When you pull on that banana-yellow or bright orange T-shirt and head out for a night on the town, certain that you won’t blend into the background, give a moment’s thought to how the colour was achieved. 

A hundred years ago, the fabric dye called Indian yellow (euxanthin)was outlawed because it was so cruel, and in fact, it may have helped to topple an empire! 

Discovered in the 1400s, Indian Yellow was a popular pigment for paints as well as being a clothing dye. It was made from ground magnesium euxanthate, which is, bluntly speaking, dried cow urine and what made this yellow pigment so popular was that, unlike many other strong yellows, it could be both bright and quite transparent.

The dye was largely banded in the early 1900s because to achieve the bright yellow hue, the cows were only fed mango leaves (most were kept in a walled mango orchard to stop them widening their diet) and water and ‘milked’ for their urine into buckets. 

The urine was was boiled for three days (lovely!) to produce a thick somewhat wet paste, like porridge, which was tipped out on the ground to dry and then ground up with a pestle and mortar.  This highly specific pigment may therefore have been the result not just of the cow’s diet but also minerals in the local soil as it was only produced in one area of India.   The way the cows were treated meant they couldn’t urinate naturally which may have contributed to their relatively early deaths. In India, where cows are sacred, this was seen as colonial cruelty and cited as one of the reasons to seek independence from the British Empire.  A synthetic version was developed very swiftly but it lacked the high transparency of the original  dye, which can still be seen in ancient cotton and silk saris and silk paintings. 

Indian cow photograph by foxypar4, used under a creative commons attribution licence.