Bizen ware Bizen yaki
One of Japan’s Six Ancient Kilns
Strong and warm baskets
Bizen Ware is a form of pottery produced in the area around the city of Bizen in the Okayama prefecture. Bizen ware is one of Japan’s Six Ancient Kilns : together with Shigaraki, Tamba, Echizen, Seto and Tokoname, it is considered to be one of the most oustanding Japanese kilns with traditions that remain down to this day.
Bizen ware has a unique manufacturing method as it does not use glaze. Generally, baked pottery is given luster and water-resistance by coating it with glaze, but since Bizen ware does not use glaze, there is no luster so only a simple impression is produced.
Glaze is also usually used for patterning, but there is no such work involved in the production of Bizen ware, so each individual pattern is different, resulting in pottery where pieces cannot be identical, and this too is one of the charms of Bizen ware. The reason for not using glaze lies in the clay known as hiyose, which is collected around Bizen and only used for Bizen ware. This clay makes the procedure of spreading the enamel more difficult than other clays but great success has been achieved in producing durable porcelain with it. The artisans had and still have to consider different ways of overcoming the nature of this clay and bake it inside kilns for a long time without touching it to make Bizen ware as it is.
Bizen ware is a form of porcelain that was developed based on the manufacturing method of "Sue pottery", which was a blue-gray pottery introduced from the Korean peninsula during the Tumulus period (around 250 to 538 AD) The prevailing theory is that it was modeled as Bizen ware during the Heian period (794-1185), beginning with the production of bowls for daily use and roof tiles. In the Kamakura period (1185–1333), items in reddish brown were deemed as being one of the characteristic colors of Bizen ware, and in the Muromachi period (1336-1573) these pieces started to use hiyose clay (see top paragraph). Also, in the Azuchi-Momoyama period (1573-1600), Bizen ware was said to be favored by Hideyoshi TOYOTOMI, who governed most of Japan at that time, and by Sen no Rikyu, a master of the tea ceremony. Many people adored the Bizen ware used in tea ceremonies because its simplicity complemented the spirit of refined simplicity found in the tea ceremonies.
The spirit of Bizen ware perdures today. In 1956, Toyo KANESHIGE was selected as a Living National Treasure for his work as a Bizen ware potter, and many other Living National Treasures were selected for their work in the same field since then, including the likes of Kei FUJIWARA and Toshu YAMAMOTO.
General Production Process
- 1.Collecting the clay-like soil
As Bizen ware does not use glaze, it immediately shows the good and bad of the raw material so selecting a good soil is one of the most important parts of the whole production process.
Soil used in Bizen ware is dug up from around 3 to 5 meters underground in fields around Bizen. The collected soil is baked just for testing to determine its good and bad points.
Although the soil has been collected, it cannot be used right away. It must be exposed to wind and rain for 1 to 2 years, then mixed thoroughly and evenly.
The soil that has been steadily exposed to wind and rain is sorted out using several methods. It begins by refining the large grains with a mortar-like machine known as a fret. Then, when the grains have been refined to a certain extent by the fret, the grains are sorted to become even finer through a process known as elutriation. Elutriation is a process that involves soaking the soil in water and retrieving only the finer grains, using the speed at which they settle at the bottom.
- 2.Spiral wedging
The sorted clay is left to rest for a period of time lasting from a few weeks to a few months, until the suitable level of hardness is obtained by adding water, and is mixed with black soil through "spiral wedging". This is a method of roughly kneading with bare feet.
The spirally wedged soil is left to rest again for a period of six months to several years.
When the soil is finally ready for use, it is wedged once again. Wedging before use is referred to as "spiral wedging", and air is removed after firmly kneading by hand before use.
This is the first stage of production after the soil has been prepared.
There are various methods of production, including methods that do not use machines (such as forming with coils or forming with boards) and others that use potter’s wheels, but the casting method is basically the same as that of the other types of porcelain.
- 4.Spatula handling
After casting, the pieces are laid on top of the potter’s wheel and patterned using a spatula.
- 5.Loading pots into the kiln
Bizen ware cannot immediately be baked inside the kiln, even if their shape have been formed. The key is to leave them alone and let them dry naturally. If cracks occur at the stage of natural drying, them must be returned to the soil.
Once they have been dried thoroughly, the kiln is ready to be loaded. The degree of baking varies depending on the position inside the kiln, so it is necessary to load the kiln while making thorough calculations.
- 6.First firing ceremony
The first firing of Bizen ware is carried out on a lucky day to ensure that the pieces will be baked well.
A ritual prayer is given to the gods at the first firing ceremony.
Although it may seem like it only involves baking in a kiln, there are several separate processes involved.
First, kuyushi is carried out during the first two days. Kuyushi refers to the process of throwing kindling onto the fire using only the fire inlets in two locations at the front of the kiln. This helps increasing strength after baking.
"Scorching" begins on day three. This is when the temperature of the kiln is raised gradually, by around 3 to 5℃ every hour, to make the pieces difficult to break.
Naka-daki is carried out once a temperature of 400℃ has been exceeded. In naka-daki, the temperature is raised by around 7 to 10℃ per hour, accelerating the rythm of temperature increase.
Once it has passed 800℃, the temperature is raised at a base of 10 to 15℃ per hour, and finally the firing process continues while keeping the temperature at around 1150℃ to 1300℃. This whole process takes around 1 to 2 weeks.
- 8.Removing the pots from the kiln
Once the firing is complete, all of the fire inlets are immediately blocked without opening the kiln, after which the inside of the kiln is slowly cooled.
This is done slowly, because the porcelain could crack if the kiln was cooled too fast.
Bizen ware pieces that have been carefully removed from the kiln are hand-polished and inspected by the artisans.
They are then sent out to the world for the first time.