Discharging of Indigo Dye

It is my belief that learning about natural dye takes a whole community of people who are willing to experiment, observe, and share. The sharing has been the most rewarding part of my own journey in natural dyeing. I have met many dyers, both in person and virtually, who are willing to be part of that communal knowledge base.

While my co-author,  Joy Boutrup, and I were preparing and writing The Art and Science of Natural Dyes, we experimented with potassium permanganate, a strong oxidizing agent that can be used to discharge indigo. It provides a unique approach to removing indigo dye. When combined with resist, such as “itajimi” clamps, wonderful resist patterning will result.  Changing the chemical treatment will result in a “permanganate brown” color. When the textile is pre-treated with a tannin, it is possible to achieve even darker brown colors juxtaposed with the indigo. All of these recipes/processes are included in the book. 

But direct application or printing with the potassium permanganate proved problematic. Any gum used to thicken the mixture rendered it chemically useless for discharge. In the book, we included a resist paste made with soy flour and lime (calcium hydroxide) in order to achieve some controlled resist printing effects. I had learned to make this paste while in China and found that the paste could be used as a resist for the potassium permanganate solution.  Unfortunately, the soy/lime paste, although effective, is harsh and very difficult to remove from the textile. 

After The Art and Science of Natural Dye was published, we received an email from Zoë Sheehan Saldana, an artist who has been using potassium permanganate. She experienced the same challenges when printing – but she solved the problem by thickening the potassium permanganate with a fine clay. The clay is inert and does not interfere with the chemical oxidation of the indigo.  Either bentonite or kaolin are suitable clays. These are the same types of fine clay that are used with the indigo resist paste. The printed application of the paste in her bandanas results in an even discharge and the printed patterns become pure white.

Use enough clay to achieve a suitable thickness for painting or printing with a screen. Varying the amount clay, as well as the application method, will result in hard lines or soft edges. When painted on, rather than printed, an uneven layer of the paste and the discharge can result.

Mix the paste in small batches, making only the amount that you think you will need.  The paste is most effective when used fresh, but if kept tightly covered it can last for a couple days.

Indigo discharge, using a painted application, by Amanda Thatch. taking advantage of the uneven thickness of paste that results from the brushed on application.

During this week of the United States holiday of Thanksgiving, I am grateful for the community of dyers and experimenters out there, who are willing to share and make our knowledge base stronger. Thank you. Happy Holidays!

Madder for the Indigo Vat

It is exciting to see such a passion for indigo these days, and especially the active exploration that is happening. With this also comes with a deeper understanding of indigo dyeing and process. 

Vats reduced with chemicals such as sodium hydrosulfite or thiourea dioxide used to be the norm when I first learned indigo dyeing in the 1970’s. But now, many dyers have abandoned those chemical reduction vats and are returning to more benign processes. They are now making quick-reduction vats that are reduced with sugar, fruit, plants, or iron – thanks to the teaching of Michel Garcia. Some are growing their own indigo to explore fresh leaf dyeing and pigment extraction. Others are making sukumo – a long process of composting persicaria tinctoria leaves – Thank you Debbie Ketchum Jirik for offering an online class this past fall. Recently, Stoney Creek Colors has introduced a natural, pre-reduced indigo. And more dyers than ever are now exploring vats that are reduced by fermentation.

Fermentation is the process that has captured my interest in recent years. The long-term committment seems to fit my own “stay at home” life right now. The lower pH is suitable for all fibers. Most of all, it’s been an interesting adventure. Something that once felt out-of-reach has now become my preferred process. 

The fermentation vat utilizes plant material to initiate and maintain an alkaline fermenting process, which causes the indigo to become soluble. During fermentation, plant material is broken down, creating bacteria. Lactic acid is produced, making it necessary to monitor the pH on a regular basis. 

Madder root is a common plant material used in a fermentation vat. There is a long history of its use in indigo vats. It is usually combined with wheat bran, which ferments readily. There are many recipes in old manuals for this Madder Vat.

From The Dyer’s Companion by Elijah Bemis (originally published in 1815, Dover Edition, 1973)

for a vat of 12 barrels (not sure what a “barrel” is)

  • 8 lbs potash
  • 5 lbs madder
  • 4 quarts wheat bran
  • 5 lbs indigo

When I first leaned of these vats made with madder, I struggled with the idea of using perfectly good madder root to reduce an indigo vat. But I have now come to understand that these vats were most likely made with “spent” or “used” madder. I remember Michel Garcia talking about how the “used” madder from professional dye studios in the past was sold to the indigo dyers after it had been used to produce red dye. Indigo dyers have no need for madder’s red colorants and thus nothing was wasted. 

So, I am dismayed each time I hear from someone who has made a fermented indigo vat using “new madder root”. “Spent” or “used” madder is every bit as effective as a fermentation booster as fresh or “unused” madder. 

Most of the madder I use in the studio is in the form of finely ground roots, though chopped roots would work as well. When my madder dyebath is finished, I strain the ground roots and dry them for later use in an indigo vat. It’s that simple! And nothing is wasted. 

Equal amounts, by weight, of “used” madder root on the left, and “new” madder root on the right. Most of the colorants have been removed from the madder in the dyeing process, leaving only the starches and sugars of the roots.

Plant materials, other than madder,  can be used in the fermentation vats. I frequently use dried indigofera leaves, as well as woad balls and have even begun a “hybrid “ vat using sukumo with indigo pigment. My most recent experiments have used both Dock root and Rhubarb root successfully. Madder, Dock and Rhubarb are all roots, all anthraquinones…..

The Surprise of Indirubin!

Why would a white plastic button turn purple from an indigo dyebath?

Indirubin is one the most curious components of indigo. It is sometimes referred to as the “red” of indigo. Indirubin only occurs in natural indigo and you will not find it in a synthetically produced pigment. Indirubin is valued for its medicinal applications.

Some dyers have been successful at manipulating the extraction and pH of indigo in order to reveal the mysterious purple/red color of indirubin on a textile. I have no real experience with this process.

At one point I did learn how to analyze an indigo pigment in order to determine the presence of indirubin. If indirubin is present, it is an indicator that the pigment is made from plants and not synthetically produced.  Natural indigo has varying amounts of indirubin. The process of analyzing uses solvents and chemicals so it is not something that I want to do on a regular basis. 

I purchase all of my indigo pigment from Stony Creek Colors, as I know that their indigo comes from plants (and, consequently, contains plenty of indirubin).

Now that I maintain several large “active” indigo vats, I will occasionally dye a ready made garment. A white linen blouse is not a good choice for wearing apparel in the dye studio, but one that has been dyed a rich indigo blue is perfect. 

After dyeing, just before the final rinse, I always boil an indigo dyed textile in order to remove any unattached dye. Cellulose is boiled vigorously with a small amount of neutral detergent for about 10 minutes. Wool and silk are brought to a near simmer and held at that temperature for the same amount of time. 

Once I started using indigo from Stony Creek I noticed that the water from the final boil was always tinted a purple hue. I assumed this was the indirubin that was being rinsed from the textile. Interestingly, I observed that the purple color in the boil water is temporary, and will disappear as the bath cools. 

Recently, I dyed some linen shirts that had plastic buttons. The buttons stayed white until the final boil. When the garment was removed from the boil bath, they had become purple. I have now learned that indirubin is less easily reduced and the undissolved indirubin will stain plastics and other petroleum derived materials. Some of the polyester threads used to sew the shirts are also tinted purple. 

Summer Arrowood, the chemist at Stony Creek Colors, tells me that all the plastic vessels in her lab are dyed purple from the indirubin!

Will these buttons remain purple after multiple washings? I don’t know. There is always more to observe and learn from the natural dye process.

Slow Process

Natural dye has never been a quick way to color my textiles. First there is the mordanting, then the extraction of plant/insect material – not to mention growing, gathering, or drying the plants. Did I mention collecting seed? And what about the weaving, where I actually make cloth from threads? 

These last 18 months at home have been a chance to dive in deeper (and slower) with some processes. Just before COVID came to our doors, a friend gave me a small jar of sourdough starter. So yes, I am one of those who has made sourdough bread every week for the last year and a half. What a gift – both sour dough starter and the time to use it!

It was my fermented indigo vats that gave me the courage to take on sourdough bread making. I thought that if I could keep indigo vats alive for a number of months, then I could certainly keep a sourdough starter going as well. That has proved to be true.

The first fermentation vat was started in July of 2019. It was a relatively small vat (20 liters) but I used it a great deal. A year later it was used it to “seed” a larger 50 liter vat. The success of this first experiment gave me the confidence to start two more 50 liter vats in 2020. All are still going strong. Over the last two years I have made many additional one-liter vats in order to test reduction material, alkalinity etc. That first large vat that I created in 2019, after being used heavily for over two years, is finally giving me lighter blues.

Now I am in the midst of another slow process – sukumo. Debbie Ketchum Jirik of Circle of Life Studios very generously took a group of zoom class participants through the entire process of small batch composting of indigo leaves based on the teaching and book of Awonoyoh. Every 3-4 days we logged in, watched the sukumo being lifted from its container and stirred by hand. Does it need water? Does it need heat? What does it smell like? Conversations were focused and interesting. Several class participants were also in the process of making their own sukumo along with Debbie. I am not so fortunate. I have to gather more seed, grow more plants, and dry more leaves before I will have enough plant material to do my own composting. 

This experience has given me a far greater appreciation of sukumo. I was recently gifted a significant amount of sukumo and had planned on making my own large sukumo vat. Now, understanding more of what sukumo is, I am experimenting with using smaller amounts of sukumo in combination with my fermented indigo pigment vats. When I told my Japanese colleague, Hisako Sumi, about this, she indicated that Japanese industrial production has used this approach since early in the early 20th century. There is even name for this hybrid: “warigate”. Yoshiko Wada translated this for me as  “WARI GATE” / “split vatting” and it was mostly done using synthetic indigo. 

I have made many small test vats, using varying amounts of sukumo, in addition to indigo pigment and other materials to boost fermentation. These test vats were ultimatley used to ‘seed” a larger vat. I now have my own 50 liter hybrid vat that combines sukumo with Stony Creek indigo pigment.

My latest “slow process” is vermiculture. I recently spent an afternoon with friends, sorting worms from castings and beginning my own worm “farm”. This is another of those long term, slow processes that bring me closer to the earth, and makes me appreciate the small miracles of watching things grow. And I know that this compost will feed my indigo plants.

But not everything must be slow….

Stony Creek Colors has just released information about their newest product: IndiGold. It is a pre-reduced liquid indigo, grown in Tennessee and designed to be used in combination with fructose and lime (calcium hydroxide). I have dyed with the earlier available pre-reduced indigo but I was never sure exactly what it was and didn’t want to use the reduction chemicals that were recommended. I stopped using that product a long time ago when Michel Garcia introduced us to the “quick reduction” vats made with sugar and lime. But there are some occasions, particularly when teaching a one-day workshop, that it is impossible to make a vat and dye with it on the same day. 

Stony Creek sent me a kit for test dyeing and I was amazed at how quickly the vat was reduced and dyeing to full strength. It took only minutes – not hours. Stony Creek Colors told me that they”skip the chemicals” and use an electric hydrogenation process plus an alkaline to reduce the indigo. There are no chemical reduction agents! I used the vat all day long and it was still in reduction the next day. 

This will not replace my slow, fermentation vats but it will make “quick” dyeing possible when needed. 

Once again, Stony Creek is changing how we think about indigo and its production. They are currently posting information through a Kickstarter Campaign to support this new venture.

Black: An Improvisation

I recently took on a small weaving commission that required the use of black wool yarn. For a brief moment I contemplated purchasing the wool in the required color and then decided that I could dye it. I was surprised at how easy it was to achieve a rich, deep black color on the wool using only indigo and madder. 

Commissioned weaving using wool yarns dye with indigo blue, madder red, black from indigo and madder

It inspired me to continue my current series of color studies, woven in cotton and linen, with an in-depth exploration of black dyes. 

Initially, I wanted to achieve all the black hues without the use of an iron mordant. My years of mixing hues with primary colors gave me the confidence to believe that I could mix a good black for cellulose using 3 primary colors: blue, red, and yellow. The key was going to be finding the correct proportions. 

The first step was to build up a deep layer of indigo blue (usually 8-10 dips in the vat) followed by a mordant, and finally red and yellow dyes. That red could be madder or cochineal but I chose to use only madder, since that is what I am growing in the garden.  My preferred yellow is weld.  Each different combination results in a subtle variation. Some “blacks” are more purple, while others are a bit more green, or brown. I began using black walnut  and cutch as a substitute for the madder and weld and sometimes added madder or weld to those.  Each is a distinct hue, and definitely in the “black” family. I am confident of the lightfastness of these hues because of the primary dyes that have been used. 

Dark indigo alone, on far left + combination of cutch and madder resulted in a neutral black
close up of “black” hues in the series on cotton and linen fabrics

These multiple shades of black, put me in mind of the paintings in The Rothko Chapel in Houston, which is the site of a series of large large “black” canvases by the artist, Mark Rothko. These black canvases are painted with layers of crimson, alizarin, and black.

But no exploration of black would be complete without some experiments using tannin and iron. Instead of building up layers of primary colors, I soaked the textile in a gall nut tannin bath, followed by a short immersion in an iron bath. I wanted to use as little iron as possible, but still achieve a very dark shade. I decided that 3% weight of fiber would be the limit of the amount of iron I would use.

Most often, I use ferrous acetate instead of ferrous sulfate because it is less damaging to the fiber. Cellulose fibers are are somewhat tolerant of ferrous sulfate so I did experiments with both. That is where I was most surprised! Without exception, the ferrous acetate resulted in deeper colors than the same amount of ferrous sulfate. 

Why? I wasn’t sure. So I consulted my colleague, Joy Boutrup, who always knows these things. 

“I think the reason for the grey instead of black with iron sulfate is due to the higher acidity of the sulfate. The acetate is much less acidic. The  tannin complex cannot form to the same degree as with acetate.”

The pH of my ferrous sulfate solution was 4. The ferrous acetate was pH 6. (My tap water is from a well and is a slightly acidic pH6.)

The grey and blacks achieved with the tannin and iron are quite one-dimensional compared with those that result from a mix of colors and not nearly as interesting, Yet they are likely a more economical approach to achieving black; the multiple indigo dips, mordanting, and over-dyeing takes considerably more time and materials than an immersion in a tannin and an iron bath. 

Always observing always learning, here in the mountains of North Carolina…

Studio image of completed woven panels

The Life of an Indigo Vat

Over the years I have built, used, and discarded many indigo vats. Sometimes I have kept them going for a very long time. I have finally declared the 5 year old, 100 liter henna vat “done”. I have added indigo pigment, lime and additional henna to it many times and although it is still dyeing well, the space available for that dyeing (above the “sludge” at the bottom) has gotten very, very small. 

As many of you know, I have spent this last year at home getting to really know my fermented indigo vats. I have followed a rather strict protocol. Each vat began with a certain amount of indigo pigment, a source of alkalinity (soda ash or wood ash lye) and various plant based materials to begin and sustain the fermentation (wheat bran, madder root, dried indigofera leaves, etc.). Only small amounts of lime and bran have been added over the last year to sustain pH and fermentation. At no time have I added additional indigo.

Last May I was trying to achieve a wide range of blue shades from the very palest to very darkest. I was a bit dismayed to find that all of my vats were dyeing too dark to give me the pale shades I desired at the time.  I knew (in theory) that if used the vats enough, the indigo content of the vats would decrease but had no idea how long that would take, or how much dyeing I would need to do. No matter how much I dyed, it didn’t seem to happen.…

Now, a year after the vats were first made, I can see progress.

Indigo on cotton cloth: 1-15 ten-minute dips. May 2020

Indigo on cotton cloth, same vat: 1-24 ten-minute dips. February, 2021

Some observations:

This is a long process….

Two dips in May, 2020 gave the equivalent shade as 5 dips in February, 2021

The dark blue that was achieved from 12 dips in May, 2020 was not achieved, even after 24 dips in February 2021

The subtle differences in the darkest shades are difficult to discern from the photos – but they are there.

I now realize the value of having a number of vats: from old to new, weak to strong. It’s something I have heard Michel Garcia say on more than one occasion, but sometimes we just have to observe and learn the lessons on our own. 

This spring, I will not discard my weakening vats, but will add another vat for the strong, deep blues that I am currently needing to build up black colors on my woven cellulose fabrics. 

One Bath Acid Dyes – and “Textile Tattoos”

I have used one-bath acid dyes extensively in my own work, especially for cross-dyeing my handwoven fabrics that are constructed of both cotton and wool. The acid dyes attach only to the wool or other protein fiber. When combined with indigo, which attaches to both cellulose and protein fibers, very interesting combinations can be achieved. 

The “one-bath acid dyes” that Joy Boutrup and I discuss in The Art and Science of Natural Dyes include henna, madder, pomegranate, cochineal, lac, and rhubarb root. Since publishing the book, I have extended the palette with the addition of other dyes, mostly due to the help from Michel Garcia when he was here in my studio several years ago. 

Michel and I were discussing dyes that I might choose NOT to use because of their poor tolerance to light. Alkanet is one of those. A purple color is extracted from alkanet root by means of an alcohol extraction. The color is beautiful and enticing , but very fugitive. Michel indicated that the alcohol extraction does some damage to the dyestuff. 

The one-bath process extracts different dyes from the plant than from those that are obtained from using more traditional methods. While experimenting, we treated alkanet as a one bath acid dye (for protein fiber only) and a beautiful purplish brown color emerged that is quite fast to light. It’s a warm neutral color that I have not achieved using any other dye. 

Safflower petals are another dye source that he showed me can be used as a one-bath acid dye. A golden yellow is dyed onto wool or silk that is quite lightfast and requires no mordant. The safflower petals can still be used after the one-bath process to extract the traditional reds and pinks by altering the pH, though the red colors are still not fast to light. 

These discoveries energized my own work and as I went deeper,  I began noticing that many of the plant dyes that are used for the one-bath acid process have also been used as natural hair dyes: henna, madder, alkanet, dock, rhubarb root, cassia leaves (Cassia obovata, also referred to as “neutral” or “colorless” henna). These can all be used successfully for one-bath acid dyes and result in very lightfast colors. Dried Indigofera tinctoria leaves (“black henna”) are also used as a dye for hair and when combined with henna results in a very dark color. 

The application of henna as both a hair dye and as mehndi, (a temporary dye for the skin) is the same: finely ground plant material is mixed into a paste with water, acidified with lemon juice, and allowed to sit on the hair or skin for several hours. When the paste is washed away the color remains. These are considered non-permanent dyes for the skin and hair and may be repeated after the color fades. 

Acid dyes are very lightfast but are not as fast to washing. (This applies to both natural acid dyes and synthetic dyes.) If applied to the skin or hair, they will eventually be washed away.  BUT importantly, we don’t wash our woolen fabrics as aggressively or as often, thus the dyes are suitable for wool or silk textiles. 

I was curious to see if these dyes could be used for direct application to woolen fabrics. There is a Moroccan tradition of using finely ground henna leaf in this way on fabrics woven of wool and cotton. It is well documented in the book Die Farbe Henna / The Color of Henna Colour of Henna: Painted Textiles from Southern Morocco by Annette Korolnik-Andersch and Marcel Korolnik.

I made a paste of each of these dyes using finely ground plant material with a small amount of water. I acidified the paste with vinegar (citric acid would damage fabrics that contained cotton) and allowed it to sit overnight once applied to the textile. The colors are strong and clear, although some dyes spread more than others. They are not quite as deep as those dyed in a heated bath, though steaming the textiles will result in deeper colors. 

hand application of dye paste

I have observed that the freshness and quality of the dyes matter. Organic henna, used for hair and skin dye, resulted in a bright clear color while other henna powders that I have used produced duller colors. 

This approach has revealed to me one more way of understanding and using natural color and given me more opportunity to combining it with my own woven textiles. It has taught me more about plant categories, alternative applications, and the need to constantly be open to new ideas. 

What Size is YOUR Indigo Vat?

I now have, and am actively using, three 50 liter (15 gallon) indigo vats, in addition to a 100 liter (30 gallon) henna vat. 

I am loving the size of the 50 liter vat! The vessel is tall and narrow. It’s just the right shape for a vat, with a relatively reduced surface area, and a great size for studio immersion dyeing. I have been dyeing samples, skeins of yarn, my own shibori work, and even clothing in those vats. 

Like most dyers, I began with what I then thought was a “large” 5 gallon vat. That is still the most practical size for teaching workshops and I am guessing that it’s the size/shape that many dyers start with – and most stay with. 

But, I don’t think it’s the best for studio work. IT’S TOO SMALL!  When working with natural indigo vats, whether they are fermentation vats or quick reduction vats, there is going to be a lot of ‘sludge” at the bottom of the vat. With some vats this can be up to 1/3, or more, of the total depth. If you keep the textiles above that sludge , it doesn’t leave much room for dyeing. I am afraid that many dyers might tend to let their textiles dip into that “wasteland” at the bottom, exposing the fibers to concentrated lime or plant material. As a result, the dyeing is not as good as it could be. 

A 50 liter/15 gallon liter vat is a much greater commitment than an 18 liter/ 5 gallon bucket, both in terms of financial investment and engagement.  Yet, it is so much more useful and the dyeing is so much better! It’s also harder to just “give up” on a larger vat. You get better at maintaining and problem solving.

This is the vessel that I use. It’s a hard, durable plastic. I place it on a wheeled dolly. Otherwise it’s too difficult to move. A heavy duty plant caddy works just fine. 

Sometimes I suspend samples and other small pieces from the top, using stainless hooks and wooden rods. 

I have experimented with several types of baskets, nets, etc. to hold my larger textiles and keep them away from the bottom of the vat. I have finally settled on using a large, mesh laundry bag. It fits the vessel nicely, is flexible, re-usable, completely contains the textiles, and prevents things from getting lost in the bottom. 

As I experiment with the fermentation vats, it becomes necessary to do a lot of dyeing. I am working on a long-term woven series, but regular dyeing has become increasingly important with my fermentation vats – and more possible, now that I am staying home.

I’ve taken some of my white or light colored clothing (too impractical to wear in the studio) and turned them into indigo dyed “dyeing clothes”. It took some courage to put a large linen tunic in the vat but I’ve been surprised at the even dyeing of even these larger,  constructed  pieces. I always do at least 3 long dips into the vat, which will assure that the dye “evens out”. I would never have attempted dyeing clothing in a 5 gallon vat.

Maintaining a good dyeing temperature is important, especially with the fermented vats. I have successfully used a band-type pail warmer and plugged it into a digital temperature controller. This has been keeping the vats at a regular temperature in my unheated studio. 

AND if you are going to make wood ash lye for a fermentation vat, this is the time of year to connect with friends who are burning wood. You will want to identify someone who burns only hard wood in an efficient wood stove. That will result in the best ash for making lye. 

A New Book from Dominque Cardon

Dominique Cardon, French researcher of natural dyes and author of the classic reference book, Natural Dyes: Sources Tradition, Technology and Science, has just provided dyers another important resource and insight into the natural dye process:  Workbook, Antoine Janot’s Colours

For several years, Cardon has been translating and publishing a series of books that document the work of 18th century French dyers. The 18th century was the classical period of wool dyeing in France. Last year, Des Couleurs pour les Lumières. Antoine Janot, Teinturier Occitan 1700-1778 was released, but only in French. This book was based on the original dye notebooks of Antoine Janot, a professional dyer from the Occitan region of the country.

Workbook, Antoine Janot’s Colours, which Dominique wrote in collaboration with her daughter Iris Brémaud, begins by providing background information on Janot and a description of the project. The most useful part of this small book to dyers is its practical nature.  It includes a full palette of Janot’s colors and their recipes along with process information. It is written in both French and English.

Both books are published by CNRS EDITIONS

The dyed colors are represented as visuals that were matched from actual wool samples from the original notebooks. Cardon used a color analyzer and the CIELAB system to accurately portray each hue. CIELAB is an international system that scientifically analyzes colors by using a system of coordinates to “map” them graphically and very precisely.

Descriptions of mordanting and dyeing include % weight of dye materials along with other additions that were made to the baths. In some cases, helpfully, an explanation of the WHY is included. 

Examples of green colors in the book which use indigo as a base.

Examples of mixed colors in the book that do not use indigo

The key to some of the color palette is a full gradation of indigo blues, from the very palest to very deep. Each blue has its own name such as “crow’s wing” (the very darkest) to “off-white blue” (the very palest). The CIELAB system allows an accurate visual description of each of these blues. 

Dominique Cardon, showing and discussing her research into the shades of indigo dyed wool at the TSA Symposium, 2014

These blue shades are critical to achieving greens, purples and greys.  Instructions for mixed colors designate which blue to start with. A full range of indigo blues, from lightest to darkest, is not an easy thing to accomplish. I have been working on that very thing consistently for the last months in my own studio, so it is especially meaningful to me right now.

Blue value tests done using different indigo vats in my own studio.
Indigo blues on woven cotton/linen from my own studio. This is a work in progress. The palest colors are the most challenging.

I have recently been doing color replication work for logwood purple using a combination of indigo and cochineal. A systematic approach to dyeing the initial indigo blues is a huge help in approaching this kind of color matching.

Attempt at matching logwood with a combination of indigo and cochineal (the cotton ties reveals which is which)

It is rare to be able to gain such a deep insight into a professional dyer’s process and results. Historical color descriptions, such as “wine soup”, “celadon green”, and “crimson” become more than just words on a page when colors are able to be seen accurately with the eye. 

For dyer’s looking for a deeper insight into the world of professional natural dye, this book is a treasure. 

I ordered my copy directly from France and it took several weeks to arrive.  According to Charlotte Kwon, the book will also soon be available from Maiwa.

Dyeing with Fresh Indigo Leaves

On some days it’s hard to believe how recently we traveled freely worldwide, meeting new people and experiencing new places. Three years ago I attended the natural dye symposium in Madagascar, where I first met Hisako Sumi who started me on my current journey of making and maintaining indigo fermentation vats. As I was harvesting Persicaria tinctoria leaves in the garden, I was reminded of the fresh leaf indigo dyeing that we saw being done in Madagascar. 

Many of us are growing indigo in our gardens right now and have likely had the pleasure of experimenting with fresh leaf indigo dyeing on silk.  It’s like magic to see the lovely turquoise color emerge from the cold leaf bath.

The indigo that grows in Madagascar is Indigofera erecta. It is a perennial in that climate and the leaves are harvested from the bushes as needed. The leaves were used to dye the raffia fibers directly. There was no vat or reduction. 

Yet, the dyers took this “cold” process one step further. The ambient temperature dyebath produced a lovely clear turquoise blue color on the raffia. When heat was applied, the color deepened and shifted.

This approach of heat application was new to me. When I inquired about it, both Hisako and Dominique Cardon indicated that they were both familiar with this phenomenon. Hisako sent me an image from a scientific report done by Dr. Kazuya Sasaki that documented the range of color that could be obtained from fresh leaf woad by increasing the temperature. Once armed with that information I was able to reproduce that range of color, nearly exactly, on silk and and on multi-fiber test strips, though the results were not precisely the same as those we saw in Madagascar. 

Indigo vat dyeing compared to fresh woad leaf dyeing of various fibers, at different temperatures.

I have always understood that the process of fresh leaf dyeing with indigo is primarily used on silk – a protein. Yet, the dyeing we witnessed in Madagascar was done on raffia. Why did this process work so well on raffia- a cellulose fiber? I posed the question to my colleague, Joy Boutrup. “Raffia is almost pure lignin” she said. Lignin is an organic polymer and has a strong affinity for dye. 

This week I repeated the tests with Polygonum tinctorium on silk broadcloth and raffia. I used a greater quantity of leaves this time – a blender full of leaves for a few small samples vs. less than 100 g. I puréed the leaves this time rather than chop them up. The “coldest” blue is a deeper shade but otherwise the results are very similar. I freely admit that I don’t understand, chemically, why the colors change with the temperature:

  • Are there other dyes attaching?
  • Has the indigo been transformed by the temperature? 

Maybe someone else can enlighten.

I have always suspected that the lightfastness of the fresh leaf indigo dye is not to the same level as the color obtained from a well reduced indigo vat. I will do lightfast tests on this range of color and report back in a later blog. 

Three years ago, the trip to Madagascar taught me about an approach to dyeing that I had never seen before –  truly one of the gems of travel. We may not be free to move around for now,  BUT other opportunities continue to present themselves on the web. One of the most exciting upcoming events is this year’s Textile Society of America Symposium: Hidden Stories: Human Lives.

Originally planned to be held in Boston this fall, Hidden Stories: Human Lives will now be live and completely online October 15-17. This biennial event brings together scholars, curators, and artists from all over the world who will present their original research in the form of organized panels and talks. Fee structures for the symposium have been completely re-vamped in order to make this event accessible to all – no matter where in the world you might be. Registration has just opened and you can see the full program here. In addition, You can also read about the keynote and plenary speakers. Hope to see you there!