In medieval India, the process of indigo extraction underwent great improvement as a result of the :

The process of indigo extraction in medieval India was significantly improved by the use of gypsum and lime mortars to waterproof the inner surfaces of indigo vats. This prevented water seepage and chemical loss during the fermentation and oxidation processes required to extract the indigo dye, leading to higher yields and better quality of the final product. This technological advancement was particularly important since indigo extraction relied on careful control of the steeping and beating processes in stone-lined vats.