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NATURAL DYEING

I have been using and growing plants for dyeing for about 40 years. I enjoy experimenting with new methods and dyestuffs as well as using tried and traditional dyes.
The gallery above shows some of my archive of samples as exhibited in August 2021.
Scroll down for specifics on some of my natural dyeing.

 

WOAD

Woad  (Isatis tinctoria) is a dye plant which has been used for hundreds of years. It is one of the few plants which gives a true blue dye - along with Indigofera species and Japanese Indigo (Persicaria tinctoria) it contains the precursor of indigo pigment. Woad is the easiest of these plants to grow in the Scottish climate, but unfortunately contains much less pigment than Indigofera. So I need to grow and use a lot of woad leaves to get a good blue!

Woad needs to be harvested at the right time to get the best pigment content. In 2021 my late August harvest (first year plants) gave less colour than my mid-September harvest, but the exact time will depend on weather conditions in the spring and summer. Second-year non-flowering plants harvested just as the flowering plants started to produce flowers gave a good colour.

I checked on the pigment in my woad with a quick tatakizome test. I sandwiched some woad leaves of different sizes in a piece of folded cotton fabric and hammered over them until I could see the leaves' imprints clearly on the fabric. At first all the imprints were quite green but the imprints of the larger leaves gradually turned more blue over a few days. Rinsing helps to remove the green chlorophyll and reveal the blue. I could see that there was more blue pigmnet in the larger leaves and also in the flowering stems.

To get the best blue colour, the process is fairly complicated and can take several hours.

First the fresh leaves must be steeped in hot water to extract the soluble Indican , which gives indoxin. I cram up to 1 kilo of leaves into a 5 litre enamelled pot and keep it at 50 degrees centigrade for an hour before straining out the leaves.

Adding soda or lime to make the solution alkaline (pH 10 to 11) and oxidising it by whisking very vigorously or pouring from one bucket to another up to 60 times links 2 indoxin molecules to give indigo which is blue but insoluble, and so will not attach to fibre.

I prefer to reduce the vat (removing the oxygen which makes it soluble ‘white indigo’ to attach to fibre) by fermentation with fruit sugar as it is more eco-friendly than the alternative of adding thiorea dioxide (spectralite) but if the vat won't reduce with fructose I will resort to spectralite rather than fail to get my blue dye.

When the vat is ready, it looks clear yellow with a 'flower' of blue bubbles and a coppery sheen on the surface.

I dip my fabric or yarn in the vat for three minutes the first time, and then for repeated one minute dips until I get the shade I want (or the vat is exhausted). Rinsing in cold water and aeration for at least 30 minutes between dips oxidises the attached indigo – it turns from yellow to blue in a few seconds and becomes insoluble so it is fixed to the fibre.

There is a second pigment in the woad leaves called indirubin, and I have recently experimented with using the leaves strained out of the first extraction, to dye with the indirubin. I simply put the strained-out leaves into a fresh dyepot of hot water and gently simmered at around 80 degrees centigrade for an hour. After straining I added un-mordanted wool to the dyepot and kept it at the same temperature for another hour. When I took the yarn out it was a peachy-tan shade, but when it dried it started to turn more pink, and with the yarn hanging in the light this change continued for a day or two until it was a salmon pink.

Another, much simpler, method for dyeing with Woad gives pretty soft teal shades. I harvested the fresh leaves and placed them in a non-reactive glass bowl. I sprinkled over a tablespoonful of salt and started to crush and squeeze the leaves with my (gloved) fingers. Soon a bright green foamy liquid appeared. I added a silk scarf to the mush and continued to squeeze and rub, Gradually the colour changed to a greenish teal. I shook off the leaf mush and hung the silk scarf outside. Once it was dry I rinsed it in cold water. As I rinsed away the chlorophyll the colour became a bluer shade of teal. A small sample of cotton fabric treated alongside the silk remained a much greener shade, but still very pretty.

 
 

BOG MYRTLE

A traditional natural dye in Scotland.

In June 2021 Naoko Mabon and I visited Monica Haddock, head weaver and dyer at Ardalanish Weavers on the Isle of Mull. After showing us her weaving and the colours she dyes with local plants, Monica took us to gather bog myrtle.

Bog Myrtle grows abundantly on the Ross of Mull. It is reputed to drive away midges, but Naoko and I certainly didn't notice that effect as we picked stems for dyeing!

Back home, Naoko helped me to strip the leaves from the stems. The leaves went into a large dyepot and I simmered them for around 2 hours. After straining the dye I added skeins of wool yarn, premordanted with aluminium sulphate, and samples of linen fabric premordanted with aluminium acetate. Some very fine yarn took up the yellow very quickly, but I left most of the wool in the dyebath, at around 80 degrees centigrade, for about 90 minutes. 

When I removed the first batch from the dyebath I could see that there was still a lot of colour, so I added more mordanted yarn for a further 90 minutes.

Because I had used different types of fibre, including some natural light grey Icelandic wool, I got a range of shades. I hung the skeins up to dry and rinsed them a few days later.

I modified a few skeins of wool by dipping them in a weak solution of iron sulphate. This changed the colour to shades of green.

I soaked the bog myrtle twigs in rainwater for about three weeks, by which time they were starting to get a bit smelly and slimy. I then boiled them up in a dyepot for about two hours before straining and adding premordanted wool yarn. The tannin-rich dye gave a good shade of chestnut brown on my fine wool yarn and lighter shades on other wool yarns.

I used the remains of both dyebaths to make lake pigments. By adding excess aluminium sulphate to the leftover dyebath, the pigment and alum molecules join to form a 'lake'. After about an hour I add enough washing soda to make the solution foam. The shift in pH causes the lake molecules to separate from the liquid. Straining it through a fine cloth overnight results in a yoghurt-like consistency, which works well as paint.

 
 

MARES' TAILS

Equisetum - an ancient plant, a nuisance weed in gardens, but useful as a natural dye.

I have dyed with Mares' Tails both in Iceland and in Scotland.
In Iceland I collected the plants around Blonduos while I was Artist in Residence at the Icelandic Textile Centre in summer 2018. I used them to dye handspun Icelandic wool which I had separated into tog and thel fibres before spinning. I had pre-mordanted the yarn with Aluminium sulphate (8% weight of fibre). As with other dyeplants that I used, the became a more intense colour than the thel yarn.
I also tried solar dyeing unseparated Icelandic fleece with Mares' Tails. The aluminium sulphate mordant was added at the same time as the dyeplants, approximately the same %WOF. The shade obtained was a lighter clear yellow - it was noticeable that the tog fibres had again dyed to a more intense shade than the thel.
In July 2021 I collected Mares' Tails on the island of Iona (off the West coast of Scotland), where they were growing abundantly at the side of the road. I made a dyebath at home the next day, simmering the plants  for about 2 hours before straining the dyebath. I added skeins of wool yarn which I had premordanted with Aluminium sulphate (8% weight of fibre). I used a variety of wools including some light grey Icelandic wool yarn. The skeins of yarn were simmered in the dyebath at around 80 degrees centigrade for about an hour. I obtained a range of shades on the different types of wool.
I later modified the colour of some of the skeins of yarn by dipping them for 5 - 10 minutes in a weak solution of iron sulphate, which produced some shades of green.