Saturday, October 27, 2012

Dyeing with Woad

Monday, October 22:

This was the last of the 4 week Special 'Spin Sox Sessions'!  Having learned to darn holey socks, make a drop spindle, spin yarn and how to knit it into a sideways (only needs 2 needles!) socks, we dyed the yarn using woad seeds.

The woad seeds were kept at a low simmer for an hour and the unmordanted colour produced was a smokey green (there are no photos of this colour as it didn't show up too well in the lights of the field house).

After adding an aluminum sulphate mordant to the woad must*, we strained it and put the wort** into 3 different jars.

One jar was acidified with vinegar, one made alkaline with dishwasher powder and one had ammonia added.  The resulting colours varied from deep blue purple to a reddish purple.  None of these colours are even close to the turquoise blue that you get when making a woad (indigo) dye vat, or the pinkish beige that you get when you boil woad strongly.

The turquoise colour of a woad vat comes from the chemical indigin.  Indigin is one of the betalin family of pigments that includes the red of beetroot (betaxanthin) and the blue of indigo (betacyanin).  I now wonder if the purple from the seeds is just a slight chemical difference that happens in the indigin as the plant runs to seed - perhaps it gets partly changed into the red betalin by the sun as the synthesis of all of those chemicals are very sunshine level dependant.

That's why we can't get a good natural blue dye from temperate climates, so indigo comes mostly from India.  We can get blue from Salvia flowers, but it's not a strong blue, and you need to pick a lot of flowers!  Note that Salvia is a Mediterranean plant, so perhaps the blue of it's flowers is darker when growing in its natural habitat rather than in the Pacific Northwest gardens.

What a versatile dye plant!  There are lots of seeds available for free in the field house for anyone who wants to plant some next year... just ask me!

* must: the plant material and water combined - either boiled or fermented
** wort: the strained liquid from a must

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