Inside the Workshop: A Japanese Denim Weaver

In Kojima, Okayama Prefecture, vintage Toyoda shuttle looms from the 1950s weave selvedge denim at roughly fifteen metres per hour, a fraction of modern projectile looms. The resulting fabric is denser, more irregular, and more characterful, making Japan the world's most revered source of premium denim.

Japan's denim obsession began in the 1960s with American military surplus. By the 1980s, Japanese manufacturers were surpassing American denim, seeking out original shuttle looms that U.S. mills had discarded and mastering dyeing techniques American producers had abandoned for efficiency.

The mills are worth knowing by name, since they and not the brands determine what you are buying. Kaihara in Hiroshima supplies denim to Levi's alongside its own lines; Kuroki, Nihon Menpu and Collect, the Kojima mill behind Momotaro and Japan Blue, weave much of what reaches Europe under other labels. Big John, also of Kojima, produced the first jeans made entirely in Japan in the mid-1960s, and the town now signposts a Jeans Street for visitors.

The indigo dyeing process involves repeated immersion of yarn in indigo vats. Each dip adds a layer of colour to the yarn's surface, leaving the core white. This rope-dyeing method creates the characteristic fading patterns enthusiasts prize: indigo wearing away to reveal white beneath in patterns unique to the wearer.

Selvedge, the self-finished edge created by the shuttle's passage, prevents fraying and indicates slower production. The coloured threads woven into the selvedge edge, visible when jeans are cuffed, have become signatures of individual mills and brands.

The weaving requires constant attention. Shuttle looms are temperamental machines that break threads and jam. A single weaver tends no more than four or five looms, compared to the dozens a modern operator oversees. This limitation is the source of the fabric's quality: slow production creates variations that give denim life.

Japanese denim culture extends to an almost philosophical approach to wear. The concept of aging raw denim without washing, allowing it to mould to the body, reflects a wabi-sabi aesthetic of finding beauty in imperfection and the passage of time.

The folklore about never washing is the category's most expensive error. Grit and salt work as an abrasive against the yarn at the knee and the crotch, which is exactly where a pair fails first. A cold wash inside out every couple of months and a flat dry costs almost nothing in fade and adds years of wear. Weight is the other trap: twelve to fifteen ounces is the workable range for daily use, and the twenty-one-ounce fabrics are an endurance test rather than an upgrade.

Price stops buying better cloth at around two hundred pounds. Entry lines from the mills' own labels sit near a hundred and fifty and come off the same looms as jeans at four times the money; beyond that you are paying for hand-detailing, short runs and occasionally natural rather than synthetic indigo. Have them hemmed on a Union Special 43200G chain-stitch machine if the shop keeps one: that stitch is why old jeans fade in a rope pattern along the hem, and no modern lockstitch reproduces it.

Visit https://www.okayama-denim.com for a guide to Japanese producers. A pair of jeans woven on these vintage looms is a collaboration between machine, weaver's attention, and the body and life of the person who wears them.