Explain the process of indigo crop …

(i)After the harvest, the indigo plant was taken to the vats in the indigo factory. Three or four vats were needed to manufacture the dye. Each vat had a separate function.

(ii)The leaves stripped off the indigo plant were first soaked in warm water in a vat, also known as fermenting or steeper vat, for several hours.
(iii)When the plants fermented, the liquid began to boil and bubble. Now the rotten leaves were taken out and the liquid drained into another vat that was placed just below the first vat.
(iv)In the second vat, also known as the beater vat, the solution was continuously stirred and beaten with paddles. When the liquid gradually turned green and then blue, lime water was added to the vat. Gradually the indigo separated out in flakes, a muddy sediment settled at the bottom of the vat and a clear liquid rose to the surface.
(v)This liquid was drained off and the sediment, i.e. indigo pulp transferred to another vat, also known as the settling vat, and then pressed and dried for sale.