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Posts Tagged ‘indigo’

dyed-yarn-balls

Dyed merino wool yarn using natural dyes. Top left: Rabbitbrush. Top right: Cochineal treated with ammonia. Bottom right: Indigo. Bottom center: Cochineal treated with citric acid. Bottom left: Madder root.

As a follow up to our inquiry lab to develop the best formulas for dyeing cloth with natural dyestuffs, I ordered some Kona 100% merino wool yarn and several yards of untreated cotton fabric from Dharma Trading Company along with indigo, cochineal, sandalwood, and madder root dye powders, and some mordants and other chemicals needed for these dyes.

As we finished up before Winter Break, I started testing these dyes and experimenting with variables to get an initial feel for how well the yarn and cotton work. My first test was rabbitbrush, as I had collected boxes of flowers before the color completely faded in October. I simmered a skein of yarn in aluminum sulfate (alum) powder as a mordant for an hour while boiling the rabbitbrush blossoms, then transferred the hot yarn into the dye bath. It accepted the color nicely.

Next came madder root. I used the same mordant bath and prepared a dye bath by soaking the madder root bits directly in hot water and letting it simmer while the yarn was in the mordant bath, then filtered the madder solution through a sieve before dyeing the yarn. The color did transfer, but was lighter than I had expected but a very nice light salmon orange. I used the same solution for about two feet of the cotton, but it turned out even lighter. Increasing the concentration of the dye bath didn’t seem to help.

cochineal-dyeing

Dyeing With Cochineal: The dye bath is bottom left. I crushed the cochineal shells in a mortar and pestle, then placed them in the sieve (top center) and boiled in the hot water. The yarn is simmered in the mordant (alum powder – to the right), then simmered in the dye bath, then rinsed out (in the sink in center).

With some confidence that the wool yarn was working well, I crushed some cochineal shells in a mortar and pestle and placed them in a sieve and the sieve into boiling water to make the dye bath. This was to prevent the shells from sticking to the yarn, which would have been hard to get off. I wanted to make a multi-colored skein, so I dyed part of the skein in plain cochineal, then added citric acid to the dye bath which made it turn bright red – the citric acid worked much better than the vinegar or tartaric acids had. It made a skein that varied from deep red to burgundy color. The color stuck to the yarn extremely well.

orange-cochineal

Dyeing cotton cloth in cochineal treated with citric acid (orange) and ammonia (red to purple). Unfortunately, these colors were not colorfast. Upon rinsing, they changed back to neutral pink.

I then took the same cochineal bath (it was quite strong) and added ammonia to turn it from red to purple, again making a variegated skein. I divided the bath in two and had part of the skein simmer in the purple, part in a pot with more citric acid added back. I think I diluted it too much. Part of the skein between the two pots didn’t get much dye and remained a lavender color. The final skein varied nicely from lavender to burgundy to magenta to purple. The cotton swatch I tried was left in the citric acid side (which was now orange) over a weekend and it looked nicely orange when I took it out, but the differences in color washed out when I rinsed them – the pH neutralized. I need to figure out a way to set the color in cotton, maybe by not rinsing it before placing it in a drier. The wool yarn retained the varied colors nicely upon rinsing and washing in the laundry.

dyed-skeins-2

Skeins of dyed yarn before untangling. Some skeins were dyed a solid color, others were variegated.

Then I tried the tricky one – indigo. I had purchased the sodium hydrosulfite, used to reduce the blue indigo to the leuco state where it dissolves and penetrates the cloth. I followed the suggested steps from my research, but ran out of time to finish the process as a fire system sprinkler pipe burst outside the school and we had to evacuate while the fire department came to fix it. I turned off the hot plate quickly and grabbed my stuff, because it was the end of the day before Winter Break. I didn’t want to wait for the all clear, so I just went home. It took me a few days to get back to school, what with preparing for Christmas and shopping, cleaning, and cooking sugar cookies with my sons, etc. The yarn and cotton had been soaking for days. By the time I rinsed everything out, the cloth and yarn were a deep blue. I think I used to much indigo powder – this stuff is strong. The cloth washed out to a light blue and after washing the yarn, it faded as well but had a nice variegated color scheme.

After Winter Break and during the start of my second semester STEAM class, we tried out one more skein dyed with walnut shells and marigold flowers. I had some marigold blossoms I picked off my flower patch right after the first deep freeze in December and had dried them out. It died the wool a golden yellow, but I tried variegating the skein using walnut shells and hulls, but the brown color washed out to an ugly tan in both the cotton and the wool yarn. A student brought in black walnuts, but the result was the same after several attempts. I tried concentrated madder dye on part of the skein, but it didn’t work well, either. I think the marigold prevents other dyes from overdyeing. Perhaps other mordants would work for the walnut. It never got as dark as I expected. So the marigold skein is my least favorite – kind of a dirty yellow. More experimentation is needed here.

failed-experiment

Experimenting with marigold dye (middle), madder root (right), and walnut shells (left). If the colors had remained this intense, it would have been OK. But the walnut shell and madder rinsed out and were much lighter upon washing.

I met Katie Wirthin, an education specialist from the Natural History Museum of Utah, when I was presenting my STEAM session at the NSTA STEM Forum in Denver last summer, and she asked if I was interested in teaching a workshop at the museum this year. We had communicated back and forth all fall, and once I finally had my Teachers for Global Classrooms online class done (more on this in a later series of posts), I was able to teach a workshop at NHMU. The week I was scheduled to teach it to about 23 teachers, they had a power outage and had to postpone the class for a week. The next week only eight people came, but it turned out well. Katie had gotten all the materials and as usual I tried to do too much in the two hours. We did marbled paper, iron gall ink (except I forgot to bring the tea bags – they were able to scrounge some green tea in their cafeteria which actually worked far better than the regular brown tea – you could really see the black pigment form). The final activity was dyeing cloth – we used terry cloth swatches, and it worked well but we ran out of time. She still has much of the supplies left, as it was designed for more people. We will probably run the workshop again on a Saturday for three hours.

dyeing-with-sandalwod

A student dyeing a swatch with sandalwood dye using a tin (II) chloride mordant. Notice the dark orange color.

Now that I have six skeins of yarn dyed, my wife has untangled it all and rolled it into balls so she can crochet a sweater from it. I’m not sure if I want the marigold color or not, but experimentation is part of this process. It might be an epically ugly sweater, but I don’t care. I will wear it proudly.

spinach-dye

Some green dye extracted from spinach leaves.

My STEAM students are beginning the lab again, and one student is using sandalwood for the first time. She used tin (II) chloride as a mordant, and the color turned a deep orangish brown, so as soon as I get more skeins of merino wool yarn, I will dye one with sandalwood. Another one is using spinach leaves for a green dye, and we’ll see how that goes. We need to order elderberry plants or leaves for another green color (it might take a while to grow the trees), and logwood for purple to black. There is still so much to experiment on before I post the final recipes. We still have to figure out how to improve the walnut shell dye. But we’ve learned a great deal so far, and I’ll report on my second semester class in a few weeks as we continue to experiment. This is what inquiry is all about.

yarn-balls-2

The skeins untangled and rolled into balls for crochet. My wife will make me a sweater from these. The cotton swatches will be turned into a patchwork quilt of our school logo.

dyed-skeins-of-yarn

Skeins of dyed merino wool yarn. Clockwise from top left: Cochineal treated with citric acid (red), rabbitbrush (yellow), indigo (blue), cochineal treated with ammonia (purples), and madder root (orange).

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woad-stained-pict-warriors-john-white-bm

Pict warriors painted blue with woad pigment. With their blue skin and red hair and mustaches, these warriors must have intimidated even the Romans.

While we were researching dyes for our dyeing lab, I came upon the history of woad, a plant that produces a blue dye used by Europeans for millennia before indigo was imported. It originated somewhere in the steppes north of Asia Minor and was grown, traded, and transplanted all across Europe until it reached Germany, France, and England. During the time of the Romans, warriors from one tribe of Britons would dye or tattoo themselves with woad in elaborate patterns to frighten their enemies. The Romans called them Picts because of the pictures they drew on themselves.

woadballs

Balls of woad. In England, woad leaves were crushed and rolled into balls, then allowed to ferment to precipitate the blue indigotin dye.

During the Renaissance, woad trading and dyeing made whole towns wealthy. In England, many acres were planted to woad. The leaves were harvested and mashed, then rolled into balls and allowed to ferment in a shed. The fermentation allowed the indigotin dye molecule to precipitate out of the plant leaves. The process smelled rather awful, and laws were passed banning any woad dyeworks within two miles of a town.

woad_mill_1752

An illustration of a woad mill in France. The leaves were gathered, crushed mechanically, formed into balls, and allowed to ferment. It was a smelly process, done in the country away from cities.

The other major source of blue dye before synthetics were invented was the indigo plant, which is native to warm and humid climates. Different cultures worldwide have invented their own methods of extracting the indigotin dye from the plants. Japanese dyers would allow the indigo leaves to ferment in a vat to remove oxygen. In India, the leaves were also soaked in vats then treaded by humans to mash the indigo and release the pigment, which was dried and pressed into cakes. Once indigo became known in Europe, it replaced woad as the choice for blue dye because the indigo plant has more indigotin and is therefore cheaper to produce. One wealthy indigo trader, Heinrich Schliemann, used his wealth to explore the ancient site of Troy. Another, Percival Lowell, used his family’s indigo wealth to build the Lowell Observatory in Flagstaff, Arizona to look for life on Mars. Levi Strauss used indigo to dye his original blue denim pants. As you can see, it’s had an impact on history.

woad-shades-031

Young woad plants, with yarn dyed using the extracted indigotin pigment.

As part of my research, I discovered something completely unexpected: dyers had imported woad to Utah in the early 1900s and tried to grow it here. Since it originated in a high desert environment, it did well in Utah’s climate. In fact, it did too well. It got away from the dyer’s fields and went wild, growing all over the western United States. It is now considered to be a Class 3 Invasive Weed, which means it is almost out of control. The only way to prevent it from spreading further is to pull up the plants before they go to seed.

woad-plant-2

A woad plant, growing in the southwest corner of Salt Lake Valley in Utah. Dyers brought woad to Utah in the early 1900s and it got away from them.

I memorized the characteristics of woad plants, knowing I would want to try to find some and take my students on a “Woad Twip.” Woad has dark green leaves with a white vein. These leaves are clustered at the base of the plant. It sends up tall flower spikes with yellow flower clusters in the late spring. By fall, the flowers become brownish-red pendular seed pods with many small black seeds.

woad-plant-3

More woad growing in Salt Lake Valley. I discovered this by accident while collecting late rabbitbrush blossoms. The seed pods can contain hundreds of thousands of seeds in a single clump of plants, and can spread quickly.

By mid October the rabbitbrush blossoms were beginning to fade. I needed to collect as much as I could for continued experiments, so I found a spot in the middle of Mountain View Corridor in southwestern Salt Lake Valley where the rabbitbrush blossoms were still bright, and I stopped there after school on a Friday. While I was out collecting the rabbitbrush blossoms, I noticed a plant I hadn’t seen before. It was woad! So I collected several bags full of leaves and some seed pods, with the idea of trying to grow some in my back yard.

woad-leaves

Cutting woad leaves to extract the indigotin dye.

My chemistry students cut the leaves into pieces and also separated out the seeds. We looked up the ancient process of woad extraction and found some websites that describe how it is still being done at small farms in England. The process involves quite a bit of chemistry. I am attaching a PDF file that describes the steps. Here it is:

woad-dyeing-process-s

whipping-woad

Whipping woad solution to add oxygen and precipitate the indigotin.

In summary, the indigotin dye in woad and indigo is a rather delicate molecule. Too much heat will destroy it, but some heat is needed to extract it from the leaves. The chopped leaves are steeped in water at 90° C for 10-15 minutes. The leaf fragments are strained out and the liquid has soda ash added to make the solution basic. To precipatate the indigotin, the solution must be whipped with an electric mixer for 15-20 minutes to add oxygen to the solution. The solution is poured into dishes and allowed to settle. The supernate is carefully poured or filtered off and the final pigment allowed to dry.

woad-settling-dishes

After adding soda ash and whipping the woad solution, we poured into dishes to allow the pigment to settle out. We then poured off the supernate.

We took it this far in chemistry class. Our next step will be to put the purified indigotin in a 50-60° bath and add some sodium hydrosulfite to the solution. This is a reducing agent that converts the blue indigotin into leuco (white) indigotin, which will dissolve in water and turn yellow-green. It takes about an hour of careful heating without stirring to do the conversion. While it is simmering (but not boiling), the fabric or yarn must be heated up in a bath with some soda ash. Once the solution turns yellow-green, the hot fabric or yarn can be carefully added without dripping or splashing. After about ten minutes, the dye has absorbed into the fabric but not yet bonded. When it is removed and exposed to the air, the fabric will turn from green to blue as the indigo converts from leuco back to blue indigo. As it precipitates out, it bonds with the fabric. Hopefully.

woad-pigment-settling

Woad dye pigment settling out on the bottom of our dishes. We poured off the supernate and dried out the final pigment.

I purchased some pure indigo from Dharma Trading Company and was in the middle of heating the dye bath with sodium hydrosulfite after school on Tuesday when our fire alarm went off – an exterior pipe in our fire suppression system had frozen and burst, so we had to evacuate the building. I quickly unplugged everything and left. It was the last day before Winter Break. I hope to return by tomorrow and continue the experiment. If it works with pure indigo, I will demonstrate the process in chemistry with our own woad pigment when we return from break. I’ll update this blog post then.

natural-dyes-andes

Andean people with naturally dyed alpaca yarn and clothing. The purples and reds come from cochineal, the oranges and yellows from tree bark, etc. All cultures have solved the problem of how to dye cloth; dyestuffs are found around the world.

All cultures around the world have found ways to solve the problem of how to dye fabrics. They’ve found dyestuffs in plants, minerals, and animals; through continual experimentation they’ve realized that certain salts (mordants) will help make the dyes colorfast. The process of oxidizing, then reducing indigo must have taken a long time to discover. It amazes me that such a complicated process could be developed in many countries and cultures, each with their own way of accomplishing the same thing, and all to get a permanent blue dye.

 

nilda-and-acopia-women

Alpaca wool yarn dyed with cochineal.

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