October, 2009 Firing.

We did a firing in October after our visiting artist, Tamura Shizuo, left us with a bunch of really nice pots, including a few exceptional Chawan
(I’ll post images of these soon), and I had a stack of work from the summer waiting to be fired. We had been bugging our wood supplier, Myron, for some Aspen (Populus Tremuloides) and he brought us a nice load of extra-long slabs plus a one-third load of the usual Tamarack. Aspen has a lower heat value than Tamarack (Larix laricina), but produces some really nice colors in the ash.

Blue Dome Vase.

Blue Dome Vase.

I had been wanting to do a longer, cooler firing, so the time seemed right with this big pile of Aspen. We loaded the kiln in the normal fashion but fired for 56 hours instead of 32, and held the temperature in the cone 6 range for a day before climbing to cone 9, with cone 11 in the throat.

Blue Dome Vase.

Blue Dome Vase 2.

You can see these vases were in an area of slight oxidation; there’s a yellow-green blush in the blue celadon. Normally considered a fault, in this case it’s a nice variation in color.

The ash colors are much more varied with the Aspen than with Tamarack, especially on the pots near the firebox. Instead of Tamarack’s mostly opaque yellows, we got a lot more golden yellow, orange, green, and purple colors. Very nice indeed! Also the ash and the glazes are much less runny at the lower temperature, which stands to reason. I prefer less grinding to more.

Here’s some of those nice Aspen colors on a bowl.

Medium Blue Dome Bowl

Medium Blue Dome Bowl

Foot of Medium Bowl

Foot of Medium Bowl

Inside of Medium Bowl

Inside of Medium Bowl

There was only one problem with this firing: we seem to have gone up to high temperature on the last night, come down a ways, and then went back up on the last day. Some of the pots (10%) have that distinctive wrinkling in the ash that can be crunched with the fingernail. On most it’s very minor, but there are a couple of pots that will have to be cleaned up and a little glaze fired back on the bare spots. Next firing, I’ll make sure we all keep an eye on the temperature so it doesn’t go too high too early.

You can see the wrinkling on the knob of this jar.

Blue Dome Jar with Hexagonal Base

Blue Dome Jar with Hexagonal Base

I’ve been doing this Cross-Star pattern (taken from Islamic tile) on pots like this Teabowl for a while now and still enjoy it. You can tell there’s quite a heavy ash buildup on this one, especially by the celadon glaze cascading over the bump at the shoulder. If this were Tamarack ash, the translucent golden-yellow ash glaze on the right side of the pot would be an opaque light yellow. Much nicer with Aspen.

Teabowl with Cross-Star pattern.

Teabowl with Cross-Star pattern.

Here’s a really great illustration of the color possibilities with the Aspen. That purple drip in the middle of the frieze would never happen with Tamarack. Also, note the delicate streaks in the glaze, both inside and outside the pot.

Blue Dome Teabowl.

Blue Dome Teabowl.

In addition to the porcelain work, I’ve been playing with a couple of dark stoneware bodies. One is quite “porcelaineous,” with two kaolins, two ball clays, Neph Sy, Flint, and 5% Newman Red as the iron source. The other is closer to what one would expect in a stoneware, with Hawthorne Bond, Goldart, Foundry HIll Cream, Neph Sy. It’s also got Newman Red in it.

These two teabowls and the coffee cup are made from the ‘stoneware.’ Where the flame hits it hard, it has a richer brown color, tending toward chocolate.

Pair of Teabowls with Cross-Star pattern and inlaid glaze.

Pair of Teabowls with Cross-Star pattern and inlaid glaze.

Coffee Cup with Cross-Star pattern.

Coffee Cup with Cross-Star pattern.

These teabowls are made with the more porcelain-like body. The difference is subtle, but the stoneware-type body is more toothy and open in appearance, especially under the foot where the atmospheric effects are minimized. The porcelain-like body is lighter in color, tending toward grey in the absence of ash, and a more orange-brown where the flame fits it hard.

Pair of Teabowls with Cross-Star Pattern.

Pair of Teabowls with Cross-Star Pattern.

We fire again in a week, and so more results are coming.

Steve

About mcleanb

Jump/Web Training Coordinator
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