What Is Denim Made of?

Regardless of the season, denim is probably always one of the most iconic fabrics in a woman's wardrobe. A denim jacket, a pair of jeans, or a denim skirt can bring you comfort and style on any occasion.

Denim, which first rose to prominence during the Gold Rush centuries ago, continues to hold a place in the fashion world, and its style and comfort have made tremendous strides. As navigating the streets or enjoying the casual freedom on weekend outings in our comfortable and stylish denim clothing, few stop to consider what they are made of and how they are made. In today’s blog, we will take you to denim from its source, a fabric that you are probably very familiar with but may never have learned in detail.

What Are the Raw Materials of Denim?

Cotton is the core raw material of denim fabric, typically accounting for over 90% of the total fabric. The natural toughness, breathability, and moisture absorption of cotton are key to denim's durability and comfort. The cotton used in denim is mostly long-staple cotton, with fibers up to 30-40mm long, so that the yarn is stronger and less prone to pilling, and the fabric is durable and soft to the touch. Some high-end denim can also be blended with linen or wool to improve the breathability or warmth of the fabric. But the proportion is usually less than 5%.

In addition to natural materials, modern denim also blends chemical fibers to enhance performance. For example, spandex is a chemical fiber often added to denim to increase its elasticity, allowing the pants to fit better and facilitate movement. Polyester fibers enhance wrinkle resistance and abrasion resistance, but excessive amounts can reduce breathability and make the fabric stiff, so they typically make up no more than 10% of the fabric.

When selecting raw materials, the fabric performance, process suitability and cost should all be considered. First, to enhance the durability of denim, prioritize long-staple cotton with longer fibers. Long fibers produce finer, stronger yarns, making the resulting fabric less prone to pilling and more uniform after dyeing. Additionally, choose cotton that is as mature as possible, as it has a higher cellulose content and offers greater elasticity and toughness; while immature cotton can easily lead to uneven dyeing. High-end denim can use top-grade long-staple cotton to enhance the texture, while mass-market denim can adopt a blend of “long-staple cotton and medium-staple cotton” to strike a balance between cost and performance.

Although the addition of spandex can increase the elasticity of denim fabrics, it is important to be careful not to add too much. Excessive addition will cause the fabric to become too loose and more likely to deform after wearing. By the same token, when adding polyester fiber, the amount used also need to be paid great attention to avoid making the denim fabric too stuffy.

The Manufacturing Process of Denim

Spinning is the first step in denim production, transforming raw cotton into continuous yarn for weaving. This process begins with cleaning and combing the cotton to remove impurities. The fibers are then combed to align them parallelly, forming uniform slivers. Multiple slivers are then combined and stretched to form roving. Finally, the roving is spun into fine yarn.

The second crucial step is dyeing. This process is integral to denim's unique color and texture. The most classic denim color is indigo. Traditionally, natural indigo is extracted from the indigo plant, while modern manufacturing techniques often utilize synthetic indigo, which is cheaper and more stable. Some high-end denim even incorporates dyes like sulfur black and coffee brown to create unique colors. Before dyeing, the warp yarns are applied with starch or polyvinyl alcohol to enhance their toughness and prevent breakage during dyeing. During the dyeing process, the warp yarns are repeatedly dipped in multiple dye vats, removed after each dip and oxidized, resulting in a blue coloration on the surface while the interior remains white. The weft yarn is usually undyed or only lightly dyed to contrast with the indigo blue of the warp yarn, enhancing the sense of layering of the fabric. The more times it is dyed, the darker the color will be.

After dyeing, we have come to the third step of weaving. First, the dyed warp yarns should be arranged and wound onto a fixed beam to ensure uniform tension during weaving, preventing uneven tightness in the fabric. The warp and weft yarns are then woven together on a loom, creating the classic twill texture of denim.

Even though we now have denim in its initial state, the manufacturing process is far from over. Finishing is a key step in optimizing the performance and appearance of denim fabrics, including washing, shrinkage prevention, softening treatment, etc., to transform the fabric from its initial state into a finished product that can be cut. First, the fabric's surface hair is burned off with flame, resulting in a smoother surface and reduced pilling. The warp yarns are then cleaned with hot water, enzymes, or an alkali solution to remove sizing, restoring the fabric's softness and enhancing the stability of the dye. Finally, the fabric is pre-shrinked by mechanical stretching or steam heating to prevent shrinkage and deformation after wear. This completes the denim production process.

How to Care Denim?

Although denim fabrics are known for their durability, improper maintenance methods can still lead to fading, deformation, hardening and other problems, affecting their appearance and service life. Therefore, although denim is not as fragile as cashmere and wool and requires a lot of effort to care for, there are some precautions in daily washing, drying and storage to extend the service life of denim.

First, the main issues to prevent during washing are fading and shrinkage. To address this, reduce the frequency of washing denim. Denim doesn't easily stain, so if there are no obvious stains after daily wear, there's no need to wash it after every wear. Additionally, soak denim in cold water for 10 minutes before the first wear to allow the fibers to shrink and set, minimizing subsequent shrinkage. If a washing machine is used, separate denim from clothes in other colors to avoid staining.

The way you dry your denim directly affects its shape and fading speed. After washing, turn your denim inside out and hang it in a cool, well-ventilated area to air dry, avoiding direct sunlight. To prevent denim from stretching and warping, hang it on a wide hanger or lay it flat on a clothesline. Never use a dryer! High temperatures can cause denim to shrink significantly, stiffen, and even damage the elastic fibers.

Denim that has not been worn for a long time should be washed and dried before storage. When hanging, keep the hangers spaced apart to avoid squeezing wrinkles; folding is suitable for storing jeans.

❌ Myth 1: Washing denim in hot water can kill bacteria—High temperatures accelerate fading and shrinkage. Washing at room temperature and airing thoroughly can kill bacteria.

❌ Myth 2: Frequently ironing denim—Denim doesn't need frequent ironing; wrinkles naturally stretch out when hung. If ironing is necessary, use a low setting.

❌ Myth 3:The more you wash jeans, the softer and more comfortable they become - excessive washing will damage the fiber structure, causing the fabric to become thinner and lose its crispness. Washing as needed can extend its life.

New Trends in Denim Manufacturing

Denim manufacturing is currently undergoing a profound transformation. The denim of the future will be a practitioner of sustainable concepts.

In addition to a greater diversity of raw materials, modern denim production also prioritizes environmental protection. While traditional denim washing processes are highly polluting, new foam washing technology significantly improves efficiency and environmental friendliness, enabling faster washing times and shortening production cycles. With growing environmental awareness, the use of recycled fibers, such as recycled cotton and recycled polyester, in denim is increasing. Some denim fabric companies are using recycled fibers as raw materials, minimizing environmental impact while meeting consumer demand for eco-friendly products.

In addition, the secondary use and recycling system of denim fabrics will be gradually established and improved, and companies will pay more attention to the whole process management of the product life cycle, from raw material procurement, production and manufacturing to product recycling and reuse, to maximize resource utilization and reduce environmental impact.

With the development of technology, denim fabrics will integrate more functions, such as antibacterial and anti-ultraviolet, to provide consumers with a more comfortable and practical wearing experience. From fiber production, yarn manufacturing, fabric processing to garment production, enterprises in all links will work closely together to jointly develop new technologies, new processes and new materials to improve the overall quality and efficiency of the industry.

Denim is not only a versatile item in the wardrobe, but also a link between traditional craftsmanship and modern technology, practical functions and emotional value. It has always maintained a tenacious and vibrant vitality as time goes by, and continues to write the immortal legend of the fabric.