The Two-Vat System of Indigo Manufacture

William Finch and F. Pelsaert on the other hand describe the two-vat system which prevailed in the Bayana-Agra-Kol region during the seventeenth Century. According to their description, there were pairs of a rectangular and circular tanks or vats in which the indigo was processed to extract the dye.

The stems and leaves of the indigo plant were first placed in a rectangular vat, the ‘long cisterne’ of Finch and the ‘put’of Pelsaert, where they were covered with water and steeped for a period of time: 16 or 17 hours according to Pelsaert; 24 hours according to Francis Fettiplace; 48 hours according to Mundy; or ‘for certaine dayes’ according to Finch.

This tank was ‘well plastered’ with lime to check any seepage and had a depth of ‘the height of an ordinary man’. According to Pelsaert the yield of one bigha or ‘12 or 20 ser according to the yield’ could be held by each of these ‘put’ or vats. The pressing of the steeped leaves and stalks of the indigo plant in these rectangular tanks was done by pressing the material ‘with many stones’. It was due to this that these rectangular tanks were also known as the ‘steeping tanks’.

These steeping vats were connected to circular tanks or cisterns which were situated at a somewhat lower level. After the ‘substance of the herbe be gone into the water’ as a result of steeping and stone-pressing, the mixture was transferred into these circular vats or tanks, which according to both Finch and Pelsaert had a small ‘bowl-shaped’ receptacle at its base. Once transferred, two or three men standing inside the vat, either stirred the liquid with ‘back and forth movement of their arms’ or stirred it with ‘great staves, like batter or white starch’. This beating and stirring continued from around 6 hours to 16 hours, all the while mixing ‘a little oil’ before letting it stand for a day or so to allow the heavy matter and pigments in the resultant blue water to settle below in the bowl-shaped receptacles.

Lucas Antheunis, writing about indigo processing at Masulipatam on the other hand, informs about mixing of a particular fruit to bring the required thickness and hue:

Here is some very fine and good and may make it generally so but that in seething they mingle with it the rinds of certain fruit like green Spanish figs, which makes it heavy and takes away his colour more or less, according as they put thereof in.

The clear water which was left at the top was then drawn out either manually or by ‘opening holes made round the tank’.

The process of beating, stirring and settling was repeated till ‘only a thicke substance’ remained. According to Pelsaert there was ‘an outlet at the level of the bottom’ of the circular beating vat through which the remaining water was drained.

The wet pure indigo which had sunk to the bowl-shaped receptacle was now collected and taken out to be dried. According to Pelsaert, the bottom of the put was spread with ashes ‘to form a crust’ and probably help in easy removal of the indigo.

The drying of the indigo was in two stages: first the substance was poured on a cotton cloth spread on the ground so that the extra water was soaked by the soil; and then the semi-dry indigo was then shaped by hand or cut into balls or cakes and kept for further drying on the sand. Ultimately the dry balls of indigo were then kept in earthen vessels which were closed tightly to prevent further drying sue to sun and winds.