Who doesn’t like blue jeans? The indigo dye that provides their distinctive color holds up to detergents, but ages into that soft, worn look. Indigo is one of the oldest dyes used for coloring textiles. For thousands of years it was extracted from tropical plants in Asia, the Middle East and the Americas, with various unpleasant side effects. This Berkeley University of California article describes the research involved in finding a cleaner route to produce the iconic dye.