For the leaves of the indigo plant to become a dye, a method that has been passed on for generations is used. The leaves are soaked over night in water with red lime (clay), the alkaline in the lime bringing out the indigo colour in the water. After 24 hours, the surface of the water will reveal a copper colour, the leaves a removed and thereafter the indigo is "beaten", imagine beating matcha, the colour is beaten out of the liquid, revealing a blue colour. The liquid dye is then left for another 24 hours to settle, therafter, it is strained through a muslin cloth leaving a thick paste indigo paste. For the paste to become a dye, it then needs goes through a fermentation process where water, clay, alcohol and fruits are added to it to create a liquid dye, thriving on the right balance of acid and alkalinity.
Each vat is different, our earliest Vat, we called Momo, was fed with tequila, white lime, tamarind and a ripe banana.