Method for using Indigo dye on clothing
Always remember to take the necessary precautions before setting off on your dyeing project. Clear a suitable area, wear gloves, old clothing and use equipment thats only used for dyeing. Work in a well ventilated area, away from pets and children.
Our natural Indigo powder can be used on practically all types of fibres, yarns, garments and textiles.
For around 1KG of material (yarns, fabric, scoured clothing) to dye you’ll need to prepare the following;
- 10g Natural Indigo Dye.
- 20g Soda Ash.
- 15g Spectralite (thiourea dioxide or thiox).
- 5 litres water at 45°C.
Make sure that the following equipment is ready;
- 10 litre stainless steel saucepan or stockpot.
- A long or probe thermometer.
- Digital Scales.
- pH paper.
- Teaspoons.
- 3-4 jam jars or other glass containers
- stirring spoon
Make sure that you take sensible precautions before embarking on your Indigo dye project. Use rubber gloves and a face mask when handling chemicals. Choose items only used for dyeing for your preparation, and then keep these separate from any food production areas at home. Use a separate weighing scale pan or jam jars to weigh the chemicals in.
1. Prepare the fibre for dyeing with indigo
If you are dyeing cotton or cotton clothing, make sure you have scoured the item very well before starting. Check our scouring guide for more information. If you are dyeing wool, it must be washed well before you dye.
Soak your wool or cotton overnight or for at least two hours. This opens up the fibres, increasing dye penetration. It also removes as much oxygen as possible and helps to prevent the fibre floating to the top of indigo dye vat.
Just before you start to weigh the ingredients, warm up the fibre by putting it in a washing up bowl or bucket with warm water at about 45°C.
2. Prepare the indigo stock solution
– Place a jam jar marked ‘soda ash’ on the scales, zero the scales and weigh the soda ash in the jam jar. Pour 200 ml of boiling water in a Pyrex (heat proof) jug. Add soda ash to the water, stirring well to dissolve it. Add 100 ml cold water and wait for the soda ash and water solution to cool to 45°C.
– Place another jam jar marked ‘indigo’ on the scales, then zero the scales and weigh the indigo. Add hot water (about 80°C), a little at a time, to the indigo to make a smooth paste, pressing with the back of a spoon against any undissolved indigo.
– Gradually add the paste to the soda ash solution, stirring slowly and leave for 30 minutes. Stir gentlytwo or three times during this period, again pressing with the back of a spoon against any undissolved indigo.
If you find it easier, you may wish to prepare your Indigo stock solution the night before your dyeing session.
Prepare the indigo vat
– Pour about 2.5 litres of boiling water into a stainless steel saucepan or stock pot. Add 1/3 teaspoon of soda ash to the water and then add enough cold water (between 1 and 2 litres) to bring the temperature down to 45°C (if your pot is small use less water).
Don’t fill it more than ¾ full; otherwise you will not have enough space for the fibre.
– Lower the indigo stock solution into the water, tilting the jug so that water enters the jug and the contents then flow smoothly into the saucepan. Do not pour from the jug whilst it is held above the saucepan.
– Leave any undissolved indigo behind in the jug (you can grind it a bit more and use to make more stock solution). Measure the pH in the saucepan; it should be at least 9 or slightly higher, but not higher than 10.
– Weigh the spectralite and sprinkle it onto the surface of the indigo vat. Put the lid on the pot to keep it warm (be careful when you lift the lid not to let the condensed steam drip back into the pot).
Keep the temperature constant at 45°C. This can be achieved by keeping the saucepan either near a radiator, in a basin with hot water, or by wrapping it with blankets.
– After 30 minutes, stir the indigo vat slowly, gently touching the bottom of the saucepan so as to stir any indigo that has settled on the bottom; be careful not to introduce air to the vat. Check that the temperature is still at 45°C. Repeat this after another 30 minutes.
After about an hour and a half the solution should be a yellow-green colour and you may see bronze colored bubbles on top. The time taken for the Indigo VAT to become ready is variable, ranging from an hour or two hours. Once it’s ready, use it right away.
Troubleshooting: If the solution did not turn greenish yellow check that the pH is still between 9 and 10. If the pH is lower than that dissolve a bit more soda ash and add to the indigo vat. You can also try to sprinkle another 3 grams of spectralite on top and into the mixture. Keep the vat warm and wait for another hour.
The final stage, dyeing your garments or fibres.
– Warm the cotton or wool in water at a similar temperature to the indigo vat. Wearing rubber gloves, squeeze the fibre while still in the soak water and keep it squeezed to ensure that any air is removed as you let the excess drip over the soak water.
– Lower the fibre into the dye vat and leave for 10 minutes (if you are dyeing cotton, you can leave it in the vat for 20 minutes). Keep moving the fibre inside the indigo vat to ensure an even distribution of color.
– Remove the fibre (which should be a yellowish green color at this stage), then expose the fibre to the air so that the blue color appears as the indigo oxidises. It should take around 15 minutes for the color to change evenly, after this time rinse the item.
– If you’re looking for a darker shade of blue, place the fibre back into the indigo vat. Leave for one or two minutes and expose for 15 minutes. You can repeat this procedure several times. Leave to air overnight and then rinse well.