Shigaraki is the name of a place in Shiga Prefecture in Japan. This place was called "Koga" once upon a time. Most Japanese knows this name, Koga, not because of the clay, but Ninja. Koga was the place where Koga Ninja was brought up. In any case, we need to clarify that Ninja has nothing to do with this clay though.

Shigaraki is one of the 6 oldest potteries in Japan. At present Shigaraki produces more than a few thousand kinds of clay and also supply various kinds of clay to many other places such as Tokoname, Bizen, Banko and Sado. In fact the most of clays being produced in Shigaraki is white clay which is suitable to get beautiful "Yohen" outlook when it is baked in wooden kiln such as "Noborigama" (Dragon Kiln). As the matter of fact, most of aritist who use Shigaraki clay to bake their product is hoping to get identical appearance. Unfortunately those clays are not suitable for teapot due to following 2 reasons.
https://en.wikipedia.org/wiki/File:Shigaraki_Jar.JPG

1. The baking temperature is too high. For the most of Shigaraki Yaki, the artist uses very high temperature to bake clay. The artist wants the surface of clay melted in order to create natural glazing and to cause the various color with fire. It is nothing wrong to use this technique for making a flower base or something which is only for aesthetic purpose. However the high temperature baking is absolutely not suitable for teapot. The high baking temperature get the mineral of clay melted and drastically reduce its surface area. Once clay reduces its surface area, it gives very less effect like glass.

2. Majority of Shigaraki clay is white clay since there are huge demand of the clay that is suitable for Yohen or natural glazing.

We selected clay from the mountain of Shigaraki based on the performance of clay. We have tasted water from various kinds of Shigaraki clay and selected one particular type of clay. The Shigaraki rough clay that we selected is very rich in iron. The crude clay looks yellow-reddish in color. It is baked in reduction fire and appears in beige-orange color. Due to the highly intense porosity, you can even detect the aroma of tea coming out from the clay teapot when brewing tea. When placing teapot on table for a short while, after remove it you can immediately observe the steam remains on the table that penetrate through the clay. We carried out tasting using water in Japan, Malaysia and China and found out that it makes the intensity of Hou Yun extremely strong. Shigaraki clay teapot is suitable for most kind of tea including Japanese green tea, oolong and puerh.

Once upon a time, people would have been aware that the clay makes taste delicious. I believe that the fact that Shigaraki used to be the 6 famous kiln in Japan would have been thanks to the performance of clay. Unfortunately most of people in Japan nowadays only care about the appearance. Ironically normal Shigaraki clay in general performs nothing special but unique in outlook.

Teapot Evaluation Technique Using Water

Teapot Evaluation Technique Using Tea