The Tomioka Silk Mill: Exploring Gunma's silken history

I love silk! Don't you? It's soft, supple, shimmering, versatile...I could go on and on. As amazing as the fabric is its almost mystical origins. The strong yet lustrous threads of the humble silkworm were first discovered and woven into fabric by the Chinese more than 4,000 years ago. The Chinese closely guarded the secret of silk for nearly 3,000 years. But eventually the secret got out.

Japan is believed to have begun producing silk in the third century. For 1,500 years, silk production in Japan was literally a cottage industry. Farm wives raised the silkworms in their season and then pulled the threads from the cocoons and wove them into cloth. Thanks to the industrialization of silk production in Japan, by 1905, Japanese raw silk was 80% of the global market.

It is this industrial phenomenon that is celebrated in Japan's 18th and most recent World Heritage listing: the Tomioka Silk Mill and related sites in Gunma Prefecture. Check this out if you like fabrics and clothes, are interested in factories and industrialization, or are a history buff.

Gunma Prefecture has the distinction of having the highest incidence of car ownership in Japan. Some say that's because Gunma's topography make travelling by car a necessity. While all of the destinations in this article can be accessed by some combination of train, bus and taxi, if you plan to visit all these sites, I recommend renting a car from JR Takasaki or Maebashi stations. The sites are rather spread out, so if you're determined to see everything, expect to spend a couple of days at the task. (Don't worry, Gunma has plenty of ryokan for overnighting.)

To really appreciate the significance of Gunma's silk industry (and therefore the World Heritage sites), begin with a visit to the Nippon Silk Center in Takasaki (open 9:30-17:00 Wednesday through Monday, closed New Year; admission 200 yen). Here you can learn about the life cycle of the silkworm and the history of silk production. You can see silkworms happily munching away on mulberry leaves or, if you're lucky, spinning their cocoons. There is also a substantial collection of samples of Japanese silk of various grades. The center hosts various activities, changing from day to day. You may have a chance to try your hand at operating a loom, dying fabric or making handicrafts from cocoons.

Armed with background information from the Silk Center, you're ready to visit the World Heritage sites. There are actually four: the Tomioka Silk Mill, the Arafune Cold Storage site, the Takayama-sha Sericulture School, and the Tajima Yahei Sericulture Farm.

The Tomioka Silk Mill is the jewel in the crown (open 9:00-17:00 daily, closed New Year; admission 500 yen). It's also the most accessible, being a 15-minute walk from Joshu-Tomioka Station (if you're not traveling by car). The mill was established as part of a Meiji government-sponsored industrialization initiative. Built with the advice and assistance of French experts, it includes wonderful examples of early Western-style architecture in Japan.

The 5.5-hectare site comprises a number of 19th century buildings -- the first one completed in 1872 -- including two cocoon-drying warehouses, the silk-reeling mill, a clinic, a dormitory for women workers, dormitories for French male engineers and female instructors, and the home of Paul Brunat, the Frenchman who was the mill's original director. At present, only the east cocoon warehouse and the silk-reeling mill can actually be entered; the other buildings can only be viewed from the outside. The east cocoon warehouse holds museum displays on how silk reeling was done in the 19th century and the innovations introduced by this "modern" facility. The silk-reeling mill contains the reeling equipment that was in use to reel silk thread at the time the mill was shut down in the 1980s, as well as a video display of the mill in operation.

Did you know that a silkworm cocoon consists of a single thread 900 to 1,500 meters long? Just as interesting as the reeling equipment is the building itself, with its imported materials including large metal-framed windows to let in the maximum amount of natural light and trusses to permit construction across a wide expanse without supporting pillars in the middle of the room.

Group tours are led by volunteers periodically throughout the day in various languages. Rental headsets (also in various languages) are available or you can download multilingual explanations to your smart phone via QR code.

It is a bit disappointing that more buildings cannot be entered, but there are plans to open the west cocoon warehouse in 2015 and other buildings are being restored to eventually be opened as well. Sadly, the cocoon-drying room in the central courtyard, a wooden building from the 1920s collapsed under heavy snow in February. Now a fenced-off ruin, there are plans to rebuild it to original specifications.

Next, head out to Shimonita, to the Arafune Cold Storage (closed December to March, due to harsh weather conditions). Nestled deep in the mountains, nearly an hour's drive from the mill, this is where the eggs of silkworms were kept cold (to keep them from hatching until needed) in the days before refrigeration was available. The arrangement of boulders on the mountain naturally results in cold air blowing out from gaps in the rock, which was captured by the construction of thick stone walls topped with a building. The day I visited, the air inside the stone walls, which are no longer capped off, was about 2 degrees C. In its heyday, eggs stored here were shipped to silkworm growers all across Japan.

From Arafune, make your way to the Takayama-sha Sericulture School in Fujioka (open 9:00-14:00 daily; closed at New Year). Here, Chogoro Takayama taught various methods of raising silkworms to produce the best possible cocoons, leading to the best quality silk. Inside the 1891 farmhouse are displays on silkworm raising and explanations of the building itself. The early mechanisms for temperature regulation are particularly interesting. The oldest building on the site is the Edo period gate, which doubled as a barn/warehouse. The remnants of the stone lined cellar where mulberry leaves were stored is also interesting. While there are no regular English language tours, if you call ahead, an English-speaking volunteer guide can be arranged.

To complete your inspection tour, travel on to the final site, the Tajima Yahei Sericulture Farm in Isesaki (open 9:00-16:00 daily; closed at New Year). Notwithstanding 19th century technological improvements, the raising of silkworms and production of cocoons remained a cottage industry undertaken at farms across Japan, but especially in this area. Yahei Tajima is credited with first conceiving the two-tiered roof design for his 1863 farmhouse, now regarded as the prototype for the others you may have seen in this area.

This style of roof provided better ventilation for the silkworms as they fed and grew in the attic. While the farmhouse is still a private residence and therefore cannot be entered, on the site you can also see the "kuwaba" mulberry leaf storage barn and the well, which is unique because it has raised foundations to prevent it from being contaminated by floodwaters. Quality freshwater is an important component of raising silkworms and the farm, being near the Tone River, was once prone to flooding.

If you have limited time, visit just the Tomioka Silk Mill itself. But if you can spend a couple of days to see all of these sites, and perhaps explore Gunma's other delights as well, you won't be disappointed.

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