Gunma’s Tomioka Silk Mill is a testament to Japan’s rapid industrialization in the latter half of the 19th century. Opened in 1872, it was Japan’s first complete industrial factory system of production and was built with the assistance of various French advisors. The mill ceased operation in 1987, but, thanks to its historical significance, it received UNESCO World Heritage listing in 2014 and many of its facilities were opened to visitors.

On October 3, 2020, the number of buildings on the mill site open for visitors increased when the West Cocoon Warehouse was opened with museum exhibits on worker life, the cocoon storage, and the construction and use of the building itself.

The West Cocoon Warehouse, along with the other two primary factory buildings, the silk reeling plant and the East Cocoon Warehouse, are built of red brick, a common construction material to the European advisors, but little-known in mid-19th century Japan. The two large warehouses were deemed necessary in order to store enough cocoons to keep the reeling plant which produced the raw silk thread operating year-round.

Some of the challenges this created for the Japanese carpenters who had to build these buildings are shown in the newly-opened West Cocoon Warehouse. The red bricks were produced in Fukushima, a village not far from Tomioka. A French engineer got several roof tile makers to produce the bricks, but there was little standardization initially, so various sizes of bricks were provided to the builders.

The builders had no idea how to make free-standing walls using bricks, so instead they built in a method that came to be known as “timber-frame brick masonry”, framing the building with wood, using familiar methods, and then filling in the frame with bricks on the outside and plastering the inside of the walls to seal the building up. Even plastering walls was an unfamiliar process for the Japanese builders, and signs of their trial and error methods can still be seen. Builders often made notes or calculations on the finished plaster walls as they worked, too.

A glass-enclosed gallery of museum exhibits on workers’ lives on the ground floor offers information about how the female mill workers lived and worked. The glass enclosure facilitates temperature control for the displays, but also allows visitors to see (but not touch) the original walls. The display of how the work clothes worn by the women evolved over the decades is especially informative.

Another exhibit provides an overview of how the silkworms were stored in the warehouse. Initially they were kept in trays on racks, similar to the ones used for raising silkworms. Later they were placed in large canvas bags holding 15 kg. each. These were easier to stack, store and move, while both permitting the cocoons to keep drying and keeping rats out.

On the upper floor of the warehouse, with its walls and floor lined with tin sheets (also to keep out rats), visitors can gain an even better perspective on how the bags of cocoons were stored.

There are also exhibits on the upper floor showing how the warehouse and other red-brick buildings of the mill were built, including a scale model with cut-aways and a reproduction of part of the roof, with its wooden shingles topped by ceramic roof tiles.

Back on the ground floor, there is a gallery of maps and photos leading toward the north end of the warehouse. These explain what happened to the raw silk reeled at the mill. From the end of the nineteenth century until the middle of the twentieth century, Japan was the world’s largest producer of raw silk. Some of the raw silk was woven into silk cloth in Japan, but most of it was exported, especially to Europe and the United States. The name “Tomioka” may well have been synonymous with raw silk in the minds of many.

The north end of the ground floor has been converted into an ultra-modern glass-enclosed event space. As with the other end of the ground floor, the glass enclosure provides a modern feel while still allowing people to see the historical features of the building. This end of the warehouse was originally much more open, as it was used to store the coal that powered the steam engine that drove the mill’s reeling equipment. Later, when electricity replaced coal, the area was enclosed using wood and large paned windows to become a workshop for the mill.

The red-brick buildings of the Tomioka Silk Mill are visually distinctive and for many Japanese may very well symbolize the modernization that took place during Japan’s Meiji period (1868-1912), just as do other red-brick buildings from the period that have survived to this day.

Access: About a 10 minute walk from Joshu-Tomioka station on the Joshin train line out of Takasaki.
Hours: Open daily, 9:00 am – 5:00 pm (last entry at 4:30 pm) (closed for New Year’s holidays)
Admission: JPY1,000 (adults); JPY250 (high school/university students); JPY150 (elementary/jr high students)

© 2020 Jigsaw-japan.com and Vicki L. Beyer
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