Naphthol Green B is primarily used as a dye in various industries. It is commonly applied in the textile industry for dyeing wool, silk, and cotton, providing a greenish hue to fabrics. In biological staining, it serves as a contrast agent in microscopy to highlight specific cellular structures. Additionally, it is utilized in the paper industry for coloring paper products. The dye is also employed in the manufacturing of inks and coatings, where it imparts a stable green color. In some cases, it is used as an indicator in analytical chemistry due to its pH-sensitive properties. Its versatility and stability make it a valuable component in multiple industrial applications.