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Have you ever wondered about that mysterious Indigo Vat?! How interesting it is to make and exhibits so much magical chemistry. Come along for the journey and see if it truly is an easy 1-2-3 Indigo Dye Vat…

The ‘Real Deal’ – Indigo!

I have had lots of fun with shibori style dyeing but I used Fibre reactive dye to mimic the indigo. Now I’m diving in to the real thing! – in this version I am using a indigo dye (synthesized, molecularly identical to the naturally occurring dye and comes pre-reduced 60%). This organic recipe uses pre-reduced Indigo, Lime and Fructose made famous by Michel Garcia. It is quite simple but there are definitely things to be aware of. Teaser: this will be used to make some amazing combinations with my beloved Eco Printing…

Supplies:

  • Pre-reduced Indigo or indigo powder
  • Lime (Calcium hydroxide, known as pickling lime, slaked lime, or hydrated lime) creates alkaline/basic environment
  • Fructose Powder (made with berries) antioxidant/reducing agent removes the oxygen from a solution
  • Large enough vessel/bucket with lid
  • Accurate scale
  • Smaller containers to mix separate ingredients
  • Spoons for scooping
  • Gloves
  • Dust mask
  • Rags
  • Jar/bottle with marbles/pebbles
  • Mixing spoon

Indigo Dye Vat Proportions:

The proportions for this recipe are 1- part Indigo to 2 – parts Lime to 3 – parts Fructose Powder. The amount of indigo to water will give the different strength of blue. A light Vat is about 2 grams of indigo per litre of water but a stronger medium blue is achieved with about 5 grams of indigo per litre. Darker blues can be achieved by multiple dips. I am not going to be dyeing large amounts so I opted for a 3.5 litre vat (liquid) in a 5 litre bucket. You need to consider the size of bucket to the size of your fabrics. My main intention is to dye silk so this small size is perfect for me. 

My Recipe:

  • 5 grams x 3.5 (litres) = 20.5 grams of indigo
  • 10 grams x 3.5 (litres) = 41 grams of lime
  • 15 x 3.5 (litres) = 61.5 grams of fructose powder

This amount of indigo should be able to dye about 2 or more pounds of fabric/fibre a medium blue.

Make sure to wear protective equipment (and clothing) as these ingredients can have air born particles and also stain very very much. Don’t say I didn’t warn you! ‘As my friend asks why my arms are blue…

To work with the indigo powder it needs to be ‘wetted’ first since it naturally repels from water (insoluble in water). Adding the indigo powder or crystals to a heat proof jar with marbles or pebbles helps mix it compared to stirring where particles escape into the air. My goal is to have a total of 3.5 litres of a final indigo vat (marked line on bucket for amount). The amount of water used in order to wet each ingredient can vary as long as the total equals the desired amount.

My bucket was filled with about 2 litres of very hot water ( too hot for my hands) so that I can add 1.5 litres with the wetting of the ingredients. (SEE VIDEO)

Wet the Indigo:

Add enough warm water to the bottle with marbles and add the indigo carefully. It is so concentrated that it can stain from the smallest particle. Shake vigorously until well mixed.

Pour into the hot water in bucket keeping the marbles from transferring, there will be foam as well. Add some more water to rinse more of the indigo into bucket.

Add enough warm water to the bottle with marbles and add the indigo carefully. It is so concentrated that it can stain from the smallest particle. Shake vigorously until well mixed.

Pour into the hot water in bucket keeping the marbles from transferring, there will be foam as well. Add some more water to rinse more of the indigo into bucket.

Wet the other ingredients:

Add lime to some hot water to dissolve, stir and add slowly to bucket. 

Mix fructose with some hot water and dissolve, stir and add to the bucket. 

Add enough hot water to bring to goal amount of 3.5 litres. There will be a foamy metallic looking mound floating on the surface called the ‘flower’.

With a long enough stir stick/spoon slowly stir in one direction so as not to splash. The idea is to not incorporate more air into the indigo vat. There is a careful balance of PH and lack of oxygen to make the vat be able to transfer the indigo. Continue stirring for a couple minutes not disturbing the flower too much. Put lid on and let rest. 

Is it ready?

The vat is ready to be used when the liquid is a yellow to amber/brownish colour. It should not be blue. Take a test strip of some cotton to see (dark vat) if it is ready. Move the ‘flower’ over or remove and return after dyeing.

As it is taken out of the vat the air will oxidize the indigo pretty quickly to make the magic happen.

It is so gratifying to see this happen after wondering about the whole technique. There is so much science involved with the indigo vat that it often intimidates me. I think it’s a matter of experience to be able to keep a vat going for a long time. It is quite inexpensive so I am not too concerned that I need to keep it for very long and it will eventually exhaust as it is used. The fabric can also be dipped numerous times to darken the blue, which gives a longer lasting dye.

Turn to blue:

Once the colour has turned from a green to blue it is ready to rinse and wash. Be careful to follow wash instructions for your specific fibre type. Rinse residual indigo (may use a weak acid solution to return to normal) from the fabric and wash with a mild PH neutral soap. This is essential how all the old blue-jeans were dyed. Be aware that the final colour will also be lighter as the fabric is dried.

When dyeing larger pieces/bundles the vat needs to large enough to avoid storing up the bottom. Avoid agitation that brings air into the mix so slowly lowering and manipulating careful under the surface is key. Squeeze excess dye out of the fabric as it is brought out of the vat so as to not incorporate unwanted air. 

Watch the blue magic happen (shibori folded clamped bundle). Rinse once oxidized until water runs clear and untie after so that whites remain white. 

The numerous methods of using the indigo make for such fun. Do however be super careful about where you work. This dye is much stronger than the fibre reactive dye since it can stain so much. My plastic laundry sink even gets stained; any small hole in your glove and you will have blue hands!

Troubleshooting the Vat

Sometimes the vat isn’t ‘happy’! If the liquid isn’t yellowish, if it’s blue it will not dye the fabric. Check the alkalinity with some litmus strips. The indigo dye vat should be about 11. If it is too low, add a spoon of lime, stir and test again after a few minutes. If the alkalinity is time then maybe the vat needs to be ‘reduced’ again. Add some of the fructose to the mix, stir gently and wait. Warming the vat also helps keep it happy. 

‘But sometimes I just can’t seem to make it happy after the initial ‘dye-dates’! Keeping it happy is on my future ambitions list! 

But stay tuned as I am combining indigo with eco printing next. ‘Even more magic will happen! 

I'm an artist & I make things... all kinds of things.

This Post Has 4 Comments

  1. This is very helpful. I have never been very succesful Indigo dyeing but will give it a try. Thanks for the inspiration Barb!

    1. I understand… It is so temperamental! The good thing is that it is pretty concentrated so trying a small vat is not that costly. It is good to avoid the sediment on the bottom to picking a vessel is important. Tall enough and also wide enough for the hand(s) and pieces. Silk scarves fit in palm of hand 🙂

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