Natural Fermentation Method with Madder

see also traditional Fermentation method using Urine
& Footnote on Fermentation vats 2019.

Preparing the woad vat and the madder
The vat requires an advance preparation time of one to two weeks. In central England, it is usually warm enough to start in June.

1. The first job is to warm the water.

Put a large black dustbin inside the greenhouse. Put some bricks in the bottom of the dustbin and half fill the dustbin with water. Also fill some plastic bottles with water and keep them inside the greenhouse as well. The water will take a day or two to warm up.

2. If you are using ground dried madder, mix it with about a litre of water and leave it for a day.

If you are using fresh madder roots (see photo), you need to dig up about 120g of roots, wash them well and chop them into small pieces with garden secateurs.
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Making up the woad vat
3. Put a handful of madder roots in the blender and add some water. Do not fill the blender more than half full or you may burn the motor. You will need about two litres of water to liquidise this amount of madder, so it is important to start the vat with the madder, otherwise the liquid will overflow.

Add the madder with all of the liquid to the plastic bucket being used as the woad vat (see photo).
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4. Dissolve the soda ash in some warm water from the plastic bottles and add the soda ash to the vat.

Let the bran soak in warm water for an hour (see photo) and then add the bran to the vat.
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5. Make a paste of the woad with warm water and add to vat. Add warm water to the vat leaving about 3cm of air space at the top. The least air space you leave the better. However, it is important not to fill the vat to the very top; otherwise it will overflow when you add the fibre.
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6. Keep the vat tightly covered with a lid and put it inside the black dustbin, resting it on the bricks. You should have enough water in the dustbin to come up to about two thirds of the vat, like a bain marie.

Put the lid on the dustbin. The temperature of the vat should be between 35°C to 43°C. This is the same temperature used for raising bread or making yogurt.
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Dipping the fibre
7. It takes between one and two weeks for the vat to become ready. Stir the vat gently up to twice a day, trying not to add air into the liquid. You want to integrate the ingredients that settled to the bottom, back into the solution. It is OK if you can only manage to stir the vat once a day.

The vat is ready for dyeing when it develops a bloom of bronze bubbles on top.
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8. Warm the fibre in water at a similar temperature to the woad vat for a day. Wearing rubber gloves, squeeze the fibre while still in the soak water and keep it squeezed as you lower the fibre into the dye vat.

Release the fibre and leave it in the vat for a couple of hours or overnight.
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Getting a dark blue
9. Remove fibre and expose to the air for an hour. Rinse. Dip the fibre into the vat for a few minutes and expose it for 15 minutes. Repeat several times to get a dark blue. Leave to air overnight or for 48 hours. Rinse well.

10. Between dyeing sessions the vat must rest overnight or an extra day. Whenever the dye weakens, you can renew it by adding more woad and the other ingredients in proportion. The vat will take four to five days to get ready again. The vat can last for a long time and some indigo vats are over 100 years old. I keep my vat going over the summer. When it becomes too cold for the vat to work, I throw the contents onto the compost and start again the following summer.
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Urine Vat (or Sig Vat)
The urine vat has a strong smell and is best used outside during the summer.

Collect enough urine to fill a five litre container. Any urine will do, but make sure you store it in a well-marked container and keep the lid on. Place the container in a warm place. A greenhouse is a possibility, providing it does not get too hot inside.

Add three teaspoons of woad powder to the bucket with the stale urine. In a few days the vat should change in colour from blue to greenish yellow.

Add well-washed wet fibre to the bucket and leave it for an hour or longer. Air the fibre and keep re-dipping it in the vat until the fibre is the shade of blue that is required. Keep the vat topped up with urine and add more woad when necessary.

Liles’s book mentions five reasons to learn to use a urine vat (see also his web excerpt).

• you can get some shades only with a fermentation vat
• the fibre can be left in the vat up to two days, producing a more permanent colour.
• once working, the vat needs little attention
• it is easier to build darker colours
• the satisfaction of reproducing a method used for thousands of years

NOTE on Fermentation Vats (August 2019):-

You will find more up to date information
on the madder indigo vat here http://www.wildcolours.co.uk/html/madder_indigo_vat.html

and on the urine vat here http://www.wildcolours.co.uk/html/urine_indigo_vat.html

See also the Chemical method

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Last updated on 31 March 2023
Website & photos - Mike Roberts © 2006-23 woad.org.uk