Here are the first of a bunch of water jars and flower vases that are going into the kiln this early fall. I really needed some practice coiling, paddling, and collaring in necks on the kickwheel and 船徳利 funadokkuri (boat flasks) are the perfect shape for it. Traditionally these were used as flasks for oil, etc. on boats. They needed to be hard to tip over, hence the wide flat bottom. Now they are mostly used for flower arrangements.
All of the water jars will have wooden lids made for them. I’ve done one or two in the past with surprising positive response from viewers/customers. The lids are fun to make, since they are a non traditional item, you can play around a bit with them. I’ll post some lids later on, if the pots make it through the firing.
Well, time to sit down with the last firing and figure out what went wrong, and what went right.
Firing and packing: Great. With this firing I figured out, FINALLY, the proper exit flue volume to use. And with it, the proper packing procedure. The kiln climbed steadily, without effort, for 45 hours and the flame in the front chamber reached front to back really nicely. It turned out to be a fairly even gradient from front to back, from cone 13 in front, to a good melted 8 in back. No sidestoking necessary.
I am going to go back to using a pyrometer for the next firing, because this firing got very reduced. I think the stoke intervals were too close, and a pyrometer may help me get a better idea of temp climb timing, and when each cycle goes into oxidation.
At one point, when we switched to stoking the 2nd chamber, the temp just started dropping. You could tell from the sound and color of the kiln. I jabbed a pyro into a peep hole and it told me right away that I was stoking to frequently. After the flame had receded into the chimney and peepholes, and the roar had died away was when the temp really started climbing in the chamber. I had been stoking when the flames receded and the kiln quieted down, but once I started waiting rather for the temp to start dropping after the rise, the kiln got back on track. This rise took longer than I imagined, sometimes up to 10 minutes. Had been stoking waaayyyyyy too much.
This firing was a watershed moment for me, regarding packing, air, and stoking. I think next time will finally be the load that makes us all smile.
Glazes: Glazed ware in the second chamber turned out really nice. Reduction was still too heavy, but we got nice surfaces. Still, I won’t aim for that in the future. Madara glazes were too yellow for my taste. The first chamber glazes were so reduced that whatever their intended color, everything turned out a semi matte green, from the excessive iron pulled from the body saturating the glaze and crystallizing. I think the stoking interval will fix this problem.
Clay body: Oops. Here is where the shit hit the fan. Too much iron, especially considering the temp and amount of reduction that happened. The clay I used for the large pieces has too much iron for that type of firing environment, which is why they almost all collapsed. Having worked with a gas kiln for so long, it is hard to get out of the mindset of adding iron rich clay to other whiter bodies in order to get a desired color. The white clays in this area have enough iron for good color in a wood kiln. I keep forgetting that, but perhaps the shock of this latest meltdown, and the subsequent pain of shelf grinding will serve to jog my memory whenever I’m mixing clay for the wood kiln.
I like the floor addition so much that I decided to fill the space in completely. It was a quick project and gives us much more space to use upstairs. We now have a place for guests to sleep, although there is still no hot water or toilet in the studio. Still, moving in the right direction. There is room enough to sleep 6 people easily in the studio now.
One problem: all of the lighting is attached to the upper beams, so the floor effectively blocks all light to the 1st floor. Some re-wiring will be done to add lighting to the first floor. I’d prefer to put in brighter lighting downstairs for working, and soft lighting upstairs for entertaining guests, with spot lights added for displayed work.
Oh, and padding for the upper beams, now that they are within forehead striking distance…
This just made me sad when I saw it this morning. We had a LOT of rain over ten last 36 hours, and I think the footers sank a bit, tilting the stack forward, then dumping it. This will take some time to clean up.
** Just one quick amendment to this post: on re-reading the post and comments, I realized that I may have mislead people to believe that the stack (chimney) went over. Not so, thankfully. Just the stack of wood. No damage to the kiln other than a few scratches to the insulating top coat, and about 5 unlucky shelves that had been sitting right where the wood struck.
During the fourth and fifth days of the Workshop in Taku 2012: The Simple Teabowl, we were treated to pottery demonstrations by Okamoto Sakurei. He made a variety of items for us using a variety of techniques. On the afternoon of day four, we visited his studio and showroom and he honored us by allowing us to view some of the older pots in his personal collection. Breathtaking Korean bowls, and a couple of Japanese bowls. They were just amazing to hold (and maybe a little bit of fondling happened too, but mum’s the word).