Eucalyptus – What’s in the dye?

Eucalyptus is not native to where I live but I have watched dyers (with a bit of envy) from other parts of the world use these plants as a source of color and tannin. Each year I grow a plant or two for experimentation. These experiments have led me to some interesting observations.

The variety commonly found at our local garden center is Silver Dollar Gum (Eucalyptus cinerea). A friend, visiting from Australia, fondly recognized it in the garden as “gummy”. It will grow as an annual here and I always dry the round “silver dollar” leaves for dye. Sometimes I can even acquire them amongst the floral arrangements in the local grocery store. This year I had a additional  variety (Eucalyptus globulus). It was grown by a friend from seeds that she brought from a tree in her yard in Ethiopia.

Dye tests were done on wool, both with and without an alum mordant, using dried leaves at 100% of the weight of fiber. Plants contain many different colorants. In the case of the Eucalyptus leaves, they contain both a flavonol and a tannin. The flavonols are typically yellow in color and require a mordant to attach to the fiber. The tannins  produce a variety of colors and do not require a mordant.

I placed non-mordanted wool fabric in the bath with the leaves. It was brought to a low simmer (approximately 190 degrees F). The color was slow to come but after about 2 hours the Eucalyptus cinerea resulted in a deep red/orange, while the Eucalyptus globulus  turned a deep brown.

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Eucalyptus cinerea (left) and Eucalyptus globulus (right) on non-mordanted wool

Alum-mordanted wool was dyed in a separate bath. The fiber quickly (within 30 minutes) turned a brilliant yellow from both varieties of eucalyptus. I removed some of the fiber from the dyebath when the yellow was still bright. As the rest of the fiber stayed in the bath, the tannins were released, changing the color of the wool from yellow to either a deep yellow/orange or a yellow brown. After two hours in the bath the mordanted fiber had been dyed by BOTH the flavonol and the tannin.

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Eucalyptus cinerea: (left to right) no mordant, 2 hour bath with mordant, 30 minute bath with mordant

 

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Eucalyptus globulus: (left to right) no mordant, 2 hour bath with mordant, 30 minute bath with mordant

Several years ago I heard Michel Garcia say that the clearest yellow color from plants may come at the beginning of a dyebath, before any tannins are extracted. As the fiber stays in the bath with the dyestuff, the tannins are released and the color becomes deeper and duller. The eucalyptus is a dramatic illustration of this principle but other plant materials also indicate the same principle.

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Alum mordanted linen fabrics were dyed with small, leafed branches of dyer’s broom (Genista tinctoria). Time in the bath ranged from 15 minutes to 2 hours. The most brilliant yellow was achieved after 30 minutes. After that time the color got deeper and duller, most likely from the tannins released.
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Henna, (Lawsonia intermis) which contains flavonols (mainly luteolin), naphthaquinone (lawsone) and tannins: (left to right) mordanted wool 30 minutes in bath, mordanted wool 1 hour in bath, un-mordanted wool 1 hour in bath. The mordanted wool is slightly more yellow than the sample with mordant.

I have not yet completed lightfastness tests on any of these samples but they are in process.  I would guess that the deeper, tannin-rich colors will be more lightfast than the brighter flavonols.

Black Walnut Season

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It’s time to collect black walnuts!  The black walnut tree (Juglans nigra) is native to eastern North America.  The outer husk of the nut is the source of dye. The colorant is juglone.  It is a direct dye, which means that no mordant is necessary when used with a protein fiber.  There are some tannins in the husk but that is very secondary to the strong juglone. I have not found a better dye to achieve a rich, fast, brown on protein fibers. Cellulose may be dyed as well, but that requires a mordant.

The best time to gather the nuts is when they are still green: newly fallen or ready to fall off the tree. If the nuts rot and turn black on the ground the dye will be damaged. I preserve the fresh nuts in the freezer for year round dyeing.

I have experimented with drying the nuts carefully on racks to prevent rotting. When I compared these dried nuts to fresh/frozen walnuts in the dyebath it was clear that they contain far less dye. On the other hand, drying may be a practical solution.

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Dry walnut vs. fresh: one walnut per 20 grams of fiber.
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Increasing the number of dry walnuts deepens the color

I have learned that the secret to dyeing with black walnut is slow dyeing and lots of patience. I put the entire nut(s) in a mesh bag (fresh or dry), cover with water and simmer until the outer skin (the exocarp) breaks open, releasing the soft husk underneath which contains the dye. Then I cool the bath a bit, add the fiber, leaving the entire nut in the bath (in the mesh bag) during the entire dyeing process. The mesh keeps the fiber clean.  I heat the dyebath slowly and leave it for a long time. There were many occasions that I was disappointed in walnut dye, only to finally learn that it takes TIME. I still have to resist the temptation to add more walnut to the bath during the first hour of dyeing, remembering that the dye will get darker with a longer bath.

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One fresh walnut was used for  20 grams of fiber. Note the effect of time in the dye bath. Heat was turned off after 4 hours and the fiber remained in the dyebath overnight

 

2 dry walnuts per 15 grams fiber
1 dry walnut per 20 grams fiber

My typical approach to dyeing with walnuts is to grab a handful of them, making a good “guess” as to how many I need. I decided to approach the dyeing more scientifically in order to control the color and know how many walnuts were actually required to obtain the color I wanted.

A  fresh walnut weighs about 90 grams.  A dry walnut  weighs about 30 grams. The dry nut contains a lot less water and now I know that it also contains a lot less dye.

  • The nut inside the husk (this is the not the dye) =  approx. 20 g
  • A fresh nut contains approx. 70 g of walnut dye material
  • A dry nut contains approx. 10 g of walnut dye material.

I now calculate about one fresh/frozen nut per 20 grams of fiber (or about 350% w.o.f.).  If I am using dry walnuts I will double that amount, at least. Many more dry walnuts will be required to achieve the same color as the fresh walnuts.

Black walnuts are a most versatile dye.  The presence of tannin means that the color can be dulled and deepened with an afterbath of ferrous but when dyed over a deep indigo, a near black color can be achieved on wool or silk without the use of any mordant.

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Wool, woven shibori, indigo dyed,  over-dyed with black walnut, textile by Catharine Ellis

 

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Catharine’s new edition of Woven Shibori, focused on natural dye, is available from local booksellers or Amazon.com

 

 

 

WATER: Monday morning bleaching and post-vacation blues

When Joy Boutrup and I were teaching at Penland earlier in the summer she told the story of “Monday morning bleaching”. In old European laundries there was a serious problem with an increased number of holes left in fabrics that were laundered on Monday mornings. During the rest of the week the problem was lessened.

Why?

The issue turned out to be iron pipes. Water that had been sitting in the pipes all weekend leached ferrous out of the metal pipes. When ferrous is combined with bleach, the fabric will be compromised, resulting in holes. Once enough water had flowed through the pipes the amount of ferrous was decreased and there was no problem the rest of the week.

I have just experienced a related phenomenon in my own dye studio. After being away from home and studio a week or more, I observed that the water coming out of the studio tap was dark in color. Did this have to do with our shallow well? Was there contamination?

I suspected iron and tested the water for ferrous by stirring a very small amount of gall nut tannin into the water. When ferrous and tannin combine, the water will turn black. This is the principle of gall nut ink, which is made from iron + gall.

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A small amount of gall nut tannin was added to both cold and hot water

Water from the studio cold tap was fine. There was no reaction whatsoever. But the hot water turned black immediately, indicating that there was likely a problem with my “on demand” hot water heater. A call to the plumber confirmed that after 10 years of use the heating element had likely deteriorated and the water was leaching iron from the housing of the tank.

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I continued to observe the water. After running the tap regularly for two days the iron content was much less but still too dark to be acceptable for dyeing.

After 5 days the hot water seemed to be almost completely clear of ferrous – but not quite.

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This was not a good situation for a dye studio and I was forced to use only water from the cold tap for all processes. Yesterday I had a new water heater installed. All water is now completely free of ferrous!

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Soft acidic water is far more likely to dissolve iron in pipes or other sources. Hard, alkaline water won’t present as much of a problem. My mountain well water is very soft and close to pH 6, which is slightly acidic – the perfect water to leach any metal available. It’s a reminder that all dyeing begins with the water. Some mysteries in the dye studio can be solved by simply looking at the water.

 

 

 

New Inspirations and Lessons

This summer took me to the Textile Center in Minneapolis, where I was invited to have a solo exhibition of naturally dyed textiles entitled Natural Dye: Experiments and Realizations.  The title pretty much sums up the way I work: testing, experimenting and finally bringing it all to a conclusion before beginning the next set of investigations.

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Natural Dyeing: Experiments and Investigations

The Textile Center in Minneapolis is a nucleus of textile energy. Also at the galleries this summer is The Power of Maya Women’s Artistry, a stunning collection of hooked rugs made by women in Guatemala using recycled cotton materials. Mary Anne Wise, the Wisconsin based rug designer who got this project started a few years ago, will be speaking at the Textile Center today, July 21, and a workshop will follow this weekend. The third exhibition on display is Naturally: A Natural Dye Invitational, which is a lively collection of eco-printed textiles done by members of the Minneapolis textile community.These exhibitions will remain in the galleries all summer.

Michel Garcia was at the Center last week as the  first Margaret Miller Artist-in-Residence, a residency named for the founding director of the Textile Center. Michel taught two fully enrolled classes: Color From Plants, A Natural Dye Workshop and Natural Indigo Dye Vat. I had the opportunity to sit in on a day of the natural dye workshop. It happened to be the day the class was working with cotton.

 

Over the last few years I have had several opportunities to learn from Michel  in both workshops and filming sessions with Natural Dye Workshop and Slow Fiber Studios. Each experience brings me a clearer understanding of process and I can never predict what I will learn.

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Michel is a philosopher as much as a dyer and chemist. He invites us to think about chemistry, process, and cultural ideas – all at the same time. It is stimulating, hard work to sift through all that he shares. One is not always ready to hear his messages. During this day, I began to get a glimpse of the way in which mordants may be affected (and damaged) by both acids and alkalines.

The next step for me, after being in a workshop with Michel, is always to go home, experiment, and really learn the lesson for myself. I have been trying to grasp the reasoning behind sequencing of dye colors with indigo. Years ago I learned to make greens and violets by dyeing indigo over yellow or red dyes. In 2011 I heard Michel Garcia state that the indigo should always be dyed first. Only then should the cloth be mordanted and dyed with another color. But I continued to work as I always had for a while – it’s sometimes difficult to un-learn what we think we know!

Over time I began observing that when indigo was dyed over a yellow or a red, the initial brilliant green or purple often becomes duller as the indigo dye is neutralized. If indigo is dyed first, and other colors dyed over the blue, the colors remain stable. WHY? Is the mordant damaged? Is the dye damaged? Is the alkalinity of the indigo vat the culprit? Is it the vinegar bath that is used for neutralizing the problem?  It’s a subtle difference but one that I was very aware of.

I made these observations on cotton, but does it hold true for all fibers?

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Cotton and ramie: the sample on the right definitely is a brighter green, when the indigo was dyed first, followed by tannin, mordant, and broom dyebath.

I wanted to test both protein and cellulose fibers that were mordanted. Instead of using indigo, I would simulate the alkalinity of an indigo vat by putting a similar amount of lime (calcium hydroxide) in water. As with indigo, I would also neutralize the cloth in vinegar after it had been in the lime bath. All samples were initially mordanted at the same time and dyed in the same dyebath. Sample #2 was dipped in an alkaline solution prior to dyeing. Sample #3 was dipped in the alkaline solution after dyeing.

from top to bottom

  • #1. Mordant, dye
  • #2. Mordant, dip in alkaline solution, neutralize in vinegar, dye
  • #3. Mordant, dye, dip in alkaline solution, neutralize

What I observed consistently on both cotton and silk is a lighter dye color after the mordanted fiber had been put in to the alkaline solution (sample #2), which would indicate that the mordant had been compromised. When the fiber was put into the alkaline solution after dyeing (sample #3) the final color was brighter than #2, but not as brilliant as #1. This brightening would be consistent with a calcium or chalk treatment of weld in the dyebath.

Wool was a slightly different story. In the past I have not observed there to be major color differences when layering colors with indigo on wool. Mordants attach to wool in a different way than on cellulose and even silk, which leaves the mordants less susceptible to damage by the alkalinity of the indigo bath.

from top to bottom

  • #1. Mordant, dye
  • #2. Mordant, dip in alkaline solution, neutralize in vinegar, dye
  • #3. Mordant, dye, dip in alkaline solution, neutralize

In the wool  samples, #2 was  nearly identical to #1. The alkaline treatment of the dye in #3 is consistent with the effect of pH and calcium on either of these dyes.

Conclusion: the mordant on cellulose and silk is very likely damaged by the alkalinity of the indigo vat. In my own practice, I had already shifted my sequence of colors when using indigo in combination with other dyes. Now I believe I understand more clearly why it is important. Cellulose and silk fibers, especially, should always be mordanted AFTER dyeing in indigo. Both the tannin and mordanting processes are acidic and will assure a thorough neutralization of the alkaline from the indigo. Although it may not be as important with wool, this same sequence may give the dyer more control over the final color.

Dyes from the Local Food Co-op

I welcome the opportunity to teach a workshop, especially when it will teach ME something new.

A few days ago I taught Dyes from the Local Food Co-op  at Cloth Fiber Workshop in Asheville. The class came about when I was measuring some herbs and spices at our local food co-op. I noticed that a number of the dried materials in the glass jars were the same as the dye plants I was using in my studio: buckthorn bark, annatto, chamomile, and dock root. Obviously, the co-op was not stocking these substances for dyers, but….. it caused me to think about the multiple uses of these plants. For many years I have been taking a tincture of Isatis tinctoria, or WOAD, prescribed by my Chinese medicine doctor. How much overlap would I find between the dye and culinary/medicinal plants?

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French Broad Co-op, Asheville, NC

After taking an inventory of the materials available at the local co-op I decided on a collection of plants for this class. The criteria for the dyes included the following:

  • Each plant has some historical reference as a dye plant, and is preferably included in Natural Dyes: Sources, Tradition, Technology, and Science by Dominique Cardon.
  • Each has an alternative use, such as medicinal or culinary.

Not all of these dyes are excellent performers. For reasons of poor light fastness or wash fastness I would not choose to use many of them in my regular studio work. But each dye has a story and may have been used throughout history because of its striking hue, availability, and/or affordability, despite a poor performance as a color over time.

Some of the dyes have been assigned a Natural Color Index Number (CI#). This is a reference database of color hues, names, and products maintained by the Society of Dyers and Colorists and the American Association of Textile Chemist and Colorists. It includes both synthetic and natural pigments. The inclusion of these natural colorants confirms the important historical reference  and unique quality of their colors.

Our dyeing was done on silk fabric. Some dyes required mordants, while others did not. Some roots and barks required alcohol extractions, while others extracted in water. Some dyes were affected by alkalinity. Others contained tannins and were altered with ferrous acetate. Alternative sources of the same plant resulted in color variations, suggesting that different parts of the plant were used, or possible changes in the growing season or drying process. When appropriate, we used alternative methods of dyeing such as a one-bath acid dye or fermentation.

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Chris Whiteman photo

The dyes we used:

  • Alkanet, Alkanna tinctoria
  • Annatto, Bixa orellana
  • Avocado pit, Persea americana
  • Black Walnut, Juglans nigra
  • Bloodroot, Sanguinaria canadensis
  • Buckthorn, Rhamnus frangula                
  • Chamomile, Matricaria chamomilla
  • Cloves, Syzygium aromaticum
  • Dock root, Rumex crispus
  • Eucalyptus leaf, Eucalyptus gunni
  • Goldenrod, Solidago canidensis
  • Henna, Lawsonia intermis
  • Mahonia, Mahonia aquifolium
  • Rhubarb root, Rheum officionale
  • Sandalwood, Pterocarpus santalinus
  • Sassafras bark, Sassafras albidum 
  • St. John’s Wort, Hypericum perforatum
  • Turmeric, Curcuma longa

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The exploration of natural dye continues….

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Woven Shibori with natural dyes is here!

Book is out! & Teaching at Penland

 

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On the shelf at the Penland Supply Store – photo by Debra Frasier

Woven Shibori has been printed and is on the shelves of your favorite bookseller (also available at Amazon).  I had some of the first copies delivered to me while teaching natural dye with Joy Boutrup at Penland School of Crafts. It was a fitting place to receive the first books. Joy has helped me over the years to understand the chemistry of natural dyes, various finishing processes, and textiles in general. I could not have completed even the first version of Woven Shibori without her input.

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Catharine and Joy at Penland  –  photo by Robin Dreyer

I love teaching at Penland! The studios are beautiful, thoughtfully cared for, and well supplied.  Our students were fabulous and ready for whatever we brought to class. We focused on experiments, observations, and clarifications. The class worked with all natural fibers, and processes included dyeing, printing, and discharge. We were focused on WHY things happen rather than simply how they are done.

Every time I teach with Joy, I  walk away feeling that I’ve taken a  a class as well. We learn from each other as we solve problems, observe results, and identify the best practices for the studio.

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So here is one of the things that FINALLY became clear to me.

I’ve heard/read for years that if animal hide glue was added to the indigo vat, then it would be better for wool or other protein fiber. But WHY? That had never been explained. Did the glue coat the fiber in some way?

The organic sugar vats, that I learned to make from Michel Garcia, use sugars from fruit or plants to create the reduction. Lime (calcium hydroxide) provides the alkalinity.

The vat begins with a quick reduction that eventually becomes a fermentation vat. These vats require a very high pH (about 13-14) in order to start the reduction. If the pH is too low the vat will not reduce. But it does not need a high pH to stay in reduction or for dyeing. A pH of 10 is more suitable for dyeing wool, while cellulose fibers do better with a higher pH of 11. The vat will eventually get to a pH 10 as the sugars create lactic acid in the fermentation but this could take a long time. I’ve had vats take weeks to reach pH 10.

photo by Robin Dreyer
Indigo!  – photo by Robin Dreyer

The addition of dissolved animal hide glue (a protein) to the vat will gently lower the pH by absorbing some of the excess lime. The glue will precipitate to the bottom of the vat along with unreduced indigo and sugars. Joy also suggested using natural gelatin (another protein) as an alternative to the glue but we did not have a chance to try this.

It’s very important to insure that the vat is fully reduced before adding anything that will lower the pH. I would wait at least a few days after making the vat before doing this.

I’ve had dyers tell me that the addition of the glue does indeed improve the hand of wool fibers. How much glue? I’m not sure. We started by using a recommendation by Michelle Whipplinger  in her Natural Dye Instruction Booklet. She suggests using the equivalent of approximately 1%  fiber weight. The glue needs to be dissolved in water.  That seemed a reasonable place to start. The key is to watch the pH and observe with both the eye and the hand.

Digging Deeper into a Single Dye – Madder (Rubia cordifolia)

I’ve been using a lot of madder. I have madder roots from my own garden and extracts on the shelf,  but right now I’m focused on the fabulous ground Rubia cordifolia from India that I purchased from Maiwa. It’s ground very, very fine. Charllotte tells me that it’s ground on a mill stone.

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Madder (Rubia cordifolia) on linen

Because the particles are so small, the dye is extracted more easily than from chopped madder root. The color is redder than I would expect from a rubia cordifolia. I love it!

Once the fibers are mordanted correctly I’ve usually been content to make a full strength dye bath. There is always leftover dye in the bath, which most often  gets turned into a dye lake. I didn’t have a full understanding of how much dye was actually in the dye pot or what  remained after the initial dyeing. In order to control my colors and  mix them effectively I needed a clearer picture of dye strength and hue.

I embarked on a systematic observation of the dye. The fiber was linen. It was treated with tannin and mordanted with aluminum acetate. I weighed out the total amount of dye that was needed for my various samples.  Typically I do 2-3 extractions in order to make my dye bath but this time I decided to continue extracting until there appeared to be no more color coming from the ground root. This took SIX 20 minute extractions! I realized that I had previously been wasting some of the dye.

The fabric was dyed with the extracted liquid. The amount of dye ranged  from 6.25% w.o.f. to 100% w.o.f. I also did exhaust baths of the dye.

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Madder exhaust bath, linen

Madder is an interesting dye because it contains so many different colorants. The alizarin is what gives us the red, but it also contains other colorants: yellow, orange an brown. The initial dye at each depth of shade was dominated by the red. Exhaust baths contained less  red, while the orange dominated. The colors obtained from the initial dyeing at 50% w.o.f. and 100% w.o.f.were very similar but the stronger bath continued to give me red before the color turned more orange.

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Dye % range and exhaust baths

The test was repeated  on wool with similar results.

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Madder % range on wool

Dye extracts are what drew me back into natural dyeing but I’m finding that working with plant material is far more compelling. Each plant and dyestuff is unique and since these are natural products they are subject to the changes in growing seasons and processing. Testing my dyes in order to understand the nuances is time well spent. It will make me a better dyer.