Solvent Black 7, also known as Nigrosine Base, is the free base form of Solvent Black 5. It is distinguished by its excellent solubility in a wide range of resins and binders, particularly shellac and synthetic resins. This property makes it a superior choice for high-quality printing inks, carbon paper, and for coloring plastics. It produces a deep, jet-black color with high strength and stability in various formulations.