Benzopurpurin 4B is primarily used as a dye in various industrial applications. It is commonly employed in the textile industry for coloring fabrics, particularly cotton and other cellulose-based materials, as well as in leather dyeing. The dye is valued for its ability to produce vibrant red or purple colors that are long-lasting and resistant to washing. Additionally, it is used in biological staining techniques, where it helps in the visualization of specific tissues or cellular components, such as elastic fibers, under a microscope. In some cases, Benzopurpurin 4B is also utilized in the paper industry for coloring paper products. Its strong affinity for certain materials makes it a useful tool in both industrial and scientific contexts.