Red powder is a polysemous term, and here are its two meanings: Firstly, red powder is a widely-used aniline red pigment, also known as 221 purple-red powder. It is primarily used for coloring coatings, inks, paints, leather, rubber, plastics, latex products, building materials, printing inks, educational and cultural goods, and cosmetics. Red powder has a broad range of applications and is an important pigment in many industries. Secondly, red powder can also refer to Rhodamine B, a bright peach-red synthetic basic fluorescent dye, also known as Rose Red B or Basic Rose. Rhodamine B is mainly used as a cell fluorescence stain in laboratories, dyeing agents, the paper industry, and in the manufacture of paints and pigments. It can also be used for dyeing fabrics and leather goods. However, Rhodamine B has certain toxicity and genetic toxicity, and is classified as a class 3 carcinogen by international research institutions, meaning its carcinogenicity to humans is suspected.