Primitive Textile Dyeing with Woad

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The results: cotton dyed with woad (blues) and overdyed with dyer's greenweed and weld (greens).

Woad (Isatis tinctoria) is rather unassuming brassica, but due to it's leaves holding a blue dye, it has an enormous cultural importance. Woad is native to the Mediterranean, and spread into Europe as early as the Neolithic (5-10,000 years ago). The first evidence of this was woad-dyed plant fibers (likely linen or hemp) that was found in I'Adaouste, Bouches-du-Rhone, a french cave [2]. Woad continued to be used, from linen wrappings for mummification by the Ancient Egyptians (2500BC) to an Iron Age dress found at Loenne Heath, Denmark from the 1st century AD [2].

Woad has now been mainly replaced by the indigo plant (Indigofera tinctoria) and, excluding a small revival recently for craft, has been largely resigned to the history books. It also remains in etymology of our place names, such as Glastonbury-" the place where the woad grows" [2] and in colours such as Kendal Green (fabric dyed with woad and overdyed with dyer's greenweed).

Last year, I was kindly given some woad seeds by a friend, so earlier this year (around March) I planted the woad seeds, and to my delight they germinated and by mid-July I had a harvestable crop. Woad is biannual and the first year rosette is used for dyeing (I'm planning on letting my plants go to seed the following year). 

Woad (Isatis tinctoria) plants. The left-hand photograph shows the new basal growth. 

The rosette continues to produce leaves from the center, so multiple harvests can be taken once the exterior leaves have fully grown. After my first harvest (early August), it actually seemed that the plants thrived and grew to fill the space made by cutting the plants back. 

I've tried two slightly different methods for dyeing which I will outline below, however, the results are very similar. When you look online for how to dye with woad a whole host of complicated recipes can be found, with percentages and certain temperatures being achieved in a set amount of time. I highly doubt that Neolithic man had access to a thermometer and timer, and I chose to follow the instructions 'liberally', especially when it comes to timings- also known as being impatient!

Attempt 1 [2]:

1) Woad was harvested by cutting close to the base of the leaf. The leaves were clean so washing was not required. The leaves were then cut, using scissors, into 2 inch lengths.
2) The woad was added to my aluminum dye pan, which was then heated to 90 degrees slowly, then left to cool to around 80 degrees for 10 minutes. This was then plunged into an ice-bath (in the sink) where the temperature rapidly decreased to around 50 degrees over 5 minutes.

Fresh woad leaves (including stems) coming up to just below boiling.

3) The woad leaves were then fished out of the solution before 2 tsp of soda ash was added to the solution (when the temperature was below 50 degrees). This changes the brown strained liquid to a green colour (with a blue foam).

Left: the strained liquid (brown) and right: the dye bath (blue/green).

4) To this, the cotton/wool was added. The cotton/wool had been soaking/scouring overnight (left to soak in a weak soapy solution).

5) This was left in for around a minute (although I believe this ought to be longer) before being removed and left to aerate. This is where the fabric/wool is exposed to oxygen and the green turns a brilliant blue colour.
6) The cotton/wool was then left for a few minutes before being washed to remove any unreacted dye.

6.5) The cotton/wool can then be rinsed and re-dipped in the dye bath to increase the intensity of the colour.  

The cotton fabric after being dipped in the dye bath and then exposed to oxygen (LHS to RHS: twice dipped, once dipped and three times dipped). Note the more intense colour, with more green tones: this is because the unreacted dye is yet to be washed out. 

7) The rinsed wool was then put rinsed with a weak vinegar solution to counter the strong alkali of the dye bath. 

The first attempt at dyeing with woad. From the LHS to the RHS: three times dipped in the dye bath, twice dipped and once dipped (all dyed after soaking and scouring overnight) and twice dipped in the dye bath (not soaked or scoured overnight, likely dyed when the dye bath was beginning to exhaust).

Attempt 2 [1]:

The second attempt was much the same as the first attempt, except step 2) was different and the leaves were frozen instead of being fresh. Instead of faffing around with ice baths etc, I poured boiling water over the frozen, chopped woad and this was left to steep for around 10 minutes. One other major difference is that because I was planning on overdying the woad with other natural dyes the wool was mordanted with alum. 

The second attempt at dyeing with woad. From LHS to RHS: three time dipped in the dye bath, twice dipped in the dye bath and once dipped (all dyed after soaking and scouring overnight).

The second attempt was mordanted because I planned to over-dye. Yellow is overdyed on top of the blue to create green. Green, counter-intuitively, is a difficult colour to dye (it can also be created with dyer's mazegill, a bracket fungus, and an iron mordant), and first a strong blue must be achieved. 

Traditionally, dyer's greenweed (Genista tinctoria), a species of broom, was overdyed to create a colour called Kendal green and weld (Reseda luteola) was overdyed to create Lincoln green. I had collected, and frozen, both dyer's greenweed and weld from St Bees and Silloth, respectively. 

Dyer's greenweed (Genista tinctoria) growing, and in the pan after being frozen. 

To fix a dye a mordant is required, although, woad doesn't require a fixative. A mordant acts a fixative and alum (alongside cream of tartar) is one of easiest mordants to use. While the dyer's greenweed didn't work to effectively (this is likely due to the dye bath being quite weak), the weld worked very well, creating a vibrant green. 

Overdying with yellow-dye producing plants. From LHS to RHS: purely woad dyed (three times dipped), overdyed with dyer's greenweed, overdyed with dyer's greenweed then weld and overdyed with just weld. 

There is a real satisfaction to dyeing from scratch. I've also been growing madder (Rubia tinctorum), a traditional red dye, and plan to dye with it, as well as dyer's mazegill fungus (Phaeolus schweinitzii) and walnut husks. I'd also like to collect raw alum from the Yorkshire coast in an attempt to dye from full first principles. 

[1] Hardman, J. and Pinhey, S., 2009. Natural Dyes. Crownwood Press. Ramsbury.

[2] Roberts, T., All About Woad. Accessed at http://www.woad.org.uk/index.html (21/08/20)