Woad - Isatis tinctoria

My first dyeing experiment was with Dandelion flowers which I picked where they grew as weeds.  Then I tried Rumex root and I have to say that there is something extremely satisfying in using something useless like a weed to make something useful and even beautiful.  The next level is to grow plants specifically for the purpose of using them to dye.  There are a few traditional dye plants that are particularly good but none of them are natives.  So I bought some seeds and sowed them this spring.  They all grew very well and as a consequence I have been busy experimenting this summer.

I have tried to be organized and have documented all my steps and I set up a system to store my samples.  For me, it was a piece of carton, punched with lots of holes and folded.  This way it's easy to attach the yarn samples.  Then I put all the cartons in a big ring binder.

I planned the experiments early this spring and the plan was to use:

1 piece of un-mordanted wool
1 piece of wool mordanted with Rhubarb leaves (since I'm a bit fascinated with Rhubarb)
1 piece of wool mordanted with Chrome
6 pieces of wool mordanted with Alum...

...5 of which would get the following treatment:

1 piece modified with Iron water
1 piece modified with Copper water
1 piece modified with an acid solution (citric acid)
1 piece modified with an alkaline solution (washing soda)
1 piece modified with Tin

I also planned to dye a sample of alum mordanted cotton and linen, as well as a small piece of silk, but for some reason I kept forgetting to add those to the dye bath.  Also, I never used the Chrome or Tin.  That will have to wait till next year.

I was very excited to experiment with the Woad.  To get a blue colour from green leaves is like magic and I wanted to try to do that myself.  I probably have well over 20 books about dyeing and have read them all and most more than once.   My favorites are two books that I have by Jenny Dean, especially Wild Colour, and I also like very much a book that was written by a couple, Dye Plants and Dyeing by John and Margaret Cannon and illustrated beautifully by Gretel Dalby-Quenet.

Woad, Isatis tinctoria, is a biennial and a native of Europe.  It grows so easily that it is classified as a noxious weed in some places in the US.  I found it very easy to grow here.  I sowed only 6 seeds and they all came up.  I'll be sowing more next spring since one needs quite a bit of the leaves to get a strong colour.   The best colour is from first year leaves, And the plant is a gready feeder so give it plenty of nitrogen rich fertilzer.  To get an harvest of fresh seeds one needs to let the plant grow in the second year.  Woad leaves need to be used when fresh, so no freezing or drying will work.  The process is very similar to that of Indigo dyeing, but Woad leaves do not tolerate too much heat, i.e. no boiling.

One can harvest the Woad a few times, I got three harvests before the cold set in.  It's important to weigh the leaves to know how much wool can be dyed.  I had about 120 grams, from my first harvest. Not a whole lot, but I did manage go get a very pretty blue.  The blue of Woad is much lighter than the dark blue of Indigo and I don't think of Woad as a substitute for Indigo, but rather a completely different blue.

The leaves were chopped and then I poured hot water over them and let it sit for an hour.  The water should turn a sherry colour.  When the temperature is about 50°C /120°F the pH should be dropped to 9, using washing soda and then aerated by pouring from one vessel to another until the foam turns blue.  Mine never really turned blue, but a blue green, but it seemed that that was enough.  Then one adds hydrosulphite to reduce the oxygen content of the vat and lets that sit for 30 minutes or so.  The liquid should now be a yellow colour.  This is the stage that the dyeing can take place.  To dye, either yarn or cloth no mardant is needed, just dip it in for a few minutes and take it out again, being careful not to stir any oxygen into the vat.  The fiber will magically turn this pretty blue colour right before your eyes.

Not many dye books speak about modifying Woad dyes colors, but I did that anyway.  I love the un mordanted blue (one more light than the other, that is the second dye bath), but also the greens that came from the Rhubarb mordanted wool and Copper treated.  The latter I just let sit in the modifyer until I see some effect in the change of colour.  I applied no heat, but the time could be anything from a few minutes up to 24 hours.  I could quite see repeating those experiments is larger quantities next summer.  The other colour chart shows some slightly pink colours, those come from the exhaust bath and I treated them in the same way:  Unmordanted, mordanted with Alum, mordanted with Rhubarb (úps - I forgot that one!), aftertreated with Iron, treated with Copper, treated with Acid and treated with Alkaline.