Matthew Blakely porcelain pottery ceramics

Glazed Porcelain

I am currently using two porcelain clays - Southern Ice from Clayworks in Australia (imported by Potclays) and Royale porcelain from Valentines. Both have quite good glaze fit and excellent translucency, and both have good fired strength. The Southern Ice is particularly nice to throw for a porcelain, but needs great care during drying.

I throw with the clay at a medium consistency as I need it to have enough strength on the wheel once thrown to distort it or drag a rib around it without it collapsing or losing its shape. I try to make the forms as completely as I can on the wheel and keep turning to a minimum. Bowls, platters and cups etc have thrown footrings to retain the softness of throwing throughout the pot. I throw all pots on batts to minimise warping of the porcelain in the kiln, also so that the surface of the pot doesn't get disturbed by handprints.

Some pots are thrown without bases, altered then have slab bases attached. Coupled with the throwing marks this gives an added tension to the piece. All pots, but especially these, are dried very slowly.

Glazes

The glazes that I am currently using include a blue celadon, a fluid blue celadon that pools on ridges as it moves down the pot, with splashes of tenmoku or cobalt to accentuate the movement, a satin white, a fluid yellow and a clear glaze. I've developed these glazes not to craze on the porcelain I'm using. This is so the pots are stronger and less likely to break (up to 4 times stronger than a similar pot with a crackle glaze) and also will not stain with food or drink during use.

Firing

The glazed porcelain is fired in a self built 1 cubic metre LPG kiln with an energy efficient design. The wall is 75mm 26 grade brick for the hotface, backed up with fibre and calcium silicate board. There is less than half a cone difference between the top and bottom of the kiln. Biscuit is to cone 06. The kiln is fired using 4 LPG burners directed vertically through the floor).

In the glaze firing a light/moderate even reduction is maintained from cone 06 to cone 8 over 3 hours. The temperature is then slowly raised over an hour or hour and a half until cone 9 is over. Then the kiln is adjusted to oxidation and the temperature very slowly raised until cone 10 is starting to go. Then the gas is turned off and the flue covered. The last half hour of the firing is in oxidation. In total the firing lasts about 12 hours. The final temperature is critical for the fluid glazes.

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Glazed Porcelain I am currently using two porcelain clays - Southern Ice from Clayworks in Australia (imported by Potclays) and Royale porcelain from Valentines. Both have quite good glaze fit and excellent translucency, and both have good fired strength. The Southern Ice is particularly nice to throw for a porcelain, but needs great care during drying. I throw with the clay at a medium consistency as I need it to have enough strength on the wheel once thrown to distort it or drag a rib around it without it collapsing or losing its shape. I try to make the forms as completely as I can on the wheel and keep turning to a minimum. Bowls, platters and cups etc have thrown footrings to retain the softness of throwing throughout the pot. I throw all pots on batts to minimise warping of the porcelain in the kiln, also so that the surface of the pot doesn't get disturbed by handprints. Some pots are thrown without bases, altered then have slab bases attached. Coupled with the throwing marks this gives an added tension to the piece. All pots, but especially these, are dried very slowly. Glazes The glazes that I am currently using include a blue celadon, a fluid blue celadon that pools on ridges as it moves down the pot, with splashes of tenmoku or cobalt to accentuate the movement, a satin white, a fluid yellow and a clear glaze. I've developed these glazes not to craze on the porcelain I'm using. This is so the pots are stronger and less likely to break (up to 4 times stronger than a similar pot with a crackle glaze) and also will not stain with food or drink during use.


I am constantly doing glaze tests to develop new colours and textures. Other glazes that I'm working on include a tenmoku, a deeper green celadon and a crystalline talc glaze. Click here for glaze recipes.
Firing The glazed porcelain is fired in a self built 1 cubic metre LPG kiln with an energy efficient design. The wall is 75mm 26 grade brick for the hotface, backed up with fibre and calcium silicate board. There is less than half a cone difference between the top and bottom of the kiln. Biscuit is to cone 06. The kiln is fired using 4 LPG burners directed vertically through the floor). In the glaze firing a light/moderate even reduction is maintained from cone 06 to cone 8 over 3 hours. The temperature is then slowly raised over an hour or hour and a half until cone 9 is over. Then the kiln is adjusted to oxidation and the temperature very slowly raised until cone 10 is starting to go. Then the gas is turned off and the flue covered. The last half hour of the firing is in oxidation. In total the firing lasts about 12 hours. The final temperature is critical for the fluid glazes.

				I pack the kiln as densely as possible, soaking at critical temperatures to get an even heat throughout the kiln. The fluid glazed pots are fired together in one firing, and the blue celadon and satin white glazed pots are fired seperately, half a cone higher, to get the best texture from the glazes. The shelves must be well coated in batt wash to prevent plucking and warping of the porcelain. The mix is roughly 1 part (by volume) china clay to 2 parts granular hydrated alumina. For supplies of kiln shelves please see links