How to Extract Woad: a Natural Blue Pigment for Dyeing and Soap Making

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The full process of how to extract woad from fresh Isatis tinctoria leaves. Woad is a blue pigment that you can use in fiber dyeing & soap making.

Originating on the steppes of central Asia, woad, also known by its Latin name Isatis Tinctoria, has been cultivated throughout Europe and the Mediterranean for millennia. Though its seeds have been found in French Neolithic sites, the first evidence of it being used in the dyeing of cloth comes from ancient Egypt. Later evidence of woad dyes comes from Roman, Viking, and Medieval sources and sites.

If I ever meet anyone who isn’t familiar with this plant, I tend to refer them to Braveheart, which nearly everyone has seen. Once I mention Mel Gibson painting his face blue, it tends to flip a switch for people, though there’s some debate over whether the Britons ever used woad for this purpose. I use woad (and indigo!) in soapmaking and am curious as to how it’s extracted from leaves. This is how I extracted woad pigment from woad leaves I grew in the garden.

Extracting natural blue pigment from the leaves of the Woad plant. The pigment has traditionally been used to dye wool but it can also be used in naturally colouring soap.
Infusing woad leaves in hot water around 175F/80C

Green Leaves into Blue Dye

It’s hard to believe that these green leaves contain such a vivid blue pigment. I wonder how the first people actually discovered it. So many of our past discoveries seem purely accidental, so I don’t doubt it was the same with woad. However, there are quite a few steps in the extraction process, making me wonder how on earth someone could have stumbled upon it.

To extract woad, you must first infuse leaves in nearly boiling water – preferably soft water such as rainwater. After ten minutes, the leaves are removed and squeezed of any juice before being discarded on the compost pile. The resulting liquid is strained, and then soda ash is added, which starts the process of extraction. Soda ash, sodium carbonate, can be sourced from the ashes of various types of plants – it creates carbonic acid when mixed with water and is also commonly used as a water softener. Through a process of aeration, settling, rinsing, filtering, and drying, you’re left with a natural blue pigment that can be stored and used indefinitely.

Extracting natural blue pigment from the leaves of the Woad plant. The pigment has traditionally been used to dye wool but it can also be used in naturally colouring soap.
Aerating the infusion with a mixer

Woad for Health and Skin

Recently I’ve come across a few people who have asked me about the use of woad in skincare and whether it is safe. My answer is that woad is a non-hazardous natural product that is safe to handle and use externally.

Woad is also taken internally, though I’ve never tried it myself. Used in both European and Chinese herbal medicine for at least two thousand years, compounds in woad are said to combat certain types of cancer and anti-inflammatory diseases. Human studies from China have also shown that woad has antimicrobial, antibacterial, antiviral, and antiparasitic qualities. [1]

Extracting natural blue pigment from the leaves of the Woad plant. The pigment has traditionally been used to dye wool but it can also be used in naturally colouring soap.
Allowing the pigment to settle in the liquid

Woad as a Dye and Colorant

There is also some misinformation on the internet on whether woad will stain your skin. I can imagine the deduction work in this assumption: Since woad is used to dye cloth, wouldn’t it also color anything else it comes into contact with? I want to assure you that woad, as a powdered pigment, colors only the soap. It works in much the same way as mineral pigments and suspends as tiny granules, only giving the illusion of dyeing the soap. To use woad as a dye, additional chemicals such as alum and spectralite are required to get it to ‘fix’ to the cloth or wool.

Another positive point of woad is that it breaks down much more easily and naturally than commercial oxides. This property makes this product a much more environmentally sensitive alternative to micas, oxides, and other laboratory-created soap coloring agents.

In short, woad is safe, won’t stain your skin, and is a lovely and authentic natural colorant for use in making handmade woad soap. I enjoy using it and growing it in my own garden and would encourage anyone else who is interested in woad to try it out as well.

[1] Isatis Tinctoria

Extracting natural blue pigment from the leaves of the woad plant. The pigment has traditionally been used to dye wool but it can also be used in naturally colouring soap.

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  1. How do you make it color-fast in cloth or yarn?

  2. Francesco says:

    What a lovely , nature-loving article.I have some Isatis in my garden and was wondering how in a historical context blue dye used to be extracted from it.You answered my
    question perfectly.Thank you.

  3. Great article. Pardon my naivity but can I dry the leaves and extract the color later? If not how can I preserve the dye for later use?

    1. Hi Kay, the pigment in both woad and indigo start to degrade as soon as you pick the leaves. Unfortunately, that means that you need to work with fresh leaves to extract dye pigment.

  4. Soda ash is not carbonic acid. Carbonic acid is what you get when you bubble CO2 in water. Sodia ash is basic because of the sodium hydroxide. Think soda = sodium; for sodium hydroxide.

  5. Elisabeth says:

    Fascinating article, I’m definitely going to try growing and using woad! Going off at a complete tangent, That Film (Braveheart) is a load of pernicious Hollywood rubbish masquerading as history – frankly, I’m appalled that so many Scots think it’s the way it was! While we know from ancient historians as well as modern entomologists that the British were heavily tattooed (the name means ‘the painted people’), by Wallace’s day, applying warpaint to the face was definitely not done! Incidentally, he was NOT the Braveheart of Scottish history, that was Robert the Bruce

    1. I am fairly new to making soap and using natural dye is the way for me so I will be using woad. Thank you for the link to getting it in powder form.
      Since we have had what is not Scottish History, to re-address the balance it was ancient Scottish hunter gatherer celts/picts who used woad liberally on their skin and also to dye cloth. Early monastic Romans recorded that women often covered their entire bodies with the blue dye. The herb has been used to react against bacteria, viruses, parasites and also reduces fever. Perhaps we are not so clueless or maybe, like many of us, they just liked the blue!

      Everyone knows blockbusters are based losely on the truth.


  6. Hey, I have a question, can you use dried herbs to prepare a blue woad pigment or is it necessary to use fresh leaves?

    1. I’ve never used dried leaves but can’t see why you wouldn’t be able to use them. You’d probably just need half the amount by weight of fresh.

  7. That’s so funny! I am coming back from a trip to France where I visited my son in Toulouse, and it’s called “Pastel de Toulouse” there! I bought some yarn, some hand cream (pastel blue, yes!!!) and some soap. Just couldn’t get enough of those items bearing my preferred color… :-) I am amazed to learn through your website that the plant is illegal to cultivate in the States, wow!

    1. I’d have loved to visit the shops where you bought the Woad items! I wonder what you’ll make with the yarn and just how pastel blue the hand cream is :)

    1. Anonymous says:

      only in some states

  8. Hola Tanya. Muy interesante la información, muchas gracias por tu buena explicación.

  9. Tanya. I'm thinking about planting part of an acre of Woad because it's invasive here in British Columbia, CANADA (there is a lot of it on this 30 acre property). I'm wondering Y how much dye I can get from X how many plants? Or specifically, how much dye would I get from a solid acre of planting? Also, please delete the SPAM guy above me.

    1. Magikal Hermit says:

      There’s an article on the Telegraph about commercial woad growing@ “Mr Howard’s experiments show that in good growing conditions with plenty of sun, almost 10 tons of woad leaves per acre can be produced twice a year. Each ton of leaf produces about 2lb of indigo pigment, worth about £200”

  10. Hello, can this extraction method be used in another plants such as carrot or flowers to get the natural pigments? and then, can i buy the soda ash from super market? because i want to take the natural pigment for making an artwork! thanks! ;)

    1. Hi Gloria, I don't think that soda ash is freely available in the shops here in the UK but you can find it online. The chemical name for it is: Sodium Carbonate / Na2CO3.

      I've never heard of using this extraction method with anything other than woad/indigo but you could do some research? I'd be fascinated to hear what you come up with!

  11. I have grown woad for a few years now. It is a biennial, forming a rosette of greens the first year then flowering a brilliant yellow on tall stalks the next. When allowed to form seeds that drop to the ground, the process begins again for another year. I never knew how to use the leaves to make dye. Thank you!

    1. You're welcome Fairegarden :) You can extract woad from first year plants by cutting leaves from the plant in summer. The plant will then grow on to produce the flower/seed spike the next year.

  12. I have honestly never heard f this plant it may be because I am in Canada I am certainly going to check it out. B

    1. I understand that Woad is invasive in parts of the USA – it may be that you too have some growing in your area?

  13. Fascinating post, Tanya. I have seeds donated to me by a friend who grows the plant for its flowers but haven't grown it myself. I'm super impressed at your knowledge – you make the process look so easy (but i'm sure it isn't!)

    1. That makes sense since the second year stalks and seed heads are commonly used by florists. If you do end up growing it, make sure it's in a place where you don't mind it spreading out…though it's a biennial, it seeds all over the place and can get a bit invasive. Maybe it might do to look for wild sources first? That's what I would do if I were just using it for personal projects or experimentation.

  14. That is so interesting! I've never heard of woad. Thanks for sharing your knowledge!

      1. NIYOGUSHIMIRWA Delphine says:

        What a genius person!I humbly thank you for sharing such a kind of knowledge with us! It’s really interesting!

  15. Have been very interested in Woad but it is classified as an invasive plant. Have you had any problems with that? Would love to see some wool yarns dyed with woad….

    1. Woad is considered invasive in some parts of the world including the US however it's a native plant in Britain :) If you find the right type growing in your area it would be an easy thing to collect it for dying your own wool and cloth. Could make for some really interesting Quilting conversations!

  16. Fascinating Tanya. It reminded me of a lady who comes to the embroidery exhibitions, who dyes solely in indigo – a rather similar colour.

    1. I love hearing about people who go out of the way to make things themselves – the lady with the self-dyed silk must be really interesting :) Also, you could probably chat to her about Woad the next time you meet. Woad is actually a form on indigo, although the concentration is far less than the indigo sourced from other types of (tropical) plants.

  17. Do you only grow the woad for the dye then Tanya?? Have you ever thought about looking into it's other uses so as to get more out of the plant itself?? How easy is it to grow?? Is it an annual plant and does it grow outside?? What sort of soil/climate conditions does it need?

    1. That's right…the rules for using some self-sourced botanicals in beauty products is that you have to grow it yourself for that particular purpose. Even if woad grew wild on the Isle of Man, which I'm fairly sure it doesn't, I wouldn't be able to harvest it for use in sale-able products.

      If you're using it in home products then I'd recommend that you find some growing wild and then harvest it when it's ready. Woad takes up a bit of space and it grows wild all over England and Wales. As a biennial it's a bit more involved in growing and harvesting than an annual but still fairly straightforward :)

  18. We must not have woad in Virginia, I wonder if it was ever used as a pigment for early paints? It is a real nice deep color.

    1. You'll have woad in Virginia Sunnybrook…in fact I believe it's classed as an invasive weed across most of the US.

      I'm not sure that woad was ever used for paint but it might be something fun for you to look into if you found it growing on your property :)

      1. It has been and still is used to stain wood in some parts of the world.
        It is said to keep mold at bay when used on wood.
        And I have read of it being used to paint by colouring egg shells blue and then making acrylic paint with the blue died shells.
        I haven’t tried it though. So I’m not shure it actually works.

    2. Actually the’ve discovered that the blue paint in the Book of Lindisfarne and the Book of Kells was made from Woad.

  19. Seriously…you make your own soap! Wow! I'm amazed :-)
    How did you learn making it?
    Is it a family tradition?

    1. I taught myself some years ago though I don't doubt that family members made it in the past. The days of modern convenience are still relatively new to people and I have photos of (long deceased) family members living in log cabins well into the 1900s.