The Life of an Indigo Vat

Over the years I have built, used, and discarded many indigo vats. Sometimes I have kept them going for a very long time. I have finally declared the 5 year old, 100 liter henna vat “done”. I have added indigo pigment, lime and additional henna to it many times and although it is still dyeing well, the space available for that dyeing (above the “sludge” at the bottom) has gotten very, very small. 

As many of you know, I have spent this last year at home getting to really know my fermented indigo vats. I have followed a rather strict protocol. Each vat began with a certain amount of indigo pigment, a source of alkalinity (soda ash or wood ash lye) and various plant based materials to begin and sustain the fermentation (wheat bran, madder root, dried indigofera leaves, etc.). Only small amounts of lime and bran have been added over the last year to sustain pH and fermentation. At no time have I added additional indigo.

Last May I was trying to achieve a wide range of blue shades from the very palest to very darkest. I was a bit dismayed to find that all of my vats were dyeing too dark to give me the pale shades I desired at the time.  I knew (in theory) that if used the vats enough, the indigo content of the vats would decrease but had no idea how long that would take, or how much dyeing I would need to do. No matter how much I dyed, it didn’t seem to happen.…

Now, a year after the vats were first made, I can see progress.

Indigo on cotton cloth: 1-15 ten-minute dips. May 2020

Indigo on cotton cloth, same vat: 1-24 ten-minute dips. February, 2021

Some observations:

This is a long process….

Two dips in May, 2020 gave the equivalent shade as 5 dips in February, 2021

The dark blue that was achieved from 12 dips in May, 2020 was not achieved, even after 24 dips in February 2021

The subtle differences in the darkest shades are difficult to discern from the photos – but they are there.

I now realize the value of having a number of vats: from old to new, weak to strong. It’s something I have heard Michel Garcia say on more than one occasion, but sometimes we just have to observe and learn the lessons on our own. 

This spring, I will not discard my weakening vats, but will add another vat for the strong, deep blues that I am currently needing to build up black colors on my woven cellulose fabrics. 

23 thoughts on “The Life of an Indigo Vat

  1. You could also try much shorter dip times, which Michel favours these days. Though in my strongest (and younges vat) even a thirty second dip is darker than what I sometimes want.

  2. In Kurume Japan, outside Tokushima, the dyers had a shed with multiple indigo vats, not all productive at the same time, but at least five were in use for different shades of blue. I was wondering about your fermentation vats. Those have been the most true for me over time. I have some pieces dyed in fermentation vats from the mid-eighties that still carry the color.

  3. As I understand it from Aboubakar Fofana, in Mali, this is how the palest blues are obtained (The Blue of Nothingness). Only by dyeing at the end of the life of a vat do you get the most stable light blues. This is in line with my own experience trying for light blues on wool and silk: short dips in a stronger bath give yarns that are more prone to fade. I assume that is because the dye sits on the surface, and a longer dip in a weaker bath allows more indigo to penetrate the fiber and be stabilized.

    Michael F. Rohde


    1. Thanks for this perspective Micheal. Yes, Aboubakar has been another inspiration and a help in my understanding of this. The real revelation is accepting the fact that I need multiple large vats if I am going to make the very most of indigo dyeing.

  4. Thank you, very interesting. I have just been reading, this morning, about the weaving and dyeing history of one of my local towns here in North Yorkshire, UK. I was surprised to learn that back in the C18th there was prosperous weaving and dyeing industry that included large scale indigo dyeing of woolen and flax/ hemp based cloth.

  5. Thank you for sharing this information. From reading your interesting and rich journey with Indigo I realize that a lifetime is probably not enough to master and understand the endless possibilities it offers to the natural dyer.

  6. Hello Catharine, I have your and Joy’s terrific book and it is my bible! I humbly offer my observations on the different indigo vats I’ve been nurturing along in my studio.
    When I first started in earnest working with an indigo vat I used Michel’s recipe for the fructose vat.
    I dyed cotton and linen, with and without my stenciled clay resist designs (His recipe and now yours too). I achieved very lovely pale blues- and when I found Aboufakar’s beautiful instagram a few months later, describing this ethereal shade as The Blue of Nothingness (as Michael confirms above) I realized I had inadvertently, being a novice, achieved that pale color.
    That was with the fructose vat. However, as you advise in your book, the fructose vat does not want a long term relationship.
    Now I have an amazing henna vat going and I call it my workhorse. However…I have not even tried to recreate those pale blues because I don’t think that this henna vat wants to go that way..even when its a little tired. With occasional additions of fructose, some more indigo and a dose of henna and calx (all this when the vat was needing a replenishing) it is consistently yielding rich medium to dark soft blues which I love.
    The other vat is the ferrous vat and I notice that those blues also are deep and rich but have a mysterious mineral content…
    Anyway I love all the indigo babies and you probably know all of this but I just wanted to share my observations.

  7. Can you please tell me how much pigment you started the vat with? I am having trouble achieving darker blues, no matter how many dips, and cannot find the reason. Wondering if I am not starting with enough pigment?

  8. Catharine, we bought the blue plastic tub you recommended and would like to start using it. But we can’t find an immersion water heater that seems well suited. Can yo give us a recommendation please? Thanks.

    1. I don’t use an immersion heater, though I know they are available. Instead, I use a heater that wraps on the outside of the bucket. and I plug that into a regulator that maintains a temperature range in the liquid.

  9. Catharine thank you for this post and your honest feedback on difficulties with the palest shades or variations in dips etc. to achieve the same intensity of colours. Have you used any wool in your experimentations? I use exclusively my own wensleydale and in 2020 achieved the palest blue which I called ‘Bleu Phantome’ in an old VAT I had left sleeping for about 2 years. It was started with Japanese Indigo, homegrown. I just threw in some sacrificial locks when it was cold and then dyed more and then some yarn. Can I repeat this colour? I cannot. Just today I tried again having left it for a year, but it was warming up and then I discovered that there was corrosion inside the vat lower down, so have ended up with a saddened version! You can see the very pale blue on my Instagram account : juliadesch1121. Hope to try again soon with a new VAT and am debating how to achieve the palest blue again.

  10. This is vastly interesting, Catherine. Now I’m going t9 set up two other vats, another fermentation vat (the house will stink!) and a henna vat (the house will stink of marijuana—a pot smoker once said one of my vats smelt like green ganja.).

  11. Hello Catherine, thank you for sharing your fermented indigo vat making journey, I’m about to embark on my own. After reading about your reflective experience in your posts, I wanted to ask if you used freshly harvested madder roots, (either spent or unspent), or dried madder roots? I was considering buying some dried madder root, doing some madder dyeing then using the residual root matter in my vat.

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