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.

99 thoughts on “Maintaining and Troubleshooting an Organic Indigo Vat

  1. EXACTLY the information I need. All too often I think that the indigo must be used up but also realize it shouldn’t be, based on amount of fabric dyed. So now I have a place to start in fixing and dying more. Happy that you are doing these blog posts. We met at Shakerag in Michel’s class. Thanks. Renee

  2. Question: When you have a large amount on flower on the surface do you remove that from the vat before adding fabric or just work around it?

    1. I keep the vat at room temperature. Winters here are more challenging since the vat is in an unheated studio space where the outdoor temperatures can get as low as 10°F (-12°C) at night. During the colder months I keep an aquarium heater immersed in the vat, which keeps the temperature at a constant 65°F (18°C). During the warm months I remove the heater.

  3. My indigo henna vat is experiencing what’s described here. It has sufficient indigo. The pH is 10; the problem is the indigo is in suspension rather than in reduction. It’s a 10 gallon vat, and I would like to know how much fructose you added to your vat before the color returned. I’m keeping good records, but have not yet arrived at a post-dyeing feeding weight for the fructose. Thanks for the info.

    1. I have to admit that I don’t have a “post-dye feeding weight” either. My additions are more intuitive. But for a 10 gallon vat I would start with 1/2 – 1 cup of fructose and see what happens. If you can see indigo in suspension, you may need quite a lot. As you add more reduction material, the pH is likely to go down so you might need more lime.
      But for a vat that size I would probably add a more “complex” sugar, such a cooked henna powder. It lasts longer in the vat than the fructose. Cooking the henna in water begins to break it down, and also adds a bit of heat to get the reduction started again.

      1. Thanks, Catherine. I looked at the images more closely and realized you had 1/2 tsp per quart feeding. This works out to 3 oz fructose for a 10 gallon vat.

        I shall wean my vat off of fructose altogether because I’m thinking it drains the vat of energy. When I gad a pure henna vat I had better color. This past week I bought two ripe plantains (very sweet when ripe and of the banana family), blended them in three cups of water, and added another six cups for the boiling.

        I’m going to boil 3 oz of henna in a bottle of this solution and add one cup to the vat to see the impact. If it works, the henna-plantain solution will be the feeder.

      2. Yes, the henna will last much longer than the fructose. I have not used plantains and would think that plain bananas would have more sugar in them. You’ll have to let me know how that works.

      3. Catherine, I’ve added quite a bit of henna to the vat with little result. I’ve tried both boiled and sifted henna. Yet, something remains off still. A friend used to comment that the vat smelled like green marijuana (not familiar with the smell so can’t verify) but that smell went away and was replaced with a sweet one or sometimes an acrid one. Today, the smell came back (it’s just a strong henna smell).

        The boiled plantain-henna mix brought the vat back to blue but the greenish tinge is still present and the indigo color is still very weak. All the signs say the vat should be doing better than it is (liquid color, pH, taste, feel, surface appearance, temperature, smell, flower size), but it’s not. It’s covered with an air-tight upholstery plastic cover that I made. The temperature is maintained at a consistent 76º-80º F.

        So, I’ve resolved to leave the vat alone for a few days and see how it does. I will keep you apprised of changes. Any insights would be welcome. Thanks.

      4. Thanks so much for this info. Do you need to cover the vat if it’s outside like on the porch? With Kombucha we cover the fermentation jars with a thick cotton cloth and wrap a rubber band around the cloth to prevent fruit flies and bugs. So am just wondering. Am brand new to this after one awesome workshop. Thanks for any guidance on whether to cover

  4. Thank you very much for this information. As Joanne says mine vat too developed mould. I thought it’s due to using fructose excessively. Have you ever encountered this problem and if so what would you suggest to do?

    I use my vat once a week and worry that by adding more fructose I will again create a great environment for mould to grow. How to keep the vat if used only occasionally?

    1. Reduction material needs to be added to keep the vat healthy and active. Mold usually happens when the pH gets too low. Occasionally I do get a little mold on the top when I’ve been away for a couple weeks and haven’t been maintaining the vat. I remove the mold, add lime, stir, and continue.

      I’ve found that an airtight lid on the vat keeps it in reduction for a long time. I can go back to a vat weeks later if the lid is airtight and find the vat still in good reduction. When I’m home, I usually stir and activate the indigo vat every couple days, even though I may not be dyeing.

      1. Thank you very much, Catherine, for your helpful answer. I was adding far too much fructose and little lime. I didn’t realise lime is there to help fructose to do the job. I used to cover the vat surface as Michel suggests but then stops due to the mould, now I will resume again. Many thanks!

      2. I’m glad to help. I started this blog because of these kinds of questions that arose from students all the time. I’m no expert, but I also learned from Michel Garcia and have been working at it ever since.
        Think about the original proportions that went into the vat. 1 part indigo, 2 parts lime, 3 parts reduction material (fructose or other plant sugar). The indigo eventually gets used up by dyeing. But the other ingredients get used up by the chemical reaction of maintaining the reduction.

      3. Thank you Catharine for this! The aquarium heater is an excellent idea for the MN-WI winters!

        I have found it helpful to cut a disk of bubble wrap and lay this carefully on the top of the vat while it is not in use. It keeps oxygen out, and heat in. Do you see any problem with covering the surface of the vat?

  5. Today, the vat is deep near dark blue in color, not because I left it alone but because I added lime, teaspoon by teaspoon, then tablespoon, then ounces. The pH strips indicated the degree of alkalinity was fine. False. The strip was waaaaaay off! The vat vacuumed the lime like a mad bad Cookie Monster. As I continued to add lime, the color began to change from green to greedy blue, from greeny blue to pale blue, pale blue to medium, and so on. The flower spread across the surface like a rash, 9″ x 8″ with ancillary small island bubbles. This was all before 9:30 AM when the vat got the final stir.

    After 12:30, the vat was a deep medium blue. Stirring it turned it a dark blue, and that’s where it is. The glass cup/syringe test showed the liquor to be amber gold–this test was run twice because the glass cup was stained by indigo blue from the dip. The syringe (from a farm supply store) didn’t have that and a little dusting of blue could be seen floating. There is some research on that color and touch of blue that needs to be revisited.

    Finally, the taste test was the most remarkable. Deeply alkaline with a good bite. Though I have had the vat since the end of March, 2015, detailed records (or any at all) were not maintained. Therefore, it is impossible, unfortunately, to compare the early and present tastes of this vat to know if this strong lime taste is the one necessary for the production of the strong blues of the early vat. The taste of the vat from 6/1/15 onwards has tended to be sweet with occasional flashes of acridity. The color strip from this more deeply alkaline vat showed a deeper blue.

    What is most noteworthy, in all of this, is the insufficiency of the pH strip as an indicator of the true health and alkaline need of the vat. This experience has taught that eyes, nose, tongue, hands might provide better information—if records are kept, of course, and cross-checked.

  6. Hello. Today, I had students make 5 vats from fresh leaf indigo using ferrous, fructose, Thiox to compare the processes. No henna vat yet. I’ve done fresh leaf and Thiox many times with good results. But I had to guesstimate the organic vats proportions based on the Thiox recipe and also another person’s blog about fresh leaf fermentation vats. Most reduced beautifully, but the pH is at 14 on the ferrous vat.
    We had 900g of leaves, 35g calx, 20g ferrous. Students were reluctant to start slowly and wanted exAct amounts which aren’t always possible. Because I am still kind of new to organic vats, I need to know how to lower the pH on iron, fructose and henna vats. Do I add citric acid to lower ph? Help and thanks

  7. Hi Catherine,
    As part of a Xmas gift for my son’s girlfriend , I made my first indigo vat on Xmas day using the same products as you have used. On that day we dyed calico samples to get the hang of the different effects from pleating and tying and stitching. The colour was light but that was okay. Ever since then , the vat has ceased to ‘live’ and I now have a pot of browny coloured liquid with a layer of sludge on the bottom.
    I don’t know whether to compost it or keep trying. At first we kept the pot in a warm bath to try and keep the temp at 50 degrees centigrade and covered it with a blanket at night but it was invariably cooler than that. I read about the bubble wrap and so did that too but that seems to dampen down any activity ? It is definitely alkaline – ph strips – in fact I tried your sprinkling lime on top to see what happened – I think it is part of the sludge . I added sugar one day , more henna another , so I have no idea of the proportions any more. I never know if stirring it is adding to the problem by oxygenating it more. The weather here is
    28 degrees centigrade, so the pot is sitting out in the sun, without the bubble wrap , without the lid and without any activity. It is the first thing I check on upon arising and one of the last things I think of at night!

    1. You did not mention if you had tried dyeing in the vat. The initial dyeing after the vat is first made is likely to be light. The vat will improve over the next few days.
      The color of a concentrated vat would likely be golden brown – but clear. Stirring is good, but you need to let the sludge settle to the bottom of the vat before doing any dyeing. Keep all fiber above that sludge.

  8. Dear Catharine,

    I have dyed with indigo several times before but am now trying to maintain my vat for the first time. You said somewhere in the comments that the blue indigo on top is unreduced indigo. Does that mean I can add it to the vat again (I take it away before I add big pieces of fabric), when I don’t plan on using the vat again right away?

    Thanks for this post, I find it very helpful and encouraging!

    1. The unreduced indigo forms a “barrier” to the oxygen on the top of the vat. A healthy vat will continue to re-make that frothy barrier. Traditional Japanese indigo dyers will take off the froth and then put it back. Others dyers do not. I am not consistent, myself, but it can’t hurt and might speed up the formation of new bubbles on the top of the vat.

  9. Aloha Catharine! I love this post, it’s the only one I could find on the net about vat troubles. I really have three questions here and would greatly appreciate any insight/tips you could give: I am having trouble starting up my vats. I made two vats, 50 and 30 gal with a soda ash, madder, bran and indigo recipe (from Aurora Silk) but it seems they are not reducing properly. I used this recipe years ago and it worked great, but this time it seems like they’re missing something and I’m not sure which way to proceed first. 1. Re. temperature: the vats are outside, under a carport (no direct sun) it has been cooler lately, high 50’s/low 60’s at night and 70’s in the day time here, so I don’t know if I need to add a heater or not to keep it at a constant temp 24/7. 2. chem balance: I tried adding more soda ash and waiting a day, and then I added more bran and waited a day (I’m out of madder right now). they both look the same, like they still need more “food” or something. The bit of indigo that was floating on top is gone, so I know it is reducing somewhat, but the liquid is still a murky brown, so I think it just needs more of everything, but… 3. do you know if I can change my soda ash/madder/bran formula to Michele Garcia’s 1-2-3 lime/fructose vat without having to start over completely? Unfortunately, I just learned about that kind of vat and would much prefer using the natural ingredients instead. I’m out of my original formula ingredients, and went out and got some lime and fructose, but do you know what would happen if I added lime and fructose to my already started soda ash/madder/bran vats? would it kill it or feed it? I understand that both soda ash and the lime are for ph balance, and the bran/madder and fructose are the “foods” so can I swap these out and just add lime and fructose from now on? I would love to get dyeing, but I need my vats healthy and happy first! Thanks so very much!

    1. Debra,
      I have only used lime as the alkaline in this sort of vat and would guess that the soda ash is not alkaline enough to fully react with the other ingredients. Have you tested the pH of your vat? Sprinkle some lime on the top of the vat. Watch to see if it gets pulled down into the liquid. If it does, then pH is likely the problem. If that is the case, I would add lime. The organic vats usually start out with a pH of around 13. The pH will go down gradually to about 11 as the lime reacts with the organic material.
      You can mix fructose with madder. The fructose will react more quickly, jumpstarting the vat. The madder will be there to sustain the vat for a longer time.
      Heat will help but is not entirely necessary. The reduction will just take longer with a colder vat.

  10. Hi Catharine!
    I found Michel’s recipe online an attempted to make it in a 15 litre bucket. (about 4 gallons) – I added 100 grams of indigo and followed the 1-2-3 rule, yet when made up in a vat, the vat goes an orange-brown copper colour and hardly any flower is forming on top! First dye attempts resulted in something slightly darker than the first shade you have up in the picture. Does this mean that the vat is not balanced? I left it overnight however after adding a bit more fructose to try, and the vat went dark copper and clear yet with no flower. I am a at a bit of a loss – any advice?

    1. The coppery color is a likely indication that the vat is already in reduction. A good strong vat is often this color. Sometimes there are bubbles and sometimes not.
      You didn’t mention how long you were dyeing your fiber in the vat. The organic vats usually require a good long dip in the vat: 15-20 minutes. Then you can increase color with multiple dips.

  11. I am a new user of indigo and have a small vat in which I dye handmade paper and kozo fiber. It seems to be dyeing lighter and greener, after a couple of weeks, as opposed to bluer so I have added both lime and fructose in the 1-2-3 formula. I am wondering if I have exhausted the indigo powder by now and if so how do I add more? Shall I add all three components at the same time? Also M Garcia recommended shaking the powder up with glass marbles, instead of making a paste. What do you do?

    1. Good question. But without knowing the size of your vat, how much indigo you put into the vat, or how much you have dyed, it’s hard to answer. A vat that begins with only a gram or two of indigo per liter of volume will get used up quickly if you are doing a lot of dyeing. When I build a vat to use for several weeks/months I begin with at least 5-8 grams of indigo per liter. If you add more indigo, add more lime and fructose in the original proportions. Or you may decide to discard this vat and begin again. If yours is a small vat, I would probably suggest this.
      I always shake my indigo in a plastic jar of marbles as Michel Garcia suggests. It not only crushes the pigment but hydrates it as well, making it easier to go into a quick reduction.

  12. I recently tried a the ferrous version of the organic 1,2,3 vat and was quite pleased with the nice depth of color. When I unwrapped the shibori bundles, however (both clamped and stitched) the resisted areas had taken on a tan/gray color. I soaked the pieces in citric acid and that helped somewhat but they are not as nice as pieces I’ve done with the fructose and henna vats. The pieces were scoured with soda ash and heat, rinsed and soaked for about an hour in bundled form before dipping. Any suggestions? (I rebalanced the vat with ferrous sulphate, as I read one should do.)

    1. I have not usually experienced this staining with the ferrous vat unless it is a brand new vat. Shibori resisted fabrics come out very clear: blue and white. I’m guessing that some of the ferrous in a new vat has not had a chance to react with the lime and indigo and is still active as ferrous sulfate. It’s also important to keep your cloth in the upper part of the vat and away from the sediment, which may contain ferrous sulfate.
      When “feeding” the vat is it best to make a concentrated “mother vat” of indigo, ferrous, and dye. Add small amounts of this when necessary. Do not add straight ferrous sulfate to the vat.

  13. Catherine, with your 30 gallon indigo vat, on average, how much calcium hydroxide do you use on a monthly basis? Thanks.

    1. Not as much as you might think. In fact I have never really measured or kept track of it. I check the pH regularly and tweak it just a bit (just a spoon or two) on a regular basis. The most significant amounts of lime are added after I’ve been a away for a couple weeks (or more), when the pH drops a lot and the vat “tells” me that it needs more lime by absorbing it quickly into the vat.

      1. Aloha Catharine,
        I’m still baby-ing my vats to life….. but have a couple more questions…. I haven’t done any dyeing yet… but think I’m getting close…. I haven’t had the money to feed it very much so they have been sitting idle for long stretches other than my stirring them… then I started feeding them and started to get a few bubbles and got up to a nice med-dark greenish color, I think they were getting close to being ready, but then I added some more lime and I think I set them back again…. so I’ve been feeding them some more, every weekend, then waiting and watching …. I’ve got bubbles again now, but still the liquid is very dark, and not very green like it was before…. so…. 1. do I need to feed it some more or if I start to get bubbles, do I wait until they subside a bit and then start dyeing? I know I will learn this with time… but am I more looking for a certain color in the vat? the color on top of the vat? or bubbles? or a combination of all that or other? 2. I’m feeding them a “slop” made out of boiled bananas, a few papayas, fructose and rice bran. Do I need to have different “food” types? You mention adding fructose to yours, but don’t mention any other “food”…. is fructose the only thing you feed the vat other then the lime and indigo of course? How often do you feed the vats? 3. Have you ever had any pests take up residence in your vat? One of my vats has an infestation of tiny 1/4” maggots right at water level! Probably a good thousand of them or so! Yup! It’s lovely. 🙂 I’m not certain, but I think they are fruit fly larva attracted to the banana slop. I grew up on a farm (with all the associated crawly things), so they’re not particularly freaking me out and I’m happy that it shows it’s “all natural”, but of course every time I stir the vat I’m stirring them into the vat where they float around until they die (and get composted into the vat) or get lucky and swim to the edge and out of the vat again. And my resident geckos are loving having a buffet every day. But I am concerned that they may interfere with the dyeing or affect it (make unwanted marks) so I am wondering what I can do, if anything, about them. LO(blue)L Debra

  14. Debra

    If the pH of your vat is high enough, you’re not likely to get an infestation – I’ve never had critters in the vat. Do you keep a lid on it. I only “feed” it after use – regularly with a little fructose and occasionally with a good dose of something more complex like henna, ground madder root (after the dye has been extracted) or liquid that fruit has been cooked in. It sounds like you should just start using the vat. How it dyes is one of the important indicators.

  15. When you are talking about fructose and lime can you refer me to what you mean? Can I get fructose from the health food store to use or do you have to buy the crazy expensive stuff from dharma trading? And When you say lime, do you mean calcium carbonate? Or is that something different? Thank you for such a wonderful post about a healthy indigo vat!

    1. You can use any source of fruit sugar. It can be purchased inexpensively online or at a local grocery. You can also use other types of fruit based sugars, such as a “syrup” made from fresh, overripe fruits such as bananas, mangos, etc. Don’t use citric fruits. Maiwa Handprints in Vancouver has a good explanation of the fruit vats on their website.

      And you are correct, the lime is calcium hydroxide.

  16. you suggest henna will help maintain vat what proportion of henna to frutose do you use and how do you cook it? thank you

    1. Henna is an alternative to fructose. It is a more complex sugar and is best cooked a bit in water to hydrate and begin the release of sugars. Michel Garcia teaches this approach with the organic indigo vats.

  17. Wow! what a useful resource. Thank you very much for taking the time to share your knowledge and expertise so generously, and answering peoples questions.
    I have just ordered natural indigo powder, lime and fructose, and will be starting my journey exploring this technique soon. I’m glad I found this site first!

  18. Catherine, thanks for this informative article. I NEED HELP. i’ve been going round and round the internet trying to come up an indigo vat RECIPE for cotton. so many mordants so many different tannins. i’m lost :(. could you help me … pretty please ?

  19. Lots of information here. Just have a question about how do I use ripe bananas. They are currently frozen. Do I blend them up and can add to an indigo vat?

    1. I would cook the bananas in water and then strain out the liquid and use that liquid in the indigo vat. Start with approximately 1 banana per liter of water in vat. You can always add fructose as needed to boost the reduction.

  20. I have started a indigo vat using Michael gracias method
    My vat is brownish goldish
    Doesn’t have bubbles and is not dyeing
    It did start to get a coppery sheen on top but not much
    I don’t know what to do
    I tried heating it not too much

  21. Hello,
    This is a great blog. Thanks for all the info!

    I have a very simple question that I have been trying to figure out..
    I have some ph strips and want to test the ph of my first ever 123 vat, but if I dip the strips in the vat they get dyed so I can’t read the strips… am I missing something here? aside from seeing if the vat gobbles up lime, how do I test the ph?

    Also i have been waiting for my vat to turn that yellow color when fabric is dipped.
    It is mostly dark blue but appears to be dying fabric very dark blue. I am wondering if it is not really dying and will wash out. I am waiting for the fabric to dry before I do a wash test.
    When I heat it, it tends to turn a little more yellow green and also the flower consolidates.
    So maybe it is working, but I am not sure…
    thanks! hope that makes sense!

  22. hi,
    this is a great blog thanks!

    How do you test the ph of the indigo vat other than seeing if the lime gets eaten up?
    I have ph strips, but they turn blue so I can’t read them when I dip them in the vat.

    Also my vat that I just started is a dark blue and when i dip cotton in it it dyes dark blue. This would be great I suppose, but I don’t really see it turning that much from the yellow green to blue. It goes from mid blue to dark blue.

    Does this mean that the vat is not really reduced and the fibers are not really being dyed… that they will just fade out eventually with washing, rubbing and light?

    I will play more with adding lime and fructose. It seems to like heat as well.
    The ph of the water where I am is 7.


    1. Reading the pH can be tricky since the vat IS blue. You’ll want to look at the color that wicks up the paper. Better still, use papers that have multiple indicator pads for more precise calibrating. Of course, you still have to take the blue of the vat into consideration. Use the papers in combination with watching to see if the vat “gobbles up” the lime.

      The leuco color of the vat is BELOW the surface. Dip a small white plastic spoon just below the top of the vat to see if the vat is truly in reduction.

  23. Hi Catharine,

    First of all, thank you for this great resource. I have been experimenting with indigo the past few months and this has been very helpful! I have a million things I would like to ask but the one that I am most curious about is whether you have tried using dextrose as a reducing agent.

    I make beer at home and have dextrose about, so I tried subbing it in to the 1-2-3 vat. The results are quite extreme, and I am not sure what the cause would be. The starter jar heats to over 80c after adding lime (though how long it takes to do this varies), and the solutions eventually turns into a burned orange-colored sludge. When added to a vat it seems dyeing is still possible, but the color seems incredibly weak – four long dips only produces a light blue, and subsequent dipping doesn’t seem to darken it noticeably. If you should shed some light on what is happening, and if/whether this will be detrimental for dyeing I would greatly appreciate it! To be honest, I am having general trouble producing darker shades even when not using dextrose, so I am not sure if dextrose is the culprit at all – though it certainly seems to be what is causing the heat and bizarre color.

    1. Rob,
      You ask an interesting question and the truth is I don’t know the complete answer. I mixed up a small sample vat using dextrose to compare with another sample vat I made a couple weeks ago with fructose. The dextrose vat has gone into reduction but the color is lighter. I don’t know if the light color is a result of the vat being younger and not as thoroughly reduced OR the sugar is not as good a reduction agent.

      Interesting thing about dextrose: it is the sugar we began using with indigo printing but we found that table sugar worked just as well for that application. But table sugar will NOT reduce an indigo vat. Sugars are not all equal!

      The best advice I can give you: Make a couple small vats in pint or quart jars. Use fructose in one and dextrose in the other. You can watch what is happening through the glass. Compare your dye results – and please let me know what you learn.


      1. I will certainly try an experiment in the next couple of days once I am back at home. Could you clear up one or two more things that I am still not sure I understand completely? After reading your comments here I am now suspect my technique/process is not right from the get-go and is making my results harder to analyze properly.

        When dyeing, would you avoid stirring the settled solution on the bottom of the vat/starter jar before doing a test dip? I was under the impression that the yellow/green solution at the bottom is where the color is, but reading some of the comments here I am now thinking I have it completely backwards and should be dyeing in the layer above this.

        I also saw you refer above to dipping a spoon into the vat to test for reduction. Do you mind explaining a bit about what exactly one should look for when testing for reduction? I had previously just assumed the color change was enough of an indicator, but if there is something else that clues me in on how good the reduction is that would be immensely helpful!

      2. Ah, that explains a lot. The vat is stirred to activate the ingredients that settle to the bottom but it all must be allowed to settle again before dyeing. The liquid should be clear (no particles floating) and yellow or bronze in color. The white plastic spoon helps you to see the nature of the liquid below the surface of the vat. Making a test vat in a small glass jar can be very instructive. It allows you to see what is happening inside the vat.

      3. Hi Catherine,

        Sorry it took so long to come back on this! I have done some tests and it seems that dextrose may not be terribly effective here, but because I am probably doing several other things wrong I can’t say for sure yet (more on this at the end).

        I did three starters:
        1. 100g indigo paste, 200g lime, 300g dextrose
        2. 100g indigo paste, 200g lime, 150g dextrose
        3. 100g indigo paste, 200g lime, 300g sugar – (more on the sugar below)

        Here are the photos of the three vats in that order:

        In the first, the dextrose causes the starter to heat to well above 80c, and turns the vat into orange sludge. I have tried dyeing with it and faint color seems possible, but I think the heat probably damages the indigo because the color is weird and washes out easily.

        The second starter had a better reaction, and while it got warm didn’t get nearly as hot. The in-vat seems better (being bright yellow) but it doesn’t seem to have a particularly good glaze on the top. Dyeing with this ratio is what I have been doing in my most recent two or three vat attempts, and it seems to produce a light sky blue very easily, but I can’t get it past a medium depth of shade, though I am unsure whether this comes down to my technique or not being patient enough to dye many times – I usually stop after 6-8 dips.

        Finally, I the third vat was the control using the sugar I used to use. Unfortunately, I can’t find fructose easily where I live, so I use this sugar from the market, which contain some amount of fructose, but it seems to vary wildly. As you can see, this particular batch wasn’t very good, and there is very little reaction here, though it did turn slightly green (though hard to make out in the photo).

        So, I am left unsure about dextrose. In small amounts the color in the vat looks great, but my results dyeing with this are not very good compared to what I have been able to achieve in the past using #3 and some added fruit. I was initially excited because I thought maybe dextrose was more efficient, but now I am not so sure that it works well at all. I wonder whether it is possible that despite having a good color the reaction is not very good and that this is still not enough sugar? If that is indeed the case, then adding more dextrose will just turn it to sludge, and it is perhaps best used as a supplement to a tried vat or something along those lines.

        As you probably noticed from my last questions, it seems my technique still needs some work, which kind of throws a wrench into the results. In the very least, though, I hope it shows that if dextrose is useable it should be used in much smaller amounts than fructose! Please let me know if there are any other experiments would like me to try with it. I would be happy to keep experimenting with this.

      4. Aaand I do have one quick question, I hope you don’t mind the double post but I didn’t want it to get buried in my wall of text.

        Regarding the plastic spoon advice you gave, here are the results in my vat, which I take it are fairly good(?):

        Assuming it is in the right direction, this means I should only be dyeing in the top clear layer, right? Or do I want to get as low as possible while not in the yellow/green at the bottom?

      5. Hi Catheirne,

        Sorry again to take up so much space here – this will be my last post. I finally got my hands on fructose and repeated the vats and was surprised to have exactly the same result – huge heat reaction in my start jar. I am left thinking I must be using too much materials for the size of the jar, but I am otherwise stumped. I assume, then, dextrose is probably perfectly fine and I need to do some in-depth work on my recipe and ratios based on my ingredients. I have also since found that my indigo that I buy locally is pre-mixed with lime (it’s a paste), and this adds a further unpredictable element to the mix it seems. Thanks again for your help!

  24. Rob, I use anywhere from 1-10 grams of indigo per liter of indigo vat solution. The larger amounts are only used when I want to keep a vat working for a very long time. One or two grams is plenty in a small test jar. I am using dry indigo pigment. You many need to adjust a bit for the paste. 1:2:3 – 1 part indigo, 2 parts lime, 3 parts sugar. I’m wondering why the indigo would be mixed with lime??? Keep an eye on your pH-it needs to be about 13 or so to begin the reduction but it will go down after that.
    I think that you’re always better off using a more “complex” sugar such as fruit or henna for a vat and then feed it with fructose, dextrose, etc.

    1. It seems mixing with lime paste is the traditional method in Thailand. I am not sure about how much is used exactly but between various accounts and testing the pH of a cup of water with a few grams of the paste in it, it seems the amount isn’t that significant. I would assume it’s more for consistency and storage than anything. The water weight seems to throw things off more than anything!

      With some very in-depth testing I have found what seems a good ratio of this wet indigo to the recipes. I will start a big vat this week and let’s see how it goes 🙂

      Thank you for the suggestion of using henna. I have tried making pure henna starters (and have just repeated this after your last comment), but have never been able to get any color without also adding dextrose or fruit. My last 3 starters test jars now are 3 days in and I am still not able to get any indigo color at all – only some pink from the henna. Does henna absolutely have to be mixed with other sugars, or should it work on its own? I am wondering if I am not boiling long enough…

      1. I use only henna f and have very vigorous reduction in just a day or two. I don’t cook the henna a long time – just enough to heat it all up and hydrate it. If the henna is finely ground I put it all in the vat. After making the vat, stir it up a few times during the first day to be sure that everything has an opportunity to start working.

      2. @Nicki – Thank you for the link! Unfortunately, I have been using that as a reference so I’m not sure where I’m going wrong.

        @Catharine – Thank you for clearing that up, but that’s what I was afraid of. Barring that I am over boiling it, then, I am totally stumped. I may give it a few more goes, but not sure what else I could do. Oh well, at least the sugar vats are improving! Thanks again for all of your suggestions.

  25. Thank you for such an informative blog catherine.
    My question is in regard to my fructose vat. I’ve had my first real success with a 20 litre vat with 60gms indigo 120 lime and 180 fructose. The vat is two days old and is giving a good medium shade of blue with multiple dips. I would like to achieve really dark shade of indigo if possible.
    Today the vat had less bubbles/flower on top but liquid is still a good yellow brown colour.
    Sadly no ph strips.
    I have fed the vat with dissolved fructose and a little lime on top and it doesn’t seem ‘hungry’ for the lime.
    My question to you is do I need to reheat the vat frequently to reactivity. I live in Australia in a hot climate but the vat feels cool. I would like to keep the vat for a long time if possible and achieve strong dark blues. Any advise would be appreciated. Many thanks🙏💙

    1. Hello, just wondering where abouts in Aus you are and where you are getting your indigo supplies from? Cheers 😊

  26. Once the vat is in reduction it does not need to be reheated. Your climate should keep it happy. You don’t always get vigorous bubbles. Sometimes your stirring technique can affect that. You might be interested in the blog I just posted today….

  27. Hi Catharine. Thanks so much for sharing all this info. I started a small indigo trial vat in a mason jar using the 1.2.3. method, subbing Madder for the fructose & it tested perfectly after about an hour. Unbeknownst to me, the jar had a crack on the bottom & started slowly leaking overnight. To make a long story relatively short, in between transferring the contents of the indigo vat into a larger vat, there was a lot of sloshing of the vat content, I’m thinking I may have introduced too much oxygen into the process. It is now in a 5 gallon bucket with approx. 4 gallons of water but not enough indigo mixture to see if I may have ‘killed’ the content (if that’s possible). I’m not sure if I should test the existing vat by adding more mixture or just start a whole new vat? I didn’t want to waste more indigo if I did in fact introduce too much oxygen during the transfer process which brings up another question which is when you went from 5 gallons all the way up to 30 gallons, did you transfer the old vat into the new & if so, how did you do it to avoid oxygenating the vat while pouring from one vat to the other? Also, I will be keeping the vat outdoors (I live in Central California Coast so it gets down to about avg. 50 degrees at night & 60-85+ depending on the season). Is it necessary to get some kind of a heater for the vat to reuse consistently? I’m starting with a plastic bucket so not clear on how to keep the vat warm or heat it back up when necessary. Thanks so much for your time!

    1. If a vat goes out of reduction (because of use, too much oxygen, etc.) that is usually reversible. Once the vat settles, the pH is is alkaline, and there is plenty of reduction material, the vat can be coaxed back into a good reduction. But I fear that if you have added a 1 quart jar of indigo vat to 5 gallons of water, the balance is just not right: too much water and too little indigo/reduction material/alkaline – water has a lot of oxygen too.
      When I made a 30 gallon vat, I started with the whole 30 gallons. I would encourage you to make a relatively smallish vat – 5 gallons is OK if you’re going to use that much but don’t hesitate to go smaller. Get comfortable with it, use it, maintain it. The heat is very helpful when starting the vat, but once the reduction is well underway, I don’t heat mine and my own temperatures are similar.

      1. Catharine, I have had excellent results in continuing to use the rinse water, and old vats as the beginning liquid. I just treat it as fresh water when making a starter or larger vat. I feel like this is similar to starting with broth rather than fresh water; the resulting vat is stronger and easier to maintain the balance. I love that my vats have been going for several years; there is beauty in that nurturing and preserving of the initial liquid. I do strain the vat once a year to get rid of smelly henna sediment.
        I just revived a vat that I let freeze over the winter in Northern Wisconsin with just a little heat and fructose, the Ph had remained stable.

      2. Thanks for your reply Catharine, I appreciate all the good info & can’t wait to get to a 30 gallon at some point!

  28. Anna, Thanks for this. It’s a good reminder to use that rinse water. I’ve only just begun to think about removing the sediment but have never done it. I was recently talking with dyers from India who do that on a regular basis. apparently they scoop it out by reaching down into the vat. The concept of straining it is a good one. Perhaps you’d be willing to share your approach.

    1. Thank you Catharine & Anna for your input on this post, I appreciate that. I was told by my indigo teacher in Portland that you can continue to re-use the old vat to start a new one so it’s good to know you have had good experience with that. I ended up using the diluted vat in the 5 gallon & added more 1.2.3. solution & it looks very happy & the ph is perfect for cellulose fiber dyeing so I’m ready to go now. I, too, would love to know how you are straining the sediment without introducing too much oxygen into the process Anna if you’d kindly share your experience.

    2. I’m happy to share:
      To keep the vat clean, I use a small strainer to bring up and discard the solids. An older vat, like my over-wintered one, may need to be poured through a cloth-covered sieve into another container. Yes, this introduces a lot of oxygen. But after I added some henna solution to that old vat and let it rest overnight, it was stronger than when I left it last fall! (Initially, I had heated it and added fructose to jump-start it. When I knew it was still viable, then I strained it and gave it the henna treatment for a longer-lasting vat, as Catharine has suggested).

      I had tried a few vats before getting one that was in proper reduction. Because I knew there was un-reduced indigo in them, I was hesitant to toss the vats. So I ended up adding them all together and using a starter solution. Finally I had a vat that worked beautifully without re-heating every time I wanted to dip. I’ve revived old vats several times with a starter solution according to Michel Garcia’s instructions. When a vat gets too light (the indigo is used up), I make a starter from the existing vat broth and more indigo.

      As the vat gets used and evaporates, the liquid level goes down. I add the heated (120F) rinse water, or old vat “broth” by slipping it in gently with a small pitcher. An old stainless coffee pot or small asparagus cooking pot works great; after heating the broth, gently lower it into the vat, then tilt it until some vat water flows into the pot. Then tilt the liquid into the vat and stir gently to incorporate.
      Hope that helps!

      1. Thanks so much ladies for sharing your valuable knowledge & wisdom. I am very grateful for our creative community.

  29. Anna,Thank you for this! The straining makes so much sense, yet it’s something I have never done. Now I know that I will. And it comes just on the heels of conversations with other dyers who practice this way. It proves, once again, how important our community of dye practitioners is and the willingness to share what we know

  30. If i want to add more indigo to an already existing vat, do i make a new solution with the indigo fructose and lime and just add it in? Thank you so much for this article it is super helpful!

    1. That is what I usually do to be sure that all is well dissolved: make a small concentrated “vat” with the indigo fructose and lime and then careful lower it into the existing vat. But there is no reason why you can’t add those other ingredients directly to the vat.

  31. Hello Catharine,

    I am very thankful for your blog, the scientific approach helps understanding the process and I keep referring back to it.

    Some years ago I learned about indigo from Michel Garcia, I even bought some beautiful indigo from Auraherbal in India but it is only now that I finally started working with it.

    The first vat I started was a fructose vat in a 2 litre (half a gallon) glass jar, it reduced well and dyed cotton and linen beautifully.
    The second vat is a bigger henna vat (8 litres/2 gallons) and this also works well, it seems more stable and dyes a lot od my merino and alpaca yarn before it needs rest and adjustment.

    As I am dyeing both cellulose and protein fibres, I would like to be sure of the ph of the vat.
    This is still puzzling me: I tried to read the “wicking up” portion of my paper but it keeps shifting colour and the uppermost portion of the paper turns invariably green, no matter the amount of lime I add.
    Whe I try to gauge the vat´s reaction to lime (does it enthusiastically welcome it or does the lime sit quietly on the surface?) I am unsure. Any advice about the ways you determine the ph would be much appreciated!


    1. Hi Eva,
      It IS tricky to get the pH right and to be able to see what you have. I would suggest two options. Use a pH paper with multiple “pads”. You still must take the the indigo dye into consideration, but with the pH registered on multiple pads, it is easier to be accurate. The other option is to use a pH meter. It should be calibrated before each use, but once you get the hang of that, it’s not difficult.

      In order to further protect your protein fibers, you can add 1% of animal hide glue or gelatin to the vat (that is 1% of your fiber weight). Dissolve the glue/gelatin a few hours before you are ready to dye. The protein of the glue/gelatin will absorb some of the excess alkalinity before it sinks to the bottom of the vat.

      1. Hi Catherine,

        I hope this isn’t too outside the general scope of this thread.

        I’m interested primarily in dyeing protein fibers too, and have played with adding Gelatin to chemical vats. I do think gelatin helps with the hand of the yarn, but I am a bit unclear as to how. I’ve read that it’s acting as a buffer, and I’ve also read your post about it precipitating as it lowers the pH. Why would it precipitate to the bottom of the vat? Why do you add it proportional to the yarn you’re adding rather than the size of the vat, surely the larger the vat the more gelatin you should add to affect it’s pH? Once you’ve added it, and dyed your yarn, can you then raise the pH again and use that same vat for cotton?

        I initially starting with a fructose vat and was unhappy with the results (and accidentally damaged a sweater quantity of yarn… oops!). One of the reasons I’ve been hesitant to try a fructose vat again was being unclear how maintaining a fructose vat + gelatin would work.

        Any insight you (or any readers) could provide would be greatly appreciated.

      2. The gelatin and animal hide glue are protein and will absorb some of the excess alkalinity before precipitating, harmlessly. It’s just another way of bringing the pH down slightly. When dyeing protein with the organic vats, you really do have to wait at least a couple weeks (after making the vat) for the pH to start dropping. Watch it carefully, and it might be worth investing in a good digital pH meter.

    1. Catharine, if I use a ferrous vat (for cellulose), would glue/gelatine protect the fibers there also? What I remember was about a very dark, shiny cloth- maybe it was treated with gelatine after dyeing.

  32. Hi Catherine
    I have recently made a fructose and lime vat for dyeing and am having problems getting a dark shade.
    I am adding fructose at the end of each day once worked and adding lime before working.
    The pH seems to be about 9/10, I am dying protein fibres but its just not getting darker than a mid blue.
    I am varying the times of dips, some for 15 mins and some for a few hours but the colour is not changing and i am mystified as to why.
    I am hoping you might be able to help.
    thanks in advance

      1. It’s in a 50 litre barrel so I would estimate currently about 40-45litres of liquid. I have added 3 separate lots of 25g of indigo (75g total)

      2. That’s only about 2 grams per liter. I would recommend that amount only for dyeing very pale colors – and it will get used up more quickly. If you want very deep colors, I would make the vat with more indigo (5-8 grams/liter). Keep all the other ingredients in proportion. You can add the additional indigo and other ingredients to the existing vat.

      3. Hello Catherine….to jump in on this question… I was reading this recent exchange and thankfully it just verified what I was wondering about my vat…. I started it up (55 gal.) and I kept trying to get everything right (lime and sugars), (even wrote you about my problems getting it going) but I never asked about indigo ratio! I still wasn’t getting anything more than a light color…. so I kinda gave up and never even dyed anything in it and it’s been sitting there for a LONG LONG time….so, for me, what does that translate for deep colors in a 55 gal barrel???… my estimates are a.liter is “roughly” the same as a quart… so that’s 220 quarts in 55 gallons… so I need from 38 – 62 oz indigo (2.4 – 3.875 lbs)… wow… I know I had less than a pound to put in it…. ok so that problem will be solved when I get some more indigo…. my main question now is if my vat has been sitting there for a LONG time (year plus) what steps would you take to start it back up (how much of what in what order) Thank you SO much for this blog… you are giving me hope 🙂 🙂 !!

      4. If the vat has been sitting that long, the pH will need a major adjustment, and it will also need reduction material. Since you will add more indigo anyway, I might make a very concentrated vat (with lime and reduction material) and add it all to the existing vat. Add the new concentrated vat while it’s still warm to boost what is happening in the larger vat. It will take some time to get the whole thing in balance again, but I think it can be done. What are you using as a reduction material for such a large vat? The more complex sugars in henna would be better than fructose.
        And no, I have never tried dyeing wood….too many other things to try. Let us know….

  33. Hi
    thanks so much for the response.
    I have ordered more indigo so will be adding a lot more to it,
    is it normal that it just won’t go darker than mid blue, would dipping multiple times not build up to a dark colour or if there is just not enough it won’t go beyond a certain depth?

    Could temperature have anything to do with it? I originally warmed it to start with but now its either room temperature or I haver an aquarium filter to bring it up to about 30 degrees C.

    1. Hi, thanks! when I first started it up, I was using a “slop” of boiled bananas, lilikoi fruit and chopped sugar cane (per Michel Garcia instruction). I thought it would be a cheap/free/renewable resource and a nice “selling point” since I’m here in Hawaii 🙂 but when I only got the light color on my test strips…so I thought I needed to feed it more so I added some fructose and rice bran to the next pot of fruit slop mix. Now I’m sure the vat was working fine, it had the right color, flower on top, etc…but I didn’t have enough indigo in it…so I gave up…. but I couldn’t bear to throw it out….I LOVE indigo… think of it as blue “gold” and didn’t want to waste the indigo already in there…. I have been planning on reviving it.. so I did buy some henna and madder root to give it some more complex food to work on. And now I know the issue with the indigo ratio so I’ll get more of that before I try again. Yes… I will let you know about the wood. I’m planning some batiked wood and Hawaiian ipu (gourd) art pieces. So happy I know what was wrong with “her”!! Thanks!

  34. hi Catherine,l am Maria.l am wandering if you can give me your opinion with some problem with my Fructuose a big one and l re check all the steps l did and l could nt find a reason why something was wrong…1.2.3. ratio for the 3 elements(maiwa pigment,lime and fructuose)l start my vat at 75C,add the pigment, the fructuose and lime as the recipe from some teacher…the liquid is dark brown from the beggining…and on the fabric is not changing from green to blue untill l rinse with water…but anyway the color doesnt build up with the immersions,The PH now is 10..cause l checked my water house and was a bit acid.5.5,then l add a bit more of lime…probably this adjustment need to be done with 50/60C?….the point is that my electric heater is very weak and l cannot find a strong one to re heat my heavy plastic pot that is 155liters…pity,,but l dont know what to do…any idea is welcome!!thanks a lot

    1. Hi Maria. That is a good size vat. For a vat that large, a more complex sugar would be better – something like henna or other plant that will last longer and give better reduction. How much indigo did you used per liter of volume? How old is the vat? What is the fiber you are dyeing?

  35. Dear Catharine,
    My vats are doing well! Thanks to you and this blog. I just read over all of the entries and learned a few new things!

    I’m a frugal dyer. I notice that my rinse water has a dark blue sediment that collects on the bottom of the pail. Is this un-reduced indigo that I should be re-capturing? Or is this dye that has already been used and will not react with fiber?

    1. Hi Anna, Yes, that rinse water has lots of good “stuff” in it: indigo, lime, and reduction materials. In fact I once had a student that spend a whole week dyeing in the rinse water! As the vat is used, its volume will inevitably decrease. The rinse water is the perfect liquid to add to the vat to bring the level back up. Yo can even heat it a bit before putting it back into the vat.

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