SIERRA DESIGNS: Supported by the Brand's Iconic "60/40 Cloth"

In 1968, SIERRA DESIGNS developed "60/40 cloth." Combining 60% cotton and 40% nylon, this fabric continues to be beloved by many fans as an iconic material representing the brand, even more than half a century after its inception.

Even as new high-performance materials emerge one after another, the structure of 60/40 cloth—which keeps out wind and rain by capitalizing on the properties of its natural fibers—still exudes a unique presence today. Another charm that cannot be measured by numbers alone is how its texture deepens the longer it is worn.

We spoke with Kento Ariga of Ariga International Co., Ltd. about the background behind the birth of 60/40 cloth and the craftsmanship of SIERRA DESIGNS, which continues to evolve with the times.

A Brand Philosophy Born from a Distressing Experience

California, USA, 1965. SIERRA DESIGNS, which would later become a giant among outdoor brands, was brought to life by two young men. Founders Bob Swanson and George Marks originally worked at an outdoor shop in California called The Ski Hut, sharing a passion for creating gear with their own hands that people could truly rely on.

The direct catalyst for establishing the brand is said to be a maritime distress incident. This grueling experience instilled a steadfast philosophy into their craftsmanship: "reliability to entrust one's life to." The two already had a strong desire to create things they themselves could truly use, and the incident at sea solidified the brand's direction.

From the beginning, they crafted not only apparel but also outdoor gear like tents and sleeping bags. At its peak, the company grew into a comprehensive outdoor brand, offering around 30 tent models in a single season.

Even today, their US product lineup features a wide variety of gear, carrying on these roots. At its core is the unwavering philosophy born from the founders' experiences in harsh nature: "to create tools that protect lives."

A Material That Changed Outdoor History

The product symbolizing the brand's philosophy was created in 1968, three years after its founding: the development of "60/40 cloth," which became synonymous with the brand. At the time, while waterproof materials existed, most of them blocked moisture and air completely. Consequently, they faced a major drawback: wearing them trapped sweat and made the wearer stuffy.

Working together with a fabric manufacturer, SIERRA DESIGNS came up with an innovative answer to this problem: 60/40 cloth, which uses cotton for the weft and nylon for the warp. The greatest feature of this fabric is that its properties change depending on the weather.

When cotton absorbs moisture from rain, the threads swell, tightening the weave of the fabric and physically blocking water from entering. On the other hand, when dry, it maintains comfortable breathability, preventing stuffiness. This mechanism, which operates without membrane films, was a groundbreaking invention at the time.

In the late 1960s—before the emergence of membrane materials like Gore-Tex—60/40 cloth was a true "high-tech material" that balanced the opposing properties of water resistance and breathability. This invention propelled the history of outdoor wear forward significantly.

The Origin of the Mountain Parka

Designed to maximize the performance of 60/40 cloth was the "Mountain Parka." Although 60/40 cloth is now used in various items, the Mountain Parka was the very first product to feature it. It is truly a soul-infused product born from the seamless union of material and design.

Its details have been passed down virtually unchanged for over half a century. For instance, the large "map pocket" located on the back was designed to allow users to pull out maps even while wearing a backpack. Additionally, though not an intended feature, it has the unique benefit of serving as insulation when stuffed with newspapers.

Every detail reveals functional design rooted in the 1960s, such as lap-seam double stitching to enhance durability and prevent rain penetration, and leather accents known as "leather cookies" used to fix drawcords. This perfected design became the prototype for outdoor parkas that followed.

A Tradition Continuously Loved in Japan

In the 1970s, 60/40 cloth expanded to other items such as down jackets and down vests, cementing its position as a brand icon. Its popularity was particularly immense in Japan.

However, the brand's history would later reach a major turning point. In its home country of the US, SIERRA DESIGNS pivoted toward becoming a more technical gear brand. Meanwhile, the classic-style SIERRA DESIGNS we know today has been supported by the enthusiasm of Japanese fans and remains in the lineup to this day.

60/40 Evolved with CORDURA

The brand's core 60/40 cloth did not stop at simply preserving tradition.

By incorporating modern updates, its value has been elevated even further today. The symbol of this evolution is the switch of the warp nylon threads to Invista's "CORDURA nylon."

CORDURA nylon is renowned for its superior strength compared to standard nylon. Adopting this material improved tear strength and abrasion resistance, giving 60/40 cloth a new level of performance.

While retaining the basic functionality of 60/40 cloth—where cotton expands to provide water resistance—the underlying durability of the material is significantly enhanced. This represents an ideal evolution made possible only through a deep understanding of the brand's heritage. An invention born over half a century ago continues to advance to the next stage by fusing with modern technology.

SIERRA DESIGNS traces its origins to the founders' core belief of creating gear you can "entrust your life to." Its iconic 60/40 cloth has preserved its tradition over half a century later, driven by the enthusiasm of Japanese fans. Its construction, which does not rely on film coatings, experiences minimal degradation over time, giving it the modern value of being repairable and wearable for years to come.

With the new strength of CORDURA nylon added to its classic functional beauty, the story of SIERRA DESIGNS continues into the future. Its path seems to offer a clear answer to how a single product can remain beloved across generations.