Unveiling the Artistry of Japanese Denim: From Kojima to Your Closet

Written by Tirsa Parrish

Stepping into your favorite pair of jeans - what could be better? Denim jeans are ubiquitous in the US, and thanks to brands like Levi Strauss, they are popular around the world. Japanese denim is a special subset of this heritage material that is relatively new, highly prized, and often sold at a luxury price. Transitioning the hard-working cotton-based material from durable pants created for the iconic American cowboy and Rebel Without A Cause culture in the US to a couture aesthetic for those with a millionaire lifestyle began in the small city of Kojima. 

Denim Takes Japan By Storm

Kojima, Japan is considered the birthplace of Japanese denim and is now home to about 40 denim makers. While denim from this city has found a luxury category to call its own, the burgeoning denim industry gained its prominence relatively recently in Kojimag. Japanese people became obsessed with everything American around the time of the 1964 Tokyo Olympics. Movies, music, and of course fashion, became free and unrestrained with the student movement of the times. In the ensuing decades, Japanese denim has reached far outside Japan. Today, it’s considered one of the finest types of denim in the world.

The Japanese denim industry approaches the sturdy material as artisans creating unique and valuable art rather than just a workwear staple. It takes one to two months to dye threads a deep indigo blue. Denim made from these threads will maintain this rich color because natural indigo is used instead of the synthetic dyes most jeans are made with today. A pair of Momotaro jeans dyed with natural indigo can cost over $2,000! But using real indigo is just one facet that makes Japanese denim unique and expensive.

Image via shaftjeans.it

The Craftsmanship Behind Japanese Denim

Each stage of production requires meticulous attention. In the most basic sense, Japanese denim refers to denim made in Japan. In today’s market, however, it often implies selvedge denim. The name comes from the way fabric is woven on shuttle looms. They weave fabric with a sealed or self-finished edge. Hence the name self-edge/selvedge. It means the end of the fabric won’t fray or unravel. You can distinguish a pair of selvedge jeans by turning up the hem. There is typically a colored line along the outseam seam allowance. Usually, this is made from a red thread, but green, white, brown, and yellow are also sometimes used. 

 Before the denim is made, however, the threads have to be dyed. The most expensive jeans come from thread that is hand-dyed with natural indigo. Indigo comes from the leaves of the indigofera plant that is part of the pea family. Dyeing fabric with natural indigo has been a valued art form in Japan for centuries.

 A skilled tradesman dyes 60 rolls of cotton over several days. Each roll is wrung out and hung up to dry before beginning the next stage. Each roll is dyed a total of approximately 30 times to achieve the desired dark blue.

Understanding the Price Tag

A kilogram of some synthetic indigo can cost $4-5. Depending on the quality, natural indigo might cost ten times as much. One bale of natural indigo cost nearly $1200 and is only enough to dye 15 pairs of jeans. Although using natural dye raises the cost of production, it has unique effects on jeans that cannot be produced using synthetic dyes. Natural indigo doesn’t just contain blue tones. There are slight amounts of other colors like yellow that subtly change the dominant blue tones when viewed from certain angles. This effect cannot be reproduced with synthetic indigo dyes.

Today, cheaper synthetic dyes have mostly replaced the more expensive natural ones. This means jeans made with natural dyes are considered a premium product. This helps explain why Momotaro’s Kinton or gold label jeans garner more than $2,000. The time and money needed to dye the threads by hand to produce the exact desired color is part of the value of these exclusive jeans. The natural indigo and individual dyeing processes used means Japanese denim products all fade in a unique and often prized way

Not all Japanese denim is made with natural indigo. Even so, the price remains high because of the way Japanese denim is woven. Before Toyota made cars, they made fabric looms under Toyoda Automatic Loom Works (yes, with a “d”). Originally introduced in the 1920s, the Toyoda shuttle looms are no longer made. Weaving with these looms takes 5 times longer than weaving on modern projectile looms. 

Toyoda loom, Image via heddels.com

Kojima:Historic Home of Japanese Denim Manufacturing

Kojima district, located in Okayama Prefecture, Japan, had always been a hotbed for textile production. Thus, it only made sense to produce the first pair of jeans in Kojima at Kurabo Mills, one of the world's longest-operating mills, now running over 130 years. These jeans were made on Toyoda machines from American-made denim in April 1965 under the Canton Brand by Maruo Clothing. In 1967, BIG JOHN jeans were produced alongside Canton jeans and were made of denim from Cone Mills. The same mill provided Levi's with their unmistakable denim. While the jeans were successful, the Japanese still craved a pair made from their own Japanese selvedge denim. 

Originally, these shuttle looms were the only way to produce denim in the world, and it was all made in the United States. These looms were hand-operated and therefore designed to be only used at an arms’ length in any direction. They were created with a maximum of 36-inch width. A century later, people paid millions of yen for vintage jeans from 1900-1920s.

Today the looms are automated, however, an experienced technician has to keep a close eye on them as they run. They check to see that each loom is working smoothly and that the threads are all correctly aligned. When a machine goes down parts from old machines are used to get the machine back up and running.

As well as weaving relatively slowly, the looms produce fabric less than a yard wide. That’s about half the width of non-selvedge denim so producers need more fabric to make a pair of selvedge jeans. This is yet another factor that increases the cost of production, and ultimately, the cost of the finished jeans. Shuttle looms are less precise than projectile looms. Variations in the fabric make each yard unique. Ironically, that’s what gives these jeans one of their biggest appeal. While most other jeans have a smooth surface, Japanese denim is a little bit rougher. Many consider this unevenness the most important aspect of this denim. It is reflected in the vertical fading of the denim as it ages.

While most Japanese denim jeans are made on automated looms, the most expensive jeans are made with an even slower, more traditional method. These are made by hand with an antique loom. It takes an experienced weaver one hour to weave just 10 cm (4 inches) of fabric. The extra effort gives the jeans a distinctly different feel. Regular denim feels a little stiff or starchy. Those that are handwoven are soft from the start and customers can feel the difference the first time they try on a pair of hand-woven jeans.

For denim enthusiasts, traveling hundreds or thousands of miles to Tokyo is worth the trip to buy their most sought-after pair of jeans. After the fabric is woven by hand or shuttle loom, it heads to cutting and on to sewing. According to Heddles, most other types of denim weigh between 11 and 14 ounces, while most Japanese denim weighs 20 ounces. A heavier fabric makes the sewers’ job more challenging. The thickest thread used is No. 0, almost as thick as kite string. It is very difficult to use. Even with years of experience, there are some parts of the jeans construction that sewers still find challenging. 

Image via japan.travel

Behind The Seams

Another cornerstone of Japanese denim is the artisan nature of the way the jeans are finally formed. At many companies, all the stitching is done by hand. The same is true for trim like the copper rivets. The final look and feel of a finished pair largely depend on the sewer’s dedication to detail. As shuttle looms are less precise, the fabric will naturally have several imperfections. But if retail stores find anything wrong with a pair of jeans, they mark it with a small sticker and send it back to the quality control room. Craftsmen sift through the flagged jeans using a tweezer to repair each marked spot. 

Not all Japanese denim is made to such exacting standards, however. As with all products, there are a range of qualities and price points based on the methods used to create the material. Post-weaving processing, or lack thereof, gives more character to the denim. Sanforization is the process by which a fabric is ’preshrunk’ to limit shrinkage after purchase. Sanforized denim generally lasts longer than unsanforized. Denim that has undergone this process, however, fades in a much softer manner, and the coveted high contrast fading doesn’t come as readily to sanforized denim. Sanforized fabrics are also softer and smoother than unsanforized when new. Aficionados looking for the characteristic roughness from shuttle woven Japanese denim won’t get the expected feel from sanforized jeans. There are additional processes that are generally used to produce a smoother finished fabric such as singeing, calendaring, or mercerization. The higher-end Japanese denim manufacturers forgo most or all of these processes so their customers get the look and feel they expect from their product.

Denim jeans have been used as statement pieces for decades and the material has been trendy in many forms. Currently, nearly any form of denim is popular - from a maxi skirt, flared jeans, or a head-to-toe denim ensemble. The unique qualities found in Japanese denim are highlighted when the selvedge material is made into high-end jeans. We would never suggest traveling to Japan to buy jeans is practical, but many brands are available online or in North American and European stores. Check your sources and add this product to your wardrobe!