Last Friday I fired the little yellow gas kiln at CSAD for my first time. Starting from about 8.40am the kiln climbed fast to begin with (up to 220C by 9am) and then rose steadily by about 100C per hour, a little slower than in previous weeks because of fluctuations in gas pressure (probably because gas was being used in the foundry). At 1000C, just before 1pm, the flue at the top back of the kiln was covered over in order to create a reduction atmosphere and was left this way for most of the final part of firing. As you can see in the image below two large pyrometric 1280 (09) cones were placed in the spyholes in the front top and back. By 3pm the top cone had completely melted while the bottom one was still only bending a little so in order to reach an even kiln temperature Gemma opened up the flue at the back which had been covered for reduction, encouraging air flow in the kiln. The firing was finished by 3.20pm.
In order to get a better impression of how the gas kiln behaves it could be an idea to place cones at the back on the right side too to see if there are hotter or cooler spots. Since the pyrometer was placed in the right side of the kiln and only read 1237C when the top cone was gone, it suggests to me that the right side might be a little cooler. It might also be valuable to place a 1300C cone at the top too to get a more accurate reading.
I was a little disappointed upon opening the kiln on Sunday since lots of the glazes hadn’t behaved as I hoped, although there were a handful of beautiful bowls and jars – my own nephyline syenite matte pink glaze worked particularly well. The main problem was that lots of the glazes were applied too thinly. My glaze application has improved since first year when I was painting them on and had lots of patchy results. Now I make a big enough batch of glaze to dip the pots in and this results in a much more even coverage. The chun and celadon which I had tested in Sweden turned out ugly patchy browns but perhaps they were just not thick enough. The best pieces seemed to be the ones most enclosed in the centre of the kiln shelves. More reduction could have been encouraged by packing the kiln tighter or even putting work in saggars. The insides of the lidded jars had a lot more brighter colours than the outsides because they’d reduced better.
While I only used one layer of glaze on the vessels, I tried layering different glazes on the test tiles above and the results turned out to be a lot more exciting this way. The shino over matte pink results in a matte lavender while the pink over chun creates a purple/blue crystalline – like glaze breaking to pale yellow where thin. The pastel colours in blues, greens, pinks and lavender have a quality of delicacy, lightness and quietness much like the glazes of Katherine Pleydell-Bouvarie. I’m drawn much more to the matter surfaces and they way they soak up the light in a soft, introverted manner. Somehow these surfaces feel more organic than the glistening, glassy ones which have an almost sticky, plastic texture. Shinyness distracts from the form too. My next step will be to experiment with overlaying these glazes on vessels in a gas firing hopefully later this week.