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Uniqlo’s Really, Really Warm Textile Revolution

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The company’s HEATTECH fabric challenges common sense.

Some 15 years ago, we had cold-weather clothing all wrong. We were convinced that in order to face brisk temperatures, freezing winds, and blizzards, we needed to pile on layer after layer of bulky garments: a warm shirt, a sweater, a coat, a scarf, and maybe a second sweater in case the temperature really took a nosedive. We’d wobble our expanded silhouette through the door into the tundra, resigned to the fact that volume, quantity, and static were inevitable features of our winter wardrobe.

But in 2003, thanks to a partnership between Uniqlo and Toray Industries, Inc., a team of engineers, designers, and textile experts in a Japanese R&D lab finally lifted the weight off of us. They cracked the magic formula for a clothing revolution and they called it HEATTECH. The principle was simple: as Masahiko Nakasuji, Co-Chief Marketing Officer of Uniqlo puts it, “The Uniqlo and Toray project team started with the goal of developing a thin, yet warm inner layer that would improve people's lives in the winter.” But figuring out the details was a bit more complicated. How could you encapsulate warmth in a lean piece of textile? Where would you put it?

The genius of HEATTECH is that it works naturally with your body to create warmth, and then stores it. Imagine a tiny water molecule moving across a surface. That movement results in kinetic energy, which turns into thermal energy. Voilà, you’re warm. And that warmth doesn’t need to be stored in a thick wool layer, because Toray Industries developed a micro-acrylic fiber thinner than a human hair that performs as well as a thicker fabric. When it’s created, this fiber is spun, resulting in air pockets that can trap heat. (Bonus: Those air pockets don’t weigh anything.)

How it works: Rayon wicks moisture away from the body and converts it into heat. Air pockets in ultra-thin microfibers trap the head and retain it.

The concept behind HEATTECH—“less is more” and “less is warmer”—reflects the minimalism that characterizes many aspects of Japanese culture. The textile also epitomizes Uniqlo’s innovative approach to design. As Hajime Ishii, Director and General Manager, Global SCM Division, Toray Industries, explains, “Our culture often assumes the approach of ‘pursuing the ultimate’. Our Japanese roots inspire our focus on long-term development, not just short-term gains.” And so throughout the process of perfecting HEATTECH, there have been many iterations. To test them, Toray and Uniqlo make good use of their R&D lab. When it comes to checking the actual warmth of apparel, for example, they give garments a test drive: “To begin [the process], we set our goals for HEATTECH's key functions: heat adsorption and heat retention,” explains Ishii. “From there, Toray leverages a special laboratory, a climate chamber, so that we can test the items in various climate conditions to ensure efficacy

Toray added a lot to make the HEATTECH textile ideal for winter wear, including argan oil for extra softness; anti-odor technology to absorb and neutralize bad smells; a way to combat static through moisture retention; extra elasticity to ensure garments retain their shape; and a quick-dry component to maintain freshness. Yes, all this is happening in one piece of clothing.

While scientific innovation is the main selling point of the HEATTECH line, aesthetic and design are also vital to Uniqlo’s formula. “We develop the essential products, and constantly improve them by not only reflecting sophisticated design, but also adding functions that make people feel more comfortable, offer them a more convenient lifestyle, and protect them from climate changes,” says Nakasuji. Achieving this has meant facing obstacles throughout the years. One of these hurdles, according to Ishii, was the treatment of the different fibers that make up the textile. “For HEATTECH we use four types of fibers: acrylic, rayon, polyester, and polyurethane. One of the biggest challenges was to dye these distinct fibers in a uniform fashion,” he explains. Each fiber would absorb the dye differently, resulting in an uneven color. Nonetheless, if you check the color palettes that Uniqlo offers, it’s clear that the dye dilemma has been solved.

HEATTECH uses lightweight materials to keep you warm without weighing you down.

In their commitment to constant improvement, Uniqlo has brought their innerwear revolution to the outerwear realm: they now offer HEATTECH gloves, jeans, pants, fleece tops, socks, and hats. As Uniqlo and Toray continue to pursue new technologies for clothing, they don’t limit their explorations to the lab. Several of their innovations have been based on customer feedback. So if you’re pondering how your winter coat could help you run errands more efficiently, or you have ideas about how to turn your sweater into an anti-flu shield, write to them. As Nakasuji puts it: “We welcome any ideas to develop better products with customers because what we create is for our customers.” So you’re in charge: The winter revolution will be customized. 

Astrid Harders is a writer and editor based in Brooklyn.