In my search for natural dyes, of course I had to come across indigo at some point. No palette would be complete without blue, and indigo is the strongest and best-known true blue dye there is. It used to be extracted from the "true" indigo plant, Indigofera tinctoria, but also from woad, Isatis tinctoria, which contains the same chemical in a lower concentration. The original blue jeans were dyed with indigo and most jeans are still dyed with a synthetic form of the substance. It's also used for japanese shibori, which is an elegant kind of tie-dye technique which seems to be very fashionable at the moment.
What I didn't know when I started this experiment, was that indigo needs a ridiculous amount of processing to get to the actual dye. The leaves need to be fermented, ground, soaked in lye and reduced (as in, the free oxygen has to be removed) in a process that is still a mystery to me. "Real" indigo dyers set up fermentation vats which have to be fed with sugar and tended to regularly - it almost sounds like having a pet. I wasn't going to do that to myself, or to the people I share my studio with. So I found a workaround: pre-reduced indigo. The plant matter is already processed and prepared so it is about 60% reduced, and there's no need for strong lye - which can be dangerous - to set up the dye vat. All it needs is soda ash (sodium carbonate), and a reduction agent called thiourea dioxide, thiox for short, for the other 40% reduction. These substances in a certain concentration should then yield a useable dye bath.
Sounds simple enough, right? Well, wrong. First of all, I found several different instructions which all gave different amounts of the different substances. One told me I should use 65g of thiox for 20g of indigo powder, the other said it should be 100g, or even more. 100g of soda, or 250g. To be safe, I started with the smallest amounts. First sign of failure: some kind of foam should form. It didn't. So I added the rest of my thiox - 100g in total - and another 100g of soda. It foamed a little bit, but still didn't look like the "flower" I was supposed to get - a thick, shiny blue foam. It still didn't look right after letting it rest for about half an hour.
Still, I had to try it out to see if it did anything. I was excited for the magical color shift that had to happen. When you dye a piece of fabric in indigo, it first comes out bright yellow-green, and only turns blue as it oxidizes in contact wit the air. I couldn't wait to see this magic happen.
This is what my very first try looked like:
That wasn't what I was going for, exactly... But I wasn't going to give up. For some reason I thought it would be a good idea to stick my gloved hands in the bath and feel around a bit - and it really was a good idea. Turns out that there were huge lumps of undissolved indigo powder at the bottom. Crushing these with my hands seemed to cause a little more foam and color. Also, I had read that it sometimes takes several dips to dye fabric a darker shade of blue. So I dipped. And dipped. After four dips, it started to look a bit like faded blue jeans - keep in mind that the fabric is still wet in this picture, so it would have dried up a lot lighter:
At this point I didn't know what else to do and went home.
Two days later, I returned to the studio to discover a dye bath that was actually quite foamy. Maybe something had happened with the chemicals that needed a little time. I dipped in another piece of fabric and bam! the color was amazing. First this crazy yellow-green, and then slowly, developing like a photograph in a darkroom, the blue emerged. It actually changed so quickly that I wasn't able to capture the brightest green - in the time it took to take off my gloves and get to the camera, some of the blue was already developing.
Now, I wouldn't be true to myself if this lovely blue didn't give me the idea to dye an equally lovely green. So I dyed some fabric with both indigo and turmeric, creating some amazing shades of green, which was of course stupid. Because a few days later the turmeric had already faded so much that the fabric turned blue again, simply from hanging on the drying rack. I definitely need a different yellow dye. Since indigo is one of the "classic" plant dyes, the yellow has got to be weld, Reseda luteola, another traditional dye plant which supposedly dyes a rather lightfast yellow. More on that when I have the weld.
Another little experiment was to dye some of the wool roving (combed, unspun wool) I have lying around for felting. It took the color quite nicely, but didn't turn out as intense as the fabric. Still, it's a nice color, and I'll definitely be using this for some of my felt work. Maybe more hand dyed felt is in my future.
After all this, my dye bath started to look rather unhealthy and didn't give off much dye anymore. It had a good amount of foam on it, this strange and shiny "flower" which you're supposed to scoop off when you want to dye, and replace when you're done. But the liquid became darker and darker green, which meant that the indigo was starting to oxidize in the water. Of course, every time I dipped a bit of fabric in the dye bath I was introducing oxygen, and although I was being careful, soaking the fabric in clean water beforehand and doing my best to reduce dripping and other bubbles, it was bound to happen. So I think I need more thiox to further reduce the dye if I want to keep going.
Being the geek I am, I now wish I had the time to study chemistry and/or biology and set up a natural indigo vat, bacterial fermentation and all. Unfortunately (or rather fortunately for my studio mates) this is not a realistic pursuit at this point. But who knows what the future holds...