Japanese Metal Casting - Experiencing the Limitless Potential of Traditional Crafts in Tokyo

What Is Metal Casting?

Humanity has been working with metal since the dawn of civilization. The oldest recorded metalworking techniques consisted of melting down copper alloys such as gold, silver, bronze, and brass, which have low melting points, and then cooling and solidifying them inside shaped molds made from sand or iron. We call this “casting,” which is an umbrella term for several forms of metallurgy used to manufacture complex objects in large quantities at low cost.

The History of Metal Casting in Japan

By dating bronze mirrors, bronze swords, and other artifacts excavated in Japan, it’s estimated that Japanese metal casting technology originated during the Yayoi period, which lasted from around the 10th century BC to the mid-3rd century AD. During the Kofun period (300-592) and Asuka period (592-710), the process became more refined, and various artifacts such as containers, folk crafts, Buddhist statues, religious implements, and other objects made via metal casting began to appear around the country.

Before the Edo period (1600-1868), metal products were unable to be mass-produced in Japan, and their supply was limited. Starting from the 17th century, however, metal casting began to flourish on a much larger scale. Iwate Prefecture’s Nambu ironware and Toyama Prefecture’s Takaoka copperware, both officially designated Traditional Crafts of Japan, are two famous examples of traditional metal casting from this era that continue to be made in the modern age. Other forms of Japanese metal casting, like the crafts of Kawaguchi in Saitama Prefecture, were developed after the Meiji period (1868-1912), and are much more modern.

Fact: Japan Is Home to the World’s Largest Work of Cast Metal!

In the beginning, Japanese metal casting was mostly limited to religious items and used by lords to display power, which is why many examples of ancient metal casting are religious artifacts and statues. The Great Buddha of Todai-ji Temple in Nara Prefecture, a well-known tourist attraction in the Kansai region, is the world's largest bronze casting, standing at 14.85 meters tall and weighing 260 tons. Emperor Shomu, a devout Buddhist, commissioned the statue in order to bring peace, stability, and happiness to the people of Japan. In order to realize his goal, he asked for donations of copper, tin, gold, and mercury from Japanese citizens, and as many as 420,000 people gave what they could.

The gigantic statue took nearly 10 years to complete. First, a clay model of the Buddha was made and then cut into eight horizontal pieces, which were then used to cast the statue from the bottom up. It’s been more than 1,300 years since the completion of the Great Buddha of Nara, and so far no other metal casting work has managed to surpass it in size and scale.

The Characteristics and Difficulties of Metal Casting

Metal casting allows for a lot of freedom in terms of materials, size, and shape. No matter how complex the design, if a mold of it can be made, then it’s possible to produce unlimited copies by pouring molten metal into the mold. While molds themselves are often crafted by hand, this process saves a lot of time and labor compared to making each new piece of metal from scratch.

Many different kinds of metals can be used for casting. For example, iron is used for manhole covers and frying pans, while durable copper alloys with excellent thermal conductivity are the go-to for plumbing parts, machinery, and art pieces such as bronze statues. Then there are the lightweight aluminum alloys, which have high thermal conductivity, a beautiful appearance, and can be easily recycled, making them suitable for the manufacturing of automotive parts and more. Magnesium, titanium, and tin are also common materials.

However, metal casting also has its downsides. Getting the correct dimensions of the mold is a common issue, while thermal expansion and shrinkage can distort the shape of the final product. Bubbles may also appear if molten metal is poured into the mold too quickly, and there is a chance that it may not reach all of the edges inside. In short, it takes a considerable amount of effort and knowledge to create a perfect piece of cast metal.

Japanese Traditional Metal Casting Crafts

Modern day Japanese metal casting can be broadly divided into two categories: traditional cast metal used for utensils, art, and more, and machine cast metal for agricultural equipment, machine parts, and automobile parts.

Yamagata cast iron is one of the leading examples of the first category. It boasts a history stretching back to the late Heian period, about 1,000 years ago. It developed after soil suitable for casting was discovered around the Mamigasaki River and Chitose Park in Yamagata City. The molds used feature unique shapes and incorporate traditional techniques such as pattern pressing, “hada-uchi” (adding irregular designs to the surface of the cast), and lacquer coating. Thanks to this, Yamagata cast iron products are light, elegant, and flaunt fine textures and shapes.

Another famous example of traditional Japanese metal casting is Nambu ironware. This craft developed during the Edo period after the feudal lord of the Nambu Domain in modern-day Iwate Prefecture invited foundry workers from Kyoto to help create a local metal casting industry. The soil here is rich in iron and perfect for metal casting, which is why there are still numerous metalworking factories and workshops in Morioka and Oshu operating today. Nambu ironware products commonly include teapots and cookware, with iron kettles being the most famous. These kettles are characterized by the countless round bumps on the exterior, and their sturdiness and durability ensures they can be passed down the generations.

A more recent (just over 400 years old)metal casting craft that remains popular today is Takaoka bronze casting, made in Takaoka, Toyama Prefecture. This craft was started in the beginning of the Edo period (the early 1600's) when the feudal lord of the Kaga domain set up a workshop and invited master metal crafters from Osaka to work for him. At first, they made pots, pans, and farming tools, but gradually they began to deal in Buddhist altarware, flower vases, and metal products in general, which became known as Takaoka bronze casting. Today, there are several makers who continue the traditions while creating products suited for use in modern life. Two of those makers are Syouryu and Nousaku, whose products can even be purchased online and shipped overseas.

Trying Japanese Metal Casting For Ourselves at meta mate

“meta mate” is a store located in Nihonbashi, Tokyo, run by Hiroshima metal casting company Castem. They sell high-quality metalware including accessories, models, tableware, sake drinking sets, business card holders, and more. Alongside original Castem products, they also stock all kinds of first-rate items from across Japan. They also offer onsite engravings, making it a great place to pick up personalized gifts or souvenirs.

To spread the appeal of Japanese metal casting, meta mate also runs several hands-on metal casting workshops on the second floor of their COREDO Muromachi Terrace store. Keen to experience the craft first-hand, we joined one of these workshops to make our own small dishes and coasters. Let’s take a look at the techniques that give Japanese metal casting its unique look and charm!

STEP 1

First, we came up with our design, and drew its outline on a piece of paper to make the mold. The freedom to make a shape and design of your choosing is one of the most appealing aspects of metal casting, but we were also reminded by the staff that the more complicated the pattern, the more difficult it will be to cast, and we should stick to simple circular shapes for the best results. Despite this, the staff mentioned that many first-timers also come looking for a challenge, and there was apparently someone who crafted a metal goldfish in the previous workshop!

STEP 2

Next, we placed our paper design under a silicon mat and cut it out with a knife.

STEP 3

We then pasted the paper together with the cut-out silicon square onto a board. The paper is used to help create a three-dimensional effect, so don't throw it away. This is all you need to do to prepare your mold - the real fun begins next!

STEP 4

We next took the tin and placed it in a pot. Turning on the heat, we watched as it melted into a liquid. The boiling point of tin is low, and it will melt at about 232°C. Watching as the solid metal turned into a liquid was surprisingly hypnotic!  A thin film formed on the surface of the molten tin, which we removed with a spoon.

STEP 5

Our mold was then fixed to a board with a pre-cut hole. Once the molten tin was ready, we poured it in the hole and waited while it cooled.

STEP 6

Once the tin had hardened, we removed the board and used pliers and a file to trim the edges of our now-complete coaster. The tin was very soft, and the staff told us that if we wanted to make a dish, all we’d need to do was bend and curve the finished product.

We ended up making two cherry blossom-shaped coasters. While they may look simple, it took a lot of effort to get the position of the paper just right to achieve our desired look. It made us marvel at the skills of professional metalworkers who can control these kinds of precise details with ease. Mold-making and metal casting are incredibly intricate arts, and if I were to sum up what we'd learned, I’d say that they’re easy to start, but difficult to master. If you’re keen to learn more about Japanese metal casting and experience it firsthand, then we definitely recommend booking a metal casting workshop at meta mate!

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