Monday, 22 February 2016

Indigo BLUES!

I held a really enjoyable workshop at the end of January at Timeless Textiles in Newcastle, followed by an equally enjoyable Introduction to Mordant Printing workshop the following weekend for ATASDA.  In between the two workshops I was also moving house after 17 years, so no prizes for guessing why I haven't posted anything until now....!
The topic of my post today is one I have been itching to write since my Indigo workshop, and one I know my students will find beneficial.  On the third day of the workshop our indigo vat, which had been behaving perfectly, decided to go sad on us and refused to cooperate.  Luckily we were all at a stage where we were getting ready to start packing up from an intensive 3 days, but it was still annoying and perplexing for me as to why it happened all of a sudden...hence the title...Indigo Blues...I was sad that all my tricks would not liven up the vat again.
Around the same time I had an email from one of my past students from last year saying the same thing had happened to her and what could I suggest the problems might be and how could she remedy it.  So here goes:
The vat we were using was an organic henna vat, I used powdered Lawsonia inermis (henna) with calcium hydroxide (builders lime) and natural indigo in the 1-2-3 ratio I was taught by Catharine Ellis. 
The vat was kept warm at night by standing it in an electric urn filled with water and then covered with plastic and blankets. The air temperature in the day was between 25-30C. In the mornings I would turn the urn back on until the vat got to dyeing temperature, I would stir it, wait at least half an hour and then take the pH and temperature before testing a small piece of white cotton before we started the day's dyeing.
So far so good.
After the vat failed we added the remainder of the 'mother vat' to it in order to spark it back up again but as this did not happen,  I realised that if that did not remedy it then I would have to monitor it more closely, as I knew that lack of indigo was not the problem, and the addition of more indigo would not produce darker results, I would just be wasting indigo. I purchased a green garbage bin with a lid from the hardware store that fit my whole vat inside it and carefully transported it back in my van to my studio in Canberra.
I put the vat outside in the sun to warm up, then I took a sample reading from the vat, took its temperature and pH.

Poor sad looking indigo vat, the flower is small and bubbles are white and pale.
The vat was not getting up to temperature, so I took it inside and warmed it in the bain marie urn again. Another stir, another test sample but still the vat refused to work.  At the end of the day I added 20g of henna powder cooked in 500ml of boiling water, then stirred it and left it over night. Here are the test samples from this first day:
The flower is in better shape and shows tinges of blue bubbles

Very pale results
 The following day I put the vat outside in the sun again and when the sun moved I bought it inside and heated it in the bain marie and took another sample.
Slightly better results

During this time I had been searching in vain to buy Fructose powder which is a more immediate form of sugar/carbohydrate for the vat (as opposed to henna).  Fructose is very difficult to find in Australia and especially in Canberra and I had a very frustrating time visiting websites and supermarkets, healthfood stores etc.  Henna and fructose both feed the vat to keep the reduction going.  Fructose is like a sprinter - it works quickly but burns up fast, whereas henna is like a marathon runner, it takes its time but lasts the distance, and the two substances can both be used as reduction agents in the organic indigo vat.
I then had to go to Sydney for a couple of days to teach a workshop, so the vat was again left to it's own devices. Whilst I was in Sydney, however, I mentioned my fructose dilemma to a friend and fellow-dyer, Sylvia Riley, who owns Silksational, the one-stop shop for fibres, fabrics and dyes.....of course she had fructose powder! What a lifesaver!!
On my return from Sydney I added 40g fructose to my vat, gave it a stir, left it outside in the sun and tested pH iand temperature. The pH was 12, but the dipped colour had gone back to pale again.All my dipped samples were for 2 minutes each in the vat, at least 2 mins oxidising.  I another variable I was monitoring, but which is hard to photograph for the blog, was the colour and clarity of the vat below the surface.  It should be clear and yellow/green when it is ready to dye with.  Mine was murky green and cloudy.
The bubbles were blue but there was also a blue halo around them.

However, the test sample is still very pale.

Moving house and life got in the way, so the next opportunity to tend to the vat came on 15th Feb, a full 2 weeks after the workshop in Newcastle.  I felt guilty for not attending to it every day, but knew if I kept at it it would come good, and that throwing the vat out was not an option because I knew there was indigo in there to use, and I hate wasting materials and money!
I added another 60g fructose to the vat, stirred and rested it. The next day (16th) I came to the studio, stirred it and tested it after half an hour.
Three tests in one day showing gradual recovery of vat
My first test at 2.30pm showed a small response from the vat - the colour was much darker than the previous day and so I continued to monitor.  At 3pm I added another 50g fructose, stirred and rested the vat then took a sample (#2).  I took the pH reading, and to my suprise the pH had dropped to around 8 - far too low for dyeing cotton, but actually predictable given that I had only been feeding the vat with either fructose or henna since it failed a couple of weeks ago. I now needed to re-balance the vat with lime.

16/2 pH tests at 3.30pm (left) and 4.30pm (right)
At 3.45pm I sprinkled a tablespoon of lime onto the surface of my vat...this was immediately sucked down into the vat, which I knew was a sign that it was time rebalance with more lime.  If the lime just sat on the surface of the vat then it would not need any lime. Over the course of a few minutes I sprinkled approximately 15g of lime onto the vat and watched it disappear into the murky depths below.  I took a video of this with my ipad and when I learn how to upload it onto my blog I will! As you can see from the samples and pH tests above, I stirred the vat, let it rest and then took a sample again at 4.30pm.  The colour had started to come back! I was on track.  I knew there was approximately only a half-strength indigo left in the vat because I had been monitoring it and the quantities I had used and the amount of fabric we had dyed in the workshop, so I realised I wouldn't get a very dark blue - that would be unreasonable - but I did know that there was indigo left in the vat and it was just a matter of working away at it to get it out again.

17/2 The Flower was looking good and the surface started to get that reflective
'oily' look on the top with a skin starting to form in the afternoon.
Final test from recovered vat.
I did a final test for pH, temperature and then took another sample. This was a beautiful mid-blue in keeping with the amount of indigo I think was left in the vat (40%).

The moral of this story is that your indigo vat may not be completely exhausted even though it is not giving you any colour - it may just need monitoring and the addition of reduction agent (henna, or fructose) and/or lime in order for the vat to recover.  If you throw it out you are wasting precious indigo.

Hopefully this post will give you some insights into how your own vat can be monitored and recovered.  Obviously if you dye a lot of fabric the indigo WILL eventually run out, however I had kept tabs on this and knew that there was indigo left in the vat...somewhere....!

 Here are two examples of  resist-paste indigo fabrics I did during the workshop I taught, intentionally alternating paste resist and indigo dipping to achieve the many shades of blue.
Multiple additions of resist paste and dipping to produce this
multi-hued indigo cotton fabric

Resist paste screenprinted onto fine cotton voile.
I am forever grateful to Catharine Ellis and Joy Boutrup for teaching me this organic indigo vat, because I had learnt how to dye with synthetic indigo about 25 years ago and was not a big fan of all the chemicals etc.  Having indigo on hand now really supports my natural dye practice, so that I can obtain more colours naturally as well as improve the fastness of them.

Hope this has helped you with your indigo vat problems and happy indigo dyeing for the future!
My website has an events page where I list my upcoming workshops, but please feel free to contact me directly at if you would like further information or you would like to book me to teach a specific workshop for your group. You can also comment directly on this post below and I would appreciate your feedback.


  1. Thank you Julie for your post. I really enjoyed your indigo workshop in Newie and have just over the last few days started my own vat. Just wondering, as mine is doing all the right things as to clear yellow, ph and depth of dye colour, kept between 25 - 45 degrees when in use, however no flower... What does it mean if no flower develops? Thanks again, Michelle

  2. Hi Michelle,
    I havent't had that problem before myself, but I will go through some steps that may help. Firstly, what is the pH? With the organic vat it should be around 11-12.
    Did you cook the henna in boiling water before adding to the vat? When setting up the vat did you stir in a clockwise fashion carefully to get all the sediment off the bottom but not let too much air in? Before you take your stick out, slowly reverse the direction as you lift the stick at the same time - this centres the flower in the middle of the vat. I do this process several times, each hour or so when I am first setting up the vat. This gives the vat a chance to reduce the indigo and ensures unreduced indigo, henna and lime are reacting. The flower is the indication of this process. The flower should be deep purply blue with a metallic sheen starting to form a skin on the surface of the vat.
    So, if you have done all that and still no flower, have you sprinkled lime onto it, even though your pH may be right? If the lime is sucked into the vat, keep adding until it slows down or settles on the top, stir in well as above and let rest for half an hour. I put a lid on my vat while this is happening. Temperature is also crucial and I put my vat inside a green garbage bin and pour boiling water into the bin, and leave it in the sun if possible. The temperature should be around 30-35C. When the vat is stirred up it should be murky green, and after resting for half to one hour it should have the flower, metallic surface and clear greeny yellow liquid under the surface. Even when I am not using my vat I stir it up every day and keep as warm as possible. If it goes cold and you leave it for a few days just warm it up, stir it, and keep repeating and testing all the variables until it looks ready to use again. Hope this has helped, if you still have a problem get back to me! And just clarify are you making the henna vat? Also have you been dyeing with the vat and if so is your colour good i.e. Not rinsing out after oxidising?

  3. Thank you julie. I was in despair over my 3rd disastrous attempt to get an indogo vat working when I read your blog. Now I am determined to get it working because as you say there is indogo in the vat!

  4. Thanks for your comment - I am glad you found my blog and I hope my own experience with the indigo vat will help you. Let me know how you get on, it is always beneficial to share experiences in order to help others.

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    1. I forgot to add that since my last comments on maintaining the indigo vat I have bought an aquarium heater to keep the temperature even and this works very well for me.