Category Archives: pottery

Processing Clay

I was lucky enough to find some easily accessible clay the other day on a morning bike ride. I’ve been spending some time processing it and thought I’d share. Here’s the hill and the pictures of the bagged clay:

 

After bringing it home, I transferred it to large jars and added water, then mixed violently with a drill mixer to break it all up.  After skimming off the junk that floats up, I mix it up a few times a day for about 3 days. Once it is mostly made into a slurry I start sieving it into another container. Whatever doesn’t pass the sieve goes back in the jar to get mixed again, and it eventually (mostly) all breaks down.

Since I have no space for a large clay drying platform, I’ve decided to try these pantlegs tied off, filled, and left to hang. Seems to be working so far, and I’m hoping to get a nice uniform sausage of clay with no dry edges. I tried a few methods to close the bottom. First, I tried sandwiching the pantleg between two pieces of wood and using screws to tighten them together. This worked, but left sharp screw ends, and when I dropped one full leg, the wood snapped and it opened up, spilling the clay.  Plywood might prevent this. Being too lazy to get out the saw and cut more wood, I decided to split what I had into thinner pieces and wire them together to bind the folded over leg end. I tied them with wire and it seems to be working just dandy. Later, when I have time, I’ll try  finding some sort of non rusting clamp device that can be applied and removed easily and quickly.

Once the legs were filled, tying them off was tricky because a leg full of clay slurry is FRICKIN HEAVY!!! First I tried rolling it down over the rope and tying, which works fine but is kind of tricky and if you don’t do it tightly, it unwinds and makes a mess. I found the best way was to twist the end and bend it over a stick, then bind it with rope. This way, you can use the stick as a handle to carry the leg which is very nice, and the stick can be used to hand the bag. The rope used to bind the end can also serve as a hanger. I hung up 12 of these yesterday, and am now waiting for them to firm up. I’m curious to see how long it will take.

Scoring Goodies

I made a trip out to the mountains in Minamihata yesterday with my mentor to collect materials for pots and glazes, and we stopped by an old kiln site as well.

We were able to collect a good amount of feldspathic sandstone, weathered feldspar, and the ever popular grey stuff (don’t know what its real name is).

First, here is what we collected that will become pots and glazes this year:

The lot of it
Grey stuff. This is softer than rock and can be stamp milled or pot milled easily into a fine slurry. It has a lot of iron, and I use it as a glaze ingredient, as a slip, or as a pigment for decoration.
Sandstone. This has more iron than I’d normally like, but beggars can’t be choosers. It takes the place of both feldspar additions to clay bodies as well as grog. I like it because it helps the body vitrify, but gives it texture as well.
More sandstone.
Glaze stone from near Okawachiyama. I’m not sure but I believe this is the glaze stone used in Nabeshima celadon. I look forward to testing this.
Closeup. You can see the feldspathic translucent pieces in the matrix, surrounded by the white powdery matrix. I think the white powdery part is high in silica, but again, need to test.
Found this in the same place as the Nabeshima glaze stone. This looks to be more pure feldspar. Very curious to see how it fires!

On the way to one of the collecting sites, we passed two old Karatsu kilns, Fujinokawachi and Kayanotani.  I was surprised because they are separated by no more than 70 meters or so. These were big kilns. Kayanotani was a 22 chamber climbing kiln 52 meters long! Between them, there were probably hundreds of potters working. We couldn’t really access Fujinokawachi, but we were able to walk around on the hill where Kayanotani once stood.

Access to Kayanotani. You can see the faint grassy steps up the hill, just to the left and down a bit from the tree.
Sign board standing at the entrance to the kiln site. The shard pile extends up and down the hill to the left of the sign.
The outside surfaces of some coil and paddle flasks. Fujinokawachi and Kayanotani are both known for their fine coil and paddle work.
Interiors of the same. Note the different clays used and the different patterns created from the paddling tools.
Hillside littered with shards and chunks of kiln wall and kiln furniture.
The feet of some ash glazed bowls. The clay is quite light in color, and really vitrified.
Detail of some flask lips. On the one, you can see some bubbling in the glaze because the clay body started to bloat. The coil and paddle clay bodies were quite varied, but much of it seemed to contain high amounts of organic matter
More bowls. One in a light clay body, the other much darker. Again, vitrified and hard. All of the trimmed pieces I found were trimmed with an economy of movement. There is no wasted time in the trimming here.
Detail of another foot. Gorgeous clay, and lively trimming.
Interior detail of bowl directly above. Note the beautifully folded over and compress lip of the piece stuck to the inside here, and the glaze window.
Paddled Chosen Karatsu flask. I wish I could get those blues!
Detail of flask neck.
Detail, lip.

Overglaze tests with iron pigment

Here is the original test cup (r), and one pulled from the last firing (l). The first cup was refired to cone 5, the second to cone 6. I was worried with the extra heat that the overglaze brushwork would bleed or run, but it didn’t.  
One thing I like about this overglaze deco is that it allows me a ‘second chance’ for decoration when refiring this kind of work. The other is that it allows for finer detail showing up in the final product. Underglaze iron tends to get absorbed into the glaze and/or clay body, so the finest lines become obscured or transparent.

PINCHING BALLS…

…is one of my favorite ways to make cups. 

Often, during a cycle of making new pots I’ll end up stuck. New design ideas don’t pan out, or I dont have the techinical skill to make what I want. 

Rather than sit suspended in frustration, I’ve found it is useful do something familiar for a day or two. This usually clears my mind for fresh ideas, because I don’t need to concentrate so hard on familiar processes. Even better, I have something to show for a days work. 

Pinching balls into cups and bowls was the first thing I learned from my mentor, and these things are still some of my best sellers.  The process is simple and efficient, and can be easy or difficult depending on the clay. 

Getting ready for Yakimon Matsuri

This Golden Week (4/28 – 5/6) is the 6th annual pottery festival in Karatsu. It is always fun to show and sell, but getting ready can be a pretty busy time. 

This year I want to show some new designs, items I’ve never made before and/or sizes I don’t normally make. I’ve made some pedestal platters, coffee droppers, and a style of tokkuri that was popular at a show this last fall.  The general theme will revolve around rim carving and brush decoration of shrimp, and English letters written to look like Japanese kana script. 

Many people tend to think that Japanese dishes are small and numerous, and this is not incorrect, but for home use a popular size is a bit larger, around 7-8 inches (7 sun) or even a bit larger. I find that dishes this size get the most use around our house as well. 

Here’s the damage from this afternoon:

Carved rims
Waiting to be carved
Various 24cm plates
Shrimp chopstick rests

1.3kg Bowls

Something I’d been putting off lately was making larger work, but i decidied it was time to warm up to it, so threw these the other morning. Figuring I could kill two birds at the same time, I made half into grinding mortars, and half as noodle bowls. These all came to 26cm wide wet, and have already shrunk down to 24cm, not even dry yet. After they are dry, I’ll knock off all the crumbs from the comb marks. If you do it wet, it turns into a lumpy mess. 

Next I’ll move up to 2kg bowls, then 3.