Azo dye
The largest family of synthetic dyes and pigments, mostly yellows, oranges and reds.
Also: azo pigment, azo colour
Azo colours are named after a link of two nitrogen atoms at the centre of their molecules. They were first made in the mid 19th century and now account for well over half of all dyes produced. They are cheap, strong and easy to vary, and are found in clothing, printing ink, plastics, paint and food colouring. Most are safe in normal use, but a small group can break down into harmful substances, and those are banned in textiles in the European Union, India and many other places.