. Rumour has it that they originally came from the clay factory at Benhar, and could be materials such as kaolin, ball clay, and feldspar...and then there is some mysterious pink stuff.  This could be a fritt, a glaze...or even a fertilizer, who knows! To anyone who doesn't know it just looks like dirt. Excavating them was a mission, as a few bags had split open over the years spreading clay dust everywhere, and I had to cart them along a muddy goat track above a steep drop to a creek. Some of those bags weren't exactly light either.

Various shades of clay ranging from yellow-white, white, grey-white, to grey. Some could be feldspar, silica or kaolin clay?

To test my clays, I'll add a little bit of water to see how it reacts. If it's a clay, it'll be sticky, plastic, buttery, waxy - and feel like clay - but if it's a feldspar or a silica it'll pack down hard like a rock in the bottom of a test container. Preliminary tests have shown that some of these materials could also be a glaze. And then there's still the mysterious pink stuff...

Some fire bricks intertwined with roots of the 'paper tree' (fuschia?) Reminiscent of a scene from Tomb Raider.

Breaking up bags of rock-hard pipe clay (?) under flourescent light, at night. This clay has a beautiful waxy feel - it could even be a fire clay. To test this, I'll fire it in a kiln to 1300 degrees Celsius to see if it vitrifies. If not, I might add some feldspar and try to construct a workable clay body.

Midwinter is a good time to clean up the tools that I've made and collected over the years. Seems like a lot but I only ever use half a dozen at a time.

Buckets of pipe clay (originally intended to make sewage pipes?) and our new kitten. I found him in the middle of the road a couple of months ago on the way out of the local 'Refuse Recycling Centre' and took him home. He's quite a character and full of curiosity, he's always on the go.

Making my own porcelain clay body - and I'll do these tests with the other clays as well. They are a warpage bar, a shrinkage bar, a small thrown beaker and a test tile to test glaze fit and vitrification. From this I should be able to formulate a throwable clay body, in porcelain and South Stone (stoneware).

I am also planning on testing everything in my glaze lab so I have something to compare these results to. A couple of years ago I got some glaze materials that also need tested so I might as well do that while I'm at it. But that will have to wait for the next blog post.


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