Used as a deep black dye for coloring wood, paper, and leather, providing a rich, uniform coloration. Commonly applied in inks, especially for printing and ballpoint pen formulations, due to its good solubility in alcohol and strong staining properties. Also utilized in biological staining to enhance contrast in microscopic examination of specimens, particularly for negative staining of bacteria and cell structures. Its alcohol solubility makes it suitable for use in spirit-based polishes and coatings where water-based dyes are ineffective.