pottery

Madara Karatsu

Madara Karatsu. Madara refers to the glaze, usually a high silica white which reacts with the clay to produce a mottled effect, with various shades of white, cream, yellow, brown, and subtle optical blues. Most modern potters use rice straw ash as the main ingredient in their madara glaze, but other types of high silica ash are sometimes used as well.

We don’t know exactly what was in these glazes traditionally, there are probably various combination of glaze ingredients and clay bodies that would yield the madara effect, and I suspect that the potters of old just used what was on hand, which would explain why some of the old kilns are known for specific types of pots. Hobashira-gama, one of the Kishidake Ko-garatsu kilns was probably the best known for its Madara Karatsu ware.

Madara Karatsu Chawan. Name: Hakuo

Hakuo is one of my favorite tea bowls, and a sort of collection of ideal Madara Karatsu traits. The glaze is not too thin, not too thick, the clay is vitrified nicely, but quite sandy so that it reacts well with the glaze. Below is another piece of a tea bowl from Hobashira-gama. This is  a shard that was given to me by a friend.

inside bottom of a tea bowl

You can see the mottling , including the blue spots, probably from ash that settled and melted in the bowl.

detail of clay/glaze interaction

There is a lot of sand in this clay body. You can see here that the glaze is not that thick. Many modern potters apply the rice straw glaze thicker, or too thick (often the case with me), resulting in a white glaze. Too thin and you end up with clear.

foot of tea bowl

When you touch this shard you can feel that it is well vitrified. It does not absorb water. There is a lot of speculation about what the body really is. Recent examination of shards like these under an electron microscope indicate that the clay body is not really clay at all, but rather powdered stone. When people talk about the technology brought to Japan by Korean potters, they always mention the climbing kiln, and glazes. Perhaps more importantly, they also brought over the technology of processing stone into a usable body for making pots. They had this technology for processing porcelain stone, but did not have a source immediately, and made pots for many years before discovering the porcelain stone deposit at Izumiyama, Arita. Suitable types of feldspathic sandstone probably served as alternative ‘clay’ bodies in the meantime.

detail of foot

25 Pound Pots

Just this last week I got my hands on some clay which is ideal for very large coil and paddle work. It had been sitting in the corner, calling out to me for a few days before I figured out what to make with it. Perfect practice shapes, new planters for the root-bound palm trees in our living room. They are waaayy overdue for a re-potting and looking a little peaked. Once they have new homes they should be really genki again.

Each of these pots is one 10kg pug of clay. Wet, they are about 47cm tall by 47cm wide. I made an important discovery this time: my electric Shimpo Whisper makes a good wheel for coil and paddle of big diameter work, because when it is disengaged, the wheel spins freely like a banding wheel. So, I can use it for paddling, then engage it for using ribs on the shape, or forming the lip. You can see the kickwheel in the photo, the flywheel is at a bad height for my body and difficult to kick. My other kickwheel is in the corner and there is not enough room around it for large work. So, the electric wheel solution was a stroke of luck.

These pots were constructed from one base slab and 3 wall slabs, stacked and paddled. These are great shapes for practicing the slab and paddle method, because they don’t require any technically difficult shaping, ie. forming a tapered shoulder or neck, and they don’t get much wider than the base. Once I get comfortable with these, I’ll go back to storage jars with more belly and more taper at the neck. Having a few of these around will be really convenient for storing glazes too.

The First Pots: Chawan and Guinomi

Here are some of the first pots to get cleaned up after the firing last week. I’ll post more over the next few days as I get things cleaned up.

Overall the firing went well, much better than the first two certainly. I’m finally starting to get a grip on how the kiln climbs, and learning not to worry about it too much. We fired both chambers this time and it took roughly 30 hours. Cone 10 flat in front, cone 9 touching in the rear, and cone 13 almost touching in the second chamber. The second chamber is a pleasure to fire, very relaxing after stoking the front. I think I can still get more aggressive with the front, taking the temp up even more, probably somewhere around cone 12 would be good for the rice straw ash glazes.

The intention was to drop cone 6 in the rear and call it quits, but it ended up getting hotter than expected, and the ware in front ended up a little too shiny. However, the middle and rear of the setting came out just about perfectly. Temp from top to bottom was quite even. We stopped stoking the second chamber when cone 11 dropped and clammed everything up after letting some of the excess heat out. Still, when I peeked in the next morning, that second chamber was still glowing, and cone 13 was mostly down. Guess that 1250kg of insulating castable does its job well.

Most of the failures this time around were caused by bad glazing, not the firing. Rice straw ash glazes were universally too thick, and an ash glaze I whipped up hoping to be a nice runny green ended up being a crusty reddish brown. Oops.

Patience Is A Virtue

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which I do not seem to have. Here is a picture of a small dish I pulled from the rear of the kiln this afternoon. Kiln is still at around 300C, so I will wait a few more days for it to cool off. Last time I waited until it was cool enough for the pots to come out, but still hot enough to cook me in the process. Not making that mistake twice. . .

mike martino, in taku

Continuing Loading… 窯詰めの続き

Finished the middle setting today. It is mostly saggared ware. I picked up these nifty saggars that are big enough for larger pieces like flower vases and mizusashi. 今日は真ん中のセッティングを完成した。殆んどはボシに入った水指と花入れです。

There is a reason for doing it like this. I’m hoping that the saggars will effectively split the front chamber into two chambers, allowing the front to achieve temp more easily.　ボシを使う理由は二つ：独特な効果を得るためと共に壁になって欲しい。大きな火立てになり、部屋が二つに分けられ、手前の部屋は温度が上がりやすくなると想定している。

Just behind the saggars are teapots along the floor, they will be covered in partially to fully covered in embers from the wood stoked directly behind them. The 4 square frame shaped kiln posts are there to prevent the stoked wood from bouncing/rolling down onto the pots.　ボシの直ぐ裏には搾り出し急須が置かれている。ここですぐ裏の焚口からの薪が熾きになり、その熾きが急須の周りと上に溜まり、炭化効果が得られると思う。薪が作品の上に転ばないよう、支柱を急須と焚口下の間に置いてある。

Two more things: got a new ember rustling tool which is a shovel head welded onto a pole. this should come in handy for tossing embers and ash around.