The Ancient Dye Made From Urine

Orcein is a vibrant purple dye derived from lichens, but it traditionally required a revolting secret ingredient. To transform raw lichen into color, producers fermented the plants in vats of human urine.

This pungent process relies on the ammonia found in urine to kickstart a chemical reaction with the lichen. For centuries, this mixture was a massive global commodity, turning rags into royal shades of violet and red. Interestingly, if you tweak the ingredients by adding minerals like calcium, the same lichen produces litmus, the classic pH indicator used in school science labs. It is fascinating that such a common scientific tool shares the same humble, smelly origins as high-end textile dyes.