A Guide to Glazing Chosen Karatsu

There is a new video up on the Karatsupots youtube channel. On it, I explain the process of glazing Chosen Karatsu ware, from applying the ame glaze, to trimming the ame, and subsequent application of the wara glaze.

Social Distance Walking

I’m lucky in that I can walk out my door and head up the hill for a walk, and I rarely encounter anyone else.

Today, I was passed by one car and was otherwise completely alone. It was a beautiful spring day after a day of rain and the mountain was lush. Several times on my way up I could smell the wild boars that must have been lurking nearby quietly. I don’t worry about them. The only time I ever see one is when they jump up to run away when I get too close on the road.

The road is roped off now, because of a landslide that damaged the road higher up, but it’s no problem for walkers to go through.

The hill slid out from under, taking half the road with it.
Another area where a slide has taken down some trees.

A very nice walk, and a nice clay discovery, I’ll be heading up again from the other side in my car to get some for pots and glaze.

Propane CGFiring Notes, 2020/03/16

Gas kiln firing, 2020/03/16. Chosen Karatsu and Madara glazes. 3 types of Madara glaze from old buckets in which the exact contents were largely forgotten.

The normal madara glaze ended up being too low in silica, and going clear in most cases. Shirakawa madara pinholed in most cases. I’d forgotten about this behaviour. New Madara glaze test shows good color, but also, low in silica perhaps, needs more straw ash added (1kg).

Shida madara much too clear, only showed white where very thick. Maybe miscalculated when mixing the glaze? Add more Shida (2kg?) to overall batch. Test again.

Gallery

Cool Color

This last firing of the gas kiln I used draw rings to get a better idea of when certain glazes matured. I’ve known this for a while, but was struck again at how colorless and boring the colors of the glaze and clay were when yanked and doused in a bucket of water. So colorless, in fact, that two different glazes appeared to be virtually identical when crash cooled. The sandstone body, also, is an uninteresting greyish white.

left: sandstone/ash 7/3 right: high silica ash / oak ash/ spar 6/4/3

Here are those same glazes after firing for 16 hours and cooling slowly in the kiln for 36 hours. (first two pics are same glaze and body as the ring on the left, above. Second two pics same as the ring on the right.)

nor
sandstone/ash

Notice a difference? Not only in the quality of the glaze surface, which is distinctly more blue with patches of sugary white, but also with the clay body color development?

nor

The changes in this glaze are even more pronounced. No longer a colorless clear, but a soft creamy white translucent.

Last is a black glaze which was a featureless glossy black on the test ring, but which given time, developed into a rich black/brown with some crystal growth.

So, with that in mind, I wonder how nice these glazes and clay body would look after a 96 hour cooling period in the wood kiln?

On an aside, here is one of five toggle buttons I made and fired in a saggar with rice husks and cockle shells. Same body as the cups above 70/30 sandstone/Izumiyama porcelain. Approx. 6cm

Clay clay clay

When I was polishing work from the fall firing yesterday, I noticed two pieces that had been glazed, fired (on shells)glazed again, and fired again (on shells). This isn’t too unusual, but in the case of these two pieces, they were literally fired side by side both times and had the same glazes applied, twice.

The only difference between the pieces is the clay body. The teabowl is clay/sandstone 50/50, and the smaller cup is clay/sandstone 10/90.

Now probably it shouldn’t, but the difference in the fired glaze surface astounds me. And all other things being equal, it must be that 40% difference in clay content that has changed that glaze.

Since the glaze is collected, I don’t have an analysis, but my guess is that the higher alumina content in the higher clay body is responsible for making that high silica glaze go clear, by adding alumina to the glaze matrix and fluxing more of the silica.

Busy busy

The first abalone dish dried successfully, so today I started making more. I also started a small run of shiboridashi teapots. These are always good sellers, because they are easy to use and clean, with no hard to reach holes or metal sieves to collect grime. 



I always carve the grooves as early as possible, because as the clay gets harder, it becomes difficult to carve without tear out. Then I put the lids on, so that they dry evenly without warping, and after trimming they will go into the kiln to be fired together, to avoid any warping.