About Nosaka Rough Clay by Tozo Watanabe
Tozo Watanabe
Mumyoi of Sado Island
The red clay found around the Aikawa gold mine and in the Osado and Kosado mountain ranges on Sado Island is called "Mumyoi". This clay has a high iron content. Pottery made from it is called "Mumyoi Yaki", the best-known pottery of Sado Island.
For the history of Mumyoi Yaki and other details, please see the link below.
More about Mumyoi Yaki of Sado Island
Sado’s Mumyoi clay is not widely known in Japan, but we believe it has great potential to enhance the taste of tea once tea is brewed in Mumyoi Yaki.
Sado, rich in clay
We took an early interest in Sado clay and have worked with potters on Sado Island to find clays and firing conditions that give tea a richer taste and a longer-lasting finish. We have studied different types of clay, whether to blend them and in what proportions, and how firing temperatures and methods affect the taste of tea. This research guides our selection of teaware.
How Nosaka differs from ordinary Mumyoi Yaki
Mumyoi Yaki is traditionally made by blending two natural clays: red clay mined around the Aikawa gold mine and yellow clay from Nosaka. The photos above show these two clays.
On Sado Island, the red clay is called "Mumyoi". It has limited plasticity on its own, so it is difficult to shape on a potter’s wheel. Potters have traditionally blended it with the more plastic Nosaka clay. As a result, Nosaka clay received little attention beyond its role in helping potters shape Mumyoi.
We became interested in Nosaka clay while searching for Japanese clays that could match the performance of old Yixing Zhuni when brewing tea. We tested many clays, varying the blend ratios, firing temperatures and firing methods, and evaluated how each affected the taste of tea.
Through these tests, we found that Nosaka clay had far more to offer than plasticity. Used on its own, it brought out an extremely rich taste and a long-lasting finish in tea.
We also noticed similarities between Nosaka clay and Yixing Zhuni. Both have a similar color and texture before firing and look very much alike after firing. Nosaka clay is yellowish beige in its raw state and turns persimmon orange when fired, although the final color depends on the firing temperature. Our interest, however, was in what Nosaka clay could do for the taste of tea.
We worked with the potter through repeated trials to find the firing conditions that brought out this potential. The result is our Nosaka series: teaware made entirely from Nosaka clay, a material once valued mainly for helping to shape another clay.
Nosaka brings strong richness and body
Tea brewed in Nosaka ware has both a full body and a long finish. The body gives the flavor and taste a rich, full feel that spreads across the mouth, while the finish leaves a lingering, concentrated aftertaste.
These effects are not limited to tea. Nosaka ware suits all types of tea and also improves the taste of other drinks and liquids, including coffee, juice, beer, wine and soup. Some customers who are familiar with these effects buy Nosaka cups for juice, coffee or wine.
Raw Nosaka clay
Nosaka is an area in Sawane, Sado City, near the Aikawa gold mine.
The video below shows where Nosaka clay is dug.
Nosaka Rough Clay is a HOJO original
We worked with the potter to refine the clay preparation and firing methods, combining the potter’s skills with our evaluation of how the teaware affects the taste of tea.
Potters on Sado Island dig and refine their own natural clay. For more details, please see the link below.
Traditional clay preparation by hand
How shudei clay affects taste varies widely
Nama-migaki, the traditional burnishing method that finishes only a few pieces a day
One feature of Sado teapots is a traditional technique called nama-migaki. Today, Sado Island is the only place making teapots with nama-migaki. For details, see the page below.
Nama-migaki, the traditional burnishing method that finishes only a few pieces a day >