Saturday, 19 September 2009

Japanese Indigo, part 3

For a second time, I filled a jar with leaves from my Japanese Indigo plants, covered the leaves with water and left them soaking.

(Other names of this plant are Persicaria Tinctoria, formally Polgonum Tinctoria, also called Dyer's Knotweed).

There were less leaves in the jar and I left it for 9 days (instead of 7) because I was busy with other things. The yellow colour of the liquid around the leaves seemed more soupy than before. It had stood in our kitchen, which was generally around 20 degrees centigrade. I took the jar as before and heated slowly in a bain marie to 68 degrees centigrade, after an hour I took it off the heat and let it cool a bit before draining off the liquid.

When this was done the leaves time were a slimy mush. Last time I used this dyestuff I had not left the leaves soaking so long beforehand and the residue at this stage was more like over cooked spinach, this time they were more like something out of a stagnent pond. That's what they smelt like too!

This method produced a much greater quantity of blue dye, even though there were less leaves. In the photograph below you can see the results of my first dyeing session on the right (100g wool, approx 30g silk) the yarns on the left (200g wool) were dyed from the second jar of leaves.

Knowing that the photo sequence I posted in part 2, showing the colour change, was of particular interest to several readers, I took some more photos of what happens as the dye oxidises. I tried to count seconds as well, but found that a bit tricky as well as holding the yarn and taking photos. I think it was less than 5 seconds, certainly not more than 5. (Please note this picture is a series of 5 photos that I have pasted together.)

The yarn looks shiny here due to being wet, and a bit more turquoise than it was when rinsed and dried.

I think that maybe the last Japanese Indigo session this year. However, I may have enough woad to give that a go (about 5 plants have survived inspite of the greedy slugs) and I have a purchased sachet of "natural indigo" to try out.

I'll be letting my plants regrow now, and expect them to flower in October / November and then produce seed for next year. I have 3 plants that I did not cut back flowering on a windowsill in the house already. I'm told that keeping seed of at least 3 plants is important to ensure genetic diversity in the seed.

Just a note about indigo in general - Persicaria tinctoria (originally from Vietnam and south China,long used in Japan and China) is just one of a large number of plants that yield indigo. Others popularly used for dyeing include:
Isatis tinctoria, the European plant "woad" called "pastel" in french);
  • Isatis indigotica - a relative of woad found in China;
  • Indigofera arrecta, originally from east Africa, also grown in Indonesia and the Phillipines;
  • Indigofera cerulea from north west India;
  • Indigofera tinctoria, from tropical Asia, probably originally India;
  • Indigofera suffruticosa, used in ancient civilisations of Mexico and in Peru, later introduced to Indonesia.
Other sources of information:
For anyone who wants to learn more about this dye plant, I recommend Teresinha's Wild Colours website. She is offering seed for sale, and I'm sure she is a good source for seed as it seems to be very important that the seed is fresh. Seed I purchased from a large seed company a couple of years ago did not germinate.

A Dyer's Garden, Rita Buchanan, pub. Interweave Press, 1995, ISBN 1-883010-07-1
two pages about the Japanese Indigo (under the name Dyer's Knotweed) and how to grow it, two more pages on dyeing with indigo plants.

A Weaver's Garden, Rita Buchanan, Dover Publications, 1999, (abridged version of longer text published by Interweave Press in 1987), ISBN 0-486-40712
18 pages on Indigo, which includes chemistry, history, dye instructions, and a page and a half dedicated to Japanese Indigo (under the name Dyer's Knotweed)

A Dyer's Manual, Jill Goodwin, 2nd edition Ashmans Publications, 2003, ISBN 0-9544401-0-2
A very useful book on dyeing from plants you can grow or find in hedgerows which has a whole chapter on "Indigo" including woad and Japanese Indigo (under the alternative name, Dyer's Knotweed).

Natural Dyes: Sources, Tradition, Technology and Science, by Dominique Cardon, published in June 2007 by Archetype Publications Ltd.
The most wonderful reference book imaginable for anyone seriously interested in natural dyes, and the only book I have found that is really good on the chemistry of natural dyes.
I have the original French edition (cheaper, bought from
Le Monde des Teintures Naturelles, par Domonique Cardon, pub. Belin, 2003, ISBN 9-782701-126784-01.

I also have to recommend the Guild I belong to, Online Guild of Weavers Spinners and Dyers. I was given the seeds and dyeing instructions by a fellow Guild member, and several members of the Guild have been involved in a valuable discussion this summer about our experiences of growing and using the plants.

This link gathers together all my posts about Japanese Indigo (in reverse order).


Life Looms Large said...

This post makes dyeing seem really appealing to me (well, except for the stagnant pond smell part!)

Thanks for the great picture of how quickly the yarn changes color.

I look forward to whatever you create with all of this fabulous yarn.


Barbara Blundell said...

Hi Dorothy,
glad to see that you are well enough to continue with the dyeing. What fantastic results and beautiful colours ! Must be exciting and satisfying to start with plant seeds I've only used indigo and synthetic powders
The turquoises one looks interesting

Peg in South Carolina said...

Here in South Carolina we can actually grow indigo, which had been used extensively in Africa and gave the bluest of blues. The British had to use the plants you used as a substitute because idigo will not grow there. It has a rather strange history here, tied up with slavery, but you might like this description I found:
Slaves placed the cut indigo in the "steeper," a large tub filled with water and sank the plants with logs or stones. In about 12-24 hours, the indigo began to ferment, making the water bubble and turn amber-green as it drew the pigment grain from the leaves. Although the colonial dye-makers described the putrid smell of the rotting indigo, they did not realize that the indigo was oxidizing, forming a liquid chemical now known as indican.

The fermented mixture was drawn down into the second "beater" vat where trash was picked out of the liquid and it was churned with paddles by the slaves to add oxygen until it turned green and then violet-blue, around two hours. Continued churning caused the indigo to condense into specks, then flakes, which sank like mud to the bottom of the vat, separating from the now clear water. (The addition of limewater hastened the process, but seems to have precipitated other particles, resulting in an inferior indigo.) Contemporary drawings show that sometimes, slaves stood inside the vat and beat the mixture with poles.

The water was drawn into the third container, leaving the indigo at the bottom of the second vat. Slaves spooned the pudding-consistency indigo into cloth bags to drain overnight. The next day, they packed the blue mud into square, brick-size containers with drainage holes. After additional pressing and drying, slaves removed the indigo from the molds and cut it into squares roughly 1½ inches in size. When completely dry, premium pieces of "pigeon neck" indigo were a sparkling, iridescent dark blue, light in weight and very hard.

"Indigo dye is not water soluble (the reason why it separates in the second vat) so when ready to be used for dying it was dissolved in stale urine, tannic acid, or wood-ash. The stinking mixture would then be introduced into water, producing a yellow-green solution. Cloth dipped into the dye solution turned yellow-green until it was removed from the liquid and exposed to oxygen--then, almost magically, as the cloth would dry, it would turn blue. Slaves who worked in the dye-houses were easy to identify; their hands were stained blue."

Laritza said...

I read your blog with interest and many others. Not my case, I think only a couple of people read mine. That's OKwhen I write I like doing it. That is what matters.

Dorothy said...

Thanks for your comments, Sue, Barbara, Peg and Laritza.

Peg, that's very interesting about the history of indigo & slavery in America. For most of us, our basic knowledge of what indigo dye looks like comes from our blue jeans, often made in the US or by US owned companies. (Although it's synthetic indigo now.)

Laritza, I'm one of your blog readers, and I enjoy the comments you leave here and on other blogs too.

Sue, weaving with these yarns is going to be a different kind of challenge! I'm nervous about it, they seem like specially valuable yarns now and I want to do something that turns out well.

Lesley said...

Hi Dot,
I'm sure this has been looked at before, but is there any dyeing potential in that bane of our life down here in Devon - the Japanese Knotweed? Also Himalayan Balsam which is equally troublesome here smothering everything in it's relentless march along river and stream banks.

Meg in Nelson said...

It looks like much patience is needed for this. Lovely stuff, but for now, I'll just enjoy it via yoru posts!

Do please post the picture of the indigo flower in due course.