Jenny Dean’s Wild Colour

The word “Celt” is apparently derived from the Greek word “keltoi”, meaning “barbarian”, and is used to describe tribal societies in Iron-Age and Roman-era Europe, who spoke Celtic languages and were loosely tied by similar language, religion and cultural expression.

In preparation for a workshop on Celtic Dyes that I led recently at Fishbourne Roman Palace near Chichester, I have been doing some research into the dyes that may have been used by the Celts in Iron -Age Britain (c.600BC – 50AD).

The proto-Celtic culture in Europe was the Hallstatt culture (c.800BC – 450BC), named after the site of rich grave finds at Hallstatt in Austria. This culture then spread over much of Europe, into Britain, France, central Europe, the Iberian Peninsular and Northern Italy. The conditions in the Hallstatt salt mines, where the graves were discovered, meant that the textiles found there were relatively well preserved and analysis carried out on some of them gives an indication of the dyes and techniques used by the Hallstatt Celts.

Woad and weld were identified on textile fragments and also tannin, although it is not possible to identify the precise source of this tannin. Other unidentified yellow dyes were also found (perhaps sawwort or chamomile) and there is a possibility that lichen purple may also have been used. The red dyes analysed are interesting – there was no trace of any of the madder-type sources of red but some indication of unidentified insect dyes, possibly Polish or Armenian cochineal, and also of kermes. Both white and naturally pigmented wool was dyed and there is evidence of over-dyeing to create further shades. The issue of mordants is problematic; iron and copper were identified on several fragments and aluminium was identified on one or two fragments. However, it is possible that these minerals were present because of contamination within the salt mine, rather than because they were intentionally used in dyeing.

For my experiments I used white and naturally-coloured brown and grey wool. As I think it is unlikely that Iron-Age dyers in Britain would have had easy access to mineral alum. I decided not to use an alum mordant. Some samples were pre-treated in tannin from oak bark and others were unmordanted. The dyes I used were: weld (Reseda luteola), hedge bedstraw (Galium mollugo), lichen purple (Ochrolechia tartarea), oak bark (Quercus spp.) and woad (Isatis tinctoria). Although there was no trace of Galium spp. dyes on the Hallstatt textiles, I felt it would be historically correct to use native bedstraws in my experiments, as there is evidence from elsewhere that these plants were used for dyeing in the Iron-Age. Some samples were then over-dyed in woad and some samples were also treated in an iron-water solution after dyeing.

Some of the results of Celtic dye experiments.

The top row shows the colours from lichen purple with vinegar added to the dye-bath (except for a couple of woad samples on the extreme right). The second row shows lichen purple colours, without vinegar added to the dye-bath. The third row shows the colours from hedge bedstraw (Galium mollugo). The fourth row shows the colours from weld (Reseda luteola) and the bottom row shows the colours from oak bark. On each row some of the samples have been over-dyed in woad.

The Romans commented on the brightness of the clothing of the native Britons and the results of my experiments indicate that, even without alum as a mordant, it was certainly possible to produce bright colours in the Iron Age. The Celts also produced fabrics patterned with checks, stripes and plaids and this must have added to the impression of brightness.

I have now done some more experiments using a combination of walnut hulls and madder root – this time using dried madder root, rather than madder extract. As the photo below shows, sadly no purple or pinks were achieved. So I assume that there must be something in the madder extract that caused the results I described in my last post. Whatever this “something” may be, it would not seem to be present in dried madder root.

From left to right: alum mordant, no mordant, no mordant + alkali, no mordant + iron, no mordant + (1) iron & (2) alkali

I simmered the walnut hulls and madder root together for about 30 minutes, then strained off the dye liquid and added the first two samples. After these had been dyed, I added the three remaining samples. After these had simmered for 45 minutes, I removed them and divided the dye bath into two. I added washing soda to one dye bath and iron to the other. I modified one dyed sample in washing soda and two in iron. I then removed one sample from the iron-modified dye bath, rinsed it well then added it to the dye bath containing the washing soda.

Sadly, no purples or pinks were achieved but the reddish-browns are attractive shades.

I tend to stick to a somewhat limited palette when producing items for myself, so I am trying to extend the range of colours I usually work with. My preference seems to be for the strong reds, purples, pinks and blues that come from madder, woad, indigo, cochineal and logwood. So for a change I decided to aim for a rich medium brown that I hoped would provide a pleasing contrast with some indigo-dyed wool I had earmarked for a jacket.

Walnut hulls seemed a reasonable choice of dye and I knew I had a container full of sludge from the fresh green walnut hulls I had collected and processed last year. Fresh green walnut hulls usually give much richer browns than dried hulls and when I used this sludge last year I achieved lovely warm shades, so I was full of enthusiasm. I used unmordanted handspun wool and set up the dyebath. First, I simmered the sludge in its accompanying liquid (plus extra cold water) for about 45 minutes to extract more colour. Then I strained off the dye solution and added more cold water, plus some oak bark solution to increase the tannin content, as this can improve the depth of colour from walnut hulls. The wetted skeins were then put into the dyebath and gently simmered for about an hour, before being left to steep as the solution cooled down.

However, when I inspected the colour on the skeins it became clear that I wasn’t going to achieve the depth of colour I wanted – instead a mid greyish brown (typical of the shades from dried walnut hulls) seemed to be the result. I was still determined to aim for a rich warm brown, so I decided to add some madder extract to the walnut solution, in the hope that adding some red would produce the colour I wanted. I mixed about a teaspoon of madder extract to a paste with hot water, removed the skeins from the dyebath and stirred the madder paste into the dyebath, then returned the skeins to the pot.

To my surprise, the (unmordanted) skeins almost immediately became a purple colour, not the rich brown I was expecting. Then I remembered this had happened before several years ago and I had assumed at that time that it was just one of those strange results that would never be repeated.

I had also made a dyebath from oak leaves and oak bark, as I wanted two slightly different shades of brown, and I had added madder extract to this dyebath too. This time the skein became a rich pink/purple. Both the purple and pink skeins retained their colours after they had been washed and rinsed.

So how do I account for these unexpected results? Well, leaving aside the possibility that some mysterious colour spirit had decided I am destined to work always with the same colour palette, I can only assume that the tannin in the walnut hulls and oak leaves and bark reacted with some pigments or chemicals in the madder extract to produce these purple colours. Perhaps the madder extract contains elements from the processing that are not present in madder root, so now I need to try out this combination using madder root, rather than extract. If this does not produce these purple colours, then the assumption would probably be that something present in madder extract , but not in madder root, was the cause of the purple colours.

If anyone has any other ideas as to how and why these purple colours resulted from these dye combinations, please let me know!

What I was expecting:

What I achieved:

I have now experimented with a stronger vat, this time using 2 teaspoons indigo, 4 teaspoons calcium hydroxide and 6 teaspoons fructose – that is, double the quantities used in my first vat.

I dyed the same quantities of fibres following the same methods but the depth of blue I achieved was no deeper than from the first, weaker, vat. This would indicate that this vat gives pale to mid blues but not the deep blues which other indigo dyeing methods give. I wonder whether this vat may be best used for patterning fabrics employing resist techniques, rather than for dyeing skeins of fibre as I tend mainly to do. I also noticed that this vat left the wool feeling rather harsh. However, I didn’t use a vinegar after-bath, which might have been advisable to counteract the effects of the strong alkalinity of this vat. (I never usually use a vinegar after-bath, so I’m afraid it didn’t occur to me to do so after this vat.)

If anyone else has any comments to add on using this type of indigo vat, I’d be delighted to receive them.

I have read several times about Michel Garcia’s indigo vats – in reports from the ISEND natural dye conference in France, in posts on Helen Melvin’s blog and most recently in an article by Jane Deane in The Journal for Weavers, Spinners and Dyers. Michel Garcia is a bio-chemist who has been researching indigo dyeing for many years and he has developed indigo vats that are simple to make and ready to use in a short space of time. Michel wants his environmentally-friendly methods to reach as many dyers as possible, so I decided to try out one of his recipes and then pass on the information, so others can use it too.

The vat I have tried is his 1-2-3 vat, so called because of the proportions of the ingredients used: 1 part indigo, 2 parts slaked lime (calcium hydroxide) and 3 parts fructose. This means that for 10gm indigo you would need 20gm calcium hydroxide and 30gm fructose, for 20gm indigo you would need 40gm calcium hydroxide and 60gm fructose and so on. Calcium hydroxide or slaked lime should be available from builders’ merchants but I bought mine on the internet from Amazon. I purchased fructose from our local health food shop but it may also be available in some supermarkets. For my  trial vat I used 1 teaspoon indigo powder, 2 teaspoons calcium hydroxide and 3 teaspoons fructose.

NB Calcium hydroxide should be handled with caution. It can irritate skin and lungs and cause serious injury if it comes into contact with the eyes. Do not pour water onto it but add it slowly to water.

To make the vat, start by putting hot water (around 40C to 50C but no hotter) in a dye pot or heatproof strong glass jar. Mix the indigo powder with hot water to make a smooth paste and make sure no gritty particles remain unmixed. (Jane Deane’s article gave a useful tip for mixing this indigo paste: put the powder and water in a small container with a well-fitting lid and add some marbles (or marble-sized smooth stones). Then shake vigorously to incorporate all the indigo particles in the solution. I’ve tried this and the marbles really help to make a smooth paste.)

Add this indigo solution to the hot water in the vat or jar, then stir in the calcium hydroxide. Finally add the fructose and stir well. The vat may take up to 45 minutes to be ready but mine was ready to use in about 5 minutes. The vat can then be used in the same way as other indigo vats. One recommendation was to add the fibres dry, rather than wetting them first, but I forgot this and wetted out my wool skein automatically, as I usually do, and it didn’t appear to matter. I suspect this recommendation probably refers mainly to cotton and silk fabrics, which I often add dry to indigo vats anyway. Another suggestion was that the pH of this vat might be too high for wool. However, my vat was pH11 but I dyed wool in it without any obvious ill effects. The wool remained in the vat for about 30 minutes and dyed to a mid-blue; further dips didn’t increase the depth of blue. I also added some silk fabric and a cotton skein to the vat and both dyed to a similar shade of blue as the wool. Jane Deane’s article implies that this vat is likely to produce only pale to mid blues but the lack of a deep blue from my vat may have been because I only used 1 teaspoon of indigo to make this trial vat. Anyway, I shall experiment further with this method and see whether deep blues can be achieved.

I found this method of indigo dyeing extremely simple and effective and, if it also dyes deep blues, it could be very useful.

This shows the vat with the ingredients added

This shows the vat ready to use

This shows the wool skein in the vat

This shows the skein on removal from the vat

This shows the dyed wool skein

I have been keen to experiment again with the native bedstraws but, since we moved house and I left my precious dye garden behind, I have been finding it difficult to harvest suitable bedstraw roots. The roots of the Lady’s Bedstraw (Galium verum) plants that I have planted in my new garden are too immature and it is against the law to uproot plants in the wild, so it seemed that any experiments might have to wait a year or two for my own plants to be ready to harvest.

However, thanks to the generosity of Leena Riihela in Finland (www.riihivilla.com) who kindly sent me some roots from her own garden, I have been able to experiment with Hedge Bedstraw, (Galium mollugo).

Compared with the roots of madder (Rubia tinctorum), bedstraw roots are very fine and delicate, and these bedstraw roots were very precious as they had come from such a long way away. So I wanted to make sure that I didn’t waste them.

For these tests I used mainly alum-mordanted wool, except for some unmordanted samples from the exhaust dyebaths. To prepare the dyebaths, I first soaked the roots overnight in water, then poured off this liquid. I then steeped the roots twice in boiling water for about 1 minute each time and added this liquid to the soaking water to make the first dyebath. I then simmered the roots twice more, using each simmering liquid for a separate dyebath. In the photos below, the orange colours on the left were from the soaking water plus the two steeping waters and also from the first 2 simmerings. I then simmered the roots again twice for about 45 minutes and used this liquid for another 2 dyebaths. The middle range of shades on the photos were from these 3rd and 4th simmerings, the redder one with an alkaline modifier (washing soda). The range on the right came from exhaust dye baths, with some unmordanted and some alum-mordanted samples. Once the fibres had been added to the dyebath, I didn’t worry too much about the temperature and allowed the dyebaths to simmer gently to improve colour take-up. (This simmering is not something I would do when dyeing with madder – see below)

I decided to work in this way, rather than combining all the extractions, because my belief is that the richest true reds lie under the yellows and browns and the best way to get reds is to first use up these yellows and browns. I don’t know whether this belief is correct but my experiences suggest it seems a good way to get reds rather than oranges. 

I now use this method when dyeing with madder and it seems to work well. After washing the madder roots well, I simmer them to extract the colour for the first dyebath, remove the roots to use again for a second dyebath and then reduce the temperature before adding the fibres.  Once the fibres have been added, I don’t simmer the madder dyebath and I keep the temperature hot but not too hot – i.e. well below simmering point. The roots can then be simmered again to extract more colour for a second dyebath. Indeed, madder is a most generous dye and the roots can often be simmered several times before the dye is exhausted, giving colour for yet more dyebaths.

I think that, when I next dye with the bedstraws, I will probably keep things simpler and try something closer to the method I use with madder. So, after soaking the roots overnight,  I will simmer them once for about 30 minutes and use this solution for my first dyebath. I will then simmer the roots again (probably for about 45 minutes) for a second dyebath and to make sure no precious dye is wasted, I will simmer the roots at least once more for a further dyebath. But first I must wait for my bedstraw roots to be mature enough to harvest.

A range of shades from Hedge Bedstraw (Galium mollugo)

A close-up image of some of  the Hedge Bedstraw colours.