Indigo workshop

It was a pleasure to return in June to the Bedfordshire Guild of Weavers, Spinners and Dyers, of which I was a member for over thirty years before we moved to West Sussex. The occasion was an indigo workshop I was leading and I was delighted to see old friends and to meet some new members.

To demonstrate the various sources of indigo dye, I made several vats using natural indigo, synthetic indigo, woad leaves, woad balls and stored woad solution.

I used the Colour Run Remover recipe given in my books with the synthetic indigo. However, as Colour Run Remover is not always easy to find in powder form (the liquid form isn’t suitable for indigo vats), I decided to try a different method with natural indigo. I was looking for a simple method and, after some experimentation, it seemed that using equal quantities of indigo powder, washing soda and sodium hydrosulphite (hydros) would work well. An added advantage is that using equal amounts of each ingredient makes this a very simple recipe. As indigo reduces better in a more concentrated solution, I decided to make a stock solution on the day before the workshop. To do this, I mixed 4 teaspoons of natural indigo powder with very hot water to make a paste. Then I dissolved 4 teaspoons of washing soda in very hot water in a strong glass jar, added the indigo paste and stirred well. I added more hot water until the glass jar was just over three-quarters full then, after checking that the temperature was not above 50C, I carefully stirred in 4 teaspoons of hydros and put the lid on the jar. I then placed the jar in a saucepan of very hot water and put this on a hotplate overnight. In the morning I checked the pH and added more washing soda to bring it to pH9. The solution looked a murky greenish yellow at this stage. When I arrived at the workshop, I filled a stainless steel bucket with very hot water (but no hotter than 50C) and added 2 teaspoons of washing soda and two teaspoons of hydros. I then gently added the contents of the glass jar. The vat was allowed to stand for about 20 minutes until the liquid below the surface was a clear greeny/yellow. (If this seems to be taking too long, add some more hydros.) This vat is very simple to make and worked well. However, I intend to experiment further to see if I can improve on this method.

Both of the indigo vats produced dark blues immediately and those students who wanted paler blues had to wait until some of the blue had been used before dyeing their samples. I also suggested that the wool samples should be dyed first, while the vats were hot, and that the cotton and silk samples should be dyed later, when the vats had cooled down. This is because wool takes up the indigo dye better in a hot solution, while cotton and linen prefer cooler solutions.

With the woad balls I used the recipe given in the revised edition of  “Wild Colour” and also in an earlier post on this blog. Unfortunately, the woad balls only produced a pale blue and not enough for all the workshop participants to dye their samples. I think the balls probably needed to steep for a longer period than we had available. We also had limited success with the fresh woad leaves, which gave very little colour. However, I suppose this was to be expected, as June is really too early to harvest the first year leaves, which hadn’t had enough time to develop their colouring potential. The woad solution, which gave deep to mid blues, was from 2008 and worked very well, so this proves (if proof is necessary) that correctly-prepared woad solution can be stored successfully for several years. The recipes I used for these two woad vats were those in my books.

The photos below show some of the materials dyed by students at the workshop.



Dyeing Cotton and other Cellulose Fibres

As I have recently been working on an article for “The Journal for Weavers, Spinners & Dyers” on using natural dyes on vegetable fibres, I thought I’d write a few words on the subject here.

 There seems to be a fairly common belief that dyeing cotton and other cellulose fibres with natural dyes is often less successful than dyeing animal fibres, such as wool. This may be because some dyers use the same mordanting methods for all fibres, rather than selecting methods appropriate to each fibre type, and this can lead to disappointing results. However, using natural dyes on cellulose fibres has become simpler and less labour-intensive since aluminium acetate is now more widely available in the UK. Before the arrival of alum acetate, the alum-mordanting method generally used for best results when dyeing cotton or linen has probably been the 3-step tannin/alum/alum (or alum/tannin/alum) method, which takes several days to complete. This involves treating the fibres in sequence with both tannin and alum sulphate, the latter plus washing soda. Some dyers favour completing the tannin process first, followed by two treatments with alum and washing soda, while others prefer to carry out the tannin process between the two alum treatments. I don’t think it really matters which sequence one chooses.  Some dyers may opt to use only the alum sulphate plus washing soda step and to omit the tannin process completely, although in my experience this tends to give less satisfactory results, unless the cellulose fibres being treated have a natural tannin content, as may be the case with raffia. (See my earlier post: “A Natural Dyeing Project in Uganda”)

Detailed recipes for mordanting vegetable fibres are given in my books, so I won’t repeat them here. However, I would suggest that dyers who haven’t yet tried alum acetate as a mordant for cellulose fibres might find it worth while experimenting with the following mordanting recipe:

Use 5% alum acetate (or 2.5 tsps per 100gms/4ozs dry weight of fibres). Dissolve the alum acetate in boiling water and add this to cool water in the pot, stirring well. Then add the wetted fibres, plus more water if necessary to allow them to move freely in the solution, heat to simmering point and hold at this temperature for one hour. Then turn off the heat, leave the fibres to cool, preferably overnight, and then remove them and rinse them well. (Note: alum acetate is available from some of the suppliers listed on my blog under “Useful Websites”)

I have found this mordanting  method gives good results on cotton and other vegetable fibres. It is also suitable for silk, but not for other animal fibres, and is widely used in Japan as a mordant for silk. I used it to mordant fine silk fibres when dyeing silk for handweaver Maggie Stearn and found it most successful. (See my earlier post: “Maggie Stearn – Handweaver”)

Naturally-dyed cotton mordanted with alum acetate. Clockwise from left to right: indigo, brazilwood, weld, weld + indigo, fustic, madder, logwood, cochineal

Naturally-dyed cotton mordanted with alum acetate. Clockwise from left to right: indigo, brazilwood, weld, weld + indigo, fustic, madder, logwood, cochineal

Some of the naturally-dyed raffia fibres, dyed by the basketweavers of Rubona, Uganda.

Some of the naturally-dyed raffia fibres dyed by the basketweavers of Rubona, Uganda.

Fresh Walnut Hulls

I suspect I am not alone in sometimes finding it difficult to achieve a really deep brown from walnut hulls. However, one solution to this problem is to use fresh green walnut hulls, rather than dried brown ones. This Autumn I was lucky enough to harvest some walnuts and, after eating the nuts, I saved the green hulls to use for dyeing. I left the hulls until they had started to become brown before I simmered them until the liquid was deep brown in colour. I then strained off the liquid, added some unmordanted wool skeins and simmered them for about an hour. I left them to steep in the cooling dyebath overnight before rinsing and washing them.

As can be seen from the first two skeins in the photo below, this dyebath gave a rich deep brown and the exhaust dyebath gave a paler shade. Now I just have to find a reliable source of fresh walnuts each year. However, I should be able to use these hulls for a year or two, as I always save the used hulls, plus their liquid, to use again and again. Don’t worry if mould forms as time passes – this will only improve the dye.

I also made a dyebath from fresh walnut leaves, which gave paler browns. (See the last two skeins in the photo below.)
Fresh green walnuts

Fresh green walnuts

Walnut leaves

Walnut leaves

The walnut hulls simmering to make the dyebath

The walnut hulls simmering to make the dyebath

Skeins dyed in the walnut dyebath

From the left, skeins 1 and 2 were dyed using fresh walnut hulls and skeins 3 and 4 were dyed using fresh walnut leaves


Dyeing at Stanmer Park, Brighton

Last week I led my first workshops in our new local area, working with dyers from several groups in Sussex for two days of plant dyeing.

The workshops took place in Stanmer Park, which is a beautiful location next to the University of Sussex, just outside Brighton. The venue for our workshops within the park was the Plumpton College potting shed, which had many stainless steel work tops, a couple of power points and a large ceramic sink, but rather limited space to move around. However, this did have the advantage of making it easy to communicate with everyone at close quarters. We used gas and electric heat sources and obtained a range of colours from madder, weld, rhubarb root, buckthorn bark, indigo and woad, plus one or two plants selected at random from the park.

Inside the potting shed

Inside the potting shed









Among the participants were experienced dyers and some relatively new to the craft. The opportunity to share and exchange skills and experiences was appreciated by all of us. One thing I learned is that storing fresh woad leaves in a fridge for over 24 hours may not be a good idea, as the vats made from fresh leaves that had been picked two days before they were to be used were not successful. The kind person who provided these leaves had kept them in the fridge for about 24 hours and I would not have expected this to have destroyed their blue dye potential, although I’ve never stored woad leaves in this way before. As we didn’t want to use them until the second day, we removed them from the fridge in the late afternoon of the first day, poured boiling water over them  and left them to steep overnight, ready to use the next morning. Unfortunately there was no way they could be persuaded to yield blues, although some generous participants declared themselves pleased with the yellowish colours achieved from the vat. However, the same leaves were then simmered to produce some pleasant pink-tan shades, so the experiment was not entirely without success.

The vat made using one woad ball was more successful. (See my earlier post for details of using woad balls.) 

One skein just removed from our small woad ball vat

One skein dyed in our small woad ball vat









Another successful experiment was with powdered rhubarb root. I made a strong, hot solution of washing soda and water, added the rhubarb root and stirred very well. The solution gradually became a deep red colour and we added some alum-mordanted and unmordanted skeins and left them to steep without heating. (NB Never heat washing soda solutions when dyeing wool or other animal fibres, as this may destroy the fibres.) After several hours both the mordanted and unmordanted skeins had become a rich madder-type rusty red. I was surprised to achieve such a rich red shade, as my earlier experiments using this method of dyeing with rhubarb root had produced paler, pinker shades. (See my earlier posts on dyeing with rhubarb root.) I suspect the difference in colour depth was probably because this time I used a stronger concentration of rhubarb root and washing soda.

The madder dye bath was made with freshly-dug madder roots, which gave excellent colours. Before use, the root was washed well and we also rubbed off some of the outer bark-like layer. We then chopped it as small as possible and poured boiling water over it. We left the root to steep in the hot water for about 2 minutes, then poured off the liquid into a dye pot. Then we poured boiling water over the same root again and left it to steep as before. Then we again poured off the liquid into the dye pot. (Note: this process removes some of the yellow and brown pigments which can make the dyed colour too rust in tone, rather than red. The liquid from these “steepings” can then be used for a further dyebath to achieve coral/rust shades.)  This pot of dye solution was put to one side for later use and we returned to the madder root, which we simmered again in fresh water for about 30 minutes until we had a rich red liquid. This was strained off and became our first dyebath. We allowed the temperature to cool a little, (if the temperature is too high when the fibres are added, they may become too brown in tone), then added unmordanted and alum-mordanted skeins. These were left to soak in the dye liquid without any further heat, until they had achieved a suitable depth of colour. Some of the skeins were then treated in acid, alkaline, copper and iron modifiers, giving a wide range of red and coral shades. Then we used the combined liquids from the first two madder root “steepings” to make a further dyebath, from which we achieved orange/coral colours. The same madder root can also be re-simmered for another dyebath, which will produce paler shades of coral.

To show the participants what can be achieved without a mordant, we used weld (dried, rather than freshly harvested) on unmordanted skeins. The weld gave good colours and the skein modified in washing soda was almost as brilliant and deep in colour as skeins mordanted in alum would have been. (Note: when storing dried weld, it’s important to keep it away from the light, otherwise much colour potential may be lost. I usually store dried weld in brown paper sacks.)

The following photos show some of the colours we achieved.

Some of the madder, weld and rhubarb root results

Some of the madder, weld and rhubarb root results

Some more dyed skeins, including the blues

Dyed skeins, including the blues

Summer is coming

I couldn’t resist taking a few photos to remind me of the delights of this garden in late Spring and early Summer, when everything looks lush and green and the roses fill the air with their wonderful fragrance.


































What to do with old stored dye solutions?

As part of my de-cluttering efforts, I’ve been sorting through my stock of stored dye solutions and deciding which to keep, which to use and which to finally discard. Sometimes the decision is easy, such as when the container releases a foul odour on opening, followed by “glops” of mouldy “gunk” when the contents are poured out. Actually, I am often relieved when this happens, because it means I can throw the contents away without feeling I’m wasting something precious. It’s more difficult when the only reason for throwing a solution away is because I just can’t motivate myself to use it up. This happens, for example, with old rhubarb leaf solutions. I know I’ll probably be able to harvest leaves, if I want to mordant with rhubarb leaf solution, and I’m far more likely to feel like making a fresh solution, rather than using up stored ones. So the old solutions can be poured onto the compost heap, although I’ll probably decide to keep one full container, just in case I need some before my plants have produced any leaves to make more. (Incidentally, if you feel hesitant about putting rhubarb leaves or solutions onto the compost heap, gardening experts now seem to agree that it’s fine to do this.)

Among the other stored solutions that cause me some heart-searching are oak-gall and walnut hull solutions. In the end, I’ve decided to offer these to other dyers in my guild, so for the moment I can avoid having to make a decision. However, if no-one else is interested in them, I’ll probably discard all the oak-gall solution, as I have enough oak galls to make some more and it’s not something I tend to use frequently. And I’ll probably decide to make some space in my shed by discarding some of the walnut hull solutions too, as I have dried walnut hulls and some walnut extract to fall back on anyway. These solutions will enrich the compost heap, I’m sure.

And now to the woad solutions I’ve found, all stored in 5-litre containers. (Details for making woad solution for storage are in my books and are outlined below.) Two containers are labelled “2008” and the contents look blue and have the characteristic woad smell. So I’ve decided these can be left and used at a later date. The other container doesn’t have a date on it and the state of the label suggests it may have been lurking in the shed for quite some time, possibly several years. On inspection, the solution looks a rather unpromising pale brown and it doesn’t smell “right” either. But I’m not prepared to throw it away without trying it out, as I know from experience that even the most unpromising-looking solutions can sometimes yield good results.

So I pour off the contents of the container and I can see that some of the blue pigment has sunk to the bottom or stuck to the sides of the container, leaving a pale brown liquid with some particles of indigo pigment floating in it. I check the pH of this liquid and it would appear to have lost some of its alkalinity. So I make a solution of washing soda dissolved in boiling water and stir this into the woad liquid until pH 9 has been reached. Then I return some of the solution to the container and shake it vigorously to try and dislodge some of the blue pigment from the sides. I also use a wooden spatula to scrape as much as I can reach back into the solution.  I decide to try out the solution, so I pour it into a dye pot and add more water to make enough liquid for the vat.



 This shows the solution, with the extra water added to make the vat.





Once the solution has been heated to about 50C and I’ve added sodium hydrosulphite to remove the oxygen, it starts to look more promising. The metallic-looking blue sheen that has formed on the surface indicates the presence of blue pigment, so I stir it gently to one side and then add 300gms of Wensleydale wool yarn and watch as the sheen disappears, leaving yellow liquid, through which the skeins are clearly visible. Then I leave the skeins to steep for about 20 minutes.



This shows the skeins steeping in the vat.






Then I remove the skeins and I’m pleased to see that they have dyed a good mid-blue, so I’m delighted I didn’t throw the solution away without trying it.



This photo shows the dyed skeins.






So what would I have done, if the solution had proved useless and the skeins had failed to turn blue? Well, I had already prepared for this possibility by making a solution of indigo powder and washing soda, ready to add to the woad solution in the pot if necessary. (I dissolved 3 teaspoons of washing soda in about half a cupful of boiling water, allowed it to cool slightly, then mixed in 3 teaspoons of indigo powder.) This solution will now be stored in a tightly-sealed glass jar until I decide to make an indigo vat. So instead of reducing my stock of stored solutions, I seem to have kept the situation exactly as it was, by using up one stored solution and then replacing it with another!

(Note on making woad solution for storage:

This is exactly like preparing a vat from fresh leaves but you stop the process just after whisking the liquid to incorporate oxygen. So firstly pour boiling water over the fresh woad leaves and leave them to steep for about 1 hour. Then pour off the liquid, remove the leaves and add washing soda until the colour of the liquid changes from brown to green (or until pH 9 or 10 is reached). Then whisk vigorously, or pour the solution from one container to another, until blue froth forms. Carry on whisking until this froth starts to become white again. Leave to stand until the froth has subsided (you can help by gently mixing the froth into the liquid but make sure not to lose any of it, as the froth contains the precipitated indigo particles) and then pour the liquid  into a airtight container with a well-fitting lid, filling it up until the liquid overflows slightly. Then fix the lid on tightly. When you want to use the stored solution, just pour it into a heatproof pot, heat it to 50C and add sodium hydrosulphite or thiourea dioxide (Spectralite or Thiox) to remove the oxygen. Then continue as usual.)

Good Old Onion Skins

I haven’t used onion skins in the dyepot for several years, although I still always save them, and I keep the red onion skins separately from the brown ones, as they often give slightly different shades in the dyepot. Whilst rummaging through some of the boxes in my workshop recently, I unearthed several bags of onion skins, so last week I decided to use some of them to dye some skeins of wool.

Onion skins will dye quite readily without the use of a mordant but for the strongest, most vivid colours I use an alum mordant. However, if you use unmordanted fibres, the use of an alkaline modifier after dyeing will increase the depth and brilliance of the shades. For very deep colours you may need to use 100% weight of onion skins to weight of fibres, but I usually find that 50% gives sufficient depth and brilliance.



Colours on wool from brown onion skins






I started off by using some brown onion skins. The above photo shows, from left to right: Alum mordant, alum + iron and, from the exhaust dyebath, alum mordant, alum + iron

I then made a dyebath using some red onion skins. In the past, I have sometimes achieved interesting green colours from red onion skins but this time the colours obtained were not as bright as I had hoped they would be, probably because I only had a handful of skins. The photo below shows from left to right: alum mordant, alum mordant + alkali, alum mordant + iron, no mordant, no mordant + alkali.




Colours on wool from red onion skins






Afterwards, I wondered why it had taken me so long to get round to dyeing with onion skins again, as they really do give lovely colours, even if their light-fastness is limited.

P.S. to my Recent Woad Experiment

As a final experiment based on Leena’s method of making a vat with fresh woad leaves, I thought I would make two more vats, using unchopped woad leaves for one and chopped leaves for the other. I felt this should give an indication as to whether chopping the leaves increases the blue potential and, as usual, I set out with my own pig-headed opinion as to which would give the better results – chopped leaves, of course. After all, I always chop other fresh dyestuff into the smallest possible pieces, in the belief that the more surface areas there are, the more dye colour will leach out. Of course, the chemistry of indigo dyeing is quite different from that of dyeing with other plant materials, so it may well be that the advantages of chopping the dyestuff do not apply to woad leaves when dyeing blue.

To make sure the experiment had some validity, I used the same preparation and dyeing methods for each vat and I also used the same weight of leaves and skeins. I first simmered the leaves, chopped and unchopped, for a few minutes before steeping them for 15 minutes. I then added cold water to bring the temperature down to 50C and continued as described in my last post.









This shows the two vats, after whisking to precipitate the indigo particles. The vat on the left was made using unchopped leaves and the one on the right was made using chopped leaves. There was very little difference between the two vats at this stage.








This shows, on the left, the 4 skeins dyed in the vat made from unchopped leaves and, on the right, the 4 skeins dyed in the vat made from chopped leaves.

 The skeins were dipped in each vat for about 5 minutes each time and in the order in which they appear in the photo. So each vat was used four times and for one skein each time. The skeins dyed in the vat made from chopped leaves are very slightly deeper in colour but the difference in depth of blue is so tiny as to be barely noticeable.

So, contrary to my expectations, it would seem that chopping the leaves makes very little difference, if any, to the depth of blue achieved. That is certainly good news for those of us who like things to be as simple as possible. Now I suppose I should try my usual method, rather than Leena’s, using both chopped and unchopped leaves, to see whether similar conclusions can be drawn when using a slightly different method. But perhaps I’ll leave that test for next year.

A Woad Experiment

I have been following Leena’s posts ( about her experiences with using her home-grown woad leaves and I was particularly interested to learn about the method which gave her the best results. Although this method is very similar to the one I have been using for over 30 years, one element of it was new to me. I usually start by pouring boiling water over the chopped woad leaves and leaving them to steep for about 30 minutes.  I then strain off the liquid and squeeze the last drops of juice from the leaves before discarding them. I then allow the liquid to cool to 50C before adding the washing soda and whisking to introduce oxygen and precipitate the indigo dye particles.  However, Leena’s preferred method requires the whole unchopped leaves to be simmered in boiling water for about 3 minutes, after which the leaves are left to steep in the hot water for 15 minutes. The water is then strained off, the leaves removed and cold water added as necessary to reduce the temperature to 50C.

Leena’s recipe then proceeds much as the recipe I always follow. In both our methods, washing soda is added until the solution is around pH10 and then the liquid is whisked until blue froth forms. This whisking continues until the froth that is forming ceases to be blue and changes to white. Both methods then continue in exactly the same way, by adding the reducing agent and then using the vat once the liquid has changed in colour to greeny-yellow.

I decided to test each of these methods using the same quantity (400gms) of leaves for each, picked on the same day and grown under the same conditions. I left the leaves for Leena’s method unchopped but chopped the leaves for my method, as that is what I usually do. I then tested the two dye vats using the same weight of the same type of wool for each dip in each vat and leaving the wool in each vat for the same length of time. This ensured that each vat was used in the same way, so the experiment had some validity.


This photo shows:

On the left: the blue froth formed following my method 

On the right: the blue froth formed following Leena’s method.



As the froth on the surface on the left seemed a much deeper blue, I was expecting to achieve deeper blues on the yarns dyed in this vat. So at this stage I was beginning to feel that my method might, after all, prove to be the better one. But “pride goes before a fall”!


The three skeins on the left were dyed in the vat made following my method (“my vat”)and the three skeins on the right were dyed in the vat made following Leena’s method (“Leena’s vat”).


 So although “my vat” seemed to form froth a much deeper blue in colour than the froth on “Leena’s vat”, to my surprise this did not appear to influence the results when the skeins were dyed. In fact, the skeins dyed in “Leena’s vat” seemed a slightly deeper blue than those dyed in “my vat”. So my earlier expectations were proved wrong.

The question now is: which method will I follow in future? For workshop or demonstration purposes, I think my method is simpler because it doesn’t require a heat source and it gives perfectly good results. However, for my own purposes, I shall probably try out Leena’s method again, as it may enable me to get slightly deeper shades of blue. So my thanks to Leena for introducing me to a new and useful method.

Mulberry Bark

Several weeks ago I was sent some mulberry bark by a kind lady who had collected some from a fallen branch from an ancient tree and thought I might like to try it out in the dyepot. As I’ve never tried mulberry bark before, I was interested to see what sort of colours it might give.

I started by leaving the bark to soak in water for a week or two and then I simmered it for about an hour, before adding some alum-mordanted and unmordanted wool fibres. I used about the same weight of fibres and bark and I kept the temperature just below a simmer, as the tannin in barks can sometimes dull the colour if the temperature is too high. When the fibres had taken up as much colour as possible, I turned off the heat and left them to soak overnight. I then applied alkaline and iron modifiers to some of the samples.

The photo below shows the colours I obtained.









Left to right: No mordant, no mordant + washing soda, no mordant + iron, alum mordant, alum + washing soda, alum + iron

Some of the colours produced from the mulberry bark are more yellow in tone than the colours often obtained from barks and I was interested to see how little they reacted to the two modifiers I used. My thanks to Ann Machin for supplying the bark for this experiment.