Category Archives: glazes

Kohiki tea cups, etc…

When Nishioka Koju passed a few years ago, a friend of a friend got some of the warehoused clay from one of Koju san’s storage areas. I was  able to get about 60kg of raw dry clay and have been waiting for the right opportunity to use it. I tested it a couple of years ago in the gas kiln and decided it needed wood to really make it jump. The clay itself is a light grey, almost white when dry, so I thought it might be fairly low in iron, but tests showed it to have significant iron and not very refractory. Probably good at around cone 6.

I made a run of about 40 cups yesterday and trimmed them this morning,  then waited for them to firm up a bit. Then, in the afternoon I applied the white slip (kohiki). This was something I have never done before on wet greenware. Last firing I tried it on dry greenware with success, but that clay was different and pretty stable for raw glazing. This clay is quite different so I didn’t know what to expect.  Many sources say to slip the inside, then let it dry, then slip the outside, to prevent the pot from collapsing. The problem with this is that you end up with too much slip around the lip of the pot, and more work is required to clean it off. I decided to apply to the whole piece at once, and did just one test piece to see what would happen. After 30 minutes the pot was still in one piece so I went ahead and did the whole group of 40.

I really like what the slip does on a wet pot. There is a lot more flow and variation in thickness, and I suspect better adhesion too. After the slip dries I will do some brush deco and give them a thin coat of clear.

At the end of the hump, there was enough left for a teabowl, so I threw one. It is intended to be a Todoya style Korean bowl, but we’ll have to see what happens in the firing. At least, this clay trims real nice. Unfortunately the bowl would not hang on to the trimming chuck, so that is the reason for the abrupt end on the interior of the ring. So as not to end up with nasty chuck rash, coupled with over trimmed foot syndrome, it got left as is. Usually trying to fix something like this just ends in disaster…

Gas kiln with saggars

People sometimes lament the limited effects possible in gas and electric kilns compared to wood kilns, but there are ways to get many interesting effects in gas and electric if you use your imagination and do some experimentation.

This time around I loaded about half of the kiln with saggared ware. 4 incense burners, 3 sake cup refires, 2 boxes, 2 teabowls, and 1 frog toilet (in porcelain, no less).

The incense burners came out most interesting, with a lot of deformation occurring in the clay, which was the goal. Nakayama kun wanted some burner bodies that were deformed and all around ‘grungy’ to fit with silver lids. They were wrapped in rice straw rope that had been soaked in a saturated solution of soda ash, mixed with some feldspar, the idea being to get some focused area effects on the pot surfaces. The soda ate into the clay in places and fluxed the feldspar nicely. One of the burners completely collapsed and stuck to the saggar and the adjacent burner, but I’ll be able to keep 2 out of the 3.

Two of the teabowls, with iron based glazes turned out nicely, but one (the black one) stuck to the saggar and will need some repair on the lip. Nakayama kun is going to do a silver repair on the lip, and I’ll post a picture when it is done. The other, and iron saturate glazed bowl, turned out nicely but I really can’t decide if I like the glaze color or not. Need to whip up some tea in it to see if it shows off the tea color well or not.

The porcelain ring boxes were a complete failure, with cooling fractures I think. I drizzled in a soda/spar slurry on the insides and it was waaay too thick. I think its expansion and/or contraction fractured the pots.

glaze crawling a bit

There was a bit of an issue with crawling over one of my clay bodies, when raw glazed. The guinomi toward the front of the kiln had this problem, but melted enough to look interesting. These bowls at the back just look dangerous. I left them after the last firing, but finally got them out yesterday and had a nice cathartic smash fest.

Karatsu Show

This last weekend we had the show in Karatsu.  It was a 3 day weekend, so we did Sat, Sun, Mon. Well, if you are thinking about having a show on a 3 day weekend, let me give you a little advice: don’t. Everyone goes somewhere else. The first two days were absolutely empty, and it was only the during the last day that I was able to make some good sales. Thanks to guests from Osaka, Kyoto, and Chiba. I guess they were using the 3 day weekend to get out of their respective areas as well.

Well, lesson learned. Overall, it was still a very enjoyable experience, with lots of time to sit and chat with friends over tea. The highlight of the show was without a doubt, the shiboridashi teapot with the river crab knob. It is a pure silver crab holding a ruby in his right claw.

Washing your Oribe

Sounds kinda dirty, somehow, or maybe that’s just me. Anyway, when you fire Oribe greens, you usually get an oxide layer over the surface that dulls the color, or in extreme cases changes the color completely to a sort of what I always imagined the color of the Great Grey Green Greasy Limpopo River to be. (always loved Rudyard Kipling)

The traditional method for cleaning this up is chestnut husks soaked in water, which creates an acidic, extremely smelly brown concoction that you soak your dishes in for a few days. Nowadays, people use a 3% solution of hydrochloric acid. Now, this is nasty stuff so if you are going to use it, use it in a very well ventilated area, with gloves, eye protection, etc… When you open the bottle, white mist rises, just like in the movies. Breathing that is not a good idea.

Here is a before after pic of a dish I cleaned up. These dishes did not have a heavy oxide layer, but the cleaned one is noticeably brighter.

Kamadashi / and a nasty case of the runs

I unloaded the kiln yesterday evening, confirming my suspicions about my glazing skills. While I got some good smaller ‘souvenir’ level work out of the kiln, the chawan and guinomi were for the most part not so good. These are the higher yen items, so I like to get more of those than less, but it does not oft happen. Two problems with them this time: the iron glaze was a bit thin, because the water was a bit too deep in my foot soaking dish, and my band of rice straw ash glaze at the top was a bit too thick.

The pieces that I needed for the upcoming show were the small dishes and yunomi, and for the most part they came out great, aside from about 10 that really ran, and had super duper pinholing. The smaller dishes that I tried out my copper green on turned out nicely as well, looking like a cross between an Oribe green and a Nuka Seiji.

I’ll post pictures of some individual pieces in the next few days, but for now here are the unloading pictures: