Fired with cones 6,7,8 on top and bottom shelves. Pyrometer at middle shelf, didn’t display over 1215C.
Hotter on bottom than top. By cone, looks like cone 9+ on the bottom, cone 9 at the middle, and cone 8+ at the top.
Reduction strong at top shelf, weaker at middle and bottom.
There is an old story around here about Nakazato Muan (12th Generation Nakazato Tarouemon, Living National Treasure) finding a really great white clay seam in the Azambaru area of Taku. Here it is in Japanese for those of you who can read it:
For those of you whose Japanese is a bit rusty, it goes like this:
In the year Showa 21 (1946), the Nakazato kiln was converted from a coal burning kiln to a wood burning kiln, and it was fired until Showa 25 (1950). During this time, Muan mostly used a white clay from the Azanbaru area of Taku. There is a story, told by his son Shigetoshi, from the day they discovered this clay seam (Nakazato Shigetoshi passed away in 2015, at the age of 85, so he was probably around 16 years old at the time of this story).
So they have all this clay loaded onto a cart, which Shigetoshi is pulling and his father Muan is pushing, to Taku train station.
On the way, they reach a downward slope, and without noticing, Muan keeps pushing down the slope, and they almost run into a car speeding down the road. Shigetoshi ends up diving to avoid the car, the car ends up in a rice field, and their cart ends up broken. When Shigetoshi gets angry and starts yelling, Muan says “I was so busy thinking about what I was going to make with this clay, I didn’t notice the slope.”, apologizing to Shigetoshi.
“That was the first time my father ever apologized to me.”, Shigetoshi commented.
So why, you say, are you telling me all of this? Well, the fabled white clay seam has been looked for now by other potters for decades with no luck, but due to a fortuitous event a few months ago (and several years of looking), I believe I have found it again. Here are some pictures from our excursion out to dig some sample material for testing.
Oh, and lastly, here’s a picture of one of Nakazato Muan’s coil and paddle built jars. This one is made from white clay from the clay seam pictured above. My firing tests have almost the same color as the unglazed bottom section of this jar (although it is hard to see from this dark picture).
This firing of the kiln went too long, resulting in Orton cone 11 flat. Ideally, it would be cone 11 touching, then sagging a bit.
Upon unloading the kiln this morning, one thing was immediately apparent: the right side was far more reduced than the left. Yellower glazes and more slumping. Even on the left side there was some slumping, because of the excessive temp., and because of the clay which contained some low temp high iron clay to help seal the ware against leakage.
Chosen Karatsu came out pretty good, but the white was on too heavy, running down the pots too much. It still came out looking ok because of the clay.
Most of the teabowls warped or sagged, so I only get to keep 2 or 3 of the 15. This is why teabowls are expensive, kids…
All in all, not a bad firing, but need to adjust clay bodies, and pay closer attention to cones. Also, figure out the over reduction on the right side. It might be that one burner that sounds a bit off.
was a real nail biter. At 4am, 10 hours into the firing, I realized that I had not gauged my propane reserves properly, when I looked at the tanks and realized that they were only about 1/5 full and covered with a thick layer of ice. I immediately put the water hose on them to melt the ice and keep them from freezing again, then I chewed my nails until 8:30 am when I could finally call the gas company for fresh tanks. They arrived just after 9am, and good thing to because I only had about 2 inches of fuel left in the tanks at that point.
The firing ran a total of about 18 hours, which is fairly normal for this type of firing, and most things came out ok, with a few exceptions:
I’ve gotten pretty far behind keeping up with the blog, falling into the bad habit of making small posts to Facebook. One of my areas of increased effort over the next year will be to work more on maintaining the blog, and getting it more integrated with other forms of social media. Trying to keep track of them all is like trying to herd cats.
I had made one promise to show before/after pictures for a couple of pieces, the first of which is the slab/paddle built sake chiller w/ feet and lugs:
The other thing I’ve been working on since early this year is getting a usable kohiki/clear glaze combination, because for some reason a lot of customers have been requesting white work. They have also been requesting black, so I’ve been working on getting a reliable semi matte black glaze. Mission not quite accomplished, but I feel I’m most of the way there. Here is the kohiki I’ve come up with and I am happy with it:
Here are some of the pieces with the new black glaze. It seems to look best thin, and as with most glazes looks nicer over interesting wild clays rather than processed clays.