Nigrosin
Nigrosin
Mixture of synthetic black dyes
In staining dyes, nigrosin (CI 50415, Solvent black 5) is a mixture of black synthetic dyes made by heating a mixture of nitrobenzene, aniline, and hydrochloric acid in the presence of copper or iron.[1] Related to induline, it is a mixture of phenazine-based compounds. Its main industrial uses are as a colorant for lacquers and varnishes and in marker pen inks. Sulfonation of nigrosin yields a water-soluble anionic dye, nigrosin WS (CI 50420, Acid black 2).[2]