Japanese Potteries (Story of Clays)

“Clay first, baking second, and workmanship third Eis one of the sayings handed down through out the in Japanese pottery history. It means that no matter how fine the workmanship is, it’s no good unless being baked well, and even though it’s baked well, what’s made wouldn’t be considered a pottery as long as the clay material is not good. As such, Japanese pottery production has been sticking to clays all the time.

In focusing on clays, not all clays is suitable for making potteries.If you take a clod of red clay that is seen at a hillside and try to bake it, that wouldn’t work, or that may sometimes be melted by heat. It is essential that the clay goes tight in heat at around 1,200 degrees Celsius with holding its shape unchanged, and that it’s sticky enough to be shaped properly.

Sueyama shrine
Sueyama shrine

In Japan, there are lots of production areas for potteries, such as Arita, Bizen, Karatsu, Satsuma, Hagi, Tobe, Tanba, Kyo, Shigaraki, Iga, Kutani, Tokoname, Seto, Mino, just as for representative examples, and plenty more places, and a different type of distinguishing clay has been used at each of the places respectively. Therefore, it is assumed that pottery arts have been so popular in Japan just because there are many places of production in use of unique variety of clays and it’s been quite easy to get a wide range of products made of various clays.

Clays can be divided into two different types, porcelain clays and china clays. Porcelain clays characteristically allow lights to slightly pass through, and most of them have a white finish after baked. China clays don’t allow lights to pass through, and the porous surface easily gets water in it, in which water inside hardly gets warmer or cooler. Among the places listed earlier, Arita, Tobe and Kutani produce porcelain clays and the others do china clays respectively.

There is a pretty wide variety of china clays in particular, and finished potteries made of those would vary in their color and texture. As clays are all different each other in a way that there are some kinds that come from mountains and some from rice paddies, that are dry, wet, or sandy, or that are in white, red, brown, black or yellow. It is also told that you can find a good china clay in a location that is nearby hot springs. Since there are so many hot springs in Japan, it might be also one of the reasons why numerous good china clays are available.

In what follows, taking up as some examples the porcelain clay in Arita and the china clay in Bizen, I’d like to tell a bit about their characteristics.

The Porcelain Clay in Arita

In Arita, the production of porcelain china started when Izumiyama toseki was discovered in 1616. The Izumiyama toseki is porcelain clay that can transform into a pottery simply by being baked, after having it finely crushed, iron-removed, and kneaded with water.

The clay was very convenient as it alone can be used as porcelain clay. However, it had weaknesses of containing iron at a higher rate and tending to get out of shape if heated at a high temperature due to its frailty. For that reason, there are many Arita wares of the early period that are almost 2cm in thickness even though it's a small plate. They were intentionally making it that way to preserve its shape. As a matter of fact, there is another reason of the thickness. Arita wares at that time had not been given it biscuit firing (initially baking it once at around 800 degrees Celsius). As scattering glazes (liquid glass coating over the surface) without applying biscuit firing, it was at risk of absorbing the moisture and getting collapsed unless it was thick enough. Therefore, making it so thick was inevitable, while zaffers (cobalt oxides) for painting and glazes are blended in superbly each other on products of that time and there are many of those works in so gentle and soft atmosphere still remains today.


Consequently, from an ease of shaping, people had gradually come into use of Amakusa Toseki, which had soon become popular because of its less inclusion of iron and handiness as well as its rich amount of reserves. However, at that time, it is said that potters in Arita had arguments, being reluctant to easily veer away to the Amakusa Toseki as the cradle land of porcelain clays was Izumiyama.

I heard that, before the Amakusa toseki would have become so common, exhibitions for Arita wares had set out a provision that accepted works or products using Izumiyama toseki only. The clay might not be just merely a low material for them but was that from the land they loved indeed. Even now, you can see a stone monument at the ex-mining of Izumiyama Toseki which is inscribed “the cradle land of Arita wares E

The Amakusa toseki has spread out to be used all over Japan, not only nearby the Arita area, thanks to its handiness and rich amount of reserves. You would notice that the clays are quite different in how they look, between the cream-colored Izumiyama toseki and the white-colored Amakusa toseki. The Amakusa clay was easy-to-be-turned on a potter’s wheel and resistant to heat, therefore, gorgeous and large-sized garnish crocks or lighting fixtures have been produced. Nowadays it is used also for sanitary wares like toilet bowls or electric components. As such it has come to be applied, not only as a material of potteries, but also to enormous number of items in our daily life.

The China Clay in Bizen

“Bizen’s mortar won’t crack even if thrown Eis a phrase we often hear when talking about Bizen wares. It means that they are so tough and tight that they won’t crack even if they’re thrown. Although there are plenty potteries now that hardly crack, they are supposed to be so valuable at those times 100 years ago.
Such Bizen’s china clays can be divided into two types for their different characteristics of clays depending on times. One is the time of mountain clays, and another is the time of paddy clays. Bizen has an area that traverses from mountains through plain fields being connected to ocean, and in the earliest period, wares were burnt in kilns utilizing the slope of mountains. The one used at that time was the mountain clay.

Bizen of Clays
Bizen of Clays

The mountain clay is very rough and rocky, and baking such clay creates a boisterous mood. However, some are well baked tight as it stands up well to heat, or on the contrary, some celebrate nature’s taste of what the clay is, even though they’re not baked well as heat might not run through properly. You may sense the landscape scenes or warmth over the baked clay.

Kobizen (Old Bizen) is refera to the one produced in such time of mountain clay, and the fact that there are plenty fans of such products makes sense. The transportation method at that time was mostly ships, and some of them ran aground and sank with cargo onboard. What has been hauled up from the sea in explorations or by fishermen is called Umiagari (one picked from ocean) that has unique textures such as one with shells clings to or one that has been discolored in the sea water for so many years. Probably fishermen around the area may have so many Umiagari, I reckon.

As the demand had increased and the kilns had become bigger and bigger, potters with the whole village started to move to plains. Accordingly, clays to be used were changed to paddy clay. Clays from rice paddies, but in fact, that used to be the bottom of ocean and then had heaved during a huge number of years, and then fully decomposed by bacteria and turned to be extremely sticky, was being used.

Such clay has a fine texture and is resistant to water. When shaping a pottery on the wheel, normally you should be careful not to use too much water as it makes clays weaker, but potters in Bizen do the shaping on the wheel with soaking it in full of water. That is possible because the clay is water-resistant, and you can turn the wheel freely no matter how much water you may use. The way of producing might be the most optimal in term of the characteristics of clay.

Another feature of paddy clay on production is that it enables producers to show workmanship. A lot of exquisite ornaments have been created, and it become possible thanks to this finely-textured clay. As the porcelain clay in Arita is finely-textured as well and many ornaments have been made with it, such finely-textured materials including china clay from paddies in Bizen are likely to be suited to bring out sensitive workmanships.

Japan has such a great number of places for potteries, and each of them brings forth artistic products utilizing its own unique clay. When you know more about clays, you may be able to have fun appreciating the products from a bit different perspective.

The next topic is about Japanese Potteries (Story of Kilns)...