The only way to learn as a stonemason is to make mistakes - Tadahiko Nakayama (Part 2)

You just learn by making mistakes. For example, when making a cylindrical object, the thickness you need to make depends on the size and the stone. Even if it's the same Aji stone, it's different for fine grain, medium grain, and rust stone. "If the rust stone is this size, it will break if you don't leave about 10mm of it left." You can't even see the scratches on the stone, so it's all about experience.

It is an easy stone to work with. Even if you use a stonemason's tool, Aji stone works well and splits straight into pieces exactly as you intended. The chisel also makes a snapping sound, sending stones of the same size flying off. Other stones would split into unwanted pieces, but (Aji stone) has a fine grain, so if you use it well, it is easy to use the chisel and the push cutter.

If you use Aji stone, you can easily chip the thin parts of the fire box of a lantern. Therefore, I think that it is a relatively easy-to-use stone for craftsmen who make decorative items (processed items with curves or steps) or lion statues.

I watch them and think they're all good. As for me, I've only been doing it for about 30 years, so I haven't done that much. But when I reached my 40s, I started thinking, "From now on, I want to make things that I think about myself." When I make a Buddhist statue, I take it to the Buddhist statue sculptor (Izumi) Yoshiteru and show it to him and say, "I made this, what do you think?" He says, "Yes, the core is there, but you're not using the chipper properly. You need to practice a bit more" (laughs).

Stone is not easy to carve, so patience is required. Civil engineering also takes three to four years to complete a job, so of course patience is required, but civil engineering involves thousands of people from various trades. But this stonemason's work requires one person to work steadily and diligently... that also requires incredible patience. The same goes for letter engraving, Buddhist statue makers, and gravestone makers. I think I've acquired that kind of patience over the past 30 years, and I think there are many craftsmen who have the habit of working steadily, with the feeling that they "can't help it."

In my case, I started playing the erhu when I was 50, and this year marks my 16th year. I think that both stone carving and erhu carving are similar in that you can play them by yourself. If you keep at it, you can keep at it for a long time...I think this is due to the patience I have gained from carving stone.

Before the AJI PROJECT started, when I was approaching 40, I was getting less work and was thinking, "I wonder if I can do something with round objects? Is there anything that has been around since ancient times?" and that's when I came up with the idea of ​​a millstone.
Stone mills were introduced from China around 1,000 years ago during the time of Kobo Daishi, so I thought they might have roots in China. Then, at the time, my younger brother was trading with China. One day, he asked me, "The products made over there are not very good quality, so can you go and inspect them?", and I spent about a week a month traveling to various parts of China for four years.

From Dalian in the north to Fujian Province in the south. I was accompanied by an interpreter... I speak a little Chinese, so sometimes I didn't have an interpreter, but in between work, I went to old castles and other places to look at millstones and take pictures. But when I asked where I went if they had millstones, they had already been replaced with machines and the millstones had been thrown away... In one place in Fujian Province, there was a millstone embedded in the castle wall that was used to defend against Japanese pirates. When I found something like that, I wondered, "How did they make that?" and took a lot of pictures.

I studied engineering at university, so at first I was thinking about things like "What is the coefficient of friction between stones?" and "How much initial maneuvering force is needed?" using formulas. "How many kg does the upper mill weigh, and if I change the roughness coefficient of this meshing from 1 to 5, how many horsepower does it need for maneuvering force?", "If it's electric, it'll need ○W..." etc. But no matter how much I tried, it didn't work out, and in the end I came to think that it was all about experience, so from then on I just kept making and making... Looking back, I guess that's just how I played around (laughs).

When I was prototyping, I tried making an electric one, but I thought it would be the most interesting to make something traditional by hand. The first thing I made was a coffee mill. My son was doing kendo, and his teacher liked coffee, so I gave him one as a gift to thank him for taking care of him. He said it worked well, so I started making some for other people too...and then I thought, "It's not interesting to just make coffee," so I started making matcha mills...and it just kept spreading.

Before making it, I spend several days imagining it in my head... I think about the fineness of the mesh, the coarseness, the depth, the curved surface, the width, and so on, and imagine what will happen to the ground material inside the millstone. Then I start making it, and if it turns out as I expected when I actually grind it, it's OK. Of course, I had to redo it many times at first, but now I can get the powder I want in about two or three tries. That kind of work is interesting.

In the past, I've had contact with a pharmaceutical company in Okayama saying, "We want to turn this into a powder," and people asking if I could extract a specific ingredient from the fish bones sold at the Tsukiji fish market... I've had a lot of different offers from various places. I've been working on the fish bones for about 10 years, going back and forth to Tokyo. It used to cost hundreds of thousands of yen a day to throw away the fish bones, so I thought I'd try grinding them all up in a millstone. You can get about 10g of the necessary ingredients from 30kg of bones, which also contain scrap iron, silver paper, and bones.

The future is bamboo fiber. If you grind bamboo fiber and use it as a reinforcing material for composite materials, you can create a material that is stronger than steel and more environmentally friendly. I think it was 15 years ago. A professor at Doshisha University made an FRP boat using bamboo fiber. It was not inferior to fiberglass and other materials in comparison tests, and it was even stronger. When the project started, an automobile manufacturer said they wanted to make car bumpers using bamboo fiber. Gradually, it became clear that "Japanese bamboo alone is not enough," and they decided to import bamboo that grows wild in Myanmar and grows about 10m in a year and grind it up. Even now, we can grind the fiber into powder, but we don't have the technology to make bumpers yet.