Red clay has a thousand different effects on taste

Sado Island, formed by underwater volcanoes, is rich in a variety of minerals.

The gold and silver produced from the former Aikawa Gold Mine are particularly famous, but the island also yields abundant copper, manganese, and other minerals.

Aikawa Gold Mine

Due to the volcanic geology, Sado’s soil is rich in minerals, among which HOJO focuses on Shudei/Zhuni for producing teaware.

Shudei/Zhuni is rich in ferric oxide, and when fired, it turns a vermilion color, hence the name.

It makes tea taste very mellow, which is why traditional Shudei/Zhuni teaware has been made in Sado, known locally as "Mumyoi." Generally, raw clay that is yellow to beige is referred to as Shudei/Zhuni.

Shudei/Zhuni clay has been valued as a raw material for teapots in Sado and other parts of Japan for centuries. However, not all Shudei/Zhuni clay has a beneficial effect on tea flavor.

The flavor impact varies depending on the type of Shudei/Zhuni. The types and amounts of minerals in the clay can sometimes worsen the taste rather than improve it.

Worsening the taste means cutting off the aftertaste, removing the depth of flavor, reducing the spread of aroma, or creating a rough sensation on the tongue.

Please understand that the term Shudei/Zhuni refers to color and does not inherently indicate the quality or performance of the clay.