What is Indigo?

Mary McMahon
Mary McMahon

Indigo is a rich blue dye that was widely used throughout the ancient world, from Indonesia to Europe. The distinctive dark blue color has made this dye famous, with a variety of synthetics being used today to produce indigo which is colorfast and fade-resistant, in contrast with that of natural origins used historically. Many craft stores sell it in their dye sections for people who want to work with this dye directly.

Denim is traditionally made with indigo.
Denim is traditionally made with indigo.

The earliest records of indigo date to around 1600 BCE, and seem to suggest that the use of this dye probably originated in India, spreading out to the Middle East and China and diffusing from there. In fact, the name comes from the Latin indicum, which means โ€œof India.โ€ Indigo quickly became a very popular color thanks to its depth and saturation, which made wool, cotton, and linen garments incredibly dark.

This dye was historically sourced from plants in the genus Indigofera, a member of the pea family native to Asia. Indigo could also be extracted from woad, as it was in the British Isles, and from some shellfish in the genus Murex, also used by the Phoenicians to make another famous dye, Tyrian Purple. The compound that creates the blue color is actually not soluble in water, so in order to turn it into a dye, people had to subject it to chemical treatments. Some of these treatments were quite harsh, leading to health problems at textile manufacturing facilities and occasionally attracting attention from social reformers.

Historically, many people simply soaked their indigo in stale urine to turn it into a dying compound, leading dyemakers to be exiled to the fringes of cities in some regions due to the smell. Indigo could also be fermented to make a dye, as was done in Asia, and some people simply painted it directly onto substances they wished to dye. Textiles also had to go through multiple dye cycles for the color to take, and it usually only penetrated the upper layers, leaving behind a white core.

Since 1900, most companies that want to work with indigo use synthetic dyes. These dyes are stronger than the natural ones, and also more predictable, ensuring that batches retain consistent coloration. Denim is one famous product traditionally made with indigo; the distinctive wear of jeans is the result of the wear patterns of the dye, which naturally fades out through repeated washes.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a wiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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Discussion Comments


Wow, I can't believe dyemakers had to use urine for this! I imagine that indigo really permeated the air, so I can see why these facilities had to be moved out of town. I wouldn't appreciate the smell of urine near my home, either!

I would think that fermenting indigo would cause a strong odor, as well. Anything that starts to spoil has a powerful smell that no one really wants to be around.

Imagine how the poor dyemakers must have felt! They surely must have become desensitized to the odors of urine and fermenting indigo over time. Otherwise, they would have had to deal with constant nausea.


I don't like it when people or textbooks say that indigo is one of the colors of the rainbow. When I was growing up, I was taught that the end of the color spectrum included blue and violet, and no mention of indigo was made.

Every reference to the colors of the rainbow that I read or hear now includes indigo. I am not alone in being upset by this. Many people say that since indigo is neither a primary nor a secondary color, it should not be grouped with the other rainbow hues that are.

When I see a rainbow in the sky, I can clearly see the blue and the violet. I don't see indigo anywhere, so I think that it is crazy to claim it is there, even though we can't see it.


@cloudel โ€“ Jeans dyed with indigo can be a nightmare to launder. I have several very dark pair that require special care to keep them from ruining my other clothes.

When I buy a new pair of dark jeans, there is usually a warning on the label to wash them separately or with like colors. I know that this means they will bleed color into the water, so I start by handwashing them in the bathtub.

After the first washing, they have lost enough of the indigo dye to make them safe for washing in cold water with other dark clothes. However, even after months of laundering, I am scared to put them in the machine with any light colored garments.


I didn't know that indigo was used to dye jeans! It seems that I own several items dyed with indigo, then. I have many jeans, some denim skirts, and a denim jacket.

I love the way that it fades over time. To me, nothing looks and feels more comfortable than jeans that have been worn for years and have lost some of the intensity of their color through many washings.

I also love how the entire garment does not fade at once. The indigo fades in sections, so you have a more natural-looking wear pattern.

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