Hiroshi Kato

While there are denim purists who will furiously debate the merits of traditional denim over modern stretch jeans, there's no denying that the public just prefers stretch — it outsells 100% cotton to the tune of four to one, according to research from the Plains Cotton Cooperative Association and Texas' American Cotton Growers. New Jersey denim brand Todd Shelton attributes the popularity to a range of causes from people prioritizing comfort to the fact that the American body type has gotten a little, well, fuller over recent decades and stretch jeans are more accommodating to larger bodies. But what are the pros and cons of stretch over non stretch? We don't mean the environmental impact of synthetic fibers, we're talking about the material differences to what it's like to wear them: is it true that stretch denim less durable, less breathable, and that it can even lose its ability to stretch? To find out, we flew to Los Angeles to visit the factory of Japanese stretch denim brand Hiroshi Kato, where denim developers Nick Noguchi and Ashley Walters answered our questions. https://www.youtube.com/watch?vXXjxsdVfyQ8 Key Takeaways: Stretch denim blends cotton with synthetic fibers for flexibility, comfort, and shape retention, ideal for active lifestyles, traveling and larger body types. While less breathable and durable than pure denim, innovations like core spun yarn and four-way stretch enhance durability, appearance, and fit. How Stretch Denim Works The threads are made with one long yarn made of a synthetic material, usually elastane, and encasing it in cotton. Core spun yarn is a more expensive method that completely covers the elastane. Filament twisted yarn or covered yarn is a more common method that exposes more of the elastane. Stretch denim blends cotton with a synthetic fibers, usually elastane, spandex, lycra, or polyurethane (PU). Practically speaking, these names all refer to what is more or less the same material, which is a petroleum byproduct. There are two main ways that the stretchy yarn is incorporated into the fabric, and they affect the look and feel of the product differently: Core Spun Yarn The synthetic fibers — in Hiroshi Kato's case, polyurethane (PU) — is completely encased in cotton, which wraps around the PU like a cable. This hides the PU and better mimics the appearance of 100% cotton denim, though you might see it peek through when the jeans are stretched out; this looks like the fabric getting just a little lighter. The core spun yarn method produces denim that looks and fades in a way that's similar to regular, non stretch denim. "By using core spun yarn, we allow the cotton to dominate the exterior and you don't see the PU at all," explains Walters. "This makes our stretch denim look and fade just like 100 percent cotton jeans while maintaining the flexibility of polyurethane." Covered Yarn, aka Filament Twisted Yarn Polyurethane and cotton are twisted together, as opposed to the cotton being spun around the poly. This is cheaper to do but exposes more of the synthetic fibers. The final product is a little shinier and won't produce the same kind of fades that traditionalists prefer. "That exposed polyurethane makes the stretch fabric look a little cheaper, you're seeing more of a shine, and it's also holding the indigo color, so it won't fade as nicely as rigid denim does," says Walters. Enjoying Kato's four-way stretch denim jeans. Two-Way vs. Four-Way Stretch Denim Two-way stretch denim only stretches horizontally, which has the most benefits for comfort Four-way stretch fabric stretches in all directions, which may be better for the fit As a twill weave, denim has threads running in two directions that overlap and criss cross with each other: they're called the warp and the weft. The warp threads run vertically and form the fabric's foundation, while the weft threads are woven horizontally through the warp. Unlike plain weaves like chambray, where the warp and weft are equally visible, in denim you see more of the warp. You can easily see what we're saying if you grab your nearest jeans, because in typical denim, the warp is dyed blue and the weft is white, or it's left undyed (which has the creamy color of ecru). That's why jeans look blue (with bits of white) from the outside, but when you turn your jeans inside out, they look a lot closer to the natural color of cotton. Picture via onlineclothingstudy.com / Prasanta Sarkar Two-Way Stretch Most stretch jeans just put stretch in the weft so that they stretch horizontally (across the width), providing comfort in key areas like the waist and thighs. Four-Way Stretch Four-way stretch, as you may have guessed, uses stretchy threads in both the warp and the weft. This added flexibility minimizes issues like knee bags (where jeans stretch out at the knee) and improves overall fit. "Four-way stretch denim stretches 360 degrees," says Walters. "It’s not just about comfort — it’s also about maintaining the shape over time, especially in areas like the knees ,where two-way stretch denim tends to bag." If you're a fan of vintage denim then you probably like selvedge jeans, which are made on old fashioned shuttle looms. Hiroshi Kato says they're the only brand making selvedge denim that's four-way stretch, giving them a pretty cool claim to fame in the space. In any case, ask the brand if their jeans are two-way or four-way stretch before making your purchase. A peek inside the Kato factory in Japan where weaving machines are hard at work Durability: How Does Stretch Denim Compare to Non-Stretch? Durability depends not only on the stretch component but also the fabric weight and the garment's construction Thicker denim (12 oz and up) will probably last longer, but rigid denim is easier to repair Overall, durability depends on the construction and percentage of synthetic fibers used. High-quality stretch denim, made with core spun yarns and a relatively low percentage of stretch fibers (5 percent or under) can rival the strength of rigid denim. "Stretch denim, depending on the percentage of synthetic fibers, can be slightly weaker over time," says Walters. "But with our core spun yarn, the density of the cotton threads ensures that our jeans are just as durable as rigid denim. filament twisted yarn will age differently, but core spun yarn should be about the same." It's worth noting that stretch denim will lose is ability to stretch over time, but it'll probably take many years for that to happen. Fading: Do Stretch Jeans Age Like Regular Jeans? A common misconception is that stretch denim doesn’t fade well. Again, this depends largely on the yarn construction: Core Spun Yarn allows the cotton exterior to fade naturally, similar to non-stretch denim. Filament Twisted Yarn not only exposes less cotton but it retains more color, resulting in uneven or muted fading. "With filament twisted yarn, the exposed polyurethane holds the indigo,, which prevents the jeans from fading as beautifully," says Walters. "Core spun yarn hides the synthetic fibers, so the cotton can fade like traditional rigid denim." If fades matter to you, ask for core spun. Diagram courtesy of Md. Bashar Uddin, Anupam Deb Nath, Kazi Sowrov, Hosne Ara Begum, Textile & Leather Review Journal Fit and Drape: How Does Stretch Denim Compare? Stretch denim drapes slightly differently than rigid denim due to its open weave and elastic fibers, resulting in a rounded silhouette. Rigid (non-stretch) denim does a better job of conforming to the wearer's body over time, creating a unique, personalized fit. Stretch denim offers a softer, more forgiving, "body-hugging" fit. "Anything with more elastic is going to drape more softly and have a slightly more open weave," says Walterrs. "But at Kato, we’ve worked hard to mimic the structure of rigid denim while keeping the flexibility." Loose, rigid denim on the left (from Left Field NYC), slimmer fitting stretch denim from Hiroshi Kato on the right. Breathability When we're talking about synthetic fabrics, breathability is always a part of the conversation. Of course, not all "natural" fabrics breathe wonderfully — waxed canvas is a famous example, but even unwaxed canvas is very dense and not as breathable as many other natural fabrics. Still, when it comes to stretch denim... "You're taking a natural fiber that is going to breathe just fine and adding a man-made fiber that has no breath. It's completely solid, and you're mixing the two together," says Walters. "So, yes, depending again on the content of the denim, it will breathe less with the synthetic fibers in it." One potential fix: it's easier to make lightweight stretch denim than lightweight rigid denim, and Kato sells a lot of jeans that are under 11 ounces per square yard. (The average rigid denim is 11 to 12 ounces.) It's not a perfect solution, but getting lighter weight stretch denim can help improve breathability. https://www.youtube.com/watch?vUkO4t_o45MM The Pros and Cons of Stretch Denim As you can see, it's not as simple as stretch denim being "better" or "worse." Here's what we learned from all our research — and all our time reviewing jeans. What We Love Comfort and Flexibility: Moves with you, perfect for active lifestyles and way more comfy for travel. Ideal for Thicker Thighs: Stretch denim is almost universally preferred for bigger folks with atypical bodies, since it provides more flexibility with fitting — you don't need to perfectly match the measurements. Shape Retention: If it's 4-way stretch, and especially if it's mixed with polyester, stretch denim retains its shape better. Rigid denim constantly stretches and shrinks based on when it's been washed and other factors. Easier to launder: Because it holds its shape better. Availability in Lighter Weights: 10.5oz (like kato’s) is common for stretch, yet very unusual for non-stretched Cheaper: Stretch denim tends to be cheaper than cotton. Things to Consider Breathability: Less airflow compared to non-stretch denim. I wear my stretch jeans in the winter. Drape and Fit: Synthetic fibers have a different, more round fit, resulting in a different silhouette that doesn't conform to your body the same a rigid jeans. Fading: If you're getting filament twisted yarns, the fades aren't as nice with stretch jeans — and usually, whoever you're talking to at the brand won't know how their stretch denim is made! Durability: It's easier to repair cotton jeans. Choosing the Perfect Denim So, you've seen the ins and outs of stretch denim and how it compares to your standard issue jeans. If you're active or looking for something that will fit more body types it can be a great choice, and thanks to our tour of Kato's factory it seems clear that not all stretch denim is created equally. Particularly with modern, in-jean-ious innovations on stretch fabrics like four-way stretch selvedge and core spun yarn, there are good reasons to give it a try even if you consider yourself something of a denim purist. Personally, after all I've learned, the breathability is the main thing that bugs me about stretch jeans — but if the weather's chilly, I have no qualms reaching for some spandex denim! Check out our video tour of Kato’s factory if you’re curious to get a deeper look into the process, and feel free to drop a comment with any strongly worded opinions!