Vat Blue 4B is primarily used in the textile industry for dyeing cotton, linen, and other cellulose fibers. It is valued for its ability to produce deep, vibrant blue shades with excellent colorfastness to light and washing. This makes it suitable for applications where durability is essential, such as in workwear, upholstery, and outdoor fabrics. Additionally, it is often employed in the production of denim, contributing to the classic blue jeans appearance. Its use extends to printing inks and paper coloring, where consistent and long-lasting color is required.