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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Extracting indigo from homegrown plants

A couple of years ago I grew Japanese indigo in my London garden for the first time, and tried dyeing with fresh leaves as well as making a reduced vat.

This year I planted more Japanese indigo – I got the seeds from Ashley Walker of Nature’s Rainbow at the natural dyeing workshop I did in January. He said that there were two variations – broad leaved and narrow leaved, and that he had found that the broad leaved variety contained more pigment. So I planted them in two separate patches, and thanks to the wet spring and summer heatwave they have grown really strongly.

I’d read about extracting pigment by drying and composting the leaves, but this seemed to be quite a large scale process – I got the impression that I would need several years’ worth of leaves before this became worthwhile! But then I joined a Facebook group on indigo pigment extraction methods, whose admin Brittany Boles published a description of aqueous alkali precipitation extraction and also linked to a detailed account of the process by Fibershed.

So last week as our heatwave reached its peak I took the plunge and had a go at fermenting some of my homegrown indigo.

indigo harvest

I cut about half the broad leaved plants down to 7-8 inches and stripped off the leaves, ending up with 215g. I covered them with bottled water (chlorinated water is a no no and there wasn’t much rainwater around!) and kept the leaves submerged with a couple of stones.

indigo fermentation start

A couple of days later I could see an oily slick on top of the water – a good sign that fermentation was happening.

indigo fermentation middle

Then only a couple of hours later the water had turned bright green and there was a characteristic fruity smell – bingo! I decided to remove the leaves, because if you leave them for too long the yield of indigo pigment apparently drops drastically.

indigo fermentation end

I added lime (calcium hydroxide) to reach pH 10 and then whisked…and whisked…and whisked until the liquid was a deep indigo blue.

Because I’d used a dark grey bucket, I decanted a bit into a clear jar so I could get an idea of how the pigment was settling. Two days later I could see a dark blue line at the bottom of the container where the indigo had settled.

indigo precipitation

So I decanted most of the liquid from the bucket, adding it to my current indigo vat.

indigo decanting

Then I poured the sludge at the bottom into a coffee filter.

indigo filtering

After filtering and drying, I was left with 4g of homegrown indigo.

indigo pigment

I also saved the stripped stalks of indigo and stuck them in a jar of water. One week later they have developed new roots – ready to replant for the next round!

indigo rooting

I don’t know how pure the pigment is – apparently this method produces fairly low grade indigo, with bits of leaf and other impurities. But it’s a great feeling to have grown and extracted my own indigo pigment! 🙂

More homegrown indigo

I’ve now got a good crop of flowers on my Japanese indigo, but before they all started developing I did another harvest of the leaves – almost 200g in all.

fresh indigo leaves

Unlike last time, I didn’t do any aqualeaf indigo, as I wanted to see if I could get a stronger colour with the reduced indigo, so I needed every leaf I could get! 🙂

This time I overdyed a linen top that I had previously ecoprinted with peony leaves. It felt a little too minimal, so I thought that a pale indigo background might lift it a bit.

ecoprint linen top white

I dipped the top three times, leaving it to oxidise in between. The result was slightly darker than last time, but still quite pale and delicate.

indigo dyed ecoprint linen top

I’m drying the flowers to get seed for next year’s crop, but I’m also going to see if any of the plants survive the winter in my London garden. They are still growing – but it has been a very mild autumn so far. I’ll have to see what happens when the frosts arrive!