Cup Nomenclature

This morning I read a very nice article about Japanese cups, defining their names and uses. You can see it here:

It is quite informative (it even mentions Karatsu) and even better, has some really stunning contemporary pieces to

see (but no Karatsu, tsk, tsk, more on this below).

There is one point in the article I would like to clarify a bit: the author mentions the word hakuji , meaning white porcelain made from kaolin clay from Izumiyama. For most folks this is probably a sufficient description, but at Karatsupots blog we are deep into ceramigeek territory, so consider yourself duly warned.

Izumiyama was the first deposit of porcelain stone discovered in Japan, in 1616, in present day Arita. Old Arita, Imari ware was made from this material. However, another porcelain deposit was discovered in Amakusa, Kumamoto, in the late 1600s, and began to be used for porcelain production in the early 18th century. Today, Amakusa stone accounts for more than 80% of porcelain in Japan. It is whiter than Izumiyama porcelain stone, is easier to work with, and much cheaper. Very few artists today work with Izumiyama porcelain (and probably no factories, but this is speculation on my part). Izumiyama is not being mined currently.

Izumiyama is still available, but not very dependably, and it is quite expensive. I use it because it is absolutely beautiful in wood firings, but is is difficult to work with and losses are high. Ok, enough on Izumiyama.

Next, guinomi, choko, and sakazuki. All are names for sake cups, with one caveat: guinomi are not just for sake, while choko and sakazuki are.

Now, to rectify the lack of Karatsu ware pictures. Again, for most folks it is not all that important, but this is Karatsupots after all, and to quote Pink Floyd’s The Trial, “this will not do.” So, here are some pictures of Karatsu cups.

Nishioka Koju. Chosen Karatsu guinomi

Maruta Munehiko. Brush decorated Karatsu guinomi

Nakazato Shigetoshi. Brush decorated Karatsu guinomi

Old Karatsu. Madara Karatsu

Old Karatsu. Brush Decorated

Old Karatsu. Kawakujira

Old Karatsu. Chosen Karatsu

Okamoto Sakurei. Brush deco Karatsu

In the hot seat

A couple of days ago I sat down with my newly acquired kickwheel to see what I could do. I’ve used my homemade kickwheel frequently for handbuilding and paddle work, not as much for throwing, because it is quite tall and the flywheel is quite high from the floor.

The new kickwheel is craftsman made, and shorter, making it easier to use without a special seat. In the two days of throwing, I discovered two things: 1. my homemade wheel spins better making it great for coil and paddle work, and 2. The new kickwheel is easier to throw on because the fly wheel is so much closer to the ground.

I decided to throw with a difficult body to keep things interesting. Stamped Izumiyama porcelain stone that had been levigated and filter pressed, with the removed large particle material re-added as 30% of the body. This makes for a pretty short body but it does have more backbone than straight filtered Izumiyama. I started with small, simple shapes for the first day, and moved to larger bowls on the second, sort of a cross between an Ido form and a wider more open shape typified in a lot of Ri period Korean work.

My goal was to keep things as light as possible off the wheel, and requiring as little trimming as possible.

I waited a bit too long with the small cups, but they trimmed with some very nice texture even though a few had some of that soft porcelain tear-out. Since they are sake ware, I’m hoping this will add to their landscape in the firing.

Very happy overall with the texture of the interior of the feet. When I first discovered that porcelain would trim like this, it was a major discovery for me, and prompted me to start working with it.

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. 

Plaster Caster

This abalone shell sat under a bush next to the pool at my grandparents house for as long as I can remember. My grandfather used to take abalone off the California coast, they were so plentiful you could pry them off the boulders at low tide. This was back decades ago before they were scarce. 
After my grandparents passed, I took this shell as a reminder of family, fun times, and good food. 

As it turns out, it was perfect for making a plaster mold for abalone dishes. This is just the first, many more to come.

Soft Porcelain Slabs

I started playing with soft slabs this week (no not that, you with the dirty mind) and made some paddled forms for sweets and food. They will go into the fall kiln once they are glazed. Here is a finished piece:

They are really simple to make, just cut a slab like a piece of cloth for a sewing project, paddle it to compress and add texture, and fold up/ join the edges. Like this:

Because they are compressed by paddling, and maybe because of the way they are assembled, there are no problems with warping when they dry, which is a very big plus. 

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