Maintaining and Troubleshooting an Organic Indigo Vat

Jacquard woven shibori, indigo dye
Jacquard woven shibori, indigo dye

The questions I receive most frequently about natural dyeing seems to center on  the indigo vat and its maintenance. Since 2011 I have been making and using organic indigo vats, an art and  skill that I learned from Michel Garcia.

My current vat began in a 5 gallon vessel over 2 years ago. I enlarged it to fill an 8 gallon vessel, and then last year I enlarged my vat again to fill a 30 gallon container. The increased size was needed because I was dyeing larger pieces of cloth.

my current indigo vat, 30 gallons
My 30 gallon indigo vat

The vat was made using henna as a reduction material. I chose to use this material because the slow release of sugars is good for a vat that will be maintained for a long time.  I add fructose after each use and additional henna when I need to boost the reduction. Lime (calcium hydroxide) is the alkaline.

The vat is used regularly and I achieve excellent color from the indigo.  The large size challenges me to solve problems as I encounter them. It would be tempting to discard a small vat that was not behaving well and begin again, but emptying this vat would require a great amount of effort. As a result I’ve learned a lot about maintaining the indigo vat.

An indigo vat is happiest when it is used on a daily basis. After each dyeing session I “feed” it with a bit of fructose, stir it to bring the un-reduced indigo and reduction materials up from the bottom, check the pH, and let it rest for a few hours before dyeing again.

Occasionally I run into problems that I need to solve. Recently I was away from home for several weeks. Before I left, the vat was dyeing rich, deep blues. The color of the vat was a golden bronze and there was a good healthy “metallic” sheen on the surface and plenty of bubbles.

surface of a healthy vat
Surface of a healthy vat

When I returned home the first thing I did was add lime to the vat.  When an indigo vat sits dormant for any amount of time it becomes more acidic and the pH goes down. I can test this with pH papers but a good visual indicator is to sprinkle some lime on top. If the lime is immediately “sucked” down into the vat – you can assume that the vat is in need of the lime. If the lime just sits on the surface, the pH is probably fine.

Next, I stirred the vat and waited for it to settle. The color of the vat looked good, as well as the surface. The vat was a clear gold color and there was a coppery sheen on top. But the first test sample resulted in barely any color at all!  That was a surprise, since I thought there was plenty of indigo in the vat. I thought I had also been “feeding” it with plenty of sugar. The vat had been used very heavily before I went away. I thought that possibly the indigo had finally been exhausted.

Before adding more indigo to the vat, I decided to add more sugar – a generous amount. Once added, the vat was stirred and I waited until the next day to do another test strip. It produced a  blue, though it was relatively light. I repeated the sugar-stir-rest and dyed again the next day. It was darker. I repeated the sequence again, and finally got back to a shade of blue similar to that which I had before going away.

dye test strips
Dye test strips

The lesson here is that before adding indigo to a vat, test it thoroughly for pH and reduction.  Although it “appeared” to be healthy, my vat was not reduced and the indigo wasn’t available to dye the fibers.

144 thoughts on “Maintaining and Troubleshooting an Organic Indigo Vat

  1. Catherine my question is about the fructose vat. Can it continue by adding more indigo or is it better to start new? I suppose it depends on how much sludge is on the bottom. (I inherited a vat from one of your recent classes and it is dyeing nicely still.
    I have read the way to add more material is to make a mother solution with all 3 fructose, lime and indigo and then carefully add that to the vat. Do you agree?
    Thank you for all the good detailed info.

    1. Maureen, I’m glad to hear that the vat is working nicely for you. Yes, you can certainly add more indigo, along with the correct proportions of the other ingredients. The advantage of making a “mother” vat is that you can easily do it with hot water, which will begin the reduction quickly.

  2. Catherine I have a 10 gal week old henna vat that was performing beautifully. I was keeping it outside in the warm air. overnight we had a cold snap and the vats temp in the morning was less than 60 and no color on an 20 minute test strip. there is also little if any coppery sheen on the surface like there had been. 4 days later the vat is inside and I’m still getting very little to no color. ph is good. Each day I’ve scooped a pan full of solution, heat it to 120 add a little henna to it and return it carefully to the vat. I’ve made no progress. the vats temp indoors is 80 degrees. I started to wonder if it needed calx, so I added some to my heated pan solution, let it sit a couple of hours and did a 20 min test strip. it was no different than the main vats test strip, and the calx is not sucking into the vat as you describe. this was a strong vat with lots of indigo and has only been lightly used. Help!!!

    1. Cindy, Be patient with your vat. Since the vat is a new one, and there is plenty of indigo, you should be able to get it back into reduction. Give it a good stir every day, and a spoon or two of fructose. You should not need more lime at this point. The heat should help a lot. Patience….. stir every day…..

      1. Thank you so much for those encouraging thoughts. I’m so accustomed to hydro vats which I can fix in an hour or two. I also have been slowly feeding it cooked henna powder, and the fructose is new information. I ordered some yesterday after searching in town was fruitless. I very much enjoy the “tending” process. It’s a peaceful beginning of my day in the studio. Your book and blogs have been my major guide, thank you for teaching us all the nuances in indigo. Ps today the vat does have a little gleam of copper on the surface and though the test strip is still pale, yesterdays test strips have kept their color overnight. So there is progress!

        Cindy Wilson


      2. Catherine two tablespoons of fructose worked! the vat is dyeing very dark (darker than originally but it was only 5 days old when it quit). Thank you so much!!! what is the disadvantage of adding too much fructose? My vat is large because of the size of waxed cloth I am inserting, but the actual use is maybe 2 or three dips a day with less than a yard of fabric. I’m trying to get a sense of how often to add fructose and how much. 1 tbp at the end of the day? Your book recommends 3 tbs per 5 gal vat but for my limited use that seems like a lot.

      3. The fructose provides a quicker reduction than the henna. It sounds like you’ve got plenty of henna in the vat in order to keep the vat reduced but it won’t help to give it a spoon of sugar or so after each use. Use your instincts! That is how you will truly learn to master the process.

  3. Hi Catherine, I think ive read every comment in this thread and cant find anyone with the same issues im experiencing with a vat right now!

    I mixed a new vat with the 1/2/3 ratio of indigo, calx and fructose in a 4 gallon stainless steel pot. I found a bag of calcium hydroxide on amazon for a great price so I grabbed that and used it for the first time in this vat. I did shake the indigo powder in a container with marbles and then added it with the calx/fructose.

    I also use a hot plate so I was maintaining the temperature to probably 40-50 degrees during the reduction period. Normally when i maintain a temp between 30-40 degrees i get good results with dyeing.

    Basically the indigo never reduced. I would add fructose and stir then leave it alone for hours, sometimes I would adjust temperature just to see if that would make a difference…trial and error is the name of the game!

    At one point the indigo and the water completely separated. I could see the indigo just sitting at the bottom of the pot 😦 A brand new vat, unused! So disapointing. I am not sure what to do! cut my losses and toss it or perhaps add more indigo? I tried adding calx and it didnt need it because it didnt “suck” the powder into the vat. I have also been testing the pH throughout, never getting lower than 11.75 and going up to 12 at times. I see you havnt commented on a post in a couple years now but I hope you will see this!

    Thank you so much!

    1. Troubleshooting indigo vats is hard, especially from a distance. There are so many variables.
      But I will ask a few questions.

      How do you know that the indigo did not reduce? What is the color of the vat? Did you try dyeing with it?

      Was your indigo sourced from a reputable supplier? Are you sure that you were using fructose? The more common cane sugar is not a reducing sugar.

      The heat you applied initially (and maintained) seems a bit high to me. I always begin my vats with very hot water (40-50°C) but I never apply heat during the reduction period. I am not sure if too much heat can damage the reduction but I’m guessing that it is possible.

      I might suggest that you repeat the vat with the same ingredients but on a much smaller scale: a one-liter glass jar. You can actually learn a lot by looking through the glass at the reduction, the color, and it’s plenty big to dye small samples.

      1. Hi Catherine! thank you so much for your reply!

        I unfortunately ended up discarding this vat and started fresh yesterday after about a week of troubleshooting.
        I could tell that the indigo was not reducing because there was complete separation of the water to the pigment. I dipped a glass in the water to observe the liquid and it was clear with some specs of blue floating around, and could see the blue pigment sitting at the bottom of the vat, as well the pH was over 12 and when i dipped a test strip in the vat, there was no transfer of colour.

        I started a new vat yesterday around 6 pm, I mixed the pigment with marbles and hot water in a container and shook for a couple minutes as my goal was to be able to use the vat for dyeing later that night if possible. (wish i had seen your comment sooner to try the smaller scale experiment) this time i did not heat the vat during the reduction, it was between 40 and 50 degrees when it was mixed.

        I was checking the pH every hour and checked on the vat this morning and it still hadnt reduced. pH was even higher and the water was a nice deep blue.

        I reheated the vat, added a tablespoon of fructose and gave a nice stir because I read that stirring the sludge at the bottom can kick up the indigo that is dormant and might release into the vat and help the reduction along. Again checked the pH and temperature and the pH las lowered slightly so thats a good sign. I am wondering if its the fructose sugar that I am using is what is causing me problems. It is from a bulk store and was described as “instant dissolving berry fruit sugar ” maybe it is too weak? or just not the proper kind?

      2. I would be suspect of something called “instant dissolving berry fruit sugar”. You don’t really know what it is! Always look for more scientific descriptions. Most of us need to order fructose as it is not carried locally in grocery stores etc. That may very well be your culprit. You can also substitute honey but that is likely more expensive.

      3. Yes, i think its the sugar i’m using that is causing the issue. Do you have a brand that you recommend for fructose? I am having a hard time finding any locally, called many bulk and health food stores in my city and none have fructose. Do you think if I just add ALOT of the sugar that I have would that eventually work?

      4. If it’s not the right kind of sugar, it doesn’t matter how much you use. It still won’t reduce. I buy mine online. Sometimes through Amazon or from that way I know I’m getting FRUCTOSE.

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