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a happy accident

Posted on Sep 23, 2010 by in indigo, natural dyes, shibori |

Sept. 2106 addendum: The post below describes one of my early experiments dyeing with my fresh indigo plants, but I used a synthetic reduction agent called Thiourea dioxide. Preferring not to use any chemicals, I am presently experimenting with a few different natural vats, based on information from Michel Garcia, via Maiwa. Recipes here.


My third Japanese indigo (Polygonum tinctorium) dye bath created a very unusual dye color. In retrospect I realize that perhaps I didn’t add enough color remover to take out the oxygen, which is required for the dye to work. (There’s a good explanation of this chemical change on Wikipedia.) My mistake caused an interesting color shift. Or at least that’s what I think caused the color shift. It could also be that I added too much baking soda so that the vat was too alkaline. I need to research this more.

I had harvested the leaves on August 30th, let them soak 24 hours, but after heating the liquid to 140° F, I didn’t have time to continue, so I let the jars stand another 24 hours. On September 2nd, I strained out the leaves and squeezed them to get out all the liquid, and then heated the liquid to 140° F again. After that I poured the liquid into a bucket, added the 2 tsp. baking soda for each gallon of liquid and wisked it until a blue foam appeared. Then I dissolved 1 Tbsp. of color remover (Thiourea dioxide, purchased from Dharma Trading Company) in warm water for each gallon of liquid, mixed it gently into the dye bath, and let it sit for 45 minutes.

I had used a shibori stitching technique to create a design on a crepe de chine scarf, which I then proceeded to wet and immerse in the dye bath. After soaking different parts of the scarf in the dye bath three separate times (anywhere from 5 to 15 minutes each time), and letting it hang in the air for 15 minutes after each immersion, I realized that it was not turning the dark indigo blue that I was used to seeing.

stiching on silk scarf

stitches pulled tight to resist dye

during the dye process

I noticed that there was a slight film on the top of the dye bath, and was wondering if this was indigo pigment, so I mixed in a bit more color remover dissolved in warm water, and let it sit for 20 minutes. (I have since learned that the iridescent film on top of the dye bath is normal, and is a result of oxygen interacting with the dye on the surface.)

I dipped the scarf two more times and let it hang to air after each dipping. The result was a surprising and lovely celadon color! I have no idea if I will get that color with indigo again, but it was a happy accident.

unexpected color from dye made from Japanese indigo (Polygonum tinctorium)

After dyeing the scarf, I added a large skein of yarn that I had dipped once in my first indigo dye bath, and twice in my second indigo dye bath on August 13th. The more times the yarn is dipped, the darker and richer the blue color. Below is a photo of a similar skein of yarn that was dipped a total of 3 times, in my first and second indigo dye baths. It actually looks darker than it appears in this photo. (See the scarf I knitted with the yarn below here.)

yarn dyed with Japanese indigo

Lastly, I added 2 small skeins of yarn to the dye bath, and they came out a lovely pale aqua color.

pale aqua from indigo dye

Now my indigo plants are all blooming, and I will be saving the seeds to share and to grow more plants next year. I plan to pluck a harvest of leaves from the stems to make one more indigo dye bath, which I will do in the next week or two.

Japanese indigo (Polygonum tinctorium)

At the end of October I am taking a class that will be taught by Rebecca Burgess on how to process indigo into balls that can be saved and used later. This will be very useful, since it’s not always convenient to use the indigo when it’s fresh. More on that after the class. The class will take place at RDI in Bolinas, as part of their Re-skilling Series and registration information is found on their website.

Last weekend Rebecca taught a class on natural dyes there, which I will write about in my next post.