Deep into KURO IWANAMIDeep into KURO IWANAMI

What is KURO IWANAMI Matcha Bowls?

New masterpieces have joined our lineup of Matcha bowls. All of these, named KURO IWANAMI, are unique due to their distinctive charm. KURO IWANAMI means waves crashing on black rocks in Japanese. Please take a look at the photos. This Matcha bowl is not simply black, but has a complex and beautiful gradation depending on the way the light hits it. Its unique wave-shaped form is powerful and attractive to the eye, but it is also surprisingly reassuring to hold in the hand. How were these special Matcha bowls with such seemingly conflicting features created?

Let's take a deep dive into these pieces created by up-and-coming ceramic artisan Mr. Yoshihiro Sako.


Shigaraki is surrounded by abundant nature.

We will explore the secret of this beauty and power.

This is a self-portrait of Mr. Sako.

Manufacturing Process - (1) The Clay

Creating an original Matcha bowl like KURO IWANAMI requires unique ideas from the clay selection stage. This Matcha bowl is made of a special clay called ZURINKO. The clay comes from the old strata of Lake Biwa, the largest freshwater lake in Japan, and is characterized by its high mineral content, fine texture, and low fire resistance. It is well known locally because, when spread over the fields, ZURINKO produces a good rice harvest. Its fine texture makes it suitable for delicate modeling. However, ZURINKO is difficult to handle due to its brittleness and blackness, so it is typically not used in ceramics.

Mr. Sako has long wondered if it would be possible to create unique pieces using this clay, which has always been considered to be unsuitable for pottery. After various trials and errors, he arrived at one answer. He mixed about 20% to 30% of ZURINKO with Shigaraki red clay, which has opposite properties. This mixture of clay was easy to handle, and the resulting Matcha bowl was distinctive with a metallic sheen and complex luster. If only common Shigaraki red clay or only ZURINKO had been used, this type of Matcha bowl would not have been possible. The exquisite combination of these two opposing clays produces this Matcha bowl with a unique charm. This attention to the clay reveals Mr. Sako's skill as an artisan, along with his creativity and technical knowledge.


This soil called ZURINKO is important.


ZURINKO is powdered and kneaded into red clay.

Mr. SAKO's workshop is full of various tools.

A smile that captures the personality of Mr. Sako


(2) Kneading Process

There is an important process before the clay is formed on the potter's wheel. It is the process of kneading the clay. First, a kneading process called ARANERI is performed, in which powdered ZURINKO is mixed with the Shigaraki red clay. ARANERI means to knead roughly. This process allows ZURINKO to blend well throughout the clay. Once this process is complete, the next step is called KIKUNERI. KIKUNERI means to knead the clay as if drawing chrysanthemum patterns. This visually pleasing process is very important to prevent the clay from cracking during wheel forming and firing. This process takes a long time, especially with special clays such as the one used for this Matcha bowl.


Mix powdered ZURINNKO with red clay.


The way he kneads the clay is very serious.

A beautiful chrysanthemum pattern emerges.


She also watches over the making of the matcha bowls.

(3) Forming Process

After the clay is kneaded, the potter's wheel comes into play. First, in a process called TSUCHIGOROSHI, the clay particles are prepared and set so that the clay is in the center of the potter's wheel. Most potters try to complete this process within three attempts, but Mr. Sako is able to place the clay perfectly in the center of the potter's wheel within only two attempts. The unique pieces he creates are backed by his skill in performing basic processes at a high level.

Next, forming on the potter's wheel begins. Once Mr. Sako starts spinning the clay on the potter's wheel, he hardly blinks and is extremely focused.

When you first see this Matcha bowl, what catches your eye most is its unique shape. The clay is three times thicker than usual. After being formed on the potter's wheel, Mr. Sako carves the clay with a paddle to produce the bold pattern. Surprisingly, this process uses three to five delicate paddles of different types. This carving process is called SHINOGI. Mr. Sako's goal is for one to experience the rough and forceful impact of waves crashing on black rocks when using this Matcha bowl.

The uneven SHINOGI seen in this Matcha bowl is very difficult to achieve. This feature is highly valued by fellow artisans. It is not a completely random pattern, but it is not all calculated either. The design represents stability within instability, disorder within order. This Matcha bowl expresses such conflicting sensations at the same time. Mr. Sako pursues this SHINOGI rhythm every time, so even the same type of Matcha bowl has a slightly different look.

Incidentally, the clay scraped off by SHINOGI and during other processes is mixed with additional surplus clay and used as recycled clay. Valuing materials is one example of Mr. Sako's pride as an artisan who respects nature.

Finally, Mr. Sako creates the KOHDAI base, known as KATAGAWA KOHDAI. It is different from the KOHDAI found in many Matcha bowls, which further enhances the atmosphere of this Matcha bowl. One of the charms of this work is that it can be enjoyed from various angles.

In creating his original Matcha bowls, Mr. Sako always pays attention to the ease of use. It is difficult to convey in a photograph, but this Matcha bowl is lighter than it looks and has a gentler feel and mouthfeel. Holding it with both hands, you will be soothed by the sense of security it provides.

No matter how beautiful it looks, if a Matcha bowl does not feel comfortable in the hand, its charm will be reduced by half. KURO IWANAMI, of course, has both beauty and usability.


This process called TSUCHIGOROSHI.

Very difficult to form unique shapes.

Separate the bowls with a thin thread.

From left to right: TSUTSUGATA, HIRAGATA, and KUTSUGATA.

This process is SHINOGI.

Cautious and bold.

It is shaved with tools of various shapes and sizes.

A beautiful wave pattern was created.

A beautiful wave pattern was created.

(4) Firing Process

The firing process is important for any Matcha bowl, but in the case of KURO IWANAMI, particular attention must be paid to the firing process. This bowl was fired in an ANAGAMA kiln using a cooling reduction technique called SUZU YAKI. It is a type of smoked ware, a traditional technique that originated in Japan around the end of the 12th century.

One of the characteristics of this firing method is that the chimney is closed after the fire is lit.

Fuel is continuously poured through the slightly opened entrance of the kiln to fill the inside of the kiln with smoke. The fuel used is red pine and oak. These ashes form a natural glaze with beautiful gradations. In this way, the carbon in the kiln is absorbed by the Matcha bowl, producing a unique black color. This is one of the features of KURO IWANAMI.

It is not a simple task to prepare the kiln. ANAGAMA pottery is usually fired continuously for 3 to 4 days, using a large amount of firewood. Mr. Sako also splits this wood by hand as much as possible. It is said that a great artisan works with passion, from the preparatory stage through to the very end.

There is another important process before firing the kiln. It is the arrangement of the pottery in the kiln. The color and pattern of each ANAGAMA ceramic is created by fire in the ANAGAMA kiln and completely depends on where it is placed in relation to the flames. The artisan must carefully consider the position, angle, and placement of each piece of pottery in the kiln. This process also shows the individuality of the artisan.

Shells are often used to add patterns on the works or adjust the burnt color. Shells are calcareous, containing high levels of calcium carbonate, so that they react to fire and create beautiful and intense color. The bottom of KURO IWANAMI reveals a unique shell pattern. The patterns were created by placing the work on AKAGAI sea shells.

Please compare the three KURO IWANAMI bowls. Some patterns are delicate and graceful, others bold and powerful. Controlling all these patterns is very difficult, even for a skilled artisan.

Such coincidences and the artist's enthusiasm combine beautifully to produce a magnificent Matcha bowl.


Pay close attention to the placement of the shells.

Matcha bowls waiting to be fired


ANAGAMA Firing Method

ANAGAMA is an ancestor of the climbing kiln, a traditional style of kiln built on an upward incline. ANAGAMA pottery was first produced in the middle ages in Japan. It was developed mainly in the Shigaraki region because Shigaraki not only produced large amounts of good clay for pottery but also was located near the Capital of Kyoto. ANAGAMA pottery is characterized by natural fiery scarlet glaze of firewood ash origin. Matcha bowls fired in the ANAGAMA kiln have been loved by successive tea masters. Today ANAGAMA pottery is known as the traditional art of the combination of earth and fire.


This is Mr. Sako's ANAGAMA kiln.




Chopping wood is also important.


The Artisan, Mr. Yoshihiro Sako

Yoshihiro Sako was born in Nara in 1971. He graduated from Ishikawa Kutaniyaki Technical Training Institute in 1995 after studying and making under Seimei Tsuji. In 2000, he established his own place of craft in Shigaraki, Shiga prefecture, and in 2010, he established a traditional ANAGAMA kiln. These three Matcha bowls were also produced from this ANAGAMA kiln. He is an up-and-coming ceramic artisan who expresses the grandeur of nature and its history in his pottery.


Apparently she is hungry.

Great smile from a great artisan.


KURO IWANAMI Matcha Bowls: Now Available!

KURO IWANAMI means waves crashing on black rocks in Japanese. This Matcha bowl is very avant-garde, yet it is based on traditional techniques, and created uniquely by the artisan, Mr. Sako.This KURO IWANAMI Matcha bowl is a unique creation based on traditional techniques of a very high standard in molding, SHINOGI carving, and firing. It has a mysterious aura that is both very innovative and also inexplicably calming to the viewer. There is certainly a charm to this Matcha bowl that cannot be conveyed by photographs alone. Enjoy a wonderful green moment with this Matcha bowl, a perfect combination of respect for nature and craftsmanship by Mr. Sako.

[Limited] KURO IWANAMI - KUTSUGATA (handcrafted Matcha bowl)US$845.00
(Now Available)
KUTSUGATA means asymmetric Matcha bowl. The soil called ZURINKO is taken from the ancient stratum of Biwa-ko, the largest freshwater lake in Japan. It is mixed with Shigaraki red clay from Shiga Prefecture. ZURINKO is rarely used in ceramics because of its brittleness and black color, which makes it difficult to handle. By using this clay...
[Limited] KURO IWANAMI - HIRAGATA (handcrafted Matcha bowl)US$845.00
(Now Available)
HIRAGATA means flat shaped Matcha bowl. The soil called ZURINKO is taken from the ancient stratum of Biwa-ko, the largest freshwater lake in Japan. It is mixed with Shigaraki red clay from Shiga Prefecture. ZURINKO is rarely used in ceramics because of its brittleness and black color, which makes it difficult to handle. By using this clay...
[Limited] KURO IWANAMI - TSUTSUGATA (handcrafted Matcha bowl)US$845.00
(Now Available)
TSUTSUGATA means cylindrical Matcha bowl. The soil called ZURINKO is taken from the ancient stratum of Biwa-ko, the largest freshwater lake in Japan. It is mixed with Shigaraki red clay from Shiga Prefecture. ZURINKO is rarely used in ceramics because of its brittleness and black color, which makes it difficult to handle. By using this clay...