Direct Black 38 is primarily used as a direct dye in the textile industry for coloring cellulosic fibers such as cotton, linen, and viscose rayon, providing deep black shades with good fastness to light and water. It is suitable for continuous dyeing processes and is ideal for products requiring intense black color, like workwear, curtains, and industrial fabrics. Additionally, it is applied in the paper industry for coloring paper products, in leather dyeing (often with aftertreatment for improved fastness), and in certain printing inks due to its strong staining properties and water solubility. Not suitable for food, pharmaceutical, or direct skin contact applications.