A Complete Journey of Cotton to Denim Fabric

Have you ever thought about why denim is blue on one side and white on the other? Or why the color changes when you wear and wash your jeans?

Maybe you’ve noticed that the legs of your jeans sometimes twist a little? And you’ve surely encountered jeans with stretch.

It’s all got something to do with how denim is made in a jeans factory.

It’s a complex process with dozens of steps performed in denim Factory, each of which impacts what the final outcome will look like, how it will feel, and (very importantly) how it fades.

When you break it down, though, you get five main stages: raw materials, spinning, dyeing, weaving, and finishing.

1: Raw Materials

The first stage of making denim is raw material. And denim is (mostly) made from cotton; a natural fiber that comes from the cotton plant. It’s well-suited for garment production because it’s comfortable, breathable and durable.

Once harvested, the jeans manufacturers send raw cotton through the ginning process at the cultivation site. This separates the fibers from the seeds. Cotton’s quality is based on a set of physical properties, including staple length, fineness and maturity (known as micronaire), strength, and color.

2: Spinning

Spinning is the process of turning fibers into yarn. It’s all about making the raw material fibers parallel, and then twisting them. To make stretch denim, denim manufacturers need to add a synthetic elastomer to the yarn in the spinning process, and you get the best result with ring spinning. That’s because the stretch is spun directly into the core of the yarn with the cotton wrapped around the elastomer. This way, you maintain the soft touch and fading capabilities of cotton, while adding stretchability.

3: Dyeing

Dyeing is where the yarn gets its color. It’s done by soaking the yarn in a liquid that contains a dyestuff. The classic kind of denim that is blue on the outside and white on the inside is ‘yarn dyed’—meaning only the warp yarn is dyed. The original blue color comes from indigo. It’s one of the oldest dyestuffs still in use today; a 6000-year-old scrap of fabric dyed with indigo was found in Peru. Indigo used to be ‘natural’ as it was made from plants. To get the dyestuff onto the yarn or the fabric, it’s solubilized in water. When the yarn or fabric is pulled out of the dyeing vat, the oxidation process binds the color to the fibers of the yarn. But the color doesn’t reach the core of the yarn, and the dyestuff only binds externally. This gives what’s known as a ring dye effect. And that’s what makes jeans fade. As the dye slowly wears and washes off, the undyed core appears.

4: Weaving

Weaving is the process of turning yarn into fabric. Two sets of yarn are interlaced at a 90° angle. For classic denim that’s mainly blue on the front and mainly white on the back, the weft yarn that runs across is undyed, and warp yarn that runs downwards is dyed. Denim belongs to the twill family of weaves. The most common type of denim is a 3×1, which has three warp yarns for each weft yarn on the front of the fabric, and a diagonal twill line that runs either to the left or the right.

You’ve surely heard about selvage denim. It’s the original way of weaving denim; connoisseurs prefer it for the great fades it yields, which is a result of the slower speed it’s woven at. It’s valued for its aesthetics and its history. To weave, you need three motions: shedding, picking and battening. In terms of production of selvage denim, where it differs from modern denim weaving is the picking. The relatively slow speed of this process is why modern high-speed looms were invented.

5: Denim Fabric Finishing

The last stage of making denim is fabric finishing. Put simply, a fabric finish is a treatment that changes the appearance, the touch, or the performance of the jeans fabric.

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