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

Pigment:Glaze Notes

Yesterday’s firing was my first gas firing of this glaze, body, and pigment, and first ever primarily porcelain firing.

This piece’s specs:

Porc:Sandstone body 6:4

Taishu:Ash glaze 7:3 @ 40°

Gosu:Oni-ita pigment 6:4 (7:3)?

Orton cone 7.5 light reduction

Pigment blacker than expected, too thick or maybe not enough reduction?

Body is not vitrified completely at this temp, but pure Izumiyama probably would be. Good for teaware and tableware, but for restaurant use should probably be fired higher.


Madara (mottled) Karatsu teabowl, late 1500’s.

When I decided to learn and make Karatsu ware, I had no idea what I was getting myself into. I knew it was several hundred years old, and the first glazed ware in Japan, but I mostly just saw some beautiful pots and thought I could reproduce. Boy, was I wrong.

I’ve been working at it for more than 10 years now, and the clay, glazes, and firings are still mostly a mystery. Trying to capture the look of the traditional ware is a continual challenge, forcing me to forget or ignore modern technology in favor of archaic, and examine 400+ year old shards, searching for clues about what the old potters and craftsmen used, and how they approached their art, which they didn’t necessarily consider to be art.


The closest I’ve come yet to a surface like the pot at the beginning of this post.

One thing I’ve learned in this time making pots is that despite the primitive technology, ancient potters had knowledge about their materials and handling of those materials that far exceeds the knowledge of most modern potters. This is what makes tradition such an important repository for us. It is the best of what has come before, proven over time and distilled for us to use. We just need to pay attention.


Chosen Karatsu teabowl, late 1500’s


Chosen Karatsu guinomi by author

Cheers,

Karatsupots

Mike @ Karatsupots
Making attractive, cool, useful stuff out of dirt since 2006.

2016-03-20 Glaze tests 釉薬の実験

Fired with cones 6,7,8 on top and bottom shelves. Pyrometer at middle shelf, didn’t display over 1215C.
Hotter on bottom than top. By cone, looks like cone 9+ on the bottom, cone 9 at the middle, and cone 8+ at the top.

Reduction strong at top shelf, weaker at middle and bottom.

棚三段、上、中、下。 オートンコーン6,7,8 使用、上:下置。温度計は中に。焼成中の温度計は1215Cを超えずが、上は8番コーンは曲がって、ヘタレ。下は8番フラット。 実際の温度は下:9+、ちゅう:9、上:8+ とみていいでしょう。
上は還元効いているようだが、中:下は中性気味。

Unloading:

Bottom shelf, front. Mid shelf, rear left. Top shelf, rear right.
Bottom shelf, front. Mid shelf, rear left. Top shelf, rear right.

Top shelf
Top shelf

Mid shelf
Mid shelf

Bottom shelf
Bottom shelf

Bottom cones
Bottom cones

Top cones
Top cones

 

Clay : Ash Blends  (Lft, to Rt.:  Bott.,Mid.,Top)

Taku shiro 90 : Dobai 10
Taku shiro 90 : Dobai 10

Taku shiro 80 : Dobai 20
Taku shiro 80 : Dobai 20

Taku shiro 70 : Dobai 30
Taku shiro 70 : Dobai 30

Taku shiro 60 : Dobai 40
Taku shiro 60 : Dobai 40

 

Stone : Ash Blends    (Lft, to Rt.:  Bott.,Mid.,Top)

Sandstone 90 : Dobai 10
Sandstone 90 : Dobai 10

Sandstone 80 : Dobai 20
Sandstone 80 : Dobai 20

Sandstone 70 : Dobai 30
Sandstone 70 : Dobai 30

Sandstone 60 : Dobai 40
Sandstone 60 : Dobai 40

 

Clay : Ash total, plus 280g Shirakawa

Clay:Ash total +280g toseki
Clay:Ash total +280g toseki

 

Stone : Ash total, plus 280g Shirakawa

Stone:Ash total + 280g toseki
Stone:Ash total + 280g toseki

 

Everything dumped together: Stone:Clay:Ash:Shirakawa

Clay:Stone:Ash:Toseki total
Clay:Stone:Ash:Toseki total

 

Stone:Ash 70:30 from top shelf (cone 8+) in the sunlight:

Stone:Ash 70:30 @ cone 8 1/2
Stone:Ash 70:30 @ cone 8 1/2

IMG_3681

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

 

Fall 2015

has been busy.

I’ve gotten pretty far behind keeping up with the blog, falling into the bad habit of making small posts to Facebook. One of my areas of increased effort over the next year will be to work more on maintaining the blog, and getting it more integrated with other forms of social media. Trying to keep track of them all is like trying to herd cats.
I had made one promise to show before/after pictures for a couple of pieces, the first of which is the slab/paddle built sake chiller w/ feet and lugs:

IMG_2176
raw unglazed

IMG_2513
Fired piece, Chosen Karatsu style glaze. Matchbook for scale.

IMG_2518
Underside detail. Fired on shells, feet not touching the shelf.

IMG_2516
Glaze detail

 

The other thing I’ve been working on since early this year is getting a usable kohiki/clear glaze combination, because for some reason a lot of customers have been requesting white work. They have also been requesting black, so I’ve been working on getting a reliable semi matte black glaze. Mission not quite accomplished, but I feel I’m most of the way there. Here is the kohiki I’ve come up with and I am happy with it:

Kohiki cups. Cup on the left is unused. Middle has been used a bit, and right has been used a lot. The patina is beautiful in my opinion, and the fineness of the crackle is something I’ve been wanting for a long time in my work.

Various guinomi from 2015, mostly from the fall firing. Guinomi make great gyokuro drinking cups.
Various guinomi from 2015, mostly from the fall firing. Guinomi make great gyokuro drinking cups.

Seabirds on white.
Seabirds on white.

The other thing I have started doing is Japanese kana inspired brushwork
The other thing I have started doing is Japanese kana inspired brushwork, except with English. This cup is decorated with vertical English writing, a Goethe quote I like: “Whatever you can do, or think you can, begin it. Boldness has genius, power, and magic in it.” One of the other said: “Don’t be a dick.” These were more popular than I had anticipated and are currently sold out. Definitely making more!

Here are some of the pieces with the new black glaze. It seems to look best thin, and as with most glazes looks nicer over interesting wild clays rather than processed clays.

Type 1 semi matte black Katakuchi with black lacquer repairs.
Type 1 semi matte black Katakuchi with black lacquer repairs.

Type 1 semi matte black dish.
Type 1 semi matte black dish.

Semi mmatte type 2: two black glazes layered
matte type 2: two black glazes layered, makes a fatter glaze surface.