The Indigo Vat

Indigo vat_tezukuri 01

Behind an indigo dyed fabric, there is the state of the indigo vat. Unlike other dyes, this one is alive and time and environment have an effect on it. In essence, it could be the success or the  biggest flaw in a piece of textile. Personally I think  it’s a real shame to see elaborated techniques that take weeks to make gone to waste due to ‘under-dyeing’.

I had to spend sometime getting to know my vat, so the studio turned temporarily into a chemistry lab! Litmus paper, chemicals, weighting scale, thermometer, notepad and pens… Somehow it didn’t feel too technical, but rather fun to discover the mysteries that the indigo Masters won’t reveal that easily.

Indigo vat_tezukuri 8

We made four different new little vats. Maintaining an equal alkali base (same ph), we added different amounts of indigo and oxygen reducing agent to each of vat. We knew they would all dye the fabric, but our aim was to discover the recipe to achieve the deepest blue with the minimum amount of waste.

This is all based on a very personal taste: if I wan’t to be able to achieve the darkest, richest blue then I don’t want to be limited by the quality of the vat. Just the opposite, I want to control the color depth by the number of dips I do.

Indigo vat_tezukuri 10

Indigo vat_tezukuri 7

Like a plant, or a pet, no indigo vat is exact to any other. Or at least not for long; we are all dyeing in different parts of the world, throughout the seasons. Many recipes have been written in the past (Dorothy Miller, Susan Bosence, dye suppliers and many others), with variations of ingredients, timings and quantities. But following them by heart won’t necessarily mean success.

Indigo vat_tezukuri 4

To my surprise, the greatest discovery after our experiment was that greater indigo amounts doesn’t necessarily imply a darker colour! But the relationship between the amount of indigo and the reducing agent does. The best result was the one that had the less amount of indigo in it! This is great news because I use natural Japanese indigo, that is exceptional but expensive.

Indigo vat_tezukuri 2

We figured out four different recipes based on previous observations. We dyed small pieces of fabric on each vat, and made swatches of 2 and 4 dips each. Then compared. All this was worth our time and effort. Everything is on paper now – we ended up with written observations just like the reports I used to write years ago for Dianita, our 10th grade teacher. Who would have though I would be making this again, just for fun.

Indigo vat_tezukuri 5

But this is not over yet, there is still the challenge of keeping the vat alive and healthy. Trial and error approach is still my safest bet but hopefully one day I’ll be able to know what the vat needs just by looking at it, like the parent-to-child relationship the Masters have with their own vats.

*All this was possible thanks to my husband’s help, support and structured thinking process. Thanks for making so much fun one of the nerdiest days of our lives together. Our baby might be born like a little smurf with blue hands just like us.


7 responses to “The Indigo Vat

  1. So what is the recipe for the best indigo vat you finally arrived at? I’d love to know as I’ve been getting weak results following Dharma’s recipe. Thanks in advance for sharing.

    • Hi Karen, it took me ages to reply, I’m sorry. I left it for later and then absolutely forgot. When I wrote this post I was working on a hydrosulphate / lime vat. Then I moved onto a soda ash / spectralite one but now I’ve decided I want to work with a real fermentation vat. I will probably post about it fairly soon.
      There could be many reasons for weak results, starting with the water you are using. Tap water may have high contents of chloride for instance, and that isn’t good for the vat. Keep making tests with your vat in terms of quantities and also take into account that your fabric may need scouring and that not every fabric dyes the same ie. vegetable fibers take up more colour than animal ones… good luck!

  2. I just stumbled upon your blog and am so glad to come across a fellow indigo experimentalist! I was wondering about your Japanese indigo: is it made from Polygonum tinctorium? I use an Indian natural indigo derived from Indigofera tinctoria that I buy locally from Maiwa, but I’d love to try Japanese indigo one of these days.

    • Hi Jessica, I’m glad you found my blog! I am pretty sure it is polygonum tictorium as that is the most common indigo plant in Japan, but to be honest, I can’t say I am a 100% sure and it’s hard to track it back since I am no longer living in Japan. It would also be good to know which exact plant does it come from, as there are different varieties of indigo plants in Japan too…

      • Whatever the case, I will have to acquire some indigo from Seiwa one of these days. I love the blues from my vat, but they are a fairly different tone from my old Japanese aizome fabrics. I don’t know where the difference comes from: the indigo, the fabric type, my techniques, the age of the fabric? Switching to a zinc lime vat didn’t make a noticeable difference, so I need more experiments!

  3. Hi there!
    How do you test the ph of an indigo vat? Isn’t color the ph indicator? Doesn’t the indigo just dye it blue? I am having challenges with my vat.

    • Hi Bridget, it’s been long since I wrote this post. I use 100% natural vats (fructose) these days and don’t need to check the ph constantly as I used to but I’d suggest if checking with ph paper, ignore the blue in the lower part of it and look for the colour at the very top – closer to your fingers, if that makes sense. Sometimes you can see it as your paper absorbs it upwards. The rest is just the paper being dyed. Otherwise, maybe getting an electrical ph reader? I can’t really recommend as I’ve never used one myself. I hope this helps and good luck!

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