After William Perkins’ synthesis of mauve in 1856, the understanding of chemical formulation in the construc- tion of colours expanded very rapidly.

The very rst azo pigment was tartrazine yellow, patented in 1884 and still in use as an artist’s pigment today. Chemists were now able to build molecules with greater understanding, and vast numbers of new azo pigments were rapidly introduced. A whole range of b-napthol azo dyes and pigments was introduced after further discoveries in 1895.

A famous family of azo pigments was discovered in 1909, known as the Hansa pigments, although they are chemically known as the Arylide group. A very bright yellow pigment, it was the rst of many hues that have been produced from lemons through to warm oranges with great commercial success.

The arylides started to be commercially available around 1925 and more widely used predominantly as a replacement for the toxic cadmium yellow after 1950.