Working With Indigo

This process is using indigo extract. You can buy this from specialist stockists such as George Weil. If you would like to grow your own indigo, you can grow Woad or Japanese indigo depending on the climate you live in. Here is a link to the process for extracting indigo from fresh woad.

How to make, maintain, and dye with an indigo dye vat.

In accordance with Michel Garcia’s 123 method.

Ingredients

1 part extracted indigo

This can some from any plant that contains indigo. Such as indigo fera tinctoria, woad, or Japanese indigo.

I generally work to the ratio of 10 grams of indigo to 1 litre of vat. Therefore for a 20litre vat, I would use 200g of indigo. The other ingredients are measures according to the 123 ratio.

Recommended UK stockist: George Weil

2 parts alkali

Michel Garcia recommends using calcium hydroxide. This is a strong alkali that is relatively safe to work with. This is builder’s lime.

Recommended stockist: Ebay

3 parts reducing agent

We need a reducing agent to remove the oxygen from the vat. Fructose is a reliable and easy to measure reducing agent. When I don’t have fructose to hand, I use the liquid from boiling orange rind in water. This works well but it does have an acidifying effect on the dye vat which needs to be balanced out.

Recommended stockist: Holland & Barrett or Ebay

Equipment

• A vessel for your indigo vat. This can be anything from 1 litre to 40+ litres. The vessel must be cylindrical, tall and thin and with a flat bottom. For smaller vats, I use a measuring jug; here is a good example. For larger vats, I use a 25-30l plastic bucket with a lid; here is a good example.

• A stirring stick. This can be a piece of wooden dowel or a straight stick foraged from a tree.

• Weighing scales with accuracy to 1 gram

• A bowl for weighing out ingredients

• A spoon

• A kettle of hot water.

• A mask for when handling the powdered calcium hydroxide and gloves for when dyeing.

Making The Vat

1. Boil a kettle.

2. Measure out your indigo and add it to the container you plan to use as your vat.

3. Add enough (hot or cold) water to cover it.

4. Vigorously stir the indigo until it is fully wetted. The indigo is not water soluble so it will never dissolve. We are aiming to wet the indigo so it does not float on the surface of the vat.

5. Weigh out the alkali and the reducing agent. Add these to the vat.

6. Add enough hot water to fill the container.

7. With your stick, very gently stir the vat in a circle, slowly speeding up to a whirl pool. From now on, we are trying to avoid introducing oxygen to the vat so you want the vat to be totally silent with no sploshing sounds. You will start to observe a colour change from blue to green, yellow, or red. A metallic sheen will appear on the vat surface. A ‘flower’ will collect on the vat.

8. Stir the vat in to a whirl pool three times.

9. Stir every 15 minutes for a hour.

10. The vat will take between 1 - 6 hours to be ready to use.

Protecting protein fibres

Protein fibres can be damaged in the vat due to the alkalinity. Here are some things you can do to protect the protein fibres.

• Warm your vat up to about 40°C. To do this, either make your vat in a stainless steel pan you can put on the hob, or make it in a small plastic container you can put in a pan of water as a bain-marie.

• Add rabbit skin glue to your vat. Add 5-10g/400g fabric. Dissolve the glue in boiled water and then add it to the vat the day before you intend to dye. This will absorb excess alkalinity and sink to the bottom of the vat.

• Soak your fabric in vinegar once you have finished dyeing. This will neutralise the alkalinity.

Dyeing

If dyeing a large quantity of cloth. Fill three buckets of water. Work in a conveyor belt.

Step 1: Remove the indigo flower with a large spoon or small container. This holds the strongest oxidised indigo. Keep this and reintroduce this to the vat at the end.

Step 2: Wet fibres in the first bucket of water. 10 mins-over night depending on how absorbent the fibres are. Squeeze out the fibres before adding them to the vat.

Step 3: Gently submerge the fibres in to the vat. Careful to not disturb the vat too much or introduce air bubbles. Leave the fabric submerged under the surface for around 1 minute. With a gloved hand, you can gently manipulate the fibres under the surface to achieve a more even result.

Step 4. Gently remove from the vat, squeezing as you lift the fibres out.

Step 6. Rinse the fibres in the second bucket. This bucket will catch any indigo not set in to the cloth that you can re-use.

Step 7. Oxidise the fibres in air or in the third bucket of water. Fibres will oxidise most quickly in fresh clean water. Let the fibres oxidise until they turn completely blue (no green).

Repeat this process at least three times for reliable blues. You can increase the time of the dip in the vat each time to deepen the colour.

Maintaining your vat

• If cared for correctly, your vat should live for years.

• Once you have finished dyeing. Add a spoonful of fructose to remove the oxygen from the vat.

• If the vat is starting to grow white mould, add some calcium hydroxide to raise the pH and kill the mould.

• If the vat goes all frothy and foamy, add calcium hydroxide.

• If the fabric comes out of the vat blue that rubs off, not green,= the vat is oxidised and needs more fructose.

• If the fabric is coming out pale and the vat is looking pale. You need to top up the indigo. To do this, make a smaller vat and gently add this to to your larger vat to replenish it.

Clearing Up

Recycling Indigo

Here is a little video showing my indigo washing/recycling set-up.

Steps to processing indigo rinse.

1. Collect the indigo in a bucket

2. Add citric acid or vinegar to neutralise the indigo if it is very alkali from the dye vat.

3. Wash the indigo by pouring off the water once the indigo has settled and then adding fresh water. Repeat until the water runs clear.

4. If the indigo goes into suspension (does not settle) add a spoon of lime (calcium hydroxide). This will cause the indigo to settle.

5. Once the indigo is clean, pour off the excess water and run the indigo through a fine cotton filter.

6. You can use the indigo dry (vats, crayons, or ink) or wet (vats or ink). You canleave the indigo to dry in the filter or remove it and lay it in a shallow tray to speed up the process.

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