TOKYO -- As an endurance runner who sometimes covers long distances over several days, Yoshihiro Machida was used to getting blisters and damp, sweaty feet after a long run. If he crossed a stream or ran into a puddle, his feet would get wet and cold.
But about 10 years ago, Machida, 58, traded in his usual socks for a five-toed pair made of washi, or Japanese paper. "At first, the socks felt stiff and a little uncomfortable. It felt like walking on sand," Machida recalls. But, he adds, "I didn't get blisters, even after running for days."
Compared with his regular running socks, the washi socks, made by Japan's ITOI LSR under the brand ITOITEX, were also lighter and dried more quickly.
With washi clothes, all you need to do is take them off and leave them for a few hours, and -- miraculously -- "the odor is gone," Machida says, adding that his washi undershirt also keeps him odor-free, even after a 30-hour run in Japan's hot, humid summer.
Lightweight and thin, yet strong, absorbent and durable, washi is attracting growing attention as a sustainable and eco-friendly alternative to both natural and synthetic fibers. In Japan, the fabric is used mainly for household products, from shoji (sliding partition doors and screens) to lanterns and umbrellas.
Garments known as kamiko, which means paper clothes, were worn by samurai, merchants and Buddhist monks for centuries. To this day, the monks of Todaiji Temple in Nara, a former Imperial capital in the Kansai region, wear kamiko paper robes during the Shuni-e ceremony held in early March, a tradition that goes back 1,200 years.
But it was only two decades ago that advances in technology and growing demand for sustainable garments rekindled efforts to use washi in everyday clothes and other products, says Hiroshi Yamauchi, a member of the board of Oji Fiber, which makes OJO+ washi yarn. Now, makers of outdoor wear and even fashion houses are increasingly turning their attention to washi as a sustainable and functional material for products ranging from underwear and jeans to towels and even shoes.
Washi has been used by Japanese fashion designer Issey Miyake as well as Tod's, the Italian high-fashion brand, which used ITOITEX's washi in 2018 inside its driver's shoes. Wildling, a German shoe company, makes 100,000 pairs of ITOITEX washi shoes a year at its factory in Portugal, while Underson Underson and SASAWASHI of Japan make a range of washi products from underwear and shirts to towels and stuffed animal toys.
Washi has a wide range of features that make it ideal, particularly for products that are used in contact with human skin, says Daizo Kubota, director of ITOI LSR. For one thing, washi naturally absorbs moisture, pollutants, bacteria, odors, and even ultraviolet rays.
Like charcoal, which also comes from trees and plants, washi has tiny pores where trillions of microbes live. There is data showing that these microbes absorb moisture, pollutants, odors and other matter from the air, but the mechanism behind this activity is still a mystery, says Yamauchi.
Washi is also said to absorb about twice as much water as cotton and also releases moisture quickly because of its many tiny pores. Consequently, socks and apparel made of washi dry very fast, making it ideal for sports and outdoors wear. Washi also feels comfortable to the skin because it minimizes friction, which leads to pilling.
For all these reasons, as many runners have found, wearing washi socks keeps feet relatively clean and sweat-free even after trekking long distances.
Washi is also a good material for shoes because it is light and breathable, so feet do not get warm and clammy, according to Anna Yona, CEO and founder of Wildling.
Because washi releases moisture quickly, even if you walk into water, shoes made of washi will dry rapidly and its deodorizing power will keep the shoes odor-free, says Yona, who describes wearing washi shoes as feeling "close to being barefoot." At the same time, washi has low thermal conductivity, which means that in cooler climates, it retains the body's warmth.
Since it is made from trees and other plants, washi is biodegradable, making it an attractive material at a time when sustainability has become critical to protect the environment. In a test by Oji Fiber, OJO+ washi yarn buried in soil with 33% moisture and kept at 30 C started to biodegrade after nine days, whereas polyester thread remained unchanged.
The main source of washi used by clothing manufacturers is the abaca, closely related to the banana plant, which is native to the Philippines and also known as Manila hemp. Abaca, also grown in Indonesia and Ecuador, matures in three years and is increasingly replacing traditional washi sources such as kozo, a deciduous mulberry shrub and mitsumata, the oriental paper bush, due to declining supplies.
Despite its many advantages, however, wider use of wearable washi still faces considerable hurdles.
In Japan, washi fabric costs five to six times as much as cotton imported from China and Southeast Asia. Producing washi is also labor-intensive and time-consuming, and requires a high level of technical expertise. After the abaca plant is cut down, it is stripped of its tough fiber, which is then decomposed to produce pulp. The pulp is then processed into very thin sheets of paper, which are slit into thin tapes.
"This takes time and effort because the washi sheet is very thin and if you cut it too fast, it might tear and the whole machine has to be stopped," says Yamauchi. The washi tape is then twisted into yarn, which is used to make fabric.
Because of the complex production process, products made from washi have long been restricted to the realm of crafts, says Kubota, who adds that industrialization is the key to making washi more accessible as a source for clothing and other wearable products.
Another drawback is that washi is not as strong as leather nor as soft as many synthetic fabrics. The fabric is durable and can be washed thousands of times, but it needs additional strength for use in shoes, so ITOI LSR weaves polyester into the sides of the shoes where the feet do no touch. Osaka-based Montbell, which makes outdoor products, uses washi as the weft and cotton as the warp for its KAMIKO brand fabric, which is used to make jeans that look like denim but are cooler in summer.
These compromises are helping to make the use of washi increasingly popular with both manufacturers and consumers. Still, says Kubota, the holy grail is to use the fabric in the most natural form possible so that wearing it "will let us live as if we were forest bathing."