The Maiwa Guide to Natural Dyes
What they are and how to use them
These organic vats were originally developed by French dye chemist and botanist, Michel Garcia. Michel has been teaching and lecturing at the Maiwa Textile Symposium since 2009. He has worked with Maiwa in India as a dye specialist, most notably at the 2011 Maiwa Masterclass. Michel and Maiwa founder Charllotte Kwon meet on a regular basis to conduct natural dye research, explore recipes and test procedures. Together they are always looking for techniques that give the most exquisite colours - made to outlast the fibres they adorn.
Let's consider each of these three things ...
Indigo
Natural indigo is obtained through a non-toxic fermentation of the indigo plant. It is an extract derived from plants. Depending on the variety of indigo available locally, some artisans will make a dye vat directly from the plant leaves. When buying indigo extract, it may be purchased as lumps (which require grinding) or as a fine powder.
A Reducing Agent
In many parts of the world chemicals are used to quickly prepare an indigo vat. Sodium hydrosulfite or thiourea dioxide are both commonly used as reducing agents.
A reducing agent removes the oxygen from a solution. In doing this, the reducing agent also takes the oxygen from the indigo molecule. With the oxygen removed, indigo becomes soluble in water at room temperature.
A reducing agent is necessary to make an indigo solution. Without it the powdered indigo is suspended in water but not actually dissolved.
What is the difference between a suspension and a solution? A fish is suspended in the ocean. But salt is dissolved in the ocean.
You can see the fish (which remains distinct) you cannot see the salt (which has dissolved by being broken down into separate components). Many natural substances will behave as reducing agents. These absorb oxygen and are known as antioxidants. In the indigo vat we can use natural sugars from fruits, medicinal plants, and even other dye-plants, as reducing agents.
A Base
Chemically speaking, a base is the opposite of an acid. A base is a substance that will allow the action of any reducing agent. Some bases are rather unpleasant; for example ammonia and caustic soda, while others are weak; such as soda ash and potassium carbonate. Weak bases are not very toxic - but by themselves they are inefficient.
The recommended base for an indigo vat is ordinary lime (calcium hydroxide) also known as “calx” or hydrated lime. Do not confuse it with “quick lime” (calcium oxide) which is much more corrosive, or chalk (calcium carbonate) which will not work. Ordinary lime is available at Maiwa or at a building supply store.
About these Indigo Vats
We suggest that you take the recipes that follow only as a guide. Adapt them to use materials that are plentiful and inexpensive where you are located. As with all natural dye recipes you may find yourself adjusting amounts to suit your particular dyeing situation. These vats give the best results when made the day before you dye with them.
Hydrating Indigo
Indigo powder always needs to be hydrated before being added to your vat. Sometimes alcohol is used to do this, but we have found a quick and efficient way to hydrate your indigo with marbles.
Simply fill a strong plastic container 2/3 full of marbles or smooth, round stones. Add indigo powder and cover the marbles with warm water. Shake vigorously for one minute. The indigo is now hydrated. Pour the hydrated indigo into the vat while using the lid to keep the marbles in the jar. Swirl a little bit of water in the jar to wash the rest of the indigo out and into your vat.
Disposal
If whisked, lime will very quickly absorb the carbonic acid of the air (CO2) and be neutralized. The lime will then be transformed into calcium carbonate (chalk or limestone) a non-toxic substance which can be poured down domestic drains. Both liquid and sediment of these vats may be used as compost.
Variations
Mixing two organic reducing agents, such as henna and fructose, gives a strong indigo vat.
Michel Garcia suggests that individuals do their own experiments. Clear glass pots of about one liter make excellent test vats. Try different combinations or experiment with local plants and fruits.
Up next - The Fruit Vat recipe.
What they are and how to use them
These organic vats were originally developed by French dye chemist and botanist, Michel Garcia. Michel has been teaching and lecturing at the Maiwa Textile Symposium since 2009. He has worked with Maiwa in India as a dye specialist, most notably at the 2011 Maiwa Masterclass. Michel and Maiwa founder Charllotte Kwon meet on a regular basis to conduct natural dye research, explore recipes and test procedures. Together they are always looking for techniques that give the most exquisite colours - made to outlast the fibres they adorn.
Let's consider each of these three things ...
Indigo
Natural indigo is obtained through a non-toxic fermentation of the indigo plant. It is an extract derived from plants. Depending on the variety of indigo available locally, some artisans will make a dye vat directly from the plant leaves. When buying indigo extract, it may be purchased as lumps (which require grinding) or as a fine powder.
 |
| Indigo being extracted from plants in south India. |
 |
| Indigo in paste form being cut into squares. |
 |
| Dried indigo. Sometimes called a cake or rock. |
A Reducing Agent
In many parts of the world chemicals are used to quickly prepare an indigo vat. Sodium hydrosulfite or thiourea dioxide are both commonly used as reducing agents.
A reducing agent removes the oxygen from a solution. In doing this, the reducing agent also takes the oxygen from the indigo molecule. With the oxygen removed, indigo becomes soluble in water at room temperature.
A reducing agent is necessary to make an indigo solution. Without it the powdered indigo is suspended in water but not actually dissolved.
What is the difference between a suspension and a solution? A fish is suspended in the ocean. But salt is dissolved in the ocean.
 |
| A fish. Suspended - but not dissolved. |
You can see the fish (which remains distinct) you cannot see the salt (which has dissolved by being broken down into separate components). Many natural substances will behave as reducing agents. These absorb oxygen and are known as antioxidants. In the indigo vat we can use natural sugars from fruits, medicinal plants, and even other dye-plants, as reducing agents.
 |
| Some fruits that make excellent reducing agents. |
A Base
Chemically speaking, a base is the opposite of an acid. A base is a substance that will allow the action of any reducing agent. Some bases are rather unpleasant; for example ammonia and caustic soda, while others are weak; such as soda ash and potassium carbonate. Weak bases are not very toxic - but by themselves they are inefficient.
The recommended base for an indigo vat is ordinary lime (calcium hydroxide) also known as “calx” or hydrated lime. Do not confuse it with “quick lime” (calcium oxide) which is much more corrosive, or chalk (calcium carbonate) which will not work. Ordinary lime is available at Maiwa or at a building supply store.
 |
| Calcium hydroxide, ordinary lime, hydrated lime, calx - many names for the same thing. The recommended base for the organic indigo vat. |
About these Indigo Vats
We suggest that you take the recipes that follow only as a guide. Adapt them to use materials that are plentiful and inexpensive where you are located. As with all natural dye recipes you may find yourself adjusting amounts to suit your particular dyeing situation. These vats give the best results when made the day before you dye with them.
Hydrating Indigo
Indigo powder always needs to be hydrated before being added to your vat. Sometimes alcohol is used to do this, but we have found a quick and efficient way to hydrate your indigo with marbles.
Simply fill a strong plastic container 2/3 full of marbles or smooth, round stones. Add indigo powder and cover the marbles with warm water. Shake vigorously for one minute. The indigo is now hydrated. Pour the hydrated indigo into the vat while using the lid to keep the marbles in the jar. Swirl a little bit of water in the jar to wash the rest of the indigo out and into your vat.
Dyeing with a Basket
When using an organic vat, rather than filtering the liquid you may use a basket to keep the yarns or cloth away from the sediment. This is particularly important with the ferrous vat as the iron may cause dots or stains. Stir the vat, wait for the sediment to settle, then use a basket.
pH
The proper pH is 9 - 9.5 for wool and 11-11.5 for cotton. You may test the pH of the vat with a test strip. If it is too low carefully add some more lime. If it is too high, then add some more fruit juice and wait a little, the pH will decrease.
The addition of more fruit juice from time to time is recommended to keep the vat reduced. Remember, the action of dyeing will introduce oxygen into the vat.
Some fruits are more acidic than others. If using very acidic fruit add more lime at the beginning until the pH is correct.
Shades
The first shades obtained from your vat will be strongest. You will increase the depth of shades by dipping more times. For very pale shades it is best to make a vat with less indigo and dip more often than to dip once in a stronger vat.
Exhausted Vats and Revived Vats
These vats may be revived until the amount of sediment becomes problematic. There is an art to reviving an indigo vat (check the pH, adjust, bring it up to temperature) and it can be satisfying to do so, but at some point it will be necessary to abandon the vat and make a fresh start.
If whisked, lime will very quickly absorb the carbonic acid of the air (CO2) and be neutralized. The lime will then be transformed into calcium carbonate (chalk or limestone) a non-toxic substance which can be poured down domestic drains. Both liquid and sediment of these vats may be used as compost.
Variations
Mixing two organic reducing agents, such as henna and fructose, gives a strong indigo vat.
Michel Garcia suggests that individuals do their own experiments. Clear glass pots of about one liter make excellent test vats. Try different combinations or experiment with local plants and fruits.
