Category Archives: clay

Slab plates

This is one way I make slab plates. I posted the pictures to FB but am reposting here with descriptions of each step. You can adjust the steps if your clay is more or less forgiving than mine. 

First cut slabs and let them rest overnight to stiffen up some. These slabs are 10mm thick. 


Trim the slab with an undercut bevel, and save the trimmed edges. 


Sprinkle something on your form to prevent the clay from sticking. I use corn starch. 

Place the trimmed slab bevel side down on your form and paddle it THOROUGHLY, from center to edge, then once more evenly all over.  You can use whatever you want as a paddle, here I used a sandbag, but I usually use a wooden paddle. 


Place the trimmed edges you saved back on the paddled slab, followed by a paper towel or other cloth, and your board. Turn over the form to release the slab onto the board. 


Press the center of the slab down gently and let the edge pieces support the edge of the plate. While supporting the edge with one hand, use the other to define a concavity in the bevel with a convex tool. Anything convex and with a curve you like will work. I used a little ball here. Sometimes I use a rib, sometimes a roller, sometimes a clamshell. I like rollers and balls because they compress the edge well. 


Finish and further compress the edge with a damp (not wet) chamois or sponge. Done!

Visiting the clay guy

I went to Shoukotoudo in Ureshino this morning to check out some of the new clay bodies they’ve been working on. Matsuo San, the owner, showed me some fired samples from a new body made to mimic the properties of the old Yamase clay. It looked so good I bought 135kg for testing. Really looking forward to playing with it. 

Here’s a picture of one of the machines in the factory, one ton batches!


And here is a freshly pugged batch, he was just feeding in the filter press cakes when I pulled up. 


And finally:

Hunting white clay (not elephants)

There is an old story around here about Nakazato Muan (12th Generation Nakazato Tarouemon, Living National Treasure) finding a really great white clay seam in the Azambaru area of Taku.  Here it is in Japanese for those of you who can read it:

中里窯は昭和二十一年に石炭使用の角窯を薪用に改造して二十五年まで焼いた。
土は主に多久高麗古窯址近くの多久市北多久の荕(あざん)原(ばる)白土を胎土とした。
この土を見つけた時のエピソードが残っている。
掘り出した土を叺(かます)に詰めて荷車で重利が梶をとり、多久駅まで運ぶ途中下り坂に差し掛かった。
後押ししていた無庵は、下り坂でも押しまくった。はずみのついた車に重利はあわてて梶棒から飛びのいた。
車はそのまま道脇の田圃に突っ込み、荷車は壊れてしまった。
重利が驚いて怒鳴ると無庵は,
「この土で何を作ろうかと考えていたので下り坂に気付かなかった」と重利に謝った。
「親父が俺に謝ったのはあの時がはじめてだった」と重利はいう。

For those of you whose Japanese is a bit rusty, it goes like this:

In the year Showa 21 (1946), the Nakazato kiln was converted from a coal burning kiln to a wood burning kiln, and it was fired until Showa 25 (1950). During this time, Muan mostly used a white clay from the Azanbaru area of Taku.  There is a story, told by his son Shigetoshi, from the day they discovered this clay seam (Nakazato Shigetoshi passed away in 2015, at the age of 85, so he was probably around 16 years old at the time of this story).
So they have all this clay loaded onto a cart, which Shigetoshi is pulling and his father Muan is pushing, to Taku train station.
On the way, they reach a downward slope, and without noticing, Muan keeps pushing  down the slope, and they almost run into a car speeding down the road. Shigetoshi ends up diving to avoid the car, the car ends up in a rice field, and their cart ends up broken.  When Shigetoshi gets angry and starts yelling, Muan says “I was so busy thinking about what I was going to make with this clay, I didn’t notice the slope.”,  apologizing to Shigetoshi.
“That was the first time my father ever apologized to me.”, Shigetoshi commented.

So why, you say, are you telling me all of this? Well, the fabled white clay seam has been looked for now by other potters for decades with no luck, but due to a fortuitous event a few months ago (and several years of looking), I believe I have found it again. Here are some pictures from our excursion out to dig some sample material for testing.

This looks promising, with the moss scraped away.
This looks promising, with the moss scraped away.

 

Making some progress, this small hole yielded over 100kg of clay.
Making some progress, this small hole yielded over 100kg of clay.

 

Two partners today, one is my mentor, in the foreground, the other a friend and fellow artist.
Two partners today, one is my mentor, in the foreground, the other a friend and fellow artist.

 

Under better lighting. Isn't it gorgeous?
Under better lighting. Isn’t it gorgeous?

 

Oh, and lastly, here’s a picture of one of Nakazato Muan’s coil and paddle built jars. This one is made from white clay from the clay seam pictured above. My firing tests have almost the same color as the unglazed bottom section of this jar (although it is hard to see from this dark picture).

IMG_3605

Gas Firing 2016.02.20 Comments and Notes

This firing of the kiln went too long, resulting in Orton cone 11 flat.  Ideally, it would be cone 11 touching, then sagging a bit.

Upon unloading the kiln this morning, one thing was immediately apparent: the right side was far more reduced than the left. Yellower glazes and more slumping. Even on the left side there was some slumping, because of the excessive temp., and because of the clay which contained some low temp high iron clay to help seal the ware against leakage.

Left side, sagging only slightly, white surface.
Left side, sagging only slightly, white surface.
Right side sagging badly, white glaze turned yellow.
Right side sagging badly, white glaze turned yellow.

Chosen Karatsu came out pretty good, but the white was on too heavy, running down the pots too much.  It still came out looking ok because of the clay.

Most of the teabowls warped or sagged, so I only get to keep 2 or 3 of the 15. This is why teabowls are expensive, kids…IMG_3399 IMG_3398

All in all, not a bad firing, but need to adjust clay bodies, and pay closer attention to cones. Also, figure out the over reduction on the right side. It might be that one burner that sounds a bit off.

Kakewake CG bowls
Kakewake CG bowls
guinomi, need more sand in the clay
guinomi, need more sand in the clay
crystals, only grew on the right side, where reduction was strongest.
crystals, only grew on the right side, where reduction was strongest.
cylindrical tea bowls
cylindrical tea bowls
yunomi
yunomi
shells on feet
shells on feet

IMG_3437

saggared and much improved.
saggared and much improved.
porcelain, saggared
porcelain, saggared

IMG_3464 IMG_3463 IMG_3462 IMG_3460 IMG_3459

 

What I’ve been up to…

I had a gas firing a couple of weeks back which was mostly line blends and other glaze combination tests.  More than half of the ware in the kiln was glaze tests. Finally trying to get to the bottom of my Chosen Karatsu glaze woes, which started after my ash source changed. Both of my bread and butter glazes stopped working, and it now seems that I just made a spectacularly bad choice for my replacement ash. I tested 3 different ash types in the load and came up with two types that seem to work pretty well. I will mix up small amounts of both glazes with this new ash and  see how they work. If things look good, I can then go ahead and mix up a larger batch.

I made a batch of soba choko as well, to take with me to Tokyo toward the end of this month. I’ll be participating in a small event and needed some small things to  take and show.

In prep for the spring firing of the wood kiln, I’ve started making work a little different that  I have done before, more playing with rim shapes and putting feet on things. The larger platters  are actually inspired by some old Shino and Karatsu pieces of similar shape. Almost everything pictured in this post is porcelain, either pretty white stuff, or ‘dirty’ having been run through my pugmill which contained red stoneware previously. I always hear how porcelain is so difficult to work with, but my experience is the opposite. It seems very forgiving compared to my usual short, large particle clay bodies.

 

Red Lungs

Getting ready to set up a whole kiln load of glaze tests to fix my misbehaving ame (iron/ash) glaze, and realize that I’m out one very important ingredient, red ochre collected from a place right here in Taku. Completely forgot that I had used the last of it in my last glaze batch mixed up a couple months ago. Doh!

So…. Delay the mixing of test glazes for tiles and cups, I had to spend the day crushing and sieving red ochre. I haven’t used my man powered stamp mill in a while, and I added too much material to the mortar. My wooden pestle (4 foot long pole) that I use to stamp the material was just not up to the task because it was too light to sink down into the material and get it circulating in the mortar.  To remedy this, I retrofitted one of my wooden pestles with some  3cm diameter round steel bar left over from a long piece of bar I cut into sections for my kiln’s grate bars.

This new pestle worked really great, so great in fact, that material was flying out of the mortar from the striking force. So I proceeded to cut down a large cardboard box to keep most of that stuff from flying out or away. It is really hard work digging it, carting it around, and crushing it, I hate to lose any at all.

So anyway, here are some pictures of today’s festivities, and I did wear a dust mask, so I don’t have to worry about getting red lungs…

Mortar full of material, big chunks.
Mortar full of material, big chunks.

WD_1020

My two 'pestles'
My two ‘pestles’
retrofitting with steel bars
retrofitting with steel bars
Now we're in business!
Now we’re in business!
Things moving along nicely now.
Things moving along nicely now.
Sieving. This is one of the jobs I dislike the most.
Sieving. This is one of the jobs I dislike the most.
This bucketful is sieved through 50 mesh. Before using it, I will re-sieve through 80 mesh, most likely.
This bucketful is sieved through 50 mesh. Before using it, I will re-sieve through 80 mesh, most likely.