A Postscript to Rhubarb

With the exception of the pale pink skein (dyed in cochineal on an alum mordant) & the pale blue skein (dyed in indigo), this photo shows some colours achieved from various dyes, using rhubarb leaves as a base or alternative mordant. The reddish colours are from madder, the pinker shades are from cochineal, the brown & tan colours are from cutch & the greeny-blue shades are from indigo. The wool skeins were first treated in the rhubarb leaf solution, then dyed. No other mordant was used.

Following a comment on my latest entry on Rhubarb Root, I thought it might be useful to clarify the difference between rhubarb leaves & rhubarb root. Rhubarb root is a very useful dyestuff, more suitable for animal, rather than vegetable, fibres, & it can be used both with or without a mordant. Used with colour modifiers, it gives shades ranging from yellow & rust to pink, red-brown & green. It doesn’t seem to matter what species of rhubarb you use. I use the roots from the edible rhubarb I grow in my garden for pies etc. Some people use the roots of ornamental rhubarbs. The rhubarb root sold commercially often comes from China & is used as an ingredient in laxatives or purgatives.

Rhubarb leaves, which contain poisonous oxalic acid so should be handled with care, can also be used as a dye on mordanted or unmordanted fibres, but they tend to give only a pale yellow colour. Their main use is as an alternative mordant or base for other colours. They work well on animal fibres but are not really recommended for vegetable fibres. Rhubarb leaves are widely used as a base for other colours by Tibetan carpet weavers, working in Himalayan regions where chemical mordants are often difficult to obtain. They are also used to assist fermentation in indigo vats.

Full details for using rhubarb root & leaves can be found in my books. (See under “My Books”)

Using Colour Modifiers

Full information for using colour modifiers is given in most of my books. For details of my latest book, “Colours from Nature”, see under “My Books” on this blog. Some information on modifiers is also given here in the entry “Colours from Dahlias”.

Basically, colour modifiers are used after the initial dyeing process to alter or modify the shades. So if you dye 5 skeins in the same dyebath, leave 1 skein unmodified, then apply a different modifier to the remaining 4, you will end up with 5 differently coloured skeins that all tone together. Modifiers may be pH alterants: acids like clear vinegar, citric acid, lemon juice; or alkalis like washing soda, soda ash or wood ash water. (See below) The other modifiers are solutions of iron or copper. A small quantity of the modifier is added either to a pot of water or to some of the used dyebath. The dyed materials are then added to these solutions (1 to each) & left to soak until a colour variation is achieved. If nothing much seems to be happening, just add some more modifier & continue with the soaking. Sometimes the colour variations are dramatic, sometimes they are more subtle & on occasions it’s difficult to notice much change at all, especially with acidic modifiers. In my experience, the most useful modifiers are the alkalis & iron. You can also heat all the modifier solutions EXCEPT THE ALKALINE MODIFIER. If you heat this, you may damage or even destroy animal fibres such as wool. BE WARNED!

NOTE: Wood ash water is made by removing the ashes from a wood-burning stove & soaking them in water for a week or two. The ashes sink to the bottom, leaving a yellow liquid which is strongly alkaline. You can tell when it’s ready because it will feel slick or slimey to the touch. Just remove the solution without disturbing the ashes & use half to one cupful as your alkaline modifier.

Rhubarb Root again

At last I’ve managed to find time to try out the colour modifiers on the rhubarb root extract dye that I wrote about earlier. The samples are on unmordanted wool.

The photo shows from top to bottom: No modifier, acidic modifier (clear vinegar), alkaline modifier (washing soda), copper modifier & iron modifier. (Note: I always put the modified samples in alphabetical order – acid, alkali, copper, iron). The last sample is from a different dyebath, made by adding an acid (this time citric acid granules, but clear vinegar would have been equally good) to the dyebath before dyeing. I added enough to turn the dyebath yellow, rather than rust, in colour. However, take care not to add too much or the colour may be too pale, so add it gradually.The unmordanted sample was then added & simmered for about 20 minutes. This latter method is a useful way of getting a clear yellow from rhubarb root, in either extract or plant form, without having to use an acidic modifer afterwards. If you dye several skeins in the acidified dyebath, they can be modified as usual, although little change occurs from an acidic modifier.

I was delighted with these results, as rhubarb root is such a useful, versatile dye, especially as it can be used without a mordant. It was good to know that the modifiers are effective when used with the dye in extract form.

Woad again

 Today the weather is cold, dull & gloomy, so I just wanted to remind myself of that chilly but bright day in November when I made a final vat using my home-grown woad leaves. Here are some of the skeins I dyed that day, hanging outside to dry.

Stored away in my shed I still have some woad solution, to use whenever the mood takes me or when the brighter weather draws me outside to set up my dye pots.

Woad solution is easy to make & can be stored for several years. All you do is follow the instructions for using fresh woad leaves, given in my earlier entries, up to & including the whisking to produce the blue froth. Then leave the solution for a while to allow the froth to settle. It’s important to make sure all the froth is incorporated into the solution, as the froth contains most of the blue pigment. Then pour the solution into a strong glass or thick plastic airtight container with a well-fitting lid. (If you use a plastic container, make sure it is made of thicker plastic than those containers used for milk. I have found that, if the plastic is too thin, the blue pigment is absorbed by the plastic, which becomes a deep blue, leaving little pigment left to dye anything else.) Allow the solution to overflow slightly, then screw the lid on well.  You can add a teaspoon of sodium metabisulphite as a preservative if you like, but I’ve never found it necessary. I have successfully stored woad solution in my shed for several years & it never seems to develop mould or deteriorate in any way .

Using Woad Balls

The photos show (left) the vat with the blue colour beginning to emerge as the yarn appears above the surface & (right) the yarns with the blue dye developing.

 Last week Ian Howard, the woad grower from Norfolk, sent me a few woad balls to experiment with. Woad balls are rare nowadays & I believe they may only be available commercially from Ian. Of course, woad is simpler to use in powder form & it is only recently that woad powder has become available. Before that, dyers keen to use woad had to grow their own. Until the 1930s woad was grown & processed in England in the fens in East Anglia, not far from where I live. The woad balls were made by crushing the leaves to a pulp between rollers, draining off any excess liquid, then rolling the pulp into balls, which were laid on racks to be dried. Sometimes woad was traded as balls, which then had to be processed further into couched woad before they were ready for dyeing. To make couched woad, the balls were pulverised, sprinkled with water & left to ferment. During this period, the mass was turned frequently & large lumps broken up. Finally, this crumbly substance, known as couched woad, was dried & packed into barrels, ready to be sent off for sale.

But back to my woad balls. As I want to save some for a fermentation vat when the weather is warmer, I just used one for this test. I was surprised at the amount of blue there seemed to be in this one ball, even after I had been distracted by a phone call & let the vat simmer on the cooker – absolutely not a good idea! Not only that, the vat kept going over several days & didn’t seem to mind getting cold overnight & being heated up next morning.

Basically, as I wasn’t planning a fermentation vat, I followed the same procedure as I use for dyeing with fresh woad leaves, except that I left the leaves in the vat throughout. So first of all I broke the ball into small pieces by bashing it with a mallet (yes, woad balls can be very hard indeed!). Then I poured a little cold water over it to just cover the pieces. I did this as a precaution, in case “shocking” it with boiling water destroyed any dye potential, although I think it would probably have been OK to start off with the boiling water. Then I poured boiling water over the pieces, about enough water to make a small vat, & left them to steep for about an hour. I then strained off the liquid, added enough washing soda (sodium carbonate) to turn the liquid from brown to greenish & began the whisking process. At this point, I should say that the smell was quite strong but, as I love the smell of woad, it didn’t bother me at all. Also, the whisking process produced no sign of any blue froth but I decided to continue, as I seemed to recall having had this experience before. After whisking for about 15 minutes, I decided to return the pieces of woad ball to the liquid & then I whisked a little more – still no blue froth. I then poured the liquid, plus woad ball pieces, into a stainless steel pot & set it on my cooker. I heated it gently to about 50C/120F (or as hot as the hand can tolerate for a count of 3 – what I call “1,2,3 ouch!”) & then added some sodium hydrosulphite to remove the oxygen. After about 10 minutes, I decided to add some wool to see if any blue had developed & was delighted with the results. The first skeins were a deep blue/green, later skeins became a little paler, & one skein was a delicate green. The colours on the second & third days were just as strong as those on the first day – probably because leaving the leaves in the vat allows the blue to continue to develop as time progresses. This vat does not look like the usual woad or indigo vats; the colour of the liquid is a murky brown/yellow, although a blue metallic sheen does appear on the surface after a while, only to disappear again later. Neither does this vat give the same shades of blue as woad vats from fresh leaves or woad powder. The blues are tinged with green, so appear more turquoise, although this is not apparent from the photo above. (However, it’s very difficult to show colours absolutely accurately in photos, unless one has sophisticated equipment & considerable skill & I have neither, I’m afraid, being a complete novice where photography is concerned.) I imagine these colours are probably influenced by the other pigments present in the leaves, such as those that give the tan shades when woad leaves are used following the usual simmering method, & the green tones occur because the leaves remain in the vat throughout. I suppose I need to do another vat without the leaves in, to see what happens without them – perhaps at a later date. I also suspect that these greeny-blue shades may be closer to the blues our early ancestors achieved when using the fermentation vat method.

To sum up: Woad balls can be used in the same way as fresh woad leaves, except that the leaves should remain in the vat throughout. Whisking may not produce any blue froth but ignore this & continue as usual. The vat itself will not look like the more usual woad or indigo vats, but this does not seem to be of any importance. The vat can be kept going over several days & the colours from this type of woad vat will be more green in tone.

NOTE: Woad balls are available from Ian Howard, just click on the link under “My Favourite Websites”. Ian also has some excellent weld dyestuff available (not in extract form) which he has grown on the farm & madder extract is also on his list. (See picture below)

This picture shows:

From left to right: Madder extract (alum mordant), madder extract (alum mordant + washing soda after-soak), weld (alum mordant), weld (alum mordant + copper modifier), weld (alum mordant + iron modifier)

Musings again

This is turning out to be a much better experience than I had expected, mainly because so many lovely people have responded so positively to my presence on the web. I still find it hard to believe that my books are known in so many countries around the world.

Also, I’ve been directed to some other natural dyeing blogs or websites & I’m discovering a new world of exciting colours & images. When I added my “favourite” websites to my blog, I was thinking of sites that might be useful to other dyers, more as sources of dyes & materials than as links to other blogs. It was Helen Melvin who kindly pointed me in the direction of Leena Riihela in Finland, whose website & blog have really inspired me – not least to order some Finnsheep fleece & some wonderful mittens (among other things) as my Christmas present from my husband. I’m beginning to realise just why so many people become addicted to the web! All the websites & blogs I’ve visited seem to have so much to offer, that I fear I shall be sorely tempted to spend time reading & looking, rather than adding to my own blog.

So thanks again for all the responses I’ve had & all the directions to the delights to be found on the web. You can share some of these delights by clicking on the links given on the “Comments” pages – but I expect you know that already.

Smoke Tree (Cotinus coggygria)

Before the last leaves dropped, I managed to photograph my Smoke Tree & I thought I’d write an entry about this interesting & historic dye plant. Formerly Rhus cotinus & now Cotinus coggygria, the Smoke Tree is also known as the Wig Tree & Venetian Sumac. Its other name is Young Fustic, to distinguish it from Old Fustic, which was a later introduction from central America & is what we now know as Fustic. The word “fustic” apparently came from the Arabic “fustug”, meaning “bush”, & describes the growth habit of Cotinus coggygria. It is native to southern & central Europe & is also found in Turkey. It was widely introduced elsewhere & is a popular ornamental shrub in parks & gardens, particularly the purple-leaved varieties. 

From the Middle Ages onwards, the heartwood & leafy branches of Young Fustic were widely used in Europe, especially Italy, for dyeing silk & wool, often in combination with other yellows, such as weld, as the yellow shade from Young Fustic tends to have a reddish hue. In addition, it was used with many other dyes to create a variety of colours & was not only versatile but also more economical than some other yellow dyes, as the heartwood has considerable tinctorial power. Its main disadvantage would seem to be its relatively poor fastness when compared with dyes such as weld, as most shades from Young Fustic tend to change to russet over time. In the past it was clearly a significant dye, as tests on many historical textiles from various parts of the world show evidence of Young Fustic, often in combination with other dyes to create compound colours. It is rich in tannin, so when used with iron it gave deep, full shades. Young Fustic continued to be of economic importance until the 19th century & was used until very recently in country districts of Albania.

The dyestuff we now know commonly as “Fustic” comes from the heartwood of Morus tinctoria or Chlorophora tinctoria, a member of the mulberry family, which grows in central America & is one of the few natural dyestuffs that continue to be used commercially. Once the sea routes to the Americas were established, Fustic was imported into Europe, where it was called “Old Fustic” in English & “palo fustete” in Spanish, indicating that the similarities in both appearance & dyeing properties between “Young Fustic” & “Old Fustic” had been recognised. Indeed, in 16th century Britain it was often difficult to tell whether the term “fustick” referred to “Young” or “Old” fustic. Sometimes both “Young” & “Old” fustics were used in combination to create an orangey shade. For further fascinating information about fustic, & virtually every other dye source, I strongly recommend Dominique Cardon’s “Natural Dyes”. This is a weighty volume, & not cheap, but it is a highly readable scholarly work that provides a most valuable resource for those seeking information on dyes & dyeing from earliest times to the present day.

More Musings

I’m amazed at the number of comments I’ve received on this blog. Fantastic! I had imagined I’d write posts for months before I had any response & that it would probably come from a friend who felt obliged to give me some encouragement. How little I know about the world of the internet! Also, it is wonderful to realise that people both near & far have read my books & found them useful. As an author one hopes this may be the case but to get some feedback is really great. I do so appreciate it. And so many links to other websites! I fear I may never find time to write my posts, if I allow myself the luxury of looking at them all. How do people do so much? However, I’m now faced with a quandary regarding “blogging etiquette”. Will I be considered rude if I don’t reply individually to each comment I receive? This is what I’ve tried to do so far. But will I find myself in the situation of thanking people for thanking me for thanking them? I can see that this might become irritating for all concerned. Perhaps the correct thing is to issue a “General Thanks” post from time to time & to only reply to comments that ask for a response or raise a particular issue? And of course, in order to write posts I’ll need to find time to do some more experiments so I have new things to write about. This will clearly require some careful thought!

More Dye Extracts

I’ve been trying out two more extracts, rhubarb root & cutch waste. Rhubarb root is a useful & versatile dye, so I was pleased to see that it is available in extract form from Pure Tinctoria. Among the other extracts on their list I came across “Cutch Waste”, which intrigued me. Cutch, rather than cutch waste, gives rich browns on all fibres &, like rhubarb root, can be used without a mordant. Cutch is one of the few dyes that has been available in extract form for very many years. In fact, I have never come across cutch in any other form. It is produced by simmering the heartwood of Acacia catechu (native to India & SE Asia) in water, then reducing & evaporating the liquid until it becomes very thick. It is then poured onto matting & left to dry & harden into a solid mass, which is cut into chunks, then powdered. Just where the cutch waste comes from, I’m afraid I don’t know. Another puzzle to be solved!

I first came across rhubarb root as a dye some years ago in an article in the Weaver’s Journal. The article was about Tibetan carpet weavers working in Nepal, for whom rhubarb is a vital dye plant. The leaves contain oxalic acid, which they use as a kind of mordant or base for other colours. They also add rhubarb leaves to organic indigo dye vats to assist fermentation. The rhubarb root is used for yellows, rusts & as an addition to brighten madder dye baths. The article suggested alum might be difficult to obtain in Nepal, unless from plant sources such as the leaves of plants that absorb aluminium from the ground, & therefore most dyes were used without a mordant. So I experimented widely with rhubarb root on unmordanted fibres, as it is so useful to have a source of yellow that doesn’t require a mordant, especially in order to obtain a green when overdyed with indigo. However, I have to say that, although rhubarb root dyes wool & silk excellently, it is less effective on cellulose fibres.

 I tested both these extracts on wool without a mordant & with an alum mordant. Both fixed well without a mordant. The rhubarb root produces a clearer yellow without a mordant & a more mustard shade on an alum mordant. The cutch waste shade is an attractive soft greyish green, (more green than grey, however) very useful as a contrast to more vivid colours. Unfortunately, the photo doesn’t really do justice to the colours.

Rather foolishly, I didn’t try out any colour modifiers with these extracts. I don’t know why, as I usually do a full set of tests. Rhubarb root in its plant form reacts well to modifiers. It gives moss green with iron, a brownish (taupe?) shade with copper & shades ranging from red-brown to red with an alkali such as washing soda. Truly a versatile dye. (More details on using modifiers in the entry about dahlias.) So now I must do these tests with the rhubarb root extract, to see if it reacts in the same way.

In my experience, not all extract dyes respond as well to colour modifiers as their plant counterparts. I think this is because some extracts are treated during the production process to reduce their sensitivity to changes in pH values & thus make the colours more stable if washed, or otherwise treated, in a non-neutral medium. I routinely wash naturally dyed fibres in dishwashing liquid & I have yet to find a dishwashing liquid that is not pH neutral when in solution. Some extracts are also probably treated during manufacture to remove some of the less desirable pigments. This would explain why madder extracts vary so much from one production company to another. The more recent Earthues madder extract gives a wonderful clear rich red, while their earlier madder extract was much more orange in tone. Some other madder extracts also produce more orange/coral tones, which can be made pinker/redder in tone by using a washing soda after-soak – but NO heat particularly if dyeing wool.

More about extracts when I’ve done some more tests.

Thank You for Your Messages

How wonderful! Today I have received several messages in response to my blog! I’m thrilled that there are actually people out there who have found my blog & have taken the trouble to send comments.

Thank you all so much. This will encourage me to keep on writing my posts.