Toluidine red

Any of several bright, transparent, synthetic azo-type organic red pigments. Toluidine reds are made using the reaction of beta-naphthol with 2-nitro-4-toluidine. Toluidine red was first synthesized in 1904 in Germany, and reached its peak of popular use in the 1970s. Toluidine reds have fair lightfastness and weather resistance: they are used in industrial coatings for air-dried and baked enamels and auto finishes, in wax crayons, pastels, and watercolors; however, they have a tendency to bleed in oil paints. It is a suspected carcinogen.