Nigrosine Acid Black

In staining dyes, nigrosin 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. Related to induline, it is a mixture of phenazine-based compounds. Its main industrial uses are as a colourant 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).

Usage of Nigrosine Acid Black:

Medicine, Manufacturing, Colouring and other.

Dyeing of Leather, Water Base Ink, Decorative laminate, Shoe Polish, Waxes, Silk Dyeing, Wool dyeing, Nylon dyeing.

Aside from its main use in lacquers, small amounts of nigrosin are used for negative staining of bacteria, as well as the capsule-containing fungus Cryptococcus neoformans. The shapes and sizes of the organisms are seen as color-free outlines against the dark background.