Para red (pigment)

Class of synthetic organic colorants that are bright, cherry-red in color with a rather bluish undertone; made by reacting beta-naphthol with paranitraniline, a coal tar derivative. Different shades are obtained by varying temperature and pH of the mixture. Para red was first synthesized in 1880 by Holliday in England. Para reds have fair lightfastness, but are not used in artists paints because of bleeding; they were previously used industrially in metal finishes and printing inks but have been replaced with more durable colors.