Invention of Indigo dye

Look down at your blue jeans. That deep blue shade has a long story, and much of it begins in India. For thousands of years, people around the world prized a blue dye made from a humble green plant. The word we use for it even means “Indian”. This is the story of indigo dye.

In this article, I’ll explain what indigo is, how it was made from leaves, how it travelled from India to Rome and Europe, the pain it caused Indian farmers under colonial rule, and how a lab in Germany changed everything. All facts here come from trusted histories, and I’ve noted a few common errors along the way.

What Is Indigo Dye?

Indigo is a natural dye with a rich blue colour. It comes from the leaves of certain plants, most of all a shrub called Indigofera tinctoria, also known as true indigo. Blue dyes are quite rare in nature, which made indigo very valuable.

Indigo does not dissolve in water. That makes it tricky to use, as we’ll see. Today, most indigo is made in factories, not from plants. According to Wikipedia, about 80,000 tonnes of synthetic indigo were made each year as of 2023, mostly to dye denim for jeans.

Where does the name come from?

The Greeks called the dye indikon, which means “Indian”. The Romans turned this into the Latin word indicum. Over time, it passed through Italian and became the English word indigo. So every time you say indigo, you are naming India.

India: The First Great Home of Indigo

Indigo was used by many old cultures, in Egypt, Mesopotamia, Peru, China and West Africa. The oldest known cloth dyed with indigo, about 6,000 years old, was found at Huaca Prieta in Peru. But India played a special role.

According to Wikipedia, the Indigofera tinctoria plant was domesticated in India. India was also the earliest major centre for making and processing the dye. Plants of the Indigofera group grow well in the tropics, especially in the Indian subcontinent.

A small correction here: some articles call Indigofera tinctoria “a variety of indigo dye”. It is actually the name of the plant. The dye comes from its leaves.

How Was Indigo Made From Leaves?

Here is the old process, explained simply.

1. Cut and soak. Fresh leaves were packed into a vat of water and left to soak.
2. Let it ferment. Over about 12 to 15 hours, natural changes in the water freed a colourless substance from the leaves and turned it into a yellowish liquid.
3. Add air. The liquid was then exposed to the air. As it met oxygen, the blue dye formed and settled out of the liquid.
4. Dry and press. The blue mud was filtered, pressed into cakes and dried. These cakes were easy to carry and sell.

Indigo leaves hold only a small amount of the colour, about 0.2 to 0.8 per cent of the starting compound. So a great many leaves were needed for a little dye.

The magic of dyeing with indigo

Because indigo doesn’t dissolve in water, dyers first had to change it into a form that would. This form is called white indigo. Cloth was dipped in it and lifted out. Then something lovely happened. As the cloth met the air, the colour came back, and the cloth turned blue right before your eyes. Dipping again and again gave deeper shades.

Indian dyers used indigo in famous textiles too. For example, the blue in painted chintz came from an indigo vat. Read more in our article on the invention of chintz.

Indigo in the Ancient World

Indian indigo travelled far. A Babylonian clay tablet from the 7th century BC gives a recipe for dyeing wool blue. Historians think the indigo used was most likely brought from India.

The Greeks and Romans valued indigo as a luxury. The Romans used it as a paint pigment, and in medicine and cosmetics. Arab merchants carried it from India to the Mediterranean. India was a main supplier of indigo to Europe as early as Greek and Roman times. To learn more about these links, read our post on Indo Roman trade relations.

Indigo was so precious that people called it “blue gold”.

It even found a place in science. When Isaac Newton wrote about the colours of the rainbow in 1675, he used the word “indigo” for one of them. That is why many of us learned the rainbow as VIBGYOR, with indigo sitting between violet and blue.

Indigo Reaches Europe by Sea

In medieval Europe, indigo stayed rare. People used woad, a European plant that gives the same dye but less of it. Then, in the late 15th century, the Portuguese explorer Vasco da Gama found a sea route to India. Traders no longer needed to pay heavy fees to middlemen on long land routes. Imports of indigo to Europe rose sharply.

Woad growers were not happy. France and Germany banned imported indigo in the 16th century to protect their own dye makers. But indigo was better, and the bans could not hold forever.

European powers then set up indigo farms in their tropical colonies, including the Caribbean and South Carolina in North America. Much of this work was done by enslaved African people. Indigo’s story, sadly, is also a story of forced labour.

The Indigo Revolt in Bengal

In India, colonial rule turned indigo into a source of misery for farmers. Indigo planting in Bengal began in 1777, when a Frenchman named Louis Bonnaud started the first plantation near Hooghly. By 1830, there were over a thousand indigo factories in Bengal.

European planters forced farmers to grow indigo instead of food crops on their own land. They gave loans, called dadon, at very high interest. Many farmers stayed in debt for life. Wikipedia reports that the price paid to them was only about 2.5 per cent of the market price.

In 1859, the farmers had had enough. In Nadia district, thousands refused to grow indigo. The revolt was led at first by Digambar Biswas and Bishnu Charan Biswas, and it spread across Bengal. This uprising is known as the Indigo Revolt, or Nil Bidroha.

The government formed an Indigo Commission in 1860. One magistrate told the commission that “not a chest of indigo reached England without being stained with human blood”. The playwright Dinabandhu Mitra wrote a play, Nil Darpan, about the farmers’ pain. It became famous, and the first play ever staged at the National Theatre in Calcutta was Nil Darpan. You can read more about the region in our guide to West Bengal.

Champaran and Mahatma Gandhi

Indigo also shaped India’s freedom struggle. In 1917, farmers in Champaran district of Bihar were being forced to grow indigo on part of their land. They got barely any payment. A local farmer, Raj Kumar Shukla, invited Mahatma Gandhi to see their plight.

Gandhi went to Champaran with leaders such as Rajendra Prasad. When officials told him to leave, he refused and was ready to face punishment. This was his first act of civil disobedience on Indian soil. The Champaran Satyagraha is seen as a turning point in the freedom movement. Learn more about the state in our article about Bihar.

Synthetic Indigo Changes Everything

The German chemist Adolf von Baeyer began working on making indigo in a lab in 1865. By 1897, the German company BASF sold synthetic indigo that was cheap and pure. In 1897, about 19,000 tons of indigo still came from plants. By 1914, that had dropped to about 1,000 tons. Natural indigo farming in India shrank fast.

Today, most indigo comes from factories. Still, some craftspeople in India and elsewhere keep natural indigo dyeing alive. Many buyers now seek out handmade, plant dyed cloth.

FAQs About Indigo Dye

Where did indigo dye originate?

Indigo was used in many ancient cultures. India was the earliest major centre for making it, and the Indigofera tinctoria plant was domesticated in India.

Why is it called indigo?

The name comes from the Greek word indikon, meaning “Indian”, through the Latin word indicum.

How is natural indigo made?

Leaves are soaked and fermented in water. The liquid is then mixed with air so the blue dye forms. It is dried and pressed into cakes.

What was the Indigo Revolt?

It was a farmers’ uprising in Bengal in 1859 against European planters who forced them to grow indigo at unfair prices.

What is the link between indigo and Gandhi?

In 1917, Gandhi led the Champaran Satyagraha in Bihar for farmers forced to grow indigo. It was his first satyagraha in India.

Is indigo still made from plants?

Mostly not. Most indigo today is synthetic, made for denim. Some artisans still use natural plant indigo.

Final Thoughts

Indigo began as a gift from Indian fields and skilled hands. It crossed oceans, coloured fine cloth around the world and earned the name blue gold. It also brought great suffering to Indian farmers, and it helped spark Gandhi’s first big fight. So the next time you pull on your jeans, remember the long and complex road that blue has travelled.