Category Archives: historic textiles

Why spin for weaving?


To make fabric like this.

I can’t look at it without smiling.

The seeds of this project were sown at SOAR, the Spin-Off Autumn Retreat at Tahoe in October 2012 when I attended Stephenie Gaustad’s ‘Spinning for a replicate or reenactment textile’ aka the Class of Awesome!  It truly was a Class of Awesome: I left with far more knowledge and confidence about spinning for weaving as well as a class handout containing descriptions of several historic textiles. ‘Donbæk Check’ – named for the burial site where it was found, near Frederikshavn in Denmark – sounded fascinating. Dating from the Iron Age, the 2/2 twill fabric had a chequerboard pattern produced by the light falling differently on the intersections of singles spun clockwise and counter-clockwise in the warp and weft. I’d heard of/seen pictures of twist-patterning in tablet-woven bands but hadn’t thought about it on fabric. Back in the UK I made a special expedition to the University Library to photocopy the reference and vowed I’d try this one day.

Fast forward to January 2017, when I was preparing to teach my first ‘Spinning for weaving’ workshop. While I enjoy making *any* fabric from my handspun, I wanted to show the students something memorable, a fabric that would be impossible or at least very difficult to weave from commercial yarns… and I remembered the Donbæk Check. Perfect. I had 2 x 100g packs of charcoal grey Wensleydale combed top from Julia Desch/Diamond Fibres: this is not pin-drafted top from giant drum carders, this is real (commercial) combed top. It’s special. It’s lovely.  I spun each 100g in a different direction using a short forward (‘worsted’) draw for a dense and shiny singles yarn that would – I hoped – reflect the light effectively.

WensFibreThe fibre: a slightly darker version of the Wensleydale top, together with a washed lock from a Wensleydale fleece. Shiny!

Sized&unsizedThe singles, before and after steaming to set the twist.

I wanted to protect the smooth surface of that yarn and wasn’t sure how much I’d use for the warp, so I used a gelatine size on all of it.

sizingThe sized singles yarns drying on the clothes tree. The plastic bin is weighted with just enough water to hold the singles taut, removing the pigtails, but with minimal stretching. Remember that wet wool is weaker than dry wool.

I wound a warp from just over half the yarn by weight, alternating clockwise and counterclockwise yarns every 26 ends to yield a rough 1″ check. Sett at 27epi for twill calculated from wpi it was seriously sleazy. I unwove the first 2″ and re-sleyed at 36epi, an eyeballed guess. This produced what I think is a lovely looking fabric that wove with a delightfully clear shed; although I hadn’t spun the yarn particularly tightly, the fact that it’s a longwool meant there were fewer ends, well locked down, so relatively little fuzz.


I was worried at this point because although I’d dutifully alternated the clockwise and counterclockwise singles in the weft (carrying the unused yarn up the selvedge), I could not see a pattern. I checked the underside… no pattern. Well. I needed to know how the cloth would behave after finishing (simple washing, in this case), and as the class had been moved forward I needed an example of it as soon as possible, so I cut that strip off as a sample, roughly stitched it to bind the ends and create a tiny ‘loom state’ sample, then washed the slightly larger piece.




The size was obscuring the pattern on the loom state fabric. It’s even more subtle than I expected: if the fabric is flat so the light does not play on the surface the pattern is scarcely visible.


I didn’t have time to finish the sample warp before the class, so I took the table loom and that small sample to show them, which was probably better than the finished sample alone, as students who hadn’t woven were able to try their hand.

Then I raced home to weave it off the loom, stitched the ends and threw it into the wool wash cycle of the washing machine. I ironed the damp fabric on the counter top (not the ironing board, which is too soft), using all my weight and the ‘linen’ setting to flatten it: the chequerboard formed hills and hollows in the unironed fabric.

Sample1Unsurprisingly the weft stripe is more obvious on one side, the warp stripe on the other, but the chequerboard is visible on either side if the light is right.

It’s even more visible if light passes through the fabric. Isn’t that interesting?  I’ll just go and find a hand-lens so I can mark the twist directions of the singles in the sample…


In The Big Book of Handspinning Alden Amos wrote “If warp and weft have the same twist direction, the threads will bed together better during the weaving … If the warp and weft have opposing twists, the individual yarns will be plainer or clearer in outline, the cloth will not be quite as dense.”

First I must consider another factor: the amount of twist I put into the singles when spinning. I almost always spin singles clockwise or ‘S’ – it’s the modern tradition – and this means my hands don’t get as much practice drafting while spinning counter-clockwise. Spinning counter-clockwise felt awkward, and I had to adjust my whorl and treadling to accommodate the slower drafting. When I look at the singles at 20x magnification, I can see that the counter-clockwise singles have a shallower twist angle – less twist – than the clockwise singles.

In that photo the clockwise (S) singles certainly do exactly as Alden suggests: they bed together tightly, forming the densest squares (S/S). Looking more closely at the fabric than I can photograph – you’ll have to take my word for it – I see that the counter-clockwise singles also bed together tightly, but only in small areas of the Z/Z squares: the variation in twist is interfering, and this is why on average the squares look less dense. In the S/Z or Z/S squares, the yarns do seem to form a more regular grid, as though the warp prevents the weft yarns from cuddling together and vice versa. It occurs to me that this sort of interaction would have caused the hills and hollows in the fabric when it came out of the washing machine – and that my hot iron and heavy pressing may have altered the ‘natural’ interactions of the singles.

All food for thought. Further experimentation is required!

The Hat of Authority

That’s a gripping title if ever I saw one. Thanks to Freyalyn, who named the hat during the ‘Spinning for Weaving’ workshop on Saturday as I put it on to call the class to order. It’s hard to miss, especially as the coins and charms chime as I move.

hatwalkingWearing The Hat in public for the first time, hiking in Derbyshire.

Two previous blog posts tell the story of the fabric of the hat: ‘The wrong fibre in the wrong place at the wrong time‘ describes how a highly unsuitable fibre preparation was re-processed to become something far more suitable (if any of the workshop attendees are reading this, note the use of a small cardboard loom-equivalent to establish whether the fabric would full), and ‘A project for the Cotswold.‘ briefly describes how I came to make a hat from it. I didn’t post more because the description became an article for Spin-Off Magazine (Summer 2014, ‘Uzbekistan by Hat’.

The executive summary, in pictures:
I work primarily with handspun singles. To prevent loss of twist, to make the yarn easier to manage and (to some extent) to protect it during the weaving process, the singles may be sized. Here the sized warp is drying on a makeshift stretcher in front of the bathroom radiator. (Workshop people, note that’s a hiking pole and chopstick stretcher, not the broom handle and hoe I use if I have more skeins!)WarpSized

From left to right: the Cotswold warp as it came off the bobbin, after steaming to set the twist, and lastly the dry sized skein.Warp

The hat fabric on the loom: Cotswold warp and handspun ‘Falklands’ (unspecified blend of Romney, merino and similar) weft.Fabric

I chose Falklands for the weft because I wanted to full the fabric, which I did in a hot indigo vat. Here the fabric is drying immediately after dyeing. I agitated it considerably in the vat to aid the fulling; the end result was not entirely even, but very beautiful. Or at least I think so.FabricDyed

Samples of the fabric for my records. Despite the fact it would be difficult to duplicate these handspun yarns (not that I can see any reason to try), the samples are useful records of how the wools and the fabric behaved. Note the tracking (the twill-like diagonal ridges) visible in the finished samples.Samples

I’d never made a hat from fabric. Clearly before I could make a hat I had to make a pattern. Having decided to make a hat inspired by those worn in Uzbekistan, I chose a style that looked as though I might be able wear it in public without dying of embarrassment, and started cutting up bits of paper to work out a pattern.hatplan

My first attempt proved to be a tiny yurt suitable for wearing on my head. But after some adjustments and more waste paper, I tacked together a fabric version to test the size and fit, then untacked it for use in cutting my fabric.TheHatProject.hats

Time passes. A LOT of time passes.

Sheila Paine and many others have written many words about the significance and meaning of folk embroidery. A gift from Sara Lamb, ‘Skullcaps of Uzbekistan‘ proved particularly interesting and useful. Reading and re-reading, I eventually could no longer postpone putting needle into cloth. What to use for the embroidery? Silk, in bright – and significant – colours. Some I dyed and spun for The Hat (it had acquired initial capitals in my thoughts), some were thrums of silks dyed and spun for my tablet-woven bag.embroiderysilks

Research suggests traditional makers usually embroider the hat fabric before the pieces are cut but, as I had never made a fabric hat before and had very little clue about what I was doing, it seemed wisest to make a hat that fit and embroider that. Having used some of the finer silk to sew the hat together, I rapidly discovered that I needed guides for the geometric patterns, hence the lines of white sewing thread.HatAgain1

Each of the patterns has – or is thought to have – a meaning or purpose, generally protective: bringing good fortune, or warding off bad luck and demons. The colours, too, have meaning: in many cultures across the globe red is apotropaic: it wards against evil.

In the photo above, the maze of complex swastikas is a demon trap in the making: entranced by the complexity they wander into the maze and are lost. The mirrors of the shisha embroidery dazzle and confuse any that elude the maze. Above, ram’s horns symbolise strength, courage and protection.

Below, one of my personal favourite symbols, a non-traditional orobouros symbolising infinity and the cycle of life becomes two owl eyes to frighten demons. The mother-of-pearl buttons used for the eyes and the silver coins are traditional embellishments, catching the sun to distract and confuse evil spirits. Hatback

Below, just visible on the left side band are two traditional Uzbek stylised birds. Apparently there is an old belief that if a bird sits on a man’s head it will make him happy (don’t ask, I don’t know). At the front is a sun disk, offering protection from the evil eye and any passing impurity. It is flanked by guardian cats.hatFront

Somewhat distorted by perspective, at the top of the hat is a band of shepherd’s crooks (protective), below which is a band of ‘amulet triangles’. Thought to be based on very, very early depictions of the Goddess, these are protective. Some of mine have diamond-shaped ‘heads’ containing four squares, the shape known as ‘fertile field’ that usually means fertility in the sense of offspring but I’ve used as heads because I’m interested in fertility in the sense of ideas. Tiny gold stars (light to distract demons) and the s-shape that may be a greatly simplified dragon (protective) also appear.  Dangling from the top of the hat are glittering, noisy coins and a miniature silver Maes Howe ‘dragon’.


When I presented my project to the spinning group I found my voice breaking with emotion as I tried to convey how I’d felt as each stitch linked me more closely to the many, many others who for millennia have made clothing to protect those they loved. Writing this I find the same emotion rising again. Think of the work involved in making a garment, even a hat, when women clothed their families in the days before millspun, machine-woven cloth. Gathering the fibre, preparing it, spinning it, weaving it, thinking of the person for whom you’re making it. Saving and bartering for cherished bright silks, shiny coins. Hoping and believing with every stitch that your embroideries are more than embellishment; you are creating a garment that may offer guidance and protection to the person who wears it, a tangible expression of your love and skill.

We’ve lost that. Our lives are so much easier… but we’ve lost something along the way.

A handspun, handwoven, mostly hand sewn jacket. Eventually.

In April 2014 I decided to spin and weave fabric a fabric from singles (unplied yarns) for my first planned garment. I bought black (‘black’ in this context means very dark brown) Shetland for the weft, above top left. It was a bit boring when spun from the top, so I carded bats including some slivers of multi-coloured silk. I thought Black Massam (the other two images) would make a good warp: the offspring of a Teeswater ram put to Dalebred or Swaledale ewes, the fibres should be longer, a bit coarser, and have more sheen than the Shetland. In the event neither of the tops were quite as I expected: the Shetland had a lot of kemp (very coarse flattened hairs) and more hair mixed in with the wool, and the Massam was shorter and very variable in thickness. Nonetheless I persevered. Once spun the warp was steamed to set the twist then sized to make it easier to manage; the weft was steamed (otherwise it can twist into little pigtails after the shuttle is thrown and before it’s locked into place by the changed shed).

The sized warp dries under light tension.

I warped and threaded my Baby Wolf loom for an 8-shaft broken diamond twill at 30 epi. The yarns behaved reasonably well on the loom although I had more breakages than I like, mainly where I’d made quick-and-dirty joins while spinning, laying the spun end from the orifice onto the fibre instead of opening up the spun end to join fuzz-to-fuzz. I wasted far more time protecting fraying joins with hair gel than I’d have done making them properly in the first place! The quick joins are fine for yarn to be plied, but they’re disasters waiting to happen if you’re weaving singles.14410873262_a0ab954361_c

I can’t remember how much fabric I had when I finished, but I do remember the wonderful feel of it washed (zig-zag stitch the ends, throw in the washing machine wool wash cycle, remember to clean the filter afterward!) finished (hot iron both sides, no cloth) and the satisfying weight of the roll. But what should I make? Laying out modern pattern pieces on my narrow fabric would be wasteful, and I’m not a tailored jacket sort of person. I decided on a jacket based on Pattern 23, ‘Man’s coat, Afghanistan’ from Dorothy Burnham’s extremely useful Cut My Cote. Never having made anything other than commercial patterns, and never having made anything that actually FIT me, I was a bit unsure of how to start from the sketches of the pattern pieces laid out on the fabric width.


I enrolled in one of Alison Smith‘s ‘Three Day Own Choice’ workshops and – amazingly – emerged having learned to translate the sketch to paper pattern pieces, use these to make a toile, adjust the pattern, cut my fabric, overlock/serger all the edges, sew the jacket AND insert a mandarin collar into the existing collar band. I can’t recommend Alison too highly! I returned home with a lightweight unlined jacket, on which my exposed selvedges are a decorative detail. (Alison’s suggestion, she liked them. All weavers may now pick up their jaws up from the ground and replace them.)


The lack of internal seam finish annoyed me. I decided to weave lengths of inkle band to cover the seam allowances but, several months and about 8m of band later, concluded this was a bad idea: the decorative bands were too bright and, worse, made the seams too stiff. The jacket went into time out (also known as a plastic bag in the closet).

Imagine the flickering calendar pages of time passing…

After seeing one of the reconstructed Herjolfsnes garments at the Ship Museum in Roskilde earlier this year, I started thinking about making some of the dresses for myself, first in a commercial fabric and then in handspun handwoven. Reading about the garments and sewing techniques in Medieval Garments Reconstructed, I remembered the abandoned jacket: I could rip off the inkle bands and practice medieval sewing techniques!

In order to sew, I had to have thread. Handspun thread. Not being able to carefully select the best hairs from my fleeces after washing and shearing my double-coated sheep, I dug through my stash to find the remaining twist of Shetland from the weft. The mix of kemp, hair and wool means it’s far from perfect, but it works.

Top left, singles spun on a light spindle; Below, my plying spindle and mugs;
Right, the final 2-ply thread.

I take pride in my ability to wind fine spun singles into balls without using a core but it is easier to ply from the balls if they don’t bounce around: using a pebble as a core adds weight, and putting each ball into a mug and wrapping the singles around the handle before taking it to the spindle makes it much easier to control. The plied yarn is well within the parameters of those used on the Herjolfsnes originals.

The book mentions the possibility that the threads were finished with something, perhaps beeswax, before sewing. I found quite a lot of information about thread finishes, something that I – a non-sewer – knew nothing about, on the internet. I decided to try running the thread across beeswax before using it, and now I’m a convert, at least for handspun wool thread.


The wax stiffens the thread, making it easier to thread the needle. Being slightly sticky it pulls off some of the fuzz from the thread (see the hairs left in the wax), which makes the thread much easier to work with. And it smells lovely.

Three or four inches at a time, I’m trimming the overlocked finish off the raw edges and binding them down to the garment.


Pebbles from California on which to wind thread, the snips I use to trim the fabric, and the bowl in which for some reason I’ve kept ALL the edges I’ve so far trimmed off the seam allowances.
I think it’s time I threw that lot away.

Before sewing, the raw edges on the Herjolfsnes garments were stabilised by ‘singling’: a fine thread was sewn to and fro into the thickness of the fabric, in from the edge, not stabbed up and down through the fabric. I haven’t enough raw edge on the seam allowances to do that, so I’m taking pains to run the needle in and out of the fabric for additional stabilising as I sew one way, then I take it back over the fabric to the starting point. A picture is worth a thousand words:


I’m trying to stitch every 2mm or a little less. You can see the waxy whiteness of the beeswax on those recent stitches, but it soon disappears as the garment is handled.

I think the end result looks good, is appropriate for a handspun, handwoven fabric, and will allow me to tell people about the astonishing finds at Herjolfsnes.


Some of the internal seams. The stitches are not generally this visible: I chose the light angle to highlight them.


Seams as they appear on the outside of the garment. The stitches pick up a thread or two of the fabric at both ends, so create a subtle and decorative ridge.

Once I finish all the internal seams (as you can see from the pattern, there are more than a few), I will try my hand (and foot) at fut-slyinging, incorporating a foot-tensioned tablet-woven decorative band along the hems. I think all this handspun thread, hand sewn and woven really should outweigh the fact that the garment seams are machine-sewn!

Also, some of those seams were even sewn with an appropriate needle. Bone.


thoughts on seeing a piece of antique lace

I think I’ve mentioned somewhere that I’m a hand spinner. I use my hands and various tools such as spindles and spinning wheels to make what I’ll loosely term ‘yarn’  from loose fibres by twisting them together. It’s an ancient skill. Yarn and the cloth made from it doesn’t usually survive to be dated (it rots, especially the early yarns made from plant materials), but sometimes the impressions of texture and pattern made by cloth and string in mud or soft soil do survive. Fragments of clay found in the Czech Republic show the pattern of cloth thought to have been woven 27,000 years ago. Some of the ‘Venus’ figures found in Europe dating from 20,000 BC have carefully carved string skirts, some so detailed that they show the skirt string is plied. Left dangling loose, a single strand of twisted fibre rapidly untwists to become loose fibre. Only if two strands – known as singles – are plied, twisted together in the opposite direction, will the dangling string remain string. Given the skills demonstrated by the things that have survived, it’s been suggested that people – probably women, as men are traditionally hunters – have been spinning fibre into string/yarn for over 40,000 years.

That’s a long time.

That’s many, many generations of my female ancestors. Only for the last 300 or so of those 40,000 years have women not needed to spin, at least in western Europe, where I come from. I am descended from a long line of women who could spin, and spin well, because the yarn they spun was needed to cloth their families, to be sold for money to pay the rent or feed their families. In the early days the string they made would have been knotted into nets to catch fish and birds. If my ancestors hadn’t been good, productive spinners, they and their children wouldn’t have survived. I wouldn’t be here.

So, as I’m spinning, I think of my ancestors, spinning. I didn’t gain my skill directly from their hands – my mentors passed on their own skills from their hands to mine – but my hands are doing the same things, going through the same motions, as those of my ancestors. Spinning unites us, hand to hand, across nearly 40,000 years.

Lynn, I search out antique handspun textiles because handling those textiles, learning new skills by examining them, is a direct link with the people who made them. For me, it’s all about the people, not the finished piece. I don’t care if something is tattered, too badly damaged for a ‘serious collector’: the ragged edges and loose threads mean I can see how it was made, whether the yarns are plied or singles, estimate their grist. I can extract individual fibres (of wool) to estimate staple length and fineness of fleece. Knowing these things I can try to replicate the yarn. Spinning it, I remember with respect the person who spun the original.


So. Here is a piece of linen lace in the style of Alençon, in northern France, dated by style and condition to the 18th century (1701–1799). Pre-Industrial Revolution, there’s no doubt the thread used for this was handspun and, for lace, of the finest quality at the time. Because in this condition it is of no value to a collector 48″ of this cost £5, but to me it’s beyond valuation. It’s 48″ of people’s lives: the skills of the flax grower, the processors, the spinners, the lacemakers.


Detail of the lace magnified 20x. The lens circle is 1cm in diameter.



The damage allows me to examine the individual strands of yarn more closely.


Above, a damaged area magnified 20x, showing what seems to be a single thread.

Below, the same area magnified 80x. 


The lustre of the individual threads and the ‘hand’ of the fabric, even after more than 200 years, suggests this is linen. I am awestruck by the fineness of the fibres in the yarn: having done some flax processing myself (this link shows the basic principles), I have some idea of just how tricky it would be to get fibres this fine. Having spun flax, I have some idea of what it takes to spin this fine. At this point I’m not even sure whether this is plied or a singles yarn. I did find a description of the spinning process in Cassell’s Illustrated Family Paper, Vol. 4 1865 on Google Books:

“Why, the flax of which the old Brussels and the point d’Alençon were made, was cultivated on purpose; it was chiefly grown in Brabant, Halle, and Courtrai, and had to be spun in underground cellars, because contact with external air made the thread brittle. The thread was so fine as almost to elude the sight; the spinner had to go by the sense of touch, examining every inch as it left the distaff, and at the slightest irregularity stopping the wheel. The room was kept in darkness, except for one single ray of light arranged to fall on the thread, which was thrown up by a background of dark paper … “No wonder,” said Goody, “that fine lace is so costly; why, I have read lately, that at the present moment, hand-spun thread is often sold at £240 sterling for one pound only.”

MeasuringWorth says £240 in 1865 would be between £20,690 and £471,100 in 2015 pounds. I am stunned.

I hold the lace and I respect the people who made it. I remember with respect the people who, generation upon generation, developed the skill to make things like this. They may not be my personal ancestors, but without them we wouldn’t be here.

All that from a piece of old lace.

How the magic works: the chemistry of blue.

dd541-woad6The transformation from green-yellow to indigo blue that takes place before your eyes when something is removed from an indigo vat is the nearest thing to real magic that I know of. But it’s not magic, it’s chemistry, and understanding it is helpful in troubleshooting vats and in choosing vats for specific fibre types.

Where does indigo come from, and why is it there in the first place?

Most of the indigo used commercially is now synthetic indigo, one of the myriad colours chemists derived from the magic compound aniline in the 19th century. I’m more interested in natural indigo, which is extracted from plants such as Woad (Isatis tinctoria, a member of the Cruciferae, related to cabbages) and Japanese Indigo (Polygonum or Persicaria tinctoria, a type of knotweed) in addition to ‘true’ Indigo, Indigofera, a member of the Leguminosae (related to beans and peas) which has several species including tinctoria and suffruticosa. In fact many plants will yield indigo, but only a few yield it in sufficient quantity to be of any use in dyeing.

I haven’t yet found a reference giving a firm reason for the presence of the indigo compounds in plants, but a couple of papers suggest in passing that it might discourage pests.

Indican, the compound that yields indigo blue, is a glycoside: a sugar (in this case a form of glucose) bound to another molecule, indoxyl. When the glycosidic bond is broken, the indoxyl is freed. When the indoxyl compound is oxidised, it becomes blue: indigo blue. Sounds simple enough, but how does the processing of the plant material and the dyeing accomplish this?

The indigo-bearing leaves (it’s usually the leaves; the lower the amount of other plant matter, the better the final grade of indigo) are harvested. In Japan the Japanese Indigo leaves are dried in the sun and stored for later use. Elsewhere the leaves are then physically damaged – chopped, pounded or trampled – presumably to release larger quantities of indican. This is the point at which woad was traditionally made into balls of leaf matter and dried for easier storage and transport. In West Africa the pounded leaves might also be dried and stored at this stage. Alternatively (in West Africa and elsewhere) the mass of fresh leaf material might be fermented; in Japan the dried leaves are later moistened and fermented; in Europe the woad balls are moistened and fermented (the process known as couching). In other words, bacteria are encouraged to consume the glucose in the indican, leaving the indoxyl molecules as highly reactive free radicals. The bacterial breakdown of glucose may be an aerobic process in which the bacteria consume oxygen, creating the reducing (low oxygen) environment necessary for the next stage of the process, or an anaerobic process in which the bacteria release hydrogen that acts as a reducing agent in the next stage.

The indoxyl free radicals bind to each other to form indigo. If an alkali is present (pH is above neutral), this takes the form of water-soluble leuco-indigo (leuco means white), also known as white indigo or white indigotin. The ‘white’ refers to the compound’s relative lack of colour: the leuco-indigo solution is a clear yellow or yellow-green. This is the form in which indigo dyes, so at this point it is possible to convert the fermentation vat to a dye vat, or to continue the process to extract indigo from the solution. Extraction is simply a matter of converting the soluble leuco-indigo to its insoluble blue form by adding oxygen: straining the fluid off the leaves, then pouring it back and forth between two containers may be sufficient, after which the blue particles of indigo can then be filtered out of the liquid. I wrote a post (with lots of pictures) about processing woad leaves in this way in 2013; you can see it here.

The actual indigo pigment content of the particles is reported to vary from 12% for Japanese Indigo, through a maximum of 40% for woad and 77% for Indigofera indigo. The remained of the mass is plant matter, mineral matter and other pigments such as indirubin (known as indigo red and one of the components of Murex purple). This mix is one reason that natural indigo produces more variable shades of blue than the purer synthetic form.


Handspun Bombyx silk indigo-dyed in three different vats. The dark blue on the left was put dry (unwetted) into a 1-2-3 Fructose vat, to which I added a little more fructose and heat to raise the temperature back to 50°C before leaving the silk for 45 mins. The patchy warm-grey-blue on the right was well-wetted before spending an hour in the urine vat. The curl of bright blue silk in the centre had 5 dips in a standard Thiox vat.

How does indigo dye?

Water carries the soluble form, leuco-indigo, as it soaks through the material in the vat. When the material is exposed to the air (or another source of oxygen such as well-oxygenated water) the leuco-indigo oxidises to blue indigo particles that physically lodge in unevennesses in the material. Unlike many other dyes, the particles are not chemically bound to the material, just wedged into cracks and crevices. This means that dense, smooth materials or those that are not easy to wet will not hold a lot of dye or will not be easy to dye. Indigo is one of the most light-stable natural dyes, but the way in which it dyes means that materials dyed with indigo ‘fade’ in two ways: as particles of indigo are dislodged and fall away from the material, and as the dyed material itself wears away to reveal undyed material. Taken together, these largely explain the classic fading of denim. (Light does degrade indigo into compounds such as isatin, but the physical damage is more significant.)

Making leuco-indigo: reducing the vat to remove oxygen

Whether they’re based on synthetic or natural indigo (including plant material that contains indigo), all indigo vats work on the same basic principle: convert the blue indigo into soluble leuco-indigo, then allow that solution to penetrate the material to be dyed. As leuco-indigo only maintains that form in the absence of oxygen, the vat must be reduced – the oxygen removed – in some way. Traditional vats use bacterial fermentation: the vats contain organic matter on which bacteria feed, such as the nutrients in urine, rice bran, the plant material that contains the indigo compounds, or even the skin flakes, sweat and manure held in a sheep fleece.

Chemical vats use raw chemistry, compounds including sodium hydrosulphite or thiourea dioxide or reducing sugarssuch as fructose to remove oxygen from the vat.

Making leuco-indigo: the vagaries of pH

pH – the acidity or alkalinity of the vat – is important, as the conversion to leuco-indigo requires an alkaline environment. It’s easiest to predict and maintain in a chemical vat, with recipes calling for measured amounts of lye (sodium hydroxide) or washing soda/soda as/soda crystals (sodium carbonate) or calc aka calcium hydroxide aka slaked lime. It’s just as important in a biological vat, but much trickier to maintain, because the fermentation process produces byproducts such as lactic acid that lower the pH. Apparently dyers in the past learned to manage their vats by tasting the fluid or feeling it between their fingers, trying for something that’s slippery (alkaline), but not too slippery. Fortunately we have pH paper, which works even for indigo vats – the blue does not appear so quickly that it prevents reading the pH.

pH also influences the dyeing process in other ways. Both cotton and indigo are ionised at higher pH; there are two forms of leuco-indigo, and the most ‘efficient’ of these in terms of dyeing is most common at pH11, which is also the pH at which de-protonation/ionisation of the cotton (and possibly other cellulosic fibres) has begun, making it attract the dye. So cellulosic fibres are best dyed at pH11.

But protein fibres such as silk and wool are damaged by high pH, and heat accelerates the damage. pH paper allowed me to confirm that my sig (urine) fermentation vat does indeed run at about pH 9 in the relative coolth of the pop-up greenhouse, whereas the 1-2-3 Fructose vat I created yesterday was pH11 at 50°C. So: to dye my handspun silk (a smooth, dense fibre, hence takes up less dye) a dark blue, I had the option of multiple dips in the urine vat OR a shorter single dip in the Fructose vat.

Having said all this, pH paper and knowing how to use it doesn’t guarantee success with a biological vat. I think the current woad vat may be a loss, possibly because I used garden lime instead of calcium hydroxide to try to control the pH. But perhaps there’s so little blue present that I’m not seeing it on the material. Further work required.


There are far too few pictures in this post, so here’s a Norwich damask, a dress fabric dating from the early 1700s. Handspun 2-ply wool warp; the purplish shadows in the pale areas hint that the warp was once dyed reddish-purple, probably with logwood, long since faded except where protected inside the seams. The handspun singles weft is clear pale indigo blue. The original fabric was probably lavender-lilac purple with red-purple patterning.

Further reading

Balfour-Paul, J, 2011. Indigo: Egyptian Mummies to Blue Jeans. British Museum Press

Hall, K, 2012. Indigo background (written specifically for South Carolina teachers).

Melo, M J, 2009. History of Natural Dyes in the Ancient Mediterranean World. In Handbook of Natural Colorants, John Wiley & Sons.

Vuorema, A, 2008. Reduction and analysis Methods of indigo