Found a Clay Seam

I found a clay seam about 40 min drive from my house in a place called Sari. It has 2 distinct kinds of clay, one in a thick strata which seems to have quite a bit of
iron, and another in a thin seam that seems to have less iron. In fact, in appearance it looks like wet decomposed granite with the spots of white, black, yellow, etc.

The pictures below are of the larger strata of high iron clay. For Karatsu potters finding a good place for your own raw clay is a great thing. It’s really the only way to reproduce the look of the older Karatsu pieces, and a great way to make some very interesting things with a lot of character. In fact it is almost unbelievable how much of a difference a nasty, lumpy, badly processed, unplastic clay makes in the overall ‘feel’ of your work.

Anyway, here are the pictures of the clay as I worked it over, in the next blog entry I’ll show the cups that I made from it. The first are the raw chunks in the bag.

Next is the clay dried and broken up into smaller pieces with a wooden mallet. It needs to be in smaller pieces to go into the usu (mortar)I use to pound it into powder. Big chunks don’t move in the usu, but smaller chunks circulate as you pound, going from the bottom, up the sides, then tumbling back down into the center, to get pounded again.

Next we have the stamper, looking fairly stamped himself. I have to stand there and pound the clay with that long wooden post. It’s good for the arms, shoulders, and heart, or so I tell myself.

After the clay is finished (rough translation: when I’m too pooped out to keep lifting that *&&^%$# post), I scoop it out and put it in a bin where I add a lot of water to it and use a drill mixer to thrash it about, then I let it settle out. I repeat that a few times over the next day or two, then I pour off the excess water and dump the clay into plaster basins for quick drying.

Finally I get to wedge the clay. It’s still very soft at this point so wedging requires very little effort. First I do a rough wedging, then follow with spiral wedging. With this clay the spiral wedging is very difficult because the clay has no plasticity and doesn’t want to be formed into a hump for throwing. Here, the humps I’ve formed are just dry enough to hold their shape on the wheel, no dryer. If you were to grab either of these humps and pull sideways, they wouldn’t bend at all, rather they would just tear apart. When centering and throwing this clay, if you apply very much pressure at all, it just breaks off in your hands. Frustrating at first. With this clay I wasn’t able to make anything much larger than guinomi/yunomi. I’ll make that the subject of the next blog entry.
Have a great day!