Seto City in Aichi Prefecture is a pottery production center with a history of over 1,000 years.
The reason for this is that the best clay for pottery, called "Gairome," can be extracted here.
Why is frog eye suitable for pottery?
Its main feature is its plasticity, which allows it to retain its shape like a shape-memory alloy, making it very easy to throw on a potter's wheel. It turns pure white when fired and is highly fire-resistant. If it is refined and the clay content is mixed with feldspar and silica, it can even be used to make porcelain clay.
It is truly a clay that was born for pottery. Thanks to this clay, pottery has been produced in Seto for over a thousand years. However, frogeye is a natural resource that is dug from the mountains, and as it is dug up, it disappears.
I would like more people to know about this.
We spoke to people involved in the ceramic raw materials industry and potteries who work with clay in Seto.
*If you would like to know more about frog eyes, please click here .
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This time we will introduce Maruishi Ceramic Materials, a ceramic raw materials company that has been in business since 1874 (Meiji 7). Using wood-bush clay, which has long been treasured in Seto alongside frogeye, as a base, the company blends various ingredients and was one of the first in Seto to develop clay for porcelain .
We had the opportunity to meet with the sixth generation owner, Yuichi Kato, and division manager Shingo Kato to show us the clay production process and to hear about their approach to clay and the future of Seto ware .
Maruishi Ceramic Materials, which originated from a porcelain factory
Shingo Kato (left), division manager of Maruishi Ceramic Materials, and Yuichi Kato, the sixth generation owner (right).
Maruishi Ceramic Raw Materials was founded in 1874 by the founder, Sekibei Kato, as Maruishi Pottery, which produced porcelain tableware known as "stoneware."
"I think Sekibei was born at the end of the Edo period, and at the time pottery was the main business. They were moving on to porcelain, so I think they wanted their eldest son, Sekibei, to take on the new style of earthenware. That's probably why the character for stone is in his name."
and the sixth generation, Yuichi Kato.
"Sekibei was apparently a very earnest person, who worked hard at manufacturing and was good at accounting, so the company grew during the second generation. However, by the third generation, he was no longer enthusiastic about the family business and instead went into managing tenement houses, which would be considered real estate investment today.
Apparently he didn't get along well with my grandfather, Takafuku Kato, the fourth generation, and he told him not to make things. A major factor was the Showa Financial Depression that occurred in 1927, when no products were sold for a year. The footsteps of war were fast approaching, and even if they worked hard to make things, they would be confiscated. That seems to have happened."
Around 1950, shortly after the factory was built. Takafuku is in the upper left.
However, Takafuku was very dexterous and good at making things. During the war, he was awarded for designing the Type 99 carrier-based bomber, which was made before the Zero fighter , and he excelled at machines and design.
After the war, he took over the family business, but at the time, many people worked at the pottery, and his job as a master was to manage them all. However, he was not good at it.
"If you can get good at machines, you can start a raw materials business. So, my grandfather started a raw materials business in 1947."
Since then, the company has changed its name to "Maruishi Ceramic Materials" and has expanded from a ceramics factory to producing clay for porcelain. It was originally one of the first pottery manufacturers in Seto to develop porcelain clay, and had a sales network overseas, including to the Korean Peninsula. Takafuku's passion and knowledge for craftsmanship helped the company get on track.
How can you make porcelain clay?
But how on earth did they make the clay for porcelain?
It is said that pottery is made from earth and porcelain is made from stone, and pottery stone is used in porcelain vessels such as Arita ware.
Unfortunately, there is no pottery stone in Seto.
When I asked him such a simple question, Yuichi became my clay teacher and taught me many things.
"Let me start by explaining how clay is generated on Earth. Magma is a high-temperature, liquid substance formed when rock melts deep underground . Magma doesn't erupt easily. It pushes up inside the mountain and solidifies inside before erupting. When this magma comes out on the surface in pieces, it becomes granite. When this granite falls and weathers, feldspar is formed. This feldspar weathers further, flows, and accumulates to become clay.
Once it flows into the sea, it can't be caught. However, in the Seto and Mino areas, it was able to stay thanks to Lake Tokai, which is six times the size of Lake Biwa. Clay was created through the workings of the Earth. The fact that clay is produced means that most of the raw materials needed for pottery are naturally gathered near the mountains.
These ingredients are miraculous products that have taken millions of years to form.
High-quality materials can be mined near the Seto Inland Sea. Unfortunately, however, pottery stone could not be mined there. So, by blending the raw materials found in the surrounding area, they created porcelain clay, and began selling the finished porcelain clay as a "product," which became Maruishi Ceramic Raw Materials.
The clay making process
This is the original soil as it was extracted from the mine.
"Can you turn the potter's wheel like this? No, you can't. First, you need to remove impurities through a process called elutriation."
From here, we were guided by Shingo, who is in charge of the factory.
"First, we melt the raw clay. We put the clay in a large hopper and loosen it to some extent."
"At the raw clay stage, it contains clay, sand, etc. and cannot be used as is. We use a large sieve to remove lignite, wood chips and other debris.”
The clay in the frog eyes acts like a shape memory device, and just adding a small amount makes it much easier to shape.
In the classifier, the raw soil dissolved in water is sucked up by an agitator through a pipe on the left side, and as it rotates, silica sand is discharged along the way.
"The way it works is that if you pour water mixed with sand into a bucket, the sand will sink and the water will overflow. The water contains clay. The sand is used as silica sand, a raw material for glass."
The silica sand is sorted by the classifier and discharged.
The accumulated waste is used as a raw material for mixing clay.
After the silica sand is discharged, the kira is also discharged, which is not often used.
From the mixer, the sand and dirt have been removed, and only the raw clay that has been dissolved in water goes to the next process. Muddy water flows from the central pipe.
Mix ingredients other than frog eye clay and mix
This is a wet grinding machine called a "ball mill" that mixes raw materials.
This is "Seto feldspar," which has the power to melt when fired . It is a raw material rich in feldspar, mined in Obara Town, Toyota City, and washed in Seto.
This is kaolin, which turns clay white. Unfortunately, it is a raw material that cannot be found in Japan. Kaolin is a clay whose main component is a mineral called kaolinite. It was excavated from a place called Kaoling near Jingdezhen, China's largest ceramics production area, and is said to have gotten its name from its long history of use.
We source our products from China, New Zealand, Germany, etc. It has a high fire resistance and low iron content, so it bakes to a pure white color.
This is Amakusa pottery stone.
The mixed clay is sucked up by a machine called a diaphragm pump and then sent to a filter press, which squeezes out excess water.
A filter press squeezes the clay. Once squeezed, the product is complete. Maruishi Ceramic Materials produces about 10 types of clay. These are widely used by pottery classes, pottery-related schools, kilns, and potters across the country.
Dealing with raw materials
Maruishi Ceramic Materials began purchasing kaolin from various countries around 1970. This was earlier than I had imagined, which is quite surprising.
"We were dealing with natural resources, so we had to maintain quality. Even back then, we had a quality control facility called a laboratory, and a small kiln, where we tested colors and developed the ware. However, it seems that they were afraid that if they used raw materials from overseas, it wouldn't be Seto ware, so they kept quiet at first."
About 30 years ago, when Yuichi was in junior high school, it was a time when raw materials were imported and production was moving overseas. He hated being asked about the family business by his teachers in class.
"When asked, 'Yuichi, where do you get the raw materials for this pottery?' one boy hesitated about whether to say that the raw materials were imported from overseas. He didn't know how it would affect his father's work."
However, Yuichi says that this is also an "old story."
As time passed, clay suitable for pottery became harder to find in production areas across the country, and the question of where the raw materials came from became less important within the industry, and the type of pottery came to be determined by the place where the finished product was made.
When soil turns into clay, it is difficult to tell what is inside just by looking at it.
Therefore, unlike food ingredients such as rice and vegetables, it may be difficult to attract attention to the question of "where it was grown."
The future of Seto ware
The natural resources of the pottery-making industry are becoming scarce. What does Shingo , the division manager who deals with raw materials every day , think about this?
"Because it's a natural ingredient, it's not something that's available indefinitely. However, we believe we can overcome this through development. We will update the composition of the ingredients themselves and try to maintain the quality as much as possible. So, I don't think there's any need to worry about it disappearing completely.
However, I think we all need to face this issue head on and share accurate information."
And here's a story that may be a bit painful to hear.
"Seto is known as a pottery town, but unfortunately, in reality it is not a town that exists solely for pottery. I think we need to be more aware of this."
When asked, "What kind of town is Seto?", the answer is naturally "pottery town." It has a long history as a production area, and the culture remains, of course. However, the reality is that the industry is in a tough situation when looking at shipping volume.
Yuichi talks about the company's future direction:
"As our roots, we will continue to make porcelain clay as long as we can secure a stable supply. I think that ultimately it will be traditional industries like tableware and dolls that will survive. Those that use up this much factory space and are profitable. The ones that are surviving now are companies that have shifted to clay-based ceramics that are different from what is commonly called Seto ware..."
As I listened to the story,
"They look sad after all! I understand that they want traditional industries to continue."
He pointed this out to me bluntly, and I was taken aback.
I'm sure that unconsciously, my selfish wish that the company would remain one that makes clay for Seto ware was reflected on my face.
However, as a business, if the scale of production does not increase to a certain extent, the factory will not be able to survive and will go bankrupt. Many of the ceramics factories in Seto are built on vast premises to meet the demands of post-war mass production, and at a glance, it is clear that the business will not survive unless large quantities are produced.
If we don't produce a large amount of clay, we won't be able to offer it at an affordable price.
"Traditional crafts are something that should be cherished and preserved, not something that can be used to make a lot of money."
That's what Yuichi says.
Maruishi Ceramic Materials also has a factory in Toyota City, and using its clay-making know-how as an extension, it produces environmental ceramic products in which food waste is sprinkled with soil and then placed in soil to promote soil formation, as well as a contract crushing business that crushes recyclable materials such as eggshells and roof tiles.As times change and what is needed changes, the company continues to sell clay for Seto ware.
"The reason I am determined to continue making clay is because the high level of skill that has been built up in the production areas will be lost. I believe that this know-how must be preserved even if it means merging or being acquired."
Approximately 150 years ago, Maruishi Ceramic Materials was at the forefront of exploring how porcelain clay could be made from raw materials found in Seto, and even now they continue to move forward while thinking about the future. I felt their strong desire to pass on their techniques.
[Listening to the Voice of the Soil: Introduction to the Series]
Part 1: From raw soil to clay. [Listening to the voice of the soil. Column on the Kasen Mine]
Part 2: "I want to leave the soil for future generations" [Listening to the voice of the soil: Column on Seto Hongyo Kiln]
Part 3: Craftsmanship is about understanding the materials. [Listening to the voice of the clay. Column by "Sakusuke Kiln" Part 4: What happens when you fire clay? [Listening to the voice of the clay. Column by "Miyama Pottery Studio"]
Part 5: In search of the beauty of white and blue. [Listening to the voice of the soil: Shin Kiln Column]
Part 6: Don't turn it into industrial waste. Think about recycling soil. [Listen to the voice of the soil. "Soujuen" column]
Part 7: What kind of clay is used in ceramic dolls? [Listening to the voice of the soil. Column compiled by Seto Tougeisha]
Part 8: Are the raw materials for pottery and glass harvested from the same mountain? [Listening to the voice of the soil: A column from "Jinya Marusen Ceramic Raw Materials"]
Part 9: Clay making by a long-established clay company founded about 150 years ago [Listening to the voice of the soil. Column on "Maruishi Ceramic Raw Materials"]
