Organic Natural Indigo vats, what are your possibilities?

I have never been a great fan of organic vats, mainly because I do not really 'get' them and I have had some major fails (think 30-liter henna vat rotting on a balcony. That stinks). I understand this is a 'me' problem. I am also not around the studio for up to a month, several times a year, so I am not available to babysit my organic vat as I should.

Over the years, I stuck to my trusted hydrosulfite vat and that would be it. But...lately, I have been teaching local communities, where success greatly depends on the availability of ingredients.

When I am teaching a small, local community with limited means, they will simply not be able to order hydros abroad and have it shipped to them. I need to find ingredients that work within their setting!

So having come to that conclusion, I am doing another ride with organic vats and I will compare them so that you too, can choose something to your liking. I am not handing out specific recipes here, it's still a work in progress, I do not wish to copy other people's methods without doing my own work, so take this blog as an overview and inspiration and take from it what you wish.

Any indigo vat relies on the following components:

1. Water.

2. An alkali component.

3. A reducer.

4. Indigo powder or paste.

   
   

   1. Water

For water, I have found it does not really matter what quality the water you use, I did not find significant or any change between using well water (unless it is very iron-rich), distilled water, or my own (horrible) tap water. If you have a different experience, I'd love to hear in the comments.

2. Alkali

   
   

   The alkali component is where things get interesting. For a hydrosulfite vat, I use soda ash, which is cheap and readily available. For an organic vat, soda ash will not work. Soda ash alone (pH ~9–10) is too weak to fully reduce indigo, so a fructose vat with only soda ash will be slow and incomplete.

However, soda ash can be combined with slaked lime to create a milder vat that still works.

Comparing Caustic Soda, Slaked Lime, and Soda Ash in a Fructose Vat

Factor	Caustic Soda (NaOH)	Slaked Lime (Ca(OH)₂)	Soda Ash (Na₂CO₃)
pH Strength	Very strong (pH 13–14)	Moderate (pH ~12)	Weak (pH ~9–10)
Reduction Speed	Fast	Moderate	Slow or incomplete
Handling & Safety	Corrosive, requires caution (USE GLOVES!)	Safer, but still alkaline	Safest to handle
Vat Longevity	Depletes quickly, needs adjustments	Stable	Less stable
Residue in Vat	Fully dissolves	Leaves sediment	Fully dissolves
Effect on Fibers	Harsh on silk/wool	Gentle on all fibers	Safe for all fibers
Best Used For	Quick, deep blues	Long-lasting, even blues	Needs stronger alkali to work fully

Based on this table, you can make your own informed decision.

3, The Reducer. A Comparison of Organic Indigo Reducing Ingredients

Organic indigo vats use natural reducing agents instead of synthetic chemicals like sodium dithionite (hydrosulfite). A natural reducing agent is a fancy word for plant-based sugars from materials like madder root, fructose, dates, henna, or even ferrous sulfate. These substances trigger a hydrolysis process that "removes" oxygen from the water, creating an anaerobic environment. In this environment, indigo is reduced to its soluble form, leuco-indigo, which can then be absorbed into the fibers of the textile you're dyeing. Once you remove the fabric from the vat and expose it to oxygen, the leuco-indigo reverts back to its insoluble indigo form, creating a permanent and vibrant color on the fabric.

I highly recommend choosing your ingredients according to what is available naturally in your environment. For me, it makes sense to use dates, because I can get them for free (they grow on the trees here). I would not use apples because I'd have to buy them, and they are not cheap. I am still on the fence (on the side of 'no) about using perfectly good food for reducing a vat...

Your options for natural fructose

• Fructose:

  • Pure fructose powder (the most common for consistency, available in health stores and big supermarkets)

  • Fruit juice or syrup (that is high in fructose, such as apple or pear juice)

  • Honey (which contains fructose as well as other sugars)

  • Date syrup (natural, high in fructose)

  • Molasses (contains a good amount of fructose, maybe a bit hard to handle because it is so thick.)

  • Agave syrup (another fructose-rich sweetener)

• Fruits with Natural Fructose:

  • Apples (fresh or as juice)

  • Pears (fresh or juice)

  • Dates (dates are rich in fructose and can be used to make syrup or juice)

  • Grapes (especially the sweeter varieties, either fresh or as juice)

  • Mangoes (high in sugars and often used for their juice)

  • Figs (both fresh and dried contain fructose)

This list is by no means conclusive, I have heard of successful vats using orange peels, but I don't have any personal experience with it.

Comparing Different Types Of Reducers For An Organic Vat

Vat Type	Speed	Maintenance	Best For	Alkali	Reducer	Special Notes
Fructose Vat	🔵 Fast	🟢 Easy	- Beginners - Stable dyeing	- Slaked lime (Ca(OH)₂) - Caustic soda (NaOH)	Fructose powder, Molasses, Fruit juice, Agave Syrup
Fermentation Vat	🟠 Slow	🔴 High	- Traditional methods - Deep blues	- Ammonia (urine) - Wood ash lye	Bacteria (from urine or plants) Yes, you will need urine, or compost.	- Needs warmth (~30°C) - Long-term care
Henna Vat	🟠 Slow	🟡 Medium	- Wool - Silk - Gentle dyeing	- Slaked lime (Ca(OH)₂)	Henna leaves or powder	- Works best at ~40°C
Iron Vat	🔵 Fast	🟡 Medium	- Silk - Wool - Low-pH needs	- Soda ash (Na₂CO₃) - Slaked lime (Ca(OH)₂)	Ferrous sulfate (iron vitriol)	- Creates olive-green tones on some fibers
Madder/Fruit Vat	🟠 Slow	🟡 Medium	Sustainable dyeing Mixed-color effects	- Slaked lime (Ca(OH)₂)	Madder root Pomegranate skins Fruit sugars	- Needs warmth (~40°C) - Tannins may shift colors
Sukumo Vat (Japanese Fermentation)	🔴 Very Slow	🔴 High	Traditional Japanese dyeing	- Wood ash lye - Sake mash	Bacteria from fermented indigo leaves	- Requires weeks of fermentation

4. Indigo

   
   

   Now that we have discussed the main players in the creation of an organic indigo vat, we should also address the star of the show: indigo.

   One of my issues with organic vats is also that it is harder to fully reduce all of the indigo powder present in the vat. This can lead to 'waste' of precious materials. Different indigos vary widely in their indigo content, so while I may need 'only' 3 grams per liter of one type of indigo, I may need 5 grams for the same color, using a different powder.

   
   

   

   Indigo from mexico

   
   

Comparison of Indigo Types by Country

Indigo Type	Country of Origin	Strength	Price	Availability	Notes
Indigofera tinctoria	India	🟢 Strong	🟡 Medium	🟢 Widely Available	Traditional, widely cultivated, long history of use.
Indigofera tinctoria	Indonesia	🟡 Medium	🟢 Affordable	🟡 Regionally Available	Slightly weaker than Indian indigo, affordable.
Indigofera tinctoria	China	🟡 Medium	🟡 Medium	🟡 Available in select regions	Grown in smaller quantities; good for industrial use.
Indigofera suffruticosa	Guatemala	🟢 Strong	🟡 Medium-High	🟡 Regionally Available	Known for vibrant blues, good for artisan use.
Indigofera tinctoria	Japan	🟠 Medium-Strong	🟡 High	🟡 Limited Availability	Cultivated for traditional Japanese dyeing methods.
Woad (Isatis tinctoria)	France	🟡 Medium	🟡 High	🟡 Limited Availability	Historically significant, much weaker than indigo.
Indigofera tinctoria	West Africa (e.g., Nigeria)	🟡 Medium	🟢 Low	🟢 Widely Available	Grown traditionally; lower price, moderate strength.
Indigofera tinctoria	Mexico	🟡 Medium	🟡 Medium	🟡 Limited Availability	Used for artisanal and traditional dyeing.
Natural Indigo (Wild Indigo)	Peru	🟠 Medium	🟡 High	🟡 Regionally Available	Often wild-harvested; less consistent than farmed indigo.

As for now, this information is kickstarting a whole lot of experimenting with the different options. I hope it does the same for you too! We can 'learn' only so much from reading, the real learning is always through the hands.