What is denim? How is it made? cotton? Why are jeans only blue on the outside? This beginner's guide gives answers and overview on how is denim made.

5 Production Stages of Making Denim

Have you ever thought about why denim is blue on one side and white on the other? Or why the colour changes when you wear and wash your jeans? Maybe you’ve noticed that the legs of your jeans sometimes twist a little? All this has something to do with how denim is made.

This is a multi-layered process with many steps, each of which affects how the result will look, how it will feel and (most importantly) how it will fade. If you break down the process, you get five main stages: cotton, spinning, dyeing, weaving and finishing.

Stage 1: Cotton

The first step in making denim is the raw material.

Cotton is a natural fiber derived from the cotton plant. A plant grown in warm climates around the world. The cotton plant is a shrub that produces seeds in a protective capsule. The seeds are surrounded by thin fibers that are used to produce the fabric known as cotton. The plant is harvested for its seeds, which are then used to produce the cotton fibers that are spun into yarn and used to make fabric.

The raw fibers are pressed into bales that weigh about 250 kilos. Each bale contains enough cotton for about 400 pairs of jeans.

Cotton fabric is used for a variety of products, including clothing, home textiles and industrial applications. Denim is a sturdy cotton twill fabric with a blue colour, most used for jeans.

Cotton is the most widely used natural fiber in the world.

Stage 2: Spinning

Spinning is the process of turning fibers into yarn.
It is the process of making the fibers of the raw material parallel and then spinning them.
Before the industrial revolution, spinning was all done with hands. To-day there are two common methods: Ring spinning was first invented in 1828, so it is the original method. It produces a soft and uneven yarn, which results in very contrasting dyes. And that is a beautiful thing.

In 1963, the new way of spinning was invented. It is called open-end spinning and is made much faster and cheaper. This method also produces a more uniform and hairy yarn that is less durable. In terms of appearance, open-end denim fades with less contrast.

Both methods have three features in common: the thickness, the texture, and the twist of the yarn.

Stage 3: Dyeing

Wail dyeing, the yarn gets its colour. To make this, the yarn is soaked in a liquid containing a colouring pigment. Classic denim, which is blue on the outside and white on the inside, is "yarn-dyed", i.e., only the warp yarn is dyed.

Natural or synthetic indigo
The original blue colour comes from indigo. It is one of the oldest dyes still in use today. In Peru in 2016, a 6000-year-old piece of fabric was discovered which was dyed with indigo. In the past, indigo was "natural" because it was extracted from plants. Today, however, almost all indigo is produced synthetically through chemical processing techniques.

Sulphur dyeing
There is a third option: dyeing with sulphur.
It was first introduced in the 1970s as a cost-saving method, but nowadays, sulphur is also used to add so-called tops and bottoms to indigo-dyed yarn to create the cast.

Stage 4: Weaving

Weaving is the process of turning yarn into fabric.
Two sets of yarns are interwoven at a 90° angle. In classic denim, which is essentially blue on the front and mainly white on the back, the weft yarn running across is under and the warp yarn running down is dyed.
Denim belongs to the family of twill fabrics. The most common type of denim is the 3×1 weave with three warp threads per weft thread on the front of the fabric and a diagonal twill line running either to the left or to the right.

Selvedge Denim

You've probably heard of selvedge denim. It is the original way of weaving denim; connoisseurs favourite it for the great fading that results from the slower weaving tempo. It is prized for its aesthetics and history. Weaving requires three operations: shearing, plucking and selvedging. The production of selvedge denim is different from modern denim weaving, mainly because of the plucking. The relatively slow speed of this process is the reason for the invention of modern high-speed looms.

Stage 5: Fabric Finishing

The final step in the production of denim is fabric finishing. In simple terms, a fabric finish is a treatment that changes the look, feel or performance of the fabric.
They fall into two categories: functional finishes, which are used to correct and prevent problems with shape retention, and creative finishes, which improve the look and feel of the fabric.
Once a denim leaves the loom, it is called "loom state". This untreated denim has no dimensional stability. If the fabric is not shrunk back to its original state, the denim will shrink, and the legs will twist when the jeans are being washed.