A Woad Experiment

I have been following Leena’s posts (www.riihivilla.com) about her experiences with using her home-grown woad leaves and I was particularly interested to learn about the method which gave her the best results. Although this method is very similar to the one I have been using for over 30 years, one element of it was new to me. I usually start by pouring boiling water over the chopped woad leaves and leaving them to steep for about 30 minutes.  I then strain off the liquid and squeeze the last drops of juice from the leaves before discarding them. I then allow the liquid to cool to 50C before adding the washing soda and whisking to introduce oxygen and precipitate the indigo dye particles.  However, Leena’s preferred method requires the whole unchopped leaves to be simmered in boiling water for about 3 minutes, after which the leaves are left to steep in the hot water for 15 minutes. The water is then strained off, the leaves removed and cold water added as necessary to reduce the temperature to 50C.

Leena’s recipe then proceeds much as the recipe I always follow. In both our methods, washing soda is added until the solution is around pH10 and then the liquid is whisked until blue froth forms. This whisking continues until the froth that is forming ceases to be blue and changes to white. Both methods then continue in exactly the same way, by adding the reducing agent and then using the vat once the liquid has changed in colour to greeny-yellow.

I decided to test each of these methods using the same quantity (400gms) of leaves for each, picked on the same day and grown under the same conditions. I left the leaves for Leena’s method unchopped but chopped the leaves for my method, as that is what I usually do. I then tested the two dye vats using the same weight of the same type of wool for each dip in each vat and leaving the wool in each vat for the same length of time. This ensured that each vat was used in the same way, so the experiment had some validity.

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This photo shows:

On the left: the blue froth formed following my method 

On the right: the blue froth formed following Leena’s method.

 

 

As the froth on the surface on the left seemed a much deeper blue, I was expecting to achieve deeper blues on the yarns dyed in this vat. So at this stage I was beginning to feel that my method might, after all, prove to be the better one. But “pride goes before a fall”!

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The three skeins on the left were dyed in the vat made following my method (“my vat”)and the three skeins on the right were dyed in the vat made following Leena’s method (“Leena’s vat”).

 

 So although “my vat” seemed to form froth a much deeper blue in colour than the froth on “Leena’s vat”, to my surprise this did not appear to influence the results when the skeins were dyed. In fact, the skeins dyed in “Leena’s vat” seemed a slightly deeper blue than those dyed in “my vat”. So my earlier expectations were proved wrong.

The question now is: which method will I follow in future? For workshop or demonstration purposes, I think my method is simpler because it doesn’t require a heat source and it gives perfectly good results. However, for my own purposes, I shall probably try out Leena’s method again, as it may enable me to get slightly deeper shades of blue. So my thanks to Leena for introducing me to a new and useful method.

9 Responses to “A Woad Experiment”

  1. Colin says:

    Interesting experiment. There are two variables, here:- chopped or whole and boiled or blanched. One or the other or both could cause the difference. Not knowing the science behind it, I would guess that chopped is better than whole and boiled is better than blanched. So the best might be chopped and boiled. But whole and blanched is more convenient.
    Regards
    Colin

    • Jenny Dean says:

      I usually chop the woad leaves before I use them, as I agree with Colin that they should yield more colour that way. So I plan to try Leena’s method again, this time with chopped leaves, as I think chopped leaves plus the pre-boil might give even deeper blues. We shall see!

  2. Leigh says:

    Great experiments and lovely results. Also, thank for the link to Leena’s blog.

  3. Debbie says:

    As I have my first successful “crop” (one plant – we have a small garden!) of woad, this is really interesting, thanks Jenny. I shall give this a try before the frost sets in and decimates my little plant. It didn’t flower, though, so I don’t have any seeds – what are the chances of it surviving winter in the cooler climes of Northern England?

  4. I am really a novice in dyeing compared to you Jenny!
    It was interesting to see the yarns dyed with the two methods, side by side, there seems to be also a difference in hue, is there?
    I have to add that the reason why I used the whole leaves was just that it was easier when I had many kilos of them to process at the same time. I think that when I dye next time with a smaller amount (next year), I will also try the chopped leaves.
    I have to say also that I picked up this method from here http://fiberarts.ca/woad%20extraction.html
    and I believe that the same method was used in the Univeristy of Bristol (I think I read it somewhere, but I’m not 100% sure).

    I’m surprised you got so deep blue even thoug the froth was so pale, I recall that I had to whisk sometimes longer than 10 minutes for the blue froth to appear and it did eventually even though at first it seemed very pale. It is interesting to think that perhaps it wouldn’t have been necessary to whisk for so long, and even the light froth was enough.

  5. mieke harinck says:

    my experience is that the colour of the froth is not a measure for the ultimate result. i had once a beautiful blue froth but almost no colour (this happend when i let the woad overcook).
    mieke

  6. cedar says:

    Thanks so much for sharing your experiences, and we are all the wiser for it…chop and boil? yes, that is what I will try next also…what fun!

  7. Helen Melvin says:

    Hi Jenny. That was a very interesting experiment.When Jane Meredith and I were demonstrating Dyeing the Blues at The Real Colour show I found that Jane used a method like Leena’a’s. Only she boiled for longer, an hour I think and used ammonia. We had a glitch with the electrics and she had to use the method that you and I use . She was very pleased with the result and said she thought she would use it in future! So I was surprised at your result, and now I want to try it too and will hunt around to see if I have any woad leaves still in the garden. Thanks

  8. Martine says:

    Thank you so much for all your work and showing it to us Jenny.
    Till now i have only dyed cold with my woad. Got a beautiful greenish blue. Next year i’ll try this vat method.
    I have still woadleaves in my garden! Unbelievable! 22/11. But not enough for a vat.
    XXXm