Indigo can dye all natural fibres. It gives beautiful shades of blue — from the palest summer sky to an almost purple black. The colour achieved depends on the type of vat, the concentration of indigo, and the number of dips.
Indigotin (the dye component of indigo powder) is insoluble in water. To use it for dyeing it must be reduced to a water-soluble form. All indigo vats need three things: Indigo cake/powder; a fructose reducing agent like dates/ jaggery and an alkaline base like Calcium Carbonate or Lime.
Process consists of four steps, which are as follows:
Build your vat.
Dip the cloth or yarn.
Oxidize the cloth or yarn.
Final wash of the cloth or yarn.
1. Collect your material: 20 litres water, 50gm indigo pigment, 100gm lime (Calcium Hydroxide), 300 gm fresh dates (fructose)
2. Mix your vat: In a 30 L bucket, add 20L water. Add indigo pigment, lime and dates to the water. Stir the liquid in the bucket with a stick in one direction in a circle creating a vortex. Continue for about 30 seconds, then stop with your stick in place, bringing the cluster of bubbles called “indigo flower” to the center. Cover your vat with a lid when it is not in use or being stirred. Do this for next 10 days or until the flowers stop appearing.
3. Check your vat: Your indigo vat is ready for dyeing when the liquid of the vat is amber yellow. You can use a spoon to check the color of the liquid. Its pH should read between 10-12.
This is the time if you want to be creative and tie different patterns across your cloth for some gradation and design on the resultant fabric.
4. Dyeing in your vat: Slowly dip your fabric into the vat. Keep it immersed for about 5-10 minutes. Take it out and dip it again. Do this for 10 to 12 times. Before you remove your fabric from the vat, squeeze out any excess dye below the surface of the liquid to prevent unnecessary dripping. You’ll notice your fabric is a bit light when it comes out of the vat.
5. Oxidize your fabric: Let your fabric oxidize in the air for 15 minutes. When it is fully oxidized, it will appear totally blue. You may repeat this process of dipping and oxidizing as many times as you like to build the color.
6. Wash your fabric: Rinse and neutralize your indigo dyed fabric. Start by rinsing it under running water until the water runs clear.
Iron the fabric once it is almost dry but slightly damp. Now show off!
7. Maintain your vat: Add indigo, dates and lime to the left over solution till it reaches the 20L mark in the bucket and continue the procedure.