Friday, 2 November 2012

Stirring up the Beast

The first time I went to Marks Pottery he was building the Beast;  up to the chamber arch and it looked big.
"What cubic capacity is it"?
" I don't know, but it's big"

He fired it sometime later, and the results had not been good. Hot at the top, but only near the front, cold from the middle down. Barely cone 7 and none of the glazes had fluxed.
Lots of remedies were discussed and finally it was decided the solid bag wall was too high.
I went to stay for a few days to make pots and help with modifications. We lowered the bag wall and opened it up, chequer board style so that flame and heat would hopefully get to the bottom of the chamber. We took a couple of courses off the chimney to slow down the flame a little and keep it in the chamber longer.
Over a year went by, Mark had not made any new work and I couldn't possibly fill a kiln that size with hand built work.
Finally we decided to fire the kiln at the end of September and as I made pots, I put them to one side whilst Mark spent four weeks intensive throwing. September turned into October when we finally set a firm date, with a plan to fire for up to thirty hours.

It took a whole day to pack the kiln, me glazing as we did so, as it was not possible to transport ready glazed pots from Leicester.
The kiln was heated with gas to drive out some of the moisture, finally the fire was lit at six o'clock the next morning and we were under way.
The kiln has a single chamber of approximately 80 cubic feet with a Bourry box. It's a scaled up version of Mark's previous kiln and the intention was to salt fire. It was decided that we would wood fire only this time, plenty of wood ready stacked, mostly Larch with some Cherry and Birch. Nice and dry as it had been there for well over a year.
Stoking progressed steadily all day and the temperature shown on the pyrometer climbed, the probe at the front showing about a hundred degrees more than the one at back, so we closed the dampers to try and even out the heat. It seemed to work, but progress was slow. By about midnight we were showing eleven hundred, but the bottom looked nowhere near that. But alarmingly the cones at the top near the front were beginning to fall.

By six o'clock in the morning the cones at the front were all flat, but still standing to attention at the bottom and cone 9  hardly bending in the middle. Over twenty five hours and a final push to get the temperature up, it was time to call it a day and clam up. It did not look promising.

One hates to admit ones failures, but there was little to come out that was any good. Some tea bowls placed on the bag wall were ok, the bottles at the top near the front were dark and had an oily appearance, every thing else was way under fired and dirty. I will re fire some of the pots in a gas kiln to see if that cleans then up, the rest will go into the next firing as they are little more than biscuit fired.
The shard pile will get the rest.

Mark tells me the Beast will be demolished and already plans are afoot to build something smaller.
Maybe a Phoenix rising from the ashes!

Mark Griffiths, Culmington Pottery.

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