Making blue dye with adequate intensity and lightfastness is difficult because it must absorb yellow and orange light efficiently. Solving this problem required lots of molecular tweaking.

A Modern Tale of an Old Blue Dye. Denise Lambert has spent decades rediscovering woad — and coping with blue hands. Listen to this article · 6:28 min Learn more. Share full article.

Described as a “color alert technology,” the battery’s dotted, negative underside releases a nontoxic, food grade blue dye when mixed with moisture, such as spit.

The chemical process for dyeing blue jeans has persisted for the last century. The denim industry uses about 50,000 tons of synthetic indigo a year, along with over 84,000 tons of sodium ...