2 types of clay used for Mumoyi Yaki in Sado Island

In Japan, the pottery in Sado Island that uses natural red clay is called the Mumyoi Yaki. The Mumyoi Yaki is defined as the clay ware made of “Shudei”, collected from the Aikawa gold mine and the surrounding mountains. However, if you understand more about the Mumyoi Yaki, you would know that there are 2 types of clays involved. One of the clays is the Nosaka clay that has a yellowish-beige color and it is sticky as it consists of very fine particles, while another type of clay is called the Mumyoi clay which is of orange-red color where the particles are coarser. Both types of clay exist around the Aikawa gold mine area. According to the definition, the clay ware is still known as the Mumyoi Yaki regardless using either one clay or both. Usually, to produce a tea ware of 100% Mumyoi clay is very difficult as it is a little too coarse for the artist to shape. In Japan, majority of artists operate on a potter's wheel for their work; thus, the clay has to be elastic enough to mold. Hence, it is a common practice to add in a certain percentage of Nosaka clay with the Mumyoi clay to make it malleable enough. Here is a summary of the Mumyoi Yaki as follow.

1. It involves Mumyoi clay and Nosaka clay or either one of 2.
2. The artist obtains the clay by themselves and carries out the entire refining process by themselves before it can be molded.
3. It resembles the traditions of China Yi Xing teapot production in many ways.

In the quest of clay that improves the taste of tea, we’ve produced teapots using 100% Nosaka Clay and Mumyoi Clay (Mumyoi clay + minor percentage of Nosaka clay). Despite the obvious difference in appearance of these clays, the color and the appearance of teapot after firing is almost indistinguishable. Through the history of Mumyoi Yaki in Sado Island, the potters would blend the clays and set a firing temperature only based on the appearance of the tea ware. We, however, discovered that these two types of clay give a completely adverse effect on the taste of water or tea; therefore, we select our own clay based on the effect of taste.

The reason why we introduced 2 types of clay from Sado Island

Nosaka increases the after taste

The Nosaka clay selectively increases the aftertaste of tea but not so much obvious in increasing the body. The tea brewed in Nosaka gives a transparent, clear and smooth image. Moreover, the flavor of tea becomes softer, yet long lasting.

Mumyoi clay increases body

The Mumyoi clay significantly increases the body of tea as well as the after taste. Plus, the flavor of tea brewed using a Mumyoi clay tea ware becomes richer, bolder and wider. This clay performs very well with fermented tea such as Oolong and Black tea. I personally love Taiwanese and Darjeeling tea being brewed in this clay.

Upgrading of the Mumyoi clay

We’ve made some improvement to the Mumyoi clay by analyzing the refining method of clay; by that, we managed to increase the level of the aftertaste and body even more than the previous batch. This is the 3rd successful improvement of this clay in my history.