The cow urine was evaporated and the resultant dry matter formed into balls by hand.

The urine was "heated in order to precipate the yellow matter, then strained, pressed into lumps by hand and dried." It's the mango not the urine that's crucial to the color: "The colourant is a calcium or magnesium salt of an organic acid released by the mango."3 By the early twentieth century the pigment was no longer available, although you can find modern substitutes sold under the name "Indian yellow".

Indeed, the cows were extremely undernourished, as mango leaves did not supply the cattle with sufficient nutrients, and they lived for only a very short time. The process was considered inhumane and, since 1908, Indian Yellow pigment has been prohibited from the market.