Tag Archives: Pottery

New Pots, Finally!

Unloaded the kiln yesterday and started cleaning up some of the keepers. This firing was good. A lot of keepers, some refires, and a few hammers.
Here are a few of the pots that are at least partially cleaned up and ready to go.

Katakuchi and Guinomi

Here are some of the last pots to be made for the upcoming firing. Katakuchi (spouted bowls) and guinomi (small drinking cups).

The katakuchi are made from 3 blended clays, with added sand and crushed porcelain stone. I got lucky with the clay for the guinomi, clay gathered from a roadside cut more than 10 years ago by an in-law. It was really nice to throw with, and trimmed like a dream. This was the last of it, so I’m really hoping to get some keepers.

The spouts are really simple. Just a lump of clay smashed out with your thumb against the palm of your hand, then attached to the pot. If you look closely you can see the creases of my hand in the undersides of the spouts.

I realized that I tend to post pictures of unfinished work more often than not. I’ll try to remember to post pictures of the finished pots after the firing, if they come through it ok.

Okamoto Sakurei Show Pictures

Karatsu potter Okamoto Sakurei just ended a show in Fukuoka this weekend at Gallery Ichibankan. For those of you who haven’t heard of him, Okamoto san is a very talented artist making Karatsu style wares. He is well known throughout the country and one of the top Karatsu ceramic artists today. He will also be doing a demonstration/lecture for the  Workshop in Taku 2012: The Simple Teabowl.

During my visit we had a chance to discuss his upcoming presentation, as well as some wood firing diagnostics. Here are some of the pictures from the show. The gallery used a lot of natural light from its windows, which made for a very nice display, however it was not so camera friendly.

Made a dent in the wood pile today…

Spend a good bit of time sorting and splitting wood for the next couple of firings today. Before the kiln was built, Craig Edwards mentioned on a couple of occasions that having the wood split and sorted makes for a much easier time firing. I understood the need for splitting, but sorting kind of stumped me. I couldn’t understand why sorting for length would help, thinking that one could estimate the volume of wood going in each stoke, more shorter pieces or less longer pieces, right?

This seems to work in theory, but when you start adding in factors like stoking under the grates vs over the grates, or doing the wooden door technique, or side stoking through a smaller hole that tilts down, then the size and length of the faggots gets pretty important pretty fast. Having to sort through a stack for  the right size during the firing makes for a stressful time. Having the right size stacked in the right place so that it doesn’t need  to be moved a lot really cuts down on the labor.

So, this time I culled out all of the longest wood and split it first, stacking it near the front of the kiln. Shorter fat pieces near the front as well, with thinner pieces toward the middle and rear for side stoking the front and rear chambers. Also a special section of extra long pieces for doing a wooden door type stoke to get over stalls, if they happen. Here are some pictures of the stacks, plus a little potter porn.

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

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.