Indigo – NB1

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Indigo is a dye that is extracted from more than 30 different species of the plant Indigofera, which is widely present in large parts of the world. It is from the green leaves that the dye is extracted. The plant has been cultivated for at least 5000 years, so it is indeed an ancient dye. Indigo also forms the basis for Mayan blue, which I wrote about earlier.

It was mainly for textile dyeing that Indigo was grown, and is still grown. In 1873, the German immigrant to the United States, Levi Strauss, created the worker’s trousers “jeans” which were dyed blue with Indigo. The classic English blue police uniform was also dyed with indigo.

True indigo has become less common over time. First, it was the German chemist Adolf von Baeyer who succeeded in extracting the dye synthetically, and a few years later, in 1897, the German company BASF patented its own synthetic indigo, a color that is now sold under the name Indanthrone.

As far as artists’ colors go, almost all that can be obtained today are just a mixture of black and blue paint, maybe with a little red as well. True indigo is hard to find, but it does exist. There are several small manufacturers of genuine Indigo watercolor paint, which can be found using the Internet. Of major manufacturers, I have only found four:

• Kremer – Indigo NB1
• Schmincke – Indigofera NB1
• A Gallo – Indigo NB1
• Maireriblu – Indigo NB1

All other manufacturers of watercolor paint, which have a color they call “Indigo” is either synthetic, or a mixture of black and a little blue and maybe even a red color. However, this text is about genuine Indigo, so the mixed and synthetic colors are not covered here.

Indigo is an intensely blackish warm blue color. Like other organic pigments, it has shortcomings in terms of light fastness. Some manufacturers describe the color as very durable, while others say it is less lightfast. But the truth is that already after a year of sunlight, the color is clearly faded. The synthetic variety PB66 (Baeyer, 1870) suffers from the same lack of lightfastness, while the other synthetic: PB60 (BASF, 1897) is durable.

The color is semi-transparent to semi-opaque and quite staining. It is not granulating, but you can see that it is slightly flocculent. It doesn’t lose much value when dried, but the color tone becomes a little less blue. The paint likes water, it is very mobile in a wet surface.

Genuine indigo is not as colorful a blue as Indanthrone or most mixed varieties, it is more greyish. But it is a beautiful color, as if it had been more lightfast, I would recommend it above all mixed colors. But the lack of lightfastness makes the color more doubtful to use for paintings that will hang on a wall. Indanthrone is a better choice for the artist who cares about such things as durability.