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:
Water.
An alkali component.
A reducer.
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.
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 |
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.