indigo facts

Indigo Facts That You Need To Know

Indigo has been used already for centuries as a natural dye for textiles. It originates from India, China, and Japan to color their clothes. For jeans, they are using indigo as well to color the yarns. These kinds of fabrics are better known as denim. A sturdy cotton fabric that is perfect to use for workwear garments as they needed clothing that could stand the test of time while doing the heavy job. These workwear clothes were originally worn by many who were called the blue color workers. They used indigo to color as the blue indigo masked stains and wear spots perfectly, so well-suited to use for these kinds of clothing. Later, these kinds of workwear styles such as jeans, denim jackets, and blue worker styles became synonymous with rebels. Nowadays, these indigo-colored pieces of clothing are truly iconic and timeless fashion pieces.

The Long History Of Indigo

In Japan, the traditional art of indigo dyeing is known as Aizome. In India, indigo has strong cultural and historical ties with traditional dyeing techniques and patterns varying across regions. The word indigo comes from the Greek word indikon, which means from India. Even, in Ancient Egypt, indigo was known to the ancient Egyptians, and it was used for dyeing textiles. There are mummies found wrapped in indigo-dyed cloth, indicating its use in burial practices. The trade of indigo likely played a role in ancient economic and cultural exchanges too.

Let’s Highlight 5 (Fun) Facts!

As you can read, indigo has such a long and rich history and is used for many different kinds of usage. Time to highlight 5 (fun) facts that you need to know to understand the importance, but above all, the beauty of this blue dyeing stuff.


  • 1) Indigofera Tinctoria Plant

The most popular plant that is used for indigo is the Indigofera Tinctoria plant. The indigo pigment from this plant is often called true indigo. This is a species of plant from the bean family that was one of the original sources of indigo dye.

Dye is obtained from the processing of the plant’s leaves. They are soaked in water and fermented to convert the glycoside indican naturally present in the plant to the blue dye indigotin. The precipitate from the fermented leaf solution is mixed with a strong base such as lye.

These days, synthetic indigo is more used than natural indigo from the Indigofera Tinctoria plant. As the demand grew so fast they needed more and faster indigo for commerical uses. But still, natural indigo is sometimes used to color the yarns of special pairs of blue jeans. Natural indigo is marketed as natural colouring where it is known as tarum in Indonesia and nila in Malaysia. In Iran and areas of the former Soviet Union, it is known as Basma.

Fun fact: The oldest known fabric dyed indigo, dated to 6,000 years ago, was discovered in Huaca Prieta, Peru.

Fun fact 2: The dye extracted from indigo is often named as blue gold.

  • 2) Magical Indigo-Dye Process

Dyeing with indigo is known as a magical process. While indigo is more greenish, instead of blue what most people think, it turns blue during the dyeing process. When white cotton yarn goes into an indigo-dye vat, it is still white, and when it comes out of the vat it looks more greenish. When the colored yarns with indigo come in contact with oxygen, it slowly turns into a more blueish color. This is the magic process. The yarns are going into indigo vats multiple times to reach the intended blue color. The result can vary from light to dark blue. Indigo dyeing is a very time-consuming process as most pairs of jeans are made with yarns that are dyed up to 12 times dipped in indigo.

Fun fact: Indigo is one of the seven colors of the rainbow and is between the colors blue and violet. If you take a look at the traditional seven-color rainbow spectrum, often named by the acronym ROYGBIV, it includes the colors: red, orange, yellow, green, blue, indigo, and violet. However, some modern representations of the rainbow exclude indigo, reducing it to six colors.

Tip: Learn how to indigo-dye yourself by joining the unique indigo-dye workshops by Blueprint Amsterdam.

  • 3) The Holy Indigo Fades

Most pairs of blue jeans are made with a denim fabric that is made with a blue and ecru yarn. The warps are blue while the weft, the filler of a fabric, is most of the time uncolored, so ecru. When you take a look inside your jeans, you will see these two different blue and ecru-colored yarns easily. Some jeans are made with a blue warp and a blue weft, so two blue yarns. These kinds of fabrics are known as blue blue or double indigo.

When you dye cotton yarns with indigo, the core will always stay white as indigo can’t penetrate so deeply. So when wearing a jeans for a longer time, the indigo on the surface will chip off. Washing your jeans regularly will speed up this process too. In the end, the white core of the yarns will be more exposed, so more visible. This explains why your jeans become lighter over time and also how the holy fades on jeans are born.

The Washing Guide

Learn how to wash your jeans in the ‘Ultimate guide to clean your jean‘.

Fun fact: In Japan, indigo became especially important during the Edo period (the period between 1603 and 1868). This was due to a growing textiles industry, and because commoners had been banned from wearing silk, leading to the increasing cultivation of cotton, and consequently indigo, one of the few substances that could dye it. During this Edo period, Japan’s noble Samurais wore a layer of indigo-dyed cloth beneath their armor to aid in the healing of injured skin.

Fun fact 2: Fireman is Japan used to wear jackets called Hikeshi-banten. A handmade garment that was made from several layers of highly absorbent indigo cotton fabric. Before going into the fire to extinguish a fire, the firemen drenched their jackets with water. The thick padding of fabric layers of their jackets allowed maximum water penetration and cushioning which helped to safeguard the fireman from burns and help blunt injuries from falling objects.

  • 4) The Symbol Of Indigo

For many years, indigo has been associated with various symbolic meanings. In color psychology, for example, indigo is often linked to intuition, spirituality, and deep contemplation. Indigo is considered as a color that represents wisdom, integrity, devotion, and sincerity. Different cultures and belief systems may attribute additional meanings to the color indigo.

Fun fact: The Indigofera Tinctoria plant is prized for its anti-inflammatory and antibacterial benefits, providing long-lasting relief, especially for sensitive skin and psoriasis.

Fun fact 2: The chemical formula of indigo is C16H10N2O2.

  • 5) Synthetic Indigo

In 1865, the German chemist Adolf von Baeyer began working on the synthesis of indigo. He described his first synthesis of indigo in 1878 and the second synthesis in 1880. He created synthetic indigo that contained a better quantity of indigo and it was also easier to use for dyeing. This is because the qualities were more consistent compared to natural indigo. These days, most pairs of jeans, are colored with synthetic indigo.

Fun fact: Some true denimheads prefer jeans made with a denim fabric that is dyed with natural indigo over synthetic indigo because of the fading results.


Tip! Learn more about denim in the previous learning articles here!

Written by Wouter Munnichs
I'm the founder of Long John. Next to running this daily magazine, I'm working as a freelance denim specialist for the industry. Titled as 'Denim Influencer 2020' by Rivet 50. Celebrated my 10th anniversary with Long John in 2021.