You can feel the difference between two pairs of jeans with your eyes closed. One is crisp and rugged, the other is soft and relaxed. This isn't an accident; it's a decision I make at the factory long before we even start weaving.

Denim is almost always made from cotton yarn. The specific type of yarn—most commonly ring-spun or open-end—is what determines the denim's final texture, strength, and how it will fade over time. The yarn is the fabric's DNA.

From my perspective as a factory owner, choosing the yarn is the most critical first step. It sets the entire personality of the final product. For a designer like Dean, specifying the yarn is how he translates a feeling—like "rugged heritage" or "soft comfort"—into a real, tangible fabric. It's the blueprint for the entire jean. The choice between a strong, traditional yarn and a soft, modern one changes everything that follows. Let's look at what that really means.

What type of yarn is used in denim?

You're holding two pairs of 100% cotton jeans. One feels tough and textured, the other feels smooth and light. How can that be?

Denim¹ primarily uses two types of cotton yarn²: ring-spun and open-end. Ring-spun is stronger and more textured, used for traditional denim. Open-end is softer and more uniform, used for lightweight and fast-fashion jeans.

Your detailed insights into yarn types are exactly what we deal with every day. The spinning method changes the core character of the cotton. At my factory, we select the yarn based on the exact feel and performance a client like Dean is looking for.

The Four Main Players in Denim Yarn

1. Ring-Spun Yarn: This is the old-school original. Long cotton fibers are twisted together tightly, making the yarn incredibly strong and durable. It has a slightly uneven surface that gives classic denim its famous slubby texture. This is the yarn for heavyweight, raw denim that's meant to last forever and fade beautifully. It's slow and expensive to produce, but for authenticity, nothing beats it.
2. Open-End Yarn: This is the modern, efficient choice. A blast of air blows loose fibers into a rotor where they are twisted together. It's much faster and cheaper than ring-spinning. The yarn is softer, fluffier, and more even, but also weaker. This is perfect for producing soft, lightweight summer jeans or the comfortable, affordable denim you find in fast-fashion.
3. Siro-Spun Yarn: This method is a smart hybrid. It takes two strands of yarn and twists them together. This creates a yarn that is smoother and less "hairy" than ring-spun, but stronger and more durable than open-end. It's a great middle-ground, balancing comfort and strength, and we see it often in mid-range jeans that need to look clean and feel good.
4. Vortex-Spun Yarn³: This is another high-tech evolution. It uses a vortex of air to twist the fibers. It's almost as fast as open-end spinning but produces a yarn that is nearly as strong as ring-spun. The result is a very smooth, clean yarn that is great for workwear or jackets that need to be tough but look uniform.

Yarn Type	Key Feature	Best Used For	Feel
Ring-Spun	Maximum Strength & Texture	Heritage raw denim4, heavyweight jeans (13oz+)	Crisp, Rugged
Open-End	Maximum Softness & Value	Lightweight summer jeans, fast-fashion	Soft, Fluffy
Siro-Spun	Balanced & Smooth	Mid-range jeans, functional denim	Smooth, Strong
Vortex-Spun	Strong & Uniform	Workwear, jackets, mid-weight denim (12-16oz)	Even, Tough

What type of thread is used on denim?

You've seen the iconic gold stitching on a pair of jeans. It has to be incredibly tough to hold everything together, a job for a very specific kind of thread.

Denim is sewn with a "core-spun" thread. This thread has a strong continuous filament polyester core for strength, which is then wrapped in a cotton sheath for a traditional look and better dyeing properties.

When executing a design for someone like Dean, the thread is a non-negotiable detail. Using the wrong thread is a guarantee of failure. In the early days of denim, jeans were sewn with 100% cotton thread. It looked great, but it would rot and break over time. It's also not strong enough for the high-speed sewing machines we use in modern factories. Core-spun thread is the perfect solution.

The polyester inside provides incredible tensile strength, so the seams won't pop when you squat down or after hundreds of washes. The cotton on the outside gives it the classic, matte look of old-school thread. It also allows the thread to fade and age along with the denim fabric, which is a detail that denim lovers really appreciate. We also vary the thickness of the thread, using a heavier thread for structural seams like the yoke and inseam, and a lighter one for less critical areas like the pocket bags.

What weave is denim for jeans made of?

Look closely at any pair of jeans. You will always see a distinct diagonal pattern in the fabric. This pattern isn't just for looks; it is the very definition of denim.

Denim is made using a "twill weave." The most common type is a 3x1 right-hand twill⁵. This construction creates the signature diagonal lines and makes the fabric exceptionally strong and durable.

Let's break this down from a weaver's point of view. A loom weaves by interlacing two sets of threads: the warp threads run lengthwise, and the weft threads run crosswise. In denim, the warp threads are dyed indigo blue, while the weft threads are left natural white. In a 3x1 twill, each weft thread goes under one warp thread and then over three warp threads.

This over-three, under-one pattern is what creates the strong diagonal line (the "wale") on the surface of the fabric. It also means that the face of the fabric is dominated by the blue warp threads, which is why your jeans are blue on the outside. The inside of the fabric has more of the white weft threads showing, which is why it's lighter. While a 3x1 right-hand twill is the industry standard (used by Levi's), there are variations. Left-hand twill (Z-twill), used by Lee, creates a softer-feeling denim.

Broken twill, created by Wrangler, alternates the direction of the twill to prevent the classic "leg twist" that happens in old jeans.

Is raw denim 100% cotton?

You hear "raw" and "authentic" and assume it must mean pure, unadulterated cotton. But in the modern market, a little bit of stretch has become very popular.

Traditionally, yes, true raw denim is 100% cotton. This non-stretch composition is what allows the fabric to crease and create the sharp, high-contrast fades that purists love. However, many modern raw denim jeans now include 1-2% elastane for comfort.

This is a huge debate in the denim world, and a decision that a designer like Dean has to make constantly. From a purist's standpoint, 100% cotton is the only way to go. The rigid, non-stretch fabric sets hard creases in the high-wear areas—your lap, behind your knees. As the indigo wears away, those set creases are what become beautiful, high-contrast fade lines.

The jeans truly become a map of your life. When you introduce stretch—usually 1% or 2% of Lycra or elastane⁶—you change the fabric's behavior. The advantage is immediate comfort. There's almost no painful break-in period, and the jeans move with you. The disadvantage is that the fabric doesn't hold those sharp creases as well. It has memory, so it wants to bounce back to its original shape.

This means the fades tend to be softer and less defined. Neither is "better," they are just different tools for different goals. It's a fundamental choice between authenticity and comfort.

Conclusion

The yarn is the soul of the jean. Choosing between ring-spun, open-end⁷, and other types gives a designer total control over the fabric's final feel, durability, and unique story.

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