Setting Up A Hydros Indigo Vat

Updated: May 5, 2020


The eternal blue of indigo, one of the most ancient dyes. From sky- to deep sea blues, it is so versatile, over-dye it with madder for lasting purples and weld for greens.

Making an indigo vat can seem like a daunting task, but trust me, once you get it done once, you will be doing it way more often. For setting up this indigo vat I used the ingredients of our Indigo Starter Kit, that has enough ingredients to set up and maintain your indigo vat.


First of all you will need Indigo powder. Most of the available indigo is produced from Indigofera Tinctoria. Other species are Indigofera suffruticosa which is native to the tropical and sub tropical Americas, and Persicaria tinctoria (Japanese Indigo) which grows well in Asian countries and Eastern Europe. You will need something that will remove the oxygen from the water, in order to make the active dye component Indigotin soluble in the water. For organic vats you can use henna, dates, fructose, but we are making a vat using Hydrosulphite, which is easy and very stable to use. The third ingredient is soda ash, which makes the water alkaline, a must for the proper reduction of our indigo.

Indigo Vat Ingredients

25 grams indigo powder, that is enough to dye a kilo of textile a medium shade of blue.

50 grams sodium hydrosulphite 100 grams of Soda Ash

Warm Water

This is to set up your initial vat of around 5 litres + maintenance, we will not need all of this immediately.

A word about hydrosulphite; it has a limited shelf life of about a year, shorter if kept in daylight or in a warm room. If you see your powder has a yellowish tint, it is probably working less and you will need more powder to get the same result.

HARDWARE 1 mason jar of another glass jar of at least one liter a metal teaspoon a water boiler or other source of HOT water. a little bowl for mixing

Ph strips

A bottle of vinegar

A larger container (5-20 litres depending on how large your projects will be) with a lid to store your indigo vat. I have a stainless steel bucket so I can re-heat my vat directly on the gas stove if I want to.


a digital (spoon) scale digital ph meter

digital thermometer plastic (disposable) gloves


Unlike other natural dyes, the amounts are not measured according to the weight of fibre but according to the total amount of water you want to use in your vat.

Strong vat; Per 1 liter of water; 5 grams of indigo = 1 lightly heaped table spoon of indigo powder

5 grams of Spectralite or Thiox = 1 teaspoon 12 grams of soda ash = 1 + 1/2 table spoon

If you have a digital measuring spoon always use that over eye-balling with a spoon.

For a WEAK vat; use 2 grams of indigo For a Medium vat use 3/4 grams of indigo

So for 5 liters of water as a STRONG vat you would need; 25 grams of indigo 25 grams of Thiox/spectralite

60 grams of soda ash

Measure, do the math and note down the ingredients you will need for your final vat.

STEP ONE - making the 'mother' in a mason jar.

- We are making a mother for the first vat, so you can see what is happening to your water, and you can visualise what a healthy vat should look like in colour, After this, you can surely work directly in a large receptacle with all the ingredients at once. -

In the little bowl, mix the soda ash with a bit of very hot water until it dissolves while stirring. Add to the mason jar.

STEP Two Measure indigo in the little bowl and mix with a little bit of hot water until you have a paste. Keep stirring until you no longer feel any grit or lumps. The paste should turn shiny on the top. This can take a couple of minutes, do not skip this step!

STEP Three Add the paste into the alkaline water while stirring well, add a bit of hot water to the little bowl and rinse to not waste any indigo paste. Top up hot water to a bit below the rim.

STEP Four Measure the reducing agent and add half of it it slowly to the indigo alkaline solution while slowly stirring (the dry powder). Keep stirring until dissolved. You can see bubbling happening. Now hold your spoon still while the water keeps turning. The water will still be blue but you will start seeing the following;

A coppery film will form on the surface a flower starts to form on the surface the water in the jar will start turning green, but particles of blue still float around in the water. Small bubbles may rise, that is the reducing of the oxygen in the water. This process may take up to 40 minutes.

You now have a mini vat of one litre.


When your 'mother' is fully reduced it is time to run a test. Wet out your fabric well Dip into the solution and keep it there for a few seconds Pull out without dripping back into the solution, we are careful not to add oxygen to our vat!

The fabric should come out green/yellow and will turn blue once exposed to air.

The fabric has to be completely blue before dipping again to build up layers and deepen the colour.

Adding the mother to the main vat;

In the bucket put HOT water (60ºC). Add the second half of reducing agent. Slowly submerge the mother in your larger vat and let the dye float into the larger vat without introducing any oxygen.

Check Ph using a Ph strip. Ph level should be anything between 9 and 11. Add more soda ash if the Ph is too low.

Let the vat rest another 30 minutes.

A healthy vat has that coppery sheen on top end a flower in the middle. The water underneath is yellow or green.

Dyeing with your indigo vat.

Dyeing in an indigo vat is called 'dipping'. Colour is built up with dips in the vat, exposing to oxygen in between. Depending on how string your vat is, you will need more or fewer dips in the vat to get your desired colour. While your fabric is still wet it will appear to be at least two shades darker than when it will be rinsed and dry!

After care for your fabric When finished, rinse in cold water until the water runs completely clear, use one round of rinsing with diluted vinegar to restore the Ph level in your fabric.


Best to use your vat until your (expensive) indigo is exhausted, you can keep a vat going for years as long as you keep it balanced with new indigo, soda ash and reducing agent. Never throw in the sewage like it is. First add half a cup of vinegar to make the vat ph neutral and whisk the vat vigorously to add oxygen.

Setting up your first Indigo Vat (Easy)
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