A week of indigo

It was definitely a blue fingernail week last week! It started with a couple of days in Hove with a wonderful group of textile friends who try to get together every couple of months to do a little felting or stitching.

This time, Barbara was rash enough to offer her garden to do some indigo dyeing – though some parts (usually featuring pale limestone!) were definitely out of bounds to people carrying dripping blue fabric. 🙂 The weather was glorious – the last two days of our prolonged heatwave – and the food and drink was plentiful and excellent. Barbara even baked a belated birthday cake for Carol, my partner in Women of the Cloth.

In between the eating, drinking and laughter we even found some time for dyeing, and everyone produced some great work.

When I got back home, it was time to filter my second indigo extraction from my homegrown indigo, which I’d fermented and left to settle while I was away. This produced another 4g of indigo.

Then on Friday I harvested 75g of indigo leaves, blended them with iced water till it was bright green and strained it through silk.

I used this to dye two silk scarves, one plain and one ecoprinted. Interestingly, some of the leaf prints seemed to resist the dye, while others changed colour as they were overdyed.

Also interestingly, the silk I used to strain the vegetation shows a range of colours, from the expected turquoise, through pale green to red from indirubin.

All natural indigo contains indigotin, the blue pigment, and indirubin, a red pigment – the indirubin is usually hidden by the indigotin, but shows up once the indigotin is exhausted.  Fascinating to see it separated out here!

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Dyeing with home-grown indigo

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Back in April I planted some seeds of Japanese indigo, or Persicaria tinctoria.

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They germinated pretty quickly – within a few days.

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In mid-May we had a warm spell, so I planted them out. They like to be kept well watered, but as we had such a wet spring, luckily I didn’t need to do much watering!

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I will leave a couple of plants to flower so that I can gather seeds for next year, but apparently once they start to flower the leaves won’t give any colour. So I’ve been torn between picking them and wondering whether I have enough to dye with! 🙂

This week I couldn’t take the suspense any more and decided to cut back some of the larger plants (apparently they will form new shoots, so this won’t harm them). This gave me around 100g of leaves.

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Following the instructions by Isabella Whitworth and Christina Chisholm in the Journal for Weavers, Spinners and Dyers, I tried two methods of dyeing with them.

First I used half the leaves to produce aqualeaf blue, a method which they credit to Jenny Balfour-Paul and Lucy Goffin. This involves soaking the leaves in iced water before blending them and straining out the vegetable matter. Then you add  your silk or wool for 3-5 minutes. No alkali, no reducing agent – just neat indigo!

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This method gave a beautiful delicate shade of turquoise on silk. If I’d had more leaves I could have blitzed some more and done another dip, but I rather like this colour.

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On wool it was less successful, giving only a faint tinge of blueish green.

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I then added the leftover liquid and the blitzed leaves to a pot containing the rest of the whole leaves and cold water. In hindsight, adding the blitzed leaves was a mistake, because all the little bits of leaves got caught up in the wool later (as you will see!). Live and learn. 🙂

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After heating it slowly for a couple of hours to 60°C I strained out the leaves, added some washing soda and whisked it. When the froth was all green, I reheated it and added some reducing agent. Once the dye was reduced I added some silk and wool.

The silk was very pale again, more blue than turquoise, despite four dips. Obviously I need to pick more indigo leaves next time!

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But the wool turned a strange shade of green. This is the shade I often see when I first remove items from an indigo vat, but it turns blue on exposure to the air. In this case the colour didn’t change – it just stayed green. The spots are the bits of ground up leaf from the aqualeaf indigo which have got caught up in it. 🙂

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Hopefully there is enough growing season left for me to get another, bigger harvest to try again before the end of the year!