Monday, 17 December 2012

Jomon-inspired heads

Recently, I was looking at images of some Japanese figurines and fragments from the middle Jomon period, and I think it must have inspired me to make these little heads. I modelled them very quickly and instinctively, using scraps of clay mixed with sand, grog and gravel. They were bisque-fired to around 1000 degrees centigrade and then smoke-fired, using newspaper and tin foil as a temporary saggar ( this technique learned from Russel Fouts' article : "Oh Yes You Can! Smoke firing in an Electric Kiln" )

The head shown above is hollow and about three inches tall pure chance, a chunk of clay fell off inside, so it happens to be a rattle as well!

This piece is only two inches tall and solid.

Thursday, 13 December 2012

Firing with banana skins

A few weeks ago I was reading about Deidre Hawthorne and how she fires some of her pots in saggars using banana skins. As I already use saggars, I was intrigued to try it for myself.

This sake cup was fired to 1300 degrees centigrade in a small saggar with a little wood and the dried skins of two bananas. The result was a rather uniform light grey colour with a metallic sheen..not terribly interesting. On Monday, I refired it in my mini wood kiln to earthenware temperature and this has re-oxidised the surface inside and out, bringing the colours to life. Now the unglazed clay body has turned a deep reddish brown in places, which was more like the colours which Deirdre Hawthorne had said she was achieving with banana skins. The inside is coated with a shino glaze which has turned a beautiful orange colour...dry near the rim but with more of a satin sheen at the bottom.

Monday, 10 December 2012

Mini wood-fire kiln a sucess..maybe

I just finished a ten-hour firing of version two of my mini wood-fire kiln. Amazingly, I managed to get it to 1300 degrees C according to the pyrometer, but unfortunately the cones (7, 9 and 10) placed on the kiln shelf didn't go down. So, either I have a very inaccurate thermocouple, or some extreme hot and cold spots, which I think is more likely. I'm hoping that at least some of the pots on the ground level, next to the firebox, will have fully matured glazes. We shall see... it was an enjoyable experience anyway, and I was fully expecting to have to modify the design based on the results.


It seems my pyrometer was telling me porky pies, and nowhere in the kiln was the real temperature much above earthenware. :(  I suspect the pyro. may have been directly in the path of the hottest flames from the firebox and this gave a completely false reading.

The glaze had begun to melt on a few pots containing soda ash, hence a lower melting point, but on the whole, very disappointing results. The kiln was certainly burning wood efficiently and drawing plenty of flame through the ware chamber..problem seems to be that most of the heat went straight up and out of the chimney! While I was firing I had alot of problems getting the temperature to rise above 1050 degrees C so I thought the exit flue from the firebox might be too small, getting choked with embers. I'm now wondering if it was actually too large for the size of kiln..and that the chimney may have been too wide, pulling too much cold air through the kiln. The outside temperature was about minus 1 centigrade which probably didn't help!