It’s black walnut season again in eastern United States – and soon the trees will be releasing their nuts and husks from the tree.
This summer I had the pleasure of teaching, again, with Joy Boutrup at Penland School of Crafts. As always, when Joy and I spend time together, we begin investigating and learning more about the practice of natural dyeing.
We were experimenting with “quick reduction” indigo vats and the used of lime (calcium hydroxide) vs. lye (sodium hydroxide) as the source of alkalinity in the vat. We made a vat that was reduced with henna (Lawsonia inermis). This is the vat that I commonly use in my studio. The sugars present in the henna reduces the indigo. Joy was looking at the molecular formula of lawsone, (the active dye ingredient in henna) and noticed that it is very similar to juglone (the active dye ingredient in black walnut hulls) They are both oxidation dyes, which means that they will dye protein without the use of mordants.
The question: Could black walnut hulls be used to reduce an indigo vat in the same way that henna does?
We tried a small test vat. When I test a new indigo vat I often make it in 1 quart mason jars. This allows me to test multiple ideas on a small scale, without risking large amounts of dye or other materials. These small vats give me enough information so that I can scale up to a larger volume at a later time. I used 4 grams of indigo, two walnut hulls, and about 10 grams of lime.
In June I had only whole frozen walnuts. I thawed them a bit, and covered them with water (no more than a quart, as this becomes the liquid for the vat).As the walnut hulls softened more, I broke them up with my fingers and cooked them for a short time. The liquid was yellow. Joy cautioned against heating too much, which would turn the liquid brown as a result of oxidation. We wanted the oxidation to occur in the indigo vat.So we stopped heating while the liquid was still very yellow. Next we strained the solid pieces out, and poured the liquid into the mason jar. We added the hydrated indigo and the lime.
Within a few hours we had a nicely reduced vat! I continued to dye test strips in the vat for a number of weeks. After a few days the color became lighter, but after the addition of supplemental organic materials (sugar, more walnut juice, cooked fruit juice etc.) the reduction improved and the blue color deepened as the indigo reduction improved.
I observed that after about 10 days the indigo blue got dull and the samples showed a wicking of a brown matter into the white cloth. Then, after about 30 days the color reverted to a clear blue again.I described this to Joy.She was not surprised and indicated that the juglone was by then inactive, having polymerized into a pigment that does not dye. Yet the sugars in the plant material continued to reduce the vat.
I also tried adding puréed pieces of walnut hull to a test vat, but there was so much plant matter it made dyeing difficult – very messy. Thus, I now use only the liquid extraction. I have made several small vats since and they have all behaved consistently.
When I collect this season’s walnuts I plan to scale up to a larger vat.
In the spirit of understanding the plants that I use, this year I have planted a single henna bush in my garden. It will not winter over. It is not a local plant for me. I am thrilled to have discovered that walnuts,a tree that grows locally in abundance,can be used to reduce an indigo vat.
The first indigo vats that I made in the 1970’s were reduced using sodium hydrosulfite. It was the only way I then knew to reduce the indigo. A few years later I began using thiourea dioxide as the reducing agent. I was never comfortable with these vats and, as a result, I never did much indigo dyeing. The vats smelled bad and I felt that I never truly understood them.
My current, and very positive, relationship with indigo began after meeting Michel Garcia in 2008. Michel introduced me to indigo vats that are reduced with natural materials: sugars, plants, or minerals. Since then I have worked hard to learn as much as I could about these vats, and have maintained them constantly in my studio. Indigo dyeing has become an integral part of my studio work and experimentations.
I know many dyers who use either sodium hydrosulfite (“hydro”) or thiourea dioxide (“thiox”) to reduce their vats. These chemicals work efficiently and predictably and can now understand why a dyer would make the choice to use them. But I’ve recently been asked about the safety of these reducing chemicals. This is not a question that I felt qualified to answer myself. I was with Joy Boutrup last week (we were teaching together in Iceland!) and I asked her to address this question.
To paraphrase Joy:
Both sodium hydrosulfite and thiourea dioxide are sulfur based and will release hydrogen sulfide. This is what causes the bad smell and can affect human health when the gas is inhaled.It can be irritating to the nose, throat, and airways and potentially paralyzing to breathing if inhaled in large quantities. Dyers with asthma should be especially cautious when using these reducing chemicals.
Both “hydro” and “thiox” also release sulfur dioxide, which is considered to be damaging to the brain. It is a chemical that has been used in photography and some photographers have suffered from long term exposure to this chemical.
When using these chemicals dyeing must be done outdoors or in a very well ventilated area! Occasional dyeing using these types of vats may not result in noticeable effects but if you stand with your head over an indigo vat day after day, then serious breathing problems could result. Joy was recently consulted by a group in Denmark, who have been using these chemical vats for many years. Some of the dyers are experiencing a variety of health problems as a result of the exposure to the chemicals. She recommended that they begin using the natural/organic vats as an alternative.
The other issue is disposal. The chemicals are very reductive and cannot just be thrown out. The reduction must be stopped before disposal but it’s not easy to keep the sulfur products from being reductive. Other chemicals can be used to stop the reduction but they are just as damaging. Some dyers simply keep their vat, adding additional indigo and reduction chemicals as necessary. Continuing to use the chemicals in the vat ispreferable to uncontrolled disposal.
One another note: I have a friend who does production dyeing. She uses an indigo vat reduced with thiourea dioxide but was having trouble achieving pale blue colors. Dyers will often just do a quick 10-30 second dip in the vat to get light blues, but this doesn’t give the indigo time to penetrate the fiber. As a result, the dye is less fast to washing and crocking and is not likely to be even. I suggested that she try my approach to achieving pale blues: use only a small amount of indigo in the vat (1-2 grams per liter).
When she told me that the small amount of indigo still resulted in a deep blue color, I did some tests myself using both “thiox” and sugar as reduction agents.
I was surprised by the results. The organic sugar vat resulted in the pale blue color that I expected, while the vat reduced with the thiox was a very deep blue, although only a small amount of indigo had been use.
Conclusion: the reduction chemicals will reduce the maximum amount of indigo, making it impossible to achieve the pale colors, while in the sugar vat, only part of the indigo is reduced at a time.This is why a sugar or other natural vat can continue to be used over many days, weeks, or months.
These reduction chemicals are used in industry and efficiently maximize the dye that can be applied to warps for blue jeans. But even industry has been concerned about the longterm effects of chemical reduction and disposal. Some industrial users have begun to use electrical reduction instead of chemicals for all vat dyes.But artisan dyers are not industry…. The naturally reduced indigo vats are not only safer to use, but they allow us better control over our color and color mixing.
Symplocos is a plant species that accumulates alum mordant. It is one of number of plants that grows in acidic soil around the world, and thus is able to absorb available aluminum from the ground. Although different parts of the tree absorb alum, it has been determined that the fallen leaves have a high concentrations of alum and are the most sustainable source of mordant. By harvesting the fallen leaves, no damage is done to the tree. These leaves can be used as an alternative and highly effective source of mineral alum, while also imparting a pale yellow color to the fiber.
One variety of symplocos is native to Indonesia and utilized by weavers and ikat dyers with when dyeing red with morinda (Morinda citrifolia) on cotton. The Bebali Foundation has been studying the mordant process for a number of years and has made symplocos available to dyers around the world, while supporting the local women who gather the leaves. Michel Garcia worked with the foundation to develop recipes for both protein and cellulose fibers. All of these recipes are available online at The Plant Mordant Project.
I have experimented with symplocos many times with great success. Recently I have been introduced to a variety of symplocos(Sympolocos tinctoria)that is native to the southeastern United States. It is described as a small tree or shrub, “deciduous or weakly evergreen”. It is also known as “horse sugar” or “sweetleaf” because horses are attracted to the sweet leaves of the plant. As I researched, I read that it grows in “very acidic soils”. It is sometimes described as a source of yellow dye, but nowhere did I read that it was a source of alum.
The symplocos tree
Distinct blossom of the Symplocos tinctoria will help identify the plant
Leigh Magar, a textile designer and dyer, brought me a handful of leaves last year that she collected at her home near Charleston, South Carolina. I proceeded to test the leaves as a source of mordant, comparing them to the symplocos that I have from the Bebali Foundation, and also to mineral alum. I ground the leaves and used Michel Garcia’s recipe. The results were very good.
Last month I was finally able to travel to Leigh’s home in South Carolina to see the plants myself and to gather some of the leaves. Our regional variety has leaves that are smaller than the Indonesian variety but they are shed in much the same way. The leaves yellow as they age and drop from the tree. They are easily gathered from the tree at this time. Leigh tells me that shedding seems to be more more prevalent in the spring, although the tree sheds its leaves all year long.
I am currently reading (and very much enjoying) Braiding Sweetgrass by Laura Wall Kimmerer. In the chapter entitled The Gift of Strawberries the author talks of wild strawberries as unexpected gifts received from the earth. Finding alum in a plant is very much like a gift – to be received gratefully – but not to be turned into a commodity. I will treasure this gift of alum and appreciate Leigh’s generosity in sharing it, but it will not replace the mineral alum that I purchase from a supplier.
symplocos leaves beneath the tree
symplocos leaves beneath the tree
And a couple notes on our book: The Art and Science of Natural Dyes. First of all, I am very appreciative of the many notes and emails I have received from so many of you. It is exciting to both Joy and me that the book is finally out and truly being used.
There is one important omission on pages 169 and 170. The mordants used for the photos of the dyed samples should cross reference mordants #1 – #5 (top to bottom), from the mordant mixing chart on p.150.
And about the spiral binding – we chose the binding very intentionally so that the book would open easily and stay open. The book is meant to be used, referred to, and likely to get stained, like a much used cookbook. Many of you have told me how much you love the binding but I have also heard from a few of you that pages can easily slip out of that spiral. A dyer in Australia showed me a perfect solution; she threaded a piece of cotton yarn through the binding, locking the pages in. I have now done this to my own book and would suggest that you do it to yours as well.
Fora number ofyears I have been usingmadder (Rubia cordifolia) sourced from Maiwa (in Vancouver, BC almost exclusively for my dyeing. I particularly appreciatethe fact that it is finely ground so thatI am usually able to just put the dye into the bath along with my textile. If dyeing yarn, however, I typically willplacethe ground dye into a net bagto keep small particles of madder from physically attaching tothe fibers.
I once heard Michel Garcia speak about the fact that you cannearly double the yield from madder root if it is finely ground. It makes sense. More surface area means that it’s easier to extract the dye.
Early last year I harvested about 5 pounds of madder roots (Rubia tinctorium) from my garden. The plants were startedfrom seed and they had been in the ground for about 5 years. I dug up the entire bed (about 4’ x 8’), pulled up the largest of the roots, leaving the smaller roots in place. I amended the soil, added some chalk, and the plants have continued to grow in the same location. My theory is that I can continue to harvest every few years byleaving the roots in the same place and repeating the amendment processWe’ll see…
digging the roots
roots from the garden
I cleaned and dried the roots. Some of the dyes are developed by in the drying process so that is important.A few weeks later, I dug up another small patch.With this second batch, it occurred to me that maybe I could grind up the roots before drying them. It was easy to chop up the fresh roots into small pieces with an old food processor that I have designated for studio use. Once chopped,the roots dried very easily on horizontal screens.
Last month, I was preparing a major piece for an exhibition and I wanted to use my own madder. The large, dried roots proved to be problematic. I wanted to grind them as fine as possible but was not sure how to proceed.
I tried a mechanical corn grinder. It was a terrible experience! The grind was very coarse, the roots jammed in the grinder, and it was not at all successful. I tried the old food processor – not powerful enough to beeffective.I even tried grinding small amounts in a dye-designated coffee/spice grinder. It was better, but still not very good and it would have taken far too long since the capacity of the grinder was very small.
Corn grinder was not an efficient way to grind madder roots.
resulting chopped madder
I did some research, and finally decided to purchase a powerful electric grinder that is recommended for medicinal herbs (roots) etc. It was amazing! First, I quickly broke the roots into smaller pieces by hand, which allowed me to pull out the “chaff” (the stem pieces with no dye). I put the smaller root pieces into the grinder and I had finely ground madder root in just two minutes!
In two minutes these whole pieces of root turned into a finely ground powder
Finely ground madder in the new grinder
I’ve learned a lot (of course). Madder root, even when dried completely, still has elements (sugars maybe?) that coated the bowl of thegrinder with a layer of sticky madder. The bowl of the new grinder cannot be immersed in water so I had to work hard to clean it out. But the madder is all ground and the grinder isnow ready to grind my dried sumac leaves and some other tannins.
In our book, The Art and Science of Natural Dyes, Joy and I discuss and show examples of how a dyer sometimes has more control over the color when using madder roots rather than extracts.The source (and type) of the roots is also a factor. Madder contains many different dyes and the two different species contain different combinations.
As I began my tests for the exhibition piece, I did many samples and used madder roots from a variety of sources. The woven shibori project utilized mordant printing with different strengths of aluminum acetate, ferrous acetate, and combinations of the two mordants. When Rubia tinctorium is used with iron mordants, it is possible to achieve distinct purple colors. The purples are not possible with Rubia cordifolia, as the dyes within the roots are different. I was very happy to observe that my own madder was the very best of all!
process and tests for the finished work
I am very encouraged to keep growing…and dyeing….
I have begun using my own copy of The Art and Science of Natural Dyes in the studio and in my teaching. No, I do not have all of those recipes committed to memory! I have found it very useful to add tabs to the book, making it easy to navigate and find exactly what I’m looking for.
Note: Maiwa now carries very finely ground Rubia tinctorium roots.
I first met Sarah Bellos of Stony Creek Colors in 2016 when she spoke at the Growing Color Symposium at the NC Arboretum in Asheville. She presented her vision for growing and extracting indigo in Tennessee. Her goal was to introduce natural indigo to the denim industry, which is currently a huge consumer of synthetic indigo (a serious source of environmental pollution). She was partnering with Tennessee farmers who had previously grown tobacco and planned to process indigo dye locally.
I must admit that I was somewhat skeptical. The project seemed too big and too optimistic. I didn’t know anyone who had successfully grown indigo dye plants on the scale that she described.Most dye plants are grown for commercial purposes in India or South America, where the price of labor is far less. Indigo was grown in the Southeast coastal regions of South Carolina and Georgia in the 17th and 18th centuries but, to my knowledge, has not been grown commercially in North America since that time.
On a recent visit to Stony Creek near Nashville, TN I was very pleasantly surprised and now believe that they are truly on the way to something successful and very much needed. I’d like to tell you why I believe this.
The first place visited was the “test farm”.I had envisioned a small plot of Persicaria tinctoria but was amazed to find that the test farm was a densely planted, multiple acre farm tract where several strains of Persicaria tinctoria are growing next to the tropical varieties of indigo(Indigofera suffruticosa and Indigofera tinctoria).
Why grow so many different types of plants? Sarah and her staff are constantly asking questions and testing: Which varieties can be sown directly in the ground? Which need to be started in the greenhouse? Some strains bloom more readily than others (great for seed production but not so good for indigo production). Which plants can be dried for future extraction? What is the indigotin content vs. the biomass of the plants? Which can be harvested most efficiently?
I believe that the Stony Creek team is concluding that there is wisdom in growing more than one variety of indigo.The farmers are currently growing many acres of indigo for pigment extraction. All farms are within a reasonable drive to the factory, as it is necessary to process the indigo leaves quickly.
The next stop was Stony Creek’s lab.Walking in the door I saw that the dye chemist, Summer Arrowood, was pulling leaves from Persicaria tinctoria stems that had been harvested earlier that morning. She was weighing those leaves and recording the leaf-to-stem ratio. Next, individual bags of leaves (from very specific plants in very carefully identified locations at the test farm) were processed to extract the indigo pigment. I sensed that this was part of each day’s work at the lab. The leaves were soaked in hot water, the liquid was pumped into vessels for aeration, the paste was allowed to settle and then filtered. Several hours later, each batch of leaves had produced a small amount of indigo pigment. These were tested, labelled and stored for future reference. They report that their indigo contains 25-35% indigotin which is a very concentrated output.
Indigofera suffruticosa seed pods
Indigofera tinctoria seed pods
The production factory is located in a county-owned, former tobacco factory and leased by Stony Creek.Here, 20,000 pounds of indigo plant material can be processed in a single batch. The factory is set up with modern equipment, carefully laid out, and efficient. Stony Creek precipitates indigo pigment without the use of lime (calcium hydroxide). When too much lime is used during the process, it will remain in the indigo pigment and skew the weight of anyavailable indigotin. The extraction without lime is one of the reasons the pigment has such high levels of indigotin. The pigment paste is carefully filtered using processes that Stony Creek has developed specifically for indigo.
How has Stony Creek come this far so quickly? Sarah Bellos has an academic background and experience in natural resources management and sustainable agriculture. She is a self-taught natural dyer; she and her sisters operated a dye business for several years under the name Artisan Natural Dyeworks. Stony Creek employs skilled and smart people, who know chemistry, plants, agriculture, and manufacturing. The farmers, who grow the indigo, are benefiting from a cash crop that has the potential to replace the tobacco that grew here for so long. Stony Creek is currently selling indigo paste to denim producers and they are able to test/replicate the warp dyeing process used by the denim industry in their lab. Sarah had a vision to produce natural indigo and they are making it a reality.
At a time when some of us are unsure if we are purchasing natural indigo or synthetic indigo (or a mix of both) Stony Creek is a beacon of light. I have used their indigo and it is excellent. Of course I will purchase my indigo from them! I will encourage other dyers to do the same.
Stony Creek is NOT yet set up for visitors. Right now, they need to focus on the work at hand and continue to develop their current products: indigo, black walnut paste extract (that really works!), and a madder extract paste (currently from Rubia tinctorium roots grown in India until their own roots are ready for harvest).
After this year’s indigo harvest they plan to move the lab to the factory location and at some time in the future will be able to offer workshops onsite. I hope that you will consider helping to grow this promising endeavor by trying out their excellent indigo, and other extracts available for order online at their website. Other dye suppliers are also beginning to carry and sell Stony Creek Indigo.
The day we visited the factory, there was no indigo being processed. It had rained the day before and the indigo plants cannot be harvested when wet; this whole process is tied closely to the land. Before we left in the afternoon, the truck and trailer had left for the fields, ready to be loaded with indigo plants early the next morning.
Yesterday I received a phone call from Schiffer Publications – the publisher of Joy’s and my upcoming natural dye book.
I am sorry to report that the release date, originally projected for the end of October, has been delayed until late January.
Why the delay?
Schiffer is taking great pains to be sure that all color reproduction is exact and precise. The book is illustrated with photos of actual samples from my dye tests. Our goal was to share some of the hundreds of samples that I have done, comparing the use of different mordants, tannins, dye treatments, times in the dyebath, etc. Many of the variations are subtle – but the differences are important.
Careful color adjustments have been made to the digital images in Art & Science of Natural Dye to ensure that the dye colorsreproduce as accurately as possible throughthe print process. Color proofs arereviewed and compared to the actual dye samples as part of this process.
Yes, it will be delayed, but the color will be the best possible printed reproduction and I’m very happy about that. It’s good to be working with a publisher that really cares about these “small” details – they are really not small at all. Below is just a small hint of what will be included.
I know that many of you have pre-ordered the book and are anxiously awaiting it. Joy and I appreciate the vote of confidence and are sorry for the delay.
I can suggest a great thing to do while you’re waiting:
Yesterday, on a long drive back home from New England, I finally had the chance to listen to a lecture given by Michel Garcia and available as a Maiwa Podcast. It’s title is Field Notes in the Color Garden, parts 1 & 2. It’s a long, wonderful, rambling lecture that Michel gave in 2015 and Maiwa uploaded as a podcast this year.It has given me much to think about in regards to dye plants, resource books, investigation, and the human scale of natural dye.
And keep dyeing!
It’s still less than a year since Joy and I turned in the manuscript and images to the publisher. My learning has not stopped and once the book is released, I look forward to sharing some of the things I’ve continued to work on and learn about since we sent the manuscript away.“Stay tuned”.
I have always enjoyed how the goldenrod grows and blooms alongside the purple asters – a beautiful combination of complimentary colors.Goldenrod (Solidago sp.) is a member of the aster family. There are many solidago species native to North America, and they can also be found in other parts of the world.
Goldenrod flowers, gathered in western North Carolina
Goldenrod and New England Asters, photo from Denver Botanical Gardens
Goldenrod and thistles, Newfoundland, CA
Is goldenrod a good source of dye? Yes, but with reservations.
Though it is not one of the “classical” dyes, and it’s lightfastness does not match that of weld, it was used as a locally available dye in North American and Europe. Dominique Cardon (Natural Dyes: Sources, Tradition, Technology, and Science) writes about goldenrod’s historical use, along with weld and Persian berries, to dye the yellow hats the Jews were required to wear in the south of France in the 13th century.
I’ve always readthat goldenrod does NOT dry well for future use – so I never tried to dry it. I can accept the fact that some dyes deteriorate in the drying process. Black walnut hulls are a good example.
A couple years ago I was teaching a class here in Asheville, NC on dyes that could be sourced from the local food co-op. I used dried goldenrod plant material, as it is used medicinally. It resulted in very good color. So I began to wonder….. CAN A GOOD DYE BE OBTAINED FROM DRIED GOLDENROD?
It’s one thing to read a statement about a plant – it’s another thing to know and understand that statement. Ihad never tried to dry goldenrod. This year I finally got around to doing my own testing.
I gathered fresh goldenrod, and used that to dye aluminum mordanted wool, silk, and cotton. There are many yellow dyes in goldenrod and they may include quercitron, isoquercitron, kaempferol, astragalin, isorhamnetin. Since the dyes in goldenrod are primarily flavonols, a mordant is required.
I dried goldenrod from that same harvest. Plants were hung upside down in a dry space with plenty of air flow. Only the flowering heads were used as a source of dye. I was able to accurately determine the weight of the plant before and after drying. 300 grams of fresh goldenrod flowers resulted in 100 grams of dry flowers.
I dyed with fresh goldenrod at 300% w.o.f, while the dried was used at 100% w.o.f. Because I knew the weight before and after drying, I was confident that I was using the same amount of dye, whether it was fresh or dry plant material.
The results: The dyes seem not to have suffered from the drying process. Careful drying is likely a key element. So yes, I will dry some goldenrod and I will complete lightfastness tests on all three fibers. The goldenrod will not replace the weld that I grow and dry each year, Weld will always be my primary yellow dye as that has proven to be the best, and most lightfast yellow dye. But it is good to know a bit more about the dyes from plants available in my neighborhood.
Thus far I have used only the flower heads for dyeing. Maybe next year I’ll experiment with the stems and leaves from the entire plant.