Just What is Indigo?

Just what is indigo? Most of us start out thinking we know, but do we?

The term indigo is, of course, used as the name of a color. To me it is
a deep navy blue with an ever-so-slightly greenish cast. But this is the description of the color called ai (藍) in Japanese. When indigo appears as one of the seven colors of the rainbow in the West it exhibits a slightly reddish cast.

Indigofera tinctoria – “true” indigo from India

Next, most of us would list it as a plant. But, which plant? Perhaps Indigofera tinctoria, commonly called true indigo? This is the one associated with the blues of India. It grows as a shrub and is in the legume family of plants along with beans and wisteria. It likes a tropical climate. The basic material we extract from the leaves to create blue is called indican.

Indigofera suffruticosa from the Americas

But indican is found in many other plants and in many other parts of the world, such as Indigofera suffruticosa. Even though it is commonly called Guatemalan indigo, this plant is native to most of the tropical and subtropical areas of the Americas including the Southern United States and all the way down to the northern reaches of Argentina.

Indigofera bracteolata – West Africa

Indigofera bracteolata grows well in the moist savannah lands of West Africa and thrives in sandy soil.

Isatis tinctoria – woad, covering Europe and the Middle East

Woad, Isatis tinctoria, is another common source of indican. It is native to the steppe and desert areas of the Middle East and Central Asia, and is related to mustard and cabbage. It is the plant associated with the blues of Britain, going all the way back back to the Celts.

Marsdenia tinctoria – covering Southeast Asia

Marsdenia tinctoria is commonly found in subtropical regions including Nepal, Thailand, Burma, and Indonesia. It is a winding shrub or vine that can grow up to fifteen feet long. It is related to a plant called dogbane.

Persicaria tinctoria – tadeai, or Japanese (buckwheat) indigo

And in Japan there is tadeai (蓼藍), (Persicaria tinctoria), also known as Polygonum tinctorium, or Japanese indigo. It is an annual that grows up to about three feet in height and grows well in temperate climates. It is classed with buckwheat.

Mercurialis leiocarpa – Japanese yama-ai

Strobilanthes cusia – Ryuukyuu-ai, Okinawan indigo

But even in Japan there are more plants than just tadeai that contain indican. There is yama-ai (山藍), Mercurialis leiocarpa, a slender perennial that hugs the ground.  Ryuukyuu-ai (琉球藍), Strobilanthes cusia, has leaves as large as a person’s hand. It is in the acanthus family and has been a long-time favorite source of blue for collectors of Okinawan textiles.

And of course, there is synthetic indigo. It made its first real commercial appearance at the tail end of the 19th century (1897) and quickly replaced the more laboriously produced natural sources. The actual core colorant of all of these sources, including the synthetic, are chemically identical. Slight visual variations can be appreciated among the numerous natural sources brought about by differing impurities in the plants or unique extraction techniques.

If you are interested in browsing a beautiful collection of photos of Indigofera, visit JuiceyImages, or this page of the Chinese Herbarium.

Fresh-Leaf Indigo, It’s Magic!

As a child, do you remember ever rubbing flowers and leaves between your fingers, perhaps smearing them in a coloring book hoping to preserve the beauty of that moment? Unfortunately, without some assistance most colorful plants won’t give us much more than a spinach-spittle brown.

Pokeweed berries are a wonderful temptation in red for young children’s artistic expression. Unfortunately for the tykes, it is poisonous.

Indigo, however, is one of the exceptions.
Try this: Take an indigo leaf (any of the varieties will do) and rub it well into the palm of your hand. Wait a moment and just like magic it will turn from green to blue and even remain on your hand after you wash it! While it is not the green of the leaf, it is something far more rare.

Magic!

The magic of indigo, even in this simple and direct method, is the expression of the blue as it breathes in fresh oxygen. Can’t you just imagine it coming to life in the palm of your hand as you watch it at first timidly, and then boldly declare its true nature?

All forms of indigo dyeing involve this concept of taking on oxygen to express the blue. The color essence contained in the leaf is called indican. It is colorless and water-soluble. In the presence of water it breaks down into β-D-glucose and indoxyl. It is this indoxyl that produces indigo blue when exposed to oxygen. Getting from here to there successfully is the joy of growing your own plants and exposing the beauty hidden within.

Let’s start with one of the most direct approaches, similar to the hands on method used above. Collect several nicely shaped indigo leaves. All varieties work, but what you have been able to grow will depend upon the climate in which you live. I live in the mountains of Northern California, so Japanese tadeai is my pet plant. It grows well in temperate climates.

The two leaves on the right were transferred using a large marble bead to give a pointillist look. The full leaf on the left was transferred using a wooden mallet – the flat surface of the mallet allowed for greater detail and definition. The partial leaf, on the far left, has additional lines of aibana pigment applied for definition. This will be explored in a later blog.

Prepare some silk, wool, cotton, or hemp (that is to say, any natural fiber) by washing thoroughly. Once dry, make an attractive arrangement with your leaves. Lay a plastic bag over the top and have at it with something hard. A mallet will work, but so will a large bead, rock, or that Tonka Toy you tripped over in the dark last night. Each has its own unique texture and will affect the outcome of the image transferred. Feeling better? Remove the plastic and peel the lacerated pulp from the surface of the cloth. Can you see what is happening? This is simply a more controlled version of the hand trick above. Allow the fabric to oxidize for a full day before washing to allow the blue to fully develop. Each leaf contains a different volume of indigo allowing for a wide range of variance. If the transfer is splotchy or ill defined wait until you are having a worse day and try again.

Arranging fresh tadeai leaves

Using an embossing machine to transfer a large arrangement of leaves. In this case the leaves are sandwiched between two layers of yardage–one hemp and one wool.

Pressed leaves on silk jacquard

Fresh-Leaf Cold Vat Scarf by John Marshall

 

The image at the left was dyed with the help of my sister and brother-in-law.  I put them to work picking and chopping leaves, dunking and wringing. The silk was immersed in a cold-water, fresh-leaf vat for about an hour. Once dry, I pounded in the image of the leaf with freshly picked indigo from my garden and a handy rock.

(click on the image to the left or just below for more information)

 

Left: John at work: Scruffy and unkempt, I’m in my element! (Notice the green of the scarf I have just pulled from the cold-water vat.) Right: Sienna is keeping an eye on us to make sure that there are no slackers. (You can see in this shot that the dye has oxidized into a beautiful robins-egg blue.)

While not as therapeutic, the wringer from an old washer or an embossing machine will give equally splendid results.

I live in an old flour mill. During renovations many boards were exposed that were worn smooth by particles of flour over time. Several of these have quite beautifully raised grains as seen in the rubbing below created with the help of the board above.

And this is just the beginning! Try placing your handkerchief over the bark of a black walnut tree or your mother-in-law’s tombstone, roll the leaves into a wad and rub vigorously. Just like transferring the image of a coin to paper with a pencil, the image beneath will be transferred to the surface your cloth. You are only limited by your imagination and the forbearance of your family.

My studio as viewed from the back. The tadeai indigo patch is in the foreground.

Cold-Water, Fresh-Leaf Indigo Vat Dyeing

Textile of the Week cards – scroll down to the bottom of this page for more details

Let’s take a look at using fresh-leaf indigo in vat form. I’d like to begin with the various shades of robin’s-egg blue, now that you have had a chance to try your hand at direct contact with indigo leaves in Fresh-Leaf Indigo, It’s Magic!

Eggs of the mapuche chicken – Who wouldn’t love these colors?

We’ll take a beginner’s look at the most basic form of indigo vat – one made simply from fresh leaves and cold water. I’ll be using the Japanese tadeai indigo, but other varieties will work well, too.

John harvesting tadeai just after sun up

Just after sunrise, on a cool mid-summer morning, use a scythe to gather a small basket full of fresh leaves. Choose plants that look healthy and are deepest in color, preferably ones that aren’t yet in bloom.

 

Add the leaves to a blender with ice water and churn until the leaves are thoroughly pulverized. Strain. The resulting liquid is your vat and you are ready to go! This particular vat works best with protein-based fibers, so primarily silks and wools.

Straining the pulverized tadeai leaves through a polyester rag, cookie brittle is optional

Wash your material thoroughly and rinse in cold water. The longer you soak the material, the richer the robin’s-egg blue. Whether you are using yarns or woven yardage you will want to keep the fiber moving for the most evenly colored results. You may simply swish the material periodically, or you may suspend it from rods and continuously turn it. Whether it is a books-on-tape thriller, or simply the neighbors going at it again next door, make sure you have something prepared to occupy your mind since this will take up to an hour or more for the color to develop.

The yardage has been sewn together at the ends to create a loop. Using a set of dowels to help hold a portion of the fabric above the vat, John is picking up and pulling the fabric toward himself as the silk cycles through the dye below.

Remove the yarn or yardage from the vat, wring, rinse, dry, and you’re done. Since this vat is pH neutral, there is no need to subject the dyed fiber to a vinegar rinse. In contrast, many Japanese like to give it a dip in a slightly alkaline solution (1 teaspoon of calcium hydroxide dissolved 3 gallons of tepid water). However, this does have the potential to take the color just a bit to the indigo-gray side.

Clamp resist on silk leno in fresh-leaf indigo vat

This method works wonderfully with resist techniques that can hold up to prolonged exposure to cold water, such as kasuri (ikat), rozome (batik), and clamp-resist methods.

Three samples of fresh-leaf, tadeai vat indigo: fresh leaves with silk (left); fresh leaves on ramie with a little calx (calcium hydroxide) added to the vat (center); and fresh leaves and calx on cotton (right)

So what about the cellulose fibers? Not to worry. We need only take the pH of the fresh-leaf vat from neutral to around 10.5 by adding dissolved calcium hydroxide (chalk) to a fresh vat and allowing the mixture to simply sit for about an hour. Repeat the steps you followed for the silk. You should wind up with a very beautiful blue –not quite as lively as the fresh-leaf dye on silk, but still a very refreshing turquoise.

This go around, the Textile of the Week samples are presented in a cluster of four to show off the range of colors available with the noncomposted, raw, fresh-leaf tadeai dye.

 




Click on the button to  purchase Textile of the Week sample below, 201520, $14.

Fresh-leaf vat after just one dip, silk damask (donsu)




Click on the button to  purchase Textile of the Week sample below, 201521, $14.

Fresh-leaf vat after two long dips, crinkle-weave silk.

The fabric above is silk, as are the other samples on this page. This particular weave is called chijimi, the weave structure will be covered in a future blog. It scrunches when wet and must be stretched out again before using it to sew.  But the scrunching brought out an interesting trait of the fresh-leaf indigo when used as a simple cold vat.

The weave structure forced the fabric to scrunch up tight once wet.

I imagine you were paying attention when I mentioned above that you must keep turning the fabric in the cold vat to prevent streaking. If you simply dump the material into the vat and come back later, the areas exposed to the larger volume of liquid will have a greater pool of colorant to pull from, even though the dye is uniformly dissolved in the water initially. Think of the person who walks into a room and seems to suck all of the oxygen out of it. That kind of person lessens the odds that there will be enough oxygen to go around – and your odds are decreased the closer you stand to the offender. The fiber is doing just that – sucking all of the color out of the liquid in close proximity. So bunched areas will quickly deplete what pigment is available to them. The surfaces on the perimeters are able to pull from passing currents and realize a deeper more fulfilled experience.

Or just cram it in the pot and be done with it. Streaks work. See below.

Uneven absorption of the indigo caused by the scrunching of the yardage when wet. This sample has been ironed out flat to exploit its visually eccentric nature.

This is the same yardage rinsed and ironed flat. The peaks (the exposed areas of the scrunched yardage) have absorbed the greatest amount of color and the valleys remain pale.

The same yardage as above, draped.

The same yardage as above, draped. The folds show off the iridescent quality the varying shades of indigo impart. Notice the little sticky-out bits of yarn, making it look a bit like a case of shingles? This is actually a very sought after and expensive look. It is called hige-tsumugi, or bearded slub weave.

 




Click on the button to  purchase Textile of the Week sample below, 201522, $14.

Cold-vat, fresh-leaf indigo vat with calx, one dip, Japanese silk jacquard (rinzu)

 




Click on the button to  purchase Textile of the Week sample below, 201523, $14.

The samples above and below have been dyed using the same yardage from the same bolt of Japanese silk jacquard (rinzu) to help you gain a better appreciation of the range of shades available. Both have been dipped into the same fresh-leaf indigo vat outlined above. They appear grayer than the first two samples because a little calx (calcium hydroxide) was added to the vat to bring up the pH a bit. The sample above was dipped once, and the sample below twice.

cold-vat, fresh-leaf indigo with calx, two dips, Japanese silk jacquard (rinzu)

Kimono Dyed with Cold-Water, Fresh-Leaf Tadeai Indigo

Below are two exquisite examples of fresh-leaf indigo dyeing in solid color. Both were executed with just the cold-water vat and no additives. The difference in color is due primarily to the length of time each was soaked in the vat, and of course the crop and month in which the leaves were harvested.

The labels were originally attached to the ends of the bolts, and as is often the case, that bit of remnant was tucked into the sleeve of the kimono to keep it from going astray.

Label describing the quality of the weave

皇后陛下
振袖生地製織工場謹製

The Empress of wearing a fresh-leaf indigo dyed kimono

皇后陛下がこの成婚の祈に宮中御内宴の席でご着用になった振袖生地を製織した由緒ある製機工場が、その誇りを失うことなく丹精を込めて織りあげたちりめんです。
丹後•大啓産業

Her Majesty the Empress
Furisode Yardage Woven with the Greatest of Care

Having been selected for our long history of producing quality weaves, we are very proud to have been able to produce this furisode-length bolt of chirimen for Her Majesty the Empress to wear on the occasion of the court dinner to offer prayers for the marriage (of her son, the Crown Prince).
Tango, Daikei Industries

 

Imperial Chrysanthemums–Detail of the inside of the right hakkake (lining on the lower inside of the kimono)

堅牢草木染
堅牢草木染は、古来中国から伝わる草木染の技法をもとに現代の特殊な技法を用いた染色する方法で、日本の美を生かした深い色調と風格は堅牢草木染ならではの味わいです。

Kenrou (Fade-Free) Natural Dyes
Today, thanks to kenrou natural dyes, we are able to experience the rich tones and subtle personality of naturally dyed textiles produced using the cherished techniques brought to us from China so very long ago.

Single crest in center back

Back view–notice the one spot of embellishment to right. It will be hidden under the left side of the kimono as the panels (okumi) overlap when worn.

Jacquard-weave rinzu (crepe) in Imperial Chrysanthemum pattern

One crest in the center back of the kimono, identical to the one on the kimono above

本草木染
草木染は古く中国で発達し、その後我が国に渡来し、日本古来からの技法と調和しました。野山に樹生する草木の花•実•葉•茎などを原料として、自然のままの美しさを、生地に染め上げた草木染秘宝に、現代の染色技法を取り入れました。自然植物による染色は絹の風合を生かした光沢ある色彩になり、また月日の経過によって深味のある落着いた色になります。

Natural Dyes
Natural dyes developed in ancient times in China were brought to our country, and since this earliest contact we have lived in harmony with these techniques, incorporting them into our modern set of skills. Flowers, fruit, leaves, and twigs are the raw materials of the mountains and valleys of our nation. We cherish the beauty of nature incorporated in woven treasures. Colors dyed with the plants of nature bring out the unique texture and luster of silk and with the passage of time only grow deeper and more nuanced.

伝統染色技法
古く古来から伝われる京染染色秘宝を忠実に再現し、現代風にアレンジした書画期的な染色技法です。
万雄彩

Traditional Dye Techniques
The skills passed down to us from time immemorial have been faithfully reintroduced through the treasured dyed textiles of Kyoto while introducing a modern design sense.

Japanese textiles, dyeing, weaving, culture, John Marshall, katazome, somemono, natural dye