Dyeing with Dried Japanese Indigo Leaves

The easiest way to save Japanese indigo is to dry the leaves. This is also the only option, really, when you grow a small amount of plants.


In traditional Japanese dyeing with Japanese indigo, the harvested leaves were composted (fermented) in a very specific way, sprinkling the leaf mass with water and turning it over. The timing had to be just right, and Jenny Balfour-Paul writes in “Indigo, Egyptian Mummies to Blue Jeans” that the indigo farmers referred to the packing of the leaves as “putting the baby to bed”. Every time the leaf mass was turned over, sacrifices of rice wine were made to Aizen Shin, the god of indigo.

Composting Japanese indigo was serious business – a difficult and big undertaking. The composting process can only get going if the leaf mass is sufficiently large, on the order of 100’s of kilos (or several hundred pounds). The end result were composted leaves that contained a higher percentage of indigo than the fresh ones. This mass is known as sukumo.

People who only grow a few plants (like I do) have to find a different method. Having read about it on Deb McClintock’s page, I decided to dry my Japanese indigo leaves last year. And I did manage to do so after some trial and error.

The dry leaves look like this:

Dry leaves of Japanese indigo, 2016 harvest.

Some of the leaves look a bit blue, and that does make you think there’s indio. I’ve been wondering why drying the leaves would work (the must have been good reasons for the traditional sukumo method) and I’ve come up with the following story:

In living leaves there’s no indigo, only a precursor called indican. Here, the meaning of the word precursor is a molecule that can undergo some reaction(s) that produce indigo.

Indican production is thought to be a defense mechanism for the plant. In living leaves, the indican is primarily found in a compartment within the cell called the vacuole (shown by a Japanese team of researchers in this paper).

The plant cell also contains enzymes that are able to break down indican, producing indoxyl and sugar, but these enzymes are found in other compartments of the cell.

When you pick leaves and dry them, cell membranes will break because of the loss of water. So at some point, indican and enzymes from other parts of the cell will mix, and indoxyl is formed. When two molecules of indoxyl combine, blue indigo is formed.

I used Deb McClintock’s version of John Marshall’s method but I fiddled about quite a bit, finding my way to do it. The main change is that I didn’t discard the yellow dye, so I get a green-teal instead of blue.

Green-teal with dried leaves of Japanese indigo. From left to right, the skeins are 1st, 2nd and 3rd dip in a vat made from 50 g of dried leaves (3rd skein was naturally grey). The skein on the left was dipped 3 times in a vat made from 25 g of dried leaves. I’m knitting from the first skein already, the striped boy’s jacket in the background.

For my first attempt, I used 50 grams of dried leaves to dye 3 100-gram skeins of wool. The vat stopped working early on, so I added a bit of this, a bit of that. That lead to no recipe, but the result was completely fine.

My next attempt was made during an indigo workshop I taught a while ago, and I know it was hugely optimistic to bring such a difficult project. That vat only gave a slight hint of mint green, but at least we got a lot of brilliant blues from the ordinary indigo vats.

Afterwards, I started thinking that the vat may have gone wrong because the temperature was too low. This also makes sense when thinking about this failed experiment where I kept leaves lukewarm for a longish time.

High temperature during part of the vat preparation seems to be important, and that is a part of the method I ended up with for my third attempt:

First, I simmered 25 grams of dried leaves in water (enough to cover them) for 20-30 minutes. It wasn’t a rolling boil, but some bubbling going on.

To dye blue, the first water should be discarded and new water poured on the leaves. I did not do that, so I kept the yellows from the leaves.

I added 5 grams of sodium dithionite and about 1 tablespoon sodium carbonate. Check that pH is 9, and add more sodium carbonate if it isn’t.

Then, I simmered the vat for 15-20 minutes. It seems wrong to boil a vat after adding reducing agent and base, but in my attempt where I didn’t boil it at this step, it didn’t work.

I took the pot off the heat and added another 5 grams of sodium dithionite. I let it sit until the temperature was 40-50 C, then strained the leaves out. For my first attempt, I left the leaves in to get as much out of them as possible, but that is not a good idea. At this point, they are quite slimy and stick to the yarn.

When the temperature was 40-50 C, I put the pot on gentle heat to stay at that temperature. At this point, the vat is ready for use. I dipped a 100-gram skein of wool 3 times, and it turned a nice teal.

I’m impressed by the dye content of the leaves. 50 grams of dried leaves gave nice color to 300 grams of yarn, and 25 g gave a brighter color to 100 grams of yarn. My last vat was not exhausted, it had turned dark the next day because the indigo had been oxidized. I didn’t have more yarn on hand, but the vat could have given light shades on another skein.

Wool dyed teal with Japanese indigo, accompanied by fresh and partially dry leaves.

But I’ve saved the best for last: light fastness. I tested light fastness of the first skein from the 50-gram vat from July 1st to September 1st. The left side was covered and not exposed, right side was exposed to the light. I can’t really see any difference between them, and that means the light fastness rivals that of indigo blue. And that is quite impressive for a green-teal color!

Light test of Japanese indigo teal. Two months of sunlight did not affect the color.

PS: I’m growing Japanese indigo again this year. I harvested the first leaves on September 17. this year, and they are drying. They look even bluer than the ones from last year…

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Lichen Windfall

Lichen windfall is perfect for natural dyeing, since it does no harm to pick up the fallen ones, they will no longer grow. One of the most common and easy-to-recognize lichens in windfall is Ramalina fastigiata.


When walking outside on rainy, windy days, I very often find lots of lichens scattered on the ground under trees. Lichens that the wind has torn down from branches. Sometimes, on the day after a big storm, I’ve come home from walks with all my pockets plus random trash bags filled with windfall. Wonderful windfall with that amazing scent that only lichens have.

Collecting windfall does no harm, since these lichens are not able to continue growing anyway. It’s the best (some would say only) way to obtain lichens for dyeing. When I come home with such a treasure, I usually spread it out on a plastic tray to dry (to prevent mold).

Lichen windfall drying at home. It looks like a big piece of Evernia pruniastri on the left, Ramalina fastigiata on the right, and probably a Parmelia species on the bottom.

But before dyeing with lichen windfall, it’s necessary to sort the lichens and determine the species, since you will need to use the boiling water method (BWM) with some species, and the ammonia method with others:

Boiling water method – it is what it sounds like. Simmer the lichen in water and cool off. Add the yarn to the dye bath and heat it for an hour without boiling.

Ammonia method – the difficult one. Steep the lichen in 1% ammonia (originally, stale urine was used) for several weeks or months, opening and shaking the jar daily to aerate. The red liquid in the jar is the dye bath.

In both methods, no mordant is required, since lichen dyes are substantive (they bind directly to wool without the help of a mordant).

Lichens steeping in 1% ammonia.

In order to type lichens, I recently bought myself a copy of “Lichens, An Illustrated Guide to the British and Irish Species” by Frank S. Dobson. It contains a detailed introduction to lichens, and a detailed key with photos and descriptions.

With my copy of Dobson, I’m planning to take a closer look at the types of lichens that are commonly found in the windfall here in my corner of Denmark. That is, how to recognize them, how to dye with them, and which colors to expect.

I’m beginning with a very common type of lichen, which may very well be the easiest one to recognize: Ramalina fastigiata. Often, large tufts of this will fall, and they are completely covered in small outgrowths that look like tiny suction cups. The outgrowths are apothecia, the fruiting bodies of the lichen. They make spores for sexual reproduction. When the spores germinate in a new location, they meet with a new alga to become a new individual lichen. But the dyer doesn’t have to worry about all that, being able to recognize apothecia is the important part.

A piece of Ramalina fastigiata, completely covered in apothecia. Tufts like this can measure up to about 5 cm (2 inches).

Karen D. Casselman mentions the Ramalina species on the list of ammonia methods lichens in her book, “Lichen Dyes, The New Source Book”.

I’ve previously tested the ammonia method on Ramalina fastigiata and achieved a light rose color (pictures here).

But Casselman also mentions the and Ramalina species in her list of boiling water method lichens, so I decided to test that method on Ramalina fastigiata. I used equal amounts of wool yarn and lichen, and achieved no color at all (no pictures!). The conclusion: Ramalina fastigiata is strictly an ammonia method lichen.


This year, instead of binge-eating and wrapping a load of stuff, then unwrapping it, we decided to go to London on a Christmas trip. I have loved all the times I’ve traveled around Christmas/New Year (Paris, Chicago, New York, and New Delhi) and London was certainly no exception.

It seems that every time I hear or read an interesting story involving plants, Kew Gardens plays a role (for example, a recent radio story about conservation of a native fern on Ascension Island). So I made it a point to go there, although we clearly saw just a very small fraction of the place.

This is a bit of what we saw in the daytime:

Shapes of the Princess of Wales Conservatory.
Meat eating plant, as big as an adult’s hand. If I had wings, I’d fly in there.
The very edge of a leaf of the Victoria waterlilly. I’ve always had a soft spot for this huge plant.

So lots of amazing plants, but I didn’t see any dye plants. The closest was henna, and although it does dye wool (and hair), I don’t really consider it a dye plant.

Henna, Lawsonia inermis


Museum shops are always a temptation, and I almost bought “50 Plants that Changed the Course of History” by Bill Laws when it struck me that it does not contain any dye plants. Back on the shelf it went. I may be willing to accept that madder doesn’t make top 50, but surely indigo should?

We returned in the evening for “Christmas at Kew”, a lit path through the garden. It was cold and crowded, but beautiful:

The light tunnel continuously changed color, and people were glued to the spot.
The Hive, an installation by the artist Wolfgang Buttress, seen from the outside with illuminated trees.
Inside The Hive

We obviously didn’t go all the way to London without visiting Loop. I looked for naturally dyed yarns to see if they were immensely more delicious than the yarn I dye myself – and found three delicious yarns, but I’m happy to say that the yarn I dye is just as yummy. The first one is Shilashdair Luxury DK, which has quite intense colors, some of them quite vigorously variegated.

The second one is Linen Lace by Artisan Yarns. Beautiful muted colors and shiny texture. I seem to have thought just that also last time I visited Loop, because I actually have such a skein in my stash that I haven’t knit with yet.

The third is Plant Dyed by Mehlsen. I have never come across this yarn before, although it seems to be made not far from where I live in Mainland Denmark. Remarkably, they the colors are really similar to the ones I dye! So they really spoke to me, and I was really tempted to buy some of this yarn, but an internal voice of reason talked me out of it.

In the end, I walked out of Loop with “Estonian Knitting 1, Traditions and Techniques” by Pink, Reimann, and Joeste, a big, excellent, clearly edited and well written book. Lots of interesting information and old photos, and lots of techniques.

Naturally dyed yarns at Loop: Shilashdair (left), Artisan Yarns (middle), and Plant Dyed by Mehlsen (right). Photos taken with the cell phone in artificial lighting, so yarn really looks much better

The Victoria and Albert Museum (V&A) was the last big highlight of the trip. This giant chandelier by Chihuly hangs in the entrance hall, it’s hard to say if it’s ugly or wonderful, but it’s certainly impressive. I find his work always is impressive. It’s also oddly at ease in the natural world – I remember seeing his work at the Botanical Garden in Chicago, and the Aquarium in Monterey, California. In both cases, the glass mimicked the living things that surrounded it.

The Chihuly chandelier at V&A.

The V&A had this amazing knitted baby’s gown, which had been displayed at the 1851 World Exhibition in London. It’s hard to really see in photos, but the knitting is so, so tiny. Tiny! The museum text tells us only that “Miss Sarah Ann Cunliffe of Saffron Walden, Essex, knitted this dress” and that “It was made with 1 1/2 million stitches and approximately 5,770 metres of sewing cotton”. We aren’t told which needle size was used, but I would think 1 mm or maybe smaller.

This picture was taken in low light and without flash, and does not do the 1851 baby gown justice.

There is also many wonderful tapestries at the V&A, and since they are made long before 1856, we can be sure that all the dyes are natural. These tapestries are clearly worth studying for those worried that natural dyes won’t last.

Here are a couple of details from a Belgian tapestry from 1718-24 titled “The March”. Some of the yellows have paled (as expected) which leads to a blueing out of greens produced by yellow with indigo blue overdye, but not disturbingly so. I’d call a color that looks like this after 300 years light-fast.

Blueing out of greens in a 300-year old tapestry

The only bad thing about our trip was that my potted Japanese indigo plant died while we were away. I uprooted this plant when I harvested the last of my plants in late October and it has been growing and flowering inside ever since. I cut it down, and looked inside the dead flowers. It looks like seeds, and it will be interesting to see if they will germinate.

Amazing Dyeing Failures 1

Failure in natural dyeing is commonly defined as not getting the result you expected. Beige, off white, baby yellow and other tones of grime are all examples of colors I have made no attempt to acheive, and yet, I have a big pile of skeins just like that. But there’s actually a lot to be learned from failures. Some give new ideas of what to try next. Others just tell you what not to do. Below, I’ll describe some of my failures – actually, I’ve failed so many times that this will only be the first installment, more to follow.

Alle de mislykkede og uønskede farver. Efter billedet blev taget overfarvede jeg med indigo.
Skeins of failure. They were all overdyed with indigo after taking the photo.

1: Bark Failure

Several books on dyeing will tell you that different types of barks are good dyestuffs. For example, Jenny Dean’s “Wild Color” mentions these barks and the color they should produce on alum mordanted wool: alder (brown-green), barberry (yellow), ash (bright yellow-green), apple (warm yellow), oak and willow (beige), and finally elm, birch, cherry, pear, and plum (pink).

For a while, the theme of my walks was bark; in the end, I found enough of these three to try them as dyestuffs:

  1. Birch (Betula) – I’ve used birch leaves several times for a sunny yellow, but not the bark. Some trees were cut down near our house, and I jumped at the chance. The trees had been left in a big pile, which I obviously had to climb to get to the good parts, and since I was of course wearing clogs, I fell down from that big pile in the end. With 60 g of birch bark in my pockets.
  2. Another day I hear some men working outside, shredding logs. On their day off, I casually walked by and managed to peel a good amount of bark off. The logs turned out to be alder (Alnus), the kind with the tiny cones. 70 g of bark.
  3. Last one is some bark from a forest walk. I jumped over a big, big ditch to get this. I’m pretty sure it’s beech (Fagus). My daughter jumped it too, so I had to save her afterwards. 94 g of bark.
Dagmar tæt på at falde i grøften
Dagmar, seen moping, came close to falling into a large ditch.

I used Jenny Dean’s general dyeing method for bark. She says that “barks are best soaked for several days or even weeks in cold water before processing. Then simmer them for one hour. Never boil bark, as this will release too much tannin”. So that’s what I did – left the three types of bark to soak for a couple of weeks. That was long enough that they started fermenting, and I can tell you that it didn’t smell that good.

But when I simmered 10 g test skeins of alum mordanted wools in the three bark dye baths, the color in the end was pale beige. I didn’t even bother taking pictures (because when you’ve seen one skein of pale beige wool, you really have seen them all), but you can see one sticking out between the pale pink skeins in the left side of the first picture above.

I have seen other dyers experiment with bark (for example, at my wool group’s dyeing day) and also get pale beige or off white. So right now, I’m not even convinced that it would ever work, and I probably won’t try it again unless someone can tell me what went wrong (please comment below if you know or if you’ve had good results dyeing with bark).

2: Slimy/Moldy Avocado Failures

There are established procedures for dyeing with avocados, but I’ve been experimenting with slightly different ways of doing it. I suppose to make the procedure easier and better, but of course ending up making it messy and complicated.

According to Carol Lee, avocado pits should not be allowed to dry before use because they will become so hard that they are impossible to chop. Instead, they should be frozen until use. I wanted to find a way to dry them anyway because my freezer is small.

So I chopped the pits and skins and then left them to dry. This worked well on a couple of occasions, but most times it did not because they became completely overgrown with mold before they had time to dry. Moldy materials may still work as dyes, but I think it is generally unwise to handle them repeatedly around the house, since many molds produce toxins that may be inhaled. So I went back to freezing the skins and pits.

Avocado pits and skin turn red as they dry, so it’s not that surprising that the dye bath they produce is also red.

Another experiment was to ferment the pits and shells for a looong time to see if they yielded more color that way. I used my dry material, soaked overnight, but I suspect the results would have been the same had I used frozen dyestuff.

I usually ferment avocado pits and skins by heating them up once in brine, then just leaving them. Normally for a few weeks or a month, this time for six months. And the dye bath did develop a deep red, but it also became extremely slimy.

Despite the sliminess, I tried dyeing a small test skein in this dye bath, but it didn’t yield good color. My guess is that the slime prevented good contact between yarn and dye. But I’m not convinced that a long fermentation couldn’t yield good color. I’ve been adviced to put avocado pits and skins in jars, close the jars, heat them up, and then ferment. Such jars should not go slimy. I’ll try that next time.

Beige med lidt rødlige striber
Beige with a red streak, that’s the look of yarn dyed with avocado slime.





Curly Dock Mordant

Dock or sorrel are useful plants for mordanting – this was a fact that I’d gotten from reading and made a mental note of. I couldn’t remember where I read it, so I decided to just go ahead and try it. I picked curly (or curled) dock (Rumex crispus) in the roadside around July-August. Curly dock is a tall plant with a reddish seedhead.

The seeds of curly dock.

Curly dock can be distinguished from other related species from the fact that its seeds are enclosed by three petals that have a growth on the outside that looks like a seed but is not.

Enclosed seeds of curly dock.

I used about 100 g of stalks with flowers for a test skein of about 12 g of wool. I boiled the curled dock the first day and let it cool off. The next day, I heated the yarn in the sorrel bath to just under boiling, then let the yarn cool off in the sorrel bath (for a couple of days in the end, because I had other fish to fry). After the sorrel mordanting in the dark red sorrel soup, the yarn was coral red.

The concoction of curly dock, and yarn treated with it.

Finally to the dyeing part of the experiment. I dyed my sorrel mordanted yarn plus two other 12-g test skeins (one unmordanted and one mordanted with 10% alum, my standard mordant) with madder. The dye bath was 40 g of madder root in rainwater, and you can see the result below. As expected, the alum mordanted wool is an intense madder red, but the unmordanted and sorrel mordanted wools are the exact same shade of orange (and a nice orange I think). But I’m going to call this a failure, since the sorrel mordant didn’t make a difference from no mordant.

Alum treatment gives the usual madder red – no mordant or treatment with curly dock both give orange.

So what went wrong? In the end, I realized that I read about sorrel mordant in India Flint’s “Eco Colour”, the exact information she gives is:

“Dry and grind the roots and mix with water to make a tannin-rich soaking solution. The leaves of this genus are also rich in oxalic acid. Even the dried seeds have mordant qualities.”

This doesn’t completely solve my mystery, though. The roots contain tannin, which only works as a mordant on plant fibers, not wool. But I used the flower stands with leaves, which (like rhubarb leaves) contain oxalic acid, which should work as a mordant on wool. Maybe the amount was just too low? I have to try tris again next year.

Woad – A History of Blue

Finally, the summer holiday is here! I’m going to spend it dyeing (with natural dyes, of course), knitting (with my naturally dyed yarn) and reading (about natural colors, what else??).

I just finished reading the Norwegian book “Vaid – En historie om blått” (Woad – A History of Blue) by Anne Sagberg, a well written and interesting book that contains a lot of information that was new to me. The author obviously did her own research instead of rehashing existing literature on this topic.

The chapters on historical finds of woad dyed Norwegian textiles are especially interesting. Wild-growing woad is found in multiple locations in Norway, including the coast of Nordland (quite far North). It’s unknown if it was previously grown for dyeing, but there are many finds of woad dyed textiles from different eras.

Woad – A A History of Blue, by Anne Sagberg.

The Oseberg Ship was discovered in 1904, and is a ship grave from the year 834. Two women were found in it – one dressed in blue, on in red. The red textile is very fine, probably imported, and the garment is embellished with silk ribbons. The woman in red is referred to as the Oseberg Queen. The blue textile is not as fine, probably a local product, so the woman in blue could be a servant.

Not only was the blue textile dyed with woad, the queen also had a small box of woad seeds with her among the grave gifts. I find this really interesting. We don’t know if the plant was cultivated in Norway at the time, but someone almost 1200 years ago found a small box of woad seeds precious or important enough that it was given to an important woman to bring with her to the afterlife.

I saw the Oseberg Ship, which is found at the Viking Ship House, some years ago. It’s impressive and beautiful, but unfortunately, I don’t remember anything about a box of woad seeds. I didn’t know to look for it at the time, but also, I don’t know if it is displayed.

Osebergskibet, udgravning tv og det istandsatte skib th.
Left: Excavation of the Oseberg ship. Right: After restoration. Photos in the public domain.

The Baldishol Tapestry is a surviving fragment of a once-larger piece – you can tell from its torn edges. Its story is incredible.

In 1879, the old church in Baldishol was torn down, and the neighbors bought some of the objects from the church. Some years later, a Louise Kildal visited from Oslo and took one of the objects home with her – a dirty rag that the organist used to drape over his legs because there was a terrible draft in the old church (!)

Home again, Louise Kildal washed the rag, and what came out? The colorful Baldishol Tapestry, a wowen picture from between 1040 and 1190. The tapestry is kept at Kunstindustrimuseet in Oslo, and next time my path goes near it, I’ll make a point of seeing it.

Meanwhile, I could easily see myself dyeing some yarn to match the tapestry’s colors. It contains several blues, probably from woad. The green color is yellow overdyed with blue, so clearly large amounts of blue went into creating this precious piece. One of the red threads (left over from earlier restorative work) was analyzed in 2013. The analysis showed that the red color comes from a member of the Rubiaceae family (to which madder belongs) but apparently couldn’t tell if the color is indeed from madder or another member of the family. The yellow has not yet been analyzed, but Anne Sagberg tells us that weld was used since early times, and could have been cultivated in Norway or imported.

Af Frode Inge Helland - http://kunsthistorie.com/fagwiki/Fil:BaldisholteppetRepr_1000.jpg, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=15836282
The Baldishol Tapestry. Photo: Frode Inge Helland

The book covers many more topics than the ones I mention here. Anne Sagberg writes about the excavation of a grave inside the stave church of Uvdal. A young woman was buried there in the latter half of the 14th century, wearing a woad dyed hood, a shape that was very fashionable at the time. Sagberg recounts the problems she encounted trying to recreate the hood (not easy!). A detailed description is also given to three wall hangings, Vossaduken, Huldreduken and Veøyduken. They are from the late 15th century, and all embroidered with geometric patterns that I’d like to knit one day.

Anyone who made it through all this text will have no doubt that I’d like to recommend Sagberg’s book to those able to read Norwegian!

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Thinking about Woad

Woad is flowering right now, in lovely yellow abundance, and I’m hoping for a good seed harvest.


Seeing the abundance of flowers made me want to knit with my woad dyed yarn from last year, and so, it’s become part of a whole obsessive-compulsive series of hats that I’m knitting these days, following Olga Buraya-Kefelian’s Hado pattern. So far, I’m knitting the third one, of course with a lot of mods although the pattern is a good one, and simple, too. The hat below has stripes of woad and poisonous orange mushrooms from last fall.


Saxon Blue

Ever since I first read about Saxon blue, produced by reaction indigo with concentrated sulfuric acid, I’ve really wanted to try it.

The lawyer Johann Christian Barth is credited with inventing the Saxon blue reaction in 1743. He treated natural indigo with sulfuric acid, then known as “oil of vitriol”. According to de Keijzer, the dye was in use in England by 1748, and Jenny Balfour-Paul writes in her book “Indigo” that the dye “can be seen in some oriental carpets, most characteristically those made in Turkey during the second half of the nineteenth century, and also in late eighteenth century Kashmir shawls”. The dye was relatively popular, even though its light- and wash-fastness is not as good as that of indigo itself.

Balfour-Paul calls the color “bright turquoisy blue” while de Kaizer mentions “bluish-green” shades.

The story about this caught my interest because it seems to be a midway point between truly natural dyes, and the synthetic dyes that came after Perkin’s discovery of mauveine in 1856. If made from natural indigo, Saxon blue is not really a synthetic dye. But it’s not fully natural, either, and the process that it was used in clearly seems to fit better into what we think of as an industrial process.

The problem for trying this at home is that you need to use concentrated sulfuric acid in order to produce Saxon blue. This is not something you can just go out and buy, and there’s a good reason for that. It’s a quite dangerous acid that reacts with carbohydrates like bread in a way that makes it look like the bread is on fire.

But now, the perfect opportunity came up, the exam project for teaching chemistry that  I’m working on right now. So here’s my little experiment with Saxon blue. I tried this in a chemistry lab, inside a fume hood, wearing lab coat and safety goggles. DO NOT TRY THIS AT HOME!!

I mixed 0.5 g of indigo powder with 5 mL of concentrated sulfuric acid, and then heated it over a simmering water bath for about 10 minutes (left photo below).

Then I diluted the indigo into water, and put in alum mordanted wool. I heated the wool in the dye bath for about 40 minutes (right photo below). Even after diluting, the solution was very acidic (pH 1).

Dyeing in the chemistry lab.

This is how the skein of wool turned out after rinsing out the excess color (there was a lot). A very clear blue, that’s actually very similar to the shade of blue you would get with indigo used as a vat dye.

Saxon blue wool.

But the chemistry behind this blue is different from the usual indigo chemistry. The reaction between indigo and sulfuric acid produces a compound called indigo carmine (this is what is called Saxon blue). Indigo carmine is an acid dye, not a vat dye. That means that it will bond to aluminum that was attached to the wool during alum mordanting.

Notice the cotton thread tied around my Saxon blue wool skein below. It’s only slightly blue-tinged. Alum does not react well with cotton, so there were only very few sites on that thread where indigo carmine could bond.

Now compare with the blue on the pile of cotton in the back. It just happened that I used the very same cotton thread for tying around clothes that I shibori dyed with indigo using the usual method. Notice how parts of the thread in the back are quite dark blue. They were exposed to the indigo vat, and the color took well, because indigo can deposit directly on cotton (there are also white parts, but they were just not exposed).

Saxon blue does not dye cotton well at all – for that, you need an indigo vat.

It was fun to try dyeing with Saxon blue (indigo carmine), but I don’t really see myself repeating the experiment for the purpose of actually dyeing wool. The fact that the light-fastness is low and the process uses concentrated sulfuric acid means that the comparison with indigo itself does not fall out in Saxon blue’s favor.

But if you are wondering what Saxon blue is up to these days, check your candy wrapper. It shouldn’t be difficult at all to find yourself some candies containing FD&C Blue #2 in the US, and E132 in the EU. That’s indigo carmine, or Saxon blue. The stuff in food does not come from natural indigo, it’s synthetic.

If you have appetite for some more dyes, you can also look for natural red 4 (US) or E120 (EU). It may also be written as carmine. Around here, it’s known as cochineal. In this case, the coloring in food does actually come from the natural source. Some people find this disgusting, but having ground the lice so many times for dyeing, I actually find it quite unoffensive.

Madder Love & a FO

Madder red has been used by humans for millennia. Or, as someone much more eloquent that me put it: “Madder’s diary goes back as far as history’s earliest written pages” (Brian Murphy in “The Root of Wild Madder”).

Whenever I dye with madder, and stop to really think about its history, I’m quite fascinated. Yes, the colors from madder are varied and wonderful, but when you know more about its history and chemistry, then you see more than just color!

At the time of the ancient civilizations around the Mediterranean (Romans, Greeks, Phoenicians), there was an extensive trade in dyestuffs: madder, indigo, and Tyrian purple. This was taking place as early as the 12th century BC (for more details about this, see chapter 1 of “Handbook of Natural Colorants” a quite expensive book, but you can see an excerpt here which includes chapter 1).

In the context of oriental carpets, the history of madder is just as long. Classical Persian and Afghan carpets are dyed with madder (and its old friend indigo), and natural dyeing is the very reason that good carpets age gracefully, and even become more beautiful with age. In a naturally dyed carpet, the colors of wool change a bit differently with time, which adds a dimension to the pattern, called abrash. Notice the bands of lighter and darker background red in this carpet:


The main dye molecule (one out of maybe 20) in madder root, alizarin (AKA 1,2-dihydroxy anthraquinone), is a very good dye. It is one of the most light-fast natural dyes in existence, and its wash-fastness in complex with a metal ion is also very good (this is one of the reasons we use alum, which provides an aluminum ion).

The first few times I attempted dyeing with madder, I was quite disappointed because I couldn’t get the deep red. It turned out that my tap water was at fault. We Danes (at least here in the mainland) get our tap water from the underground where it rests on chalk deposits, so it is full of carbonates that interfere with the dyeing process. After switching to rainwater, I always get good results.

The first madder bath yields a deep red, and the next baths a series of progressively lighter coral shades. I’ve always loved the deep red, but the corals from the later baths have really grown on me.

And now I’ve finished a sweater for myself in such a coral shade of madder. The pattern is Folded by Veera Välimäki, and the yarn is Supersoft (575m/100g). I absolutely love the color, it really brightens the day when you are surrounded by people who mostly wear black and grey. The dye job is not very even, and that is actually what gives a nice fake abrash to my sweater. And I love how lightweight and comfy my it is, just 153 g. That’s because I knit the Supersoft quite loosely on a 3.5 mm needle


The part that I’m less thrilled about is the fit of the sweater in the area around the shoulders. I followed the upper part of the pattern without modification, and the shoulders just don’t have enough fabric in them because the raglan seam is not long enough. I put the folds on the back of the sweater instead of the front, and I think that makes it much more flattering than the original.

The Quest for Light-Fast Purple, Part One

Purple! This color has spelled trouble for the natural dyer for centuries, millennia even…

Tyrian purple, the famous purple used in antiquity, came from Phoenicia (around present-day Lebanon) where the coastal waters were full of snails of the Murex family, from which the dye (6,6′-dibromoindigo) was extracted.

In ancient times, Tyrian purple was an immense luxury, so expensive that only the very few could afford it. I don’t know exactly how expensive it was back then, but I looked up today’s price here: 27.444 kr per gram (that’s $4120 or 3675 euros). Per gram. I don’t know how much fabric that would have dyed, I’m guessing it couldn’t possibly be more than a kg (and probably much less) so we are talking about one expensive color.

I imagine there must have been quite the excitement when logwood purple hit the stage. Logwood (Haematoxylum campechianum) is a tree that grows in Mexico and Central America, and was brought back to Europe, where it became a much used dyestuff.

The dye molecule in logwood is hematoxylin, a molecule that is used for staining in cell biology even today!

Logwood can be used to dye a very nice purple on alum mordanted wool:


A very lovely purple indeed. But there’s just one big problem – the light-fastness is really low!

At a higher dyestuff to wool ratio, logwood and alum together give a blue color, which also has a terrible light-fastness.

My Danish book, “Farvning med planter” by Esther Nielsen, says that logwood blue was nevertheless used, and may have been OK for a while because people had little light indoors in the past. But the same book tells you that French dyers of high color were not allowed to have logwood in their workshops at all, because they also had alum, and those two together could be used to produce the inferior logwood blue which was forbidden for the dyers of high color – they had to dye blue with indigo.

Plain dyers, on the other hand, were allowed to have logwood, but they mainly used it to dye black. This is done by addition of iron, which makes the color somewhat more light-fast. The German name for plain dyer is “Schwarzfärber” which actually means dyer of black (this interesting article has more information on the dyer’s guild’s division into plain dyers and dyers of high color).

Historically, natural purple pretty much came to an end in 1856 with Perkin’s discovery of mauveine, the first synthetic dye. This discovery is often described as serendipitous, but I think that’s not so accurate. It is true that Perkins first made the molecule by happy accident, but he then noticed that the solution in his flask was purple. That was the first step. The second step was to quit his studies and turn mauveine into a successful business, something that required a lot of skill and effort over many years (this BBC program tells the interesting story, and also talks about the other top seller his company made: chemically synthesized madder red!).

But I’m not giving up on purple just yet, so I’ve decided to do a slightly systematic study of indigo overdyeing of some reds and pinks. To get an idea, I’ve played a bit with a color blending tool. Just to get an idea: this is a strong pink (cochineal) overdyed with weak blue (indigo), and  this is a weak red-orange (madder) overdyed with strong blue (indigo). Next step is to actually carry out the overdying experiment, more on those results later!