Indigo Mysteries

So we had extracted indigo, concentrated and dried it. During that process, we witnessed the colorless, water soluble, indican oxidize and change into the blue, insoluble, indigo.

To use this blue indigo as a dye, we would have to remove that oxygen atom and change the indigo into leuco-indigo. Leuco-indigo is a colorless, water soluble substance, very much like the indican. With this we could dye cloth by soaking the cloth in leuco-indigo and then exposing it to the oxygen in the air. This would return the leuco-indigo to indigo, but now trapped inside the tiny spaces in the fibers of the cloth.

Now there is a mystery already. Indigo the dye, is blue.


But the word indigo also refers to a color, which is not blue, but rather the color between blue and violet in the rainbow. So while indigo dye is blue, our language "remembers" the word indigo as the name of a color different than the dye now mostly used to dye denim blue. There is the hint here that once upon a time, indigo dye was not exactly what we would call blue. A hint that once indigo could dye cloth the color we call indigo.

That brings me to another mystery about indigo. As I said, we would have to strip the oxygen atom off the indigo to make it water soluble so that it could permanently dye cloth. Very nearly every human culture has worked indigo. Confronted with the challenges of this dye, most cultures found a way to make it work. These methods that were developed range in complexity from the Northern European method to the Japanese method.

In Europe the method devised involved using a vat of stale urine to reduce the indigo. As the urine decomposed, it produced ammonia. Bacteria that thrived on rotting urine and ammonia produce hydrogen gas. This hydrogen stripped the oxygen from the indigo. It is said that there was an unpleasant odor associated with this process.

In Japan the method devised involved composting the leaves for many months, then mixing them with water, plant ash extract (potassium hydroxide and some sodium hydroxide), sake, and wheat bran. This all required painstaking attention from a master indigo producer.

We were looking for something in between the Japanese method and the European method.

From many different recipes for fermentation vats, we learned that urine is not absolutely required. Nor is sake. So we worked a fermentation vat using indigo blue, masa (nixtimal) , and calcium hydroxide.

This didn't work.

Here was a keen frustration. While researching the extraction process it became apparent that most if not all of the descriptions of the process were simplified. That is to say, certain steps were left out of the instruction, or the reason for various steps was not explained. Indigo was at one time a highly competitive industry and it seemed that all the "trade secrets" had been left unpublished.

Despite the lack of information and some misdirection, we had managed to extract indigo. Now we were having a terrible time reducing it so that we could dye cloth. So many little secrets to the process had been worked out in previous times, yet now, it felt like they might be lost.

Eventually I ran across a Liberian legend concerning indigo. In the legend several ingredients are mentioned.

After a long time of weeping, Asi falls asleep. The water spirits come to her in a dream. They tell her that for blue to come down to earth and stay, these things are needed: salt, urine, and ashes to live with the leaves of the indigo. Now that the water spirits had Asi's child instead of Asi, they made an end of requiring sacrifice from Asi. She was ordered to teach the old women of her people how to make blue go for down and stay.
The indigo leaves must be placed in a clay pot with clean river water, with salt that is leached from wood ashes, and the urine of a young girl. As the dye women of Foya Kamara stir their dye pots and wait for them to ferment, they bless the memory of Asi, whose child was sacrificed in order for them to have their skill in bringing down blue and making it stay.
http://www1.umn.edu/ships/modules/chem/indigo.doc

Even here there is a slight discrepancy. In the first quoted paragraph salt is mentioned as an ingredient. In the second, salt is described as leached from wood ashes. That would be lye, or potassium hydroxide, not sodium chloride.

Most of the recipes I found use sodium hydroxide. But it is always suggested that this is needed to bring up the ph of the dye vat. It is never hinted that there is any other reason. So we were using calcium hydroxide which was easier for us to obtain and would raise the ph as well as sodium hydroxide.

As I mentioned, the indigo was not reducing properly in our dye vat. It did not change to yellow or green. It remained blue, and insoluble.

So I (everyone else had lost interest) was left with a number of mysteries regarding indigo. Why is it now considered to be a blue dye when once it probably actually stained indigo? What is the best time during extraction from leaves to add caustic? Why was I having such difficulty getting it to reduce in the dye vat?

This is about where I was at with indigo when we lost a sheep and I was a bit distracted from posting about indigo. I was also becoming discouraged that I would ever understand the old technology of using natural indigo.

The development of synthetic indigo began in 1865 and began displacing natural indigo by 1897. After more than one hundred years, synthetic indigo had displaced natural indigo in nearly all the dye pots in the world. The advanced techniques for working with natural indigo had been abandoned as even dyers in the most rustic of places switched to the cheaper synthetic indigo over two generations ago. Deep in Africa the dyers were using the same blue that their grandparents had used, synthetic indigo. It seemed that all that remained was the most basic understanding of a precious human technological treasure.

Something then happened. I will share that in a separate post, because it is possible that I will later wish to delete what I write about what happened next.