fluorescent brightening agent

Fluorescent brighteners are chemical agents used to enhance the appearance of materials by making them appear whiter and brighter. These compounds are not dyes in the traditional sense. Instead, they absorb ultraviolet light and reemit it as visible blue light. This process masks the natural yellowish tint found in materials like raw natural fibers, paper, and plastics, which is caused by light absorption or natural pigments.12

Originally developed in 1927 for banknote security, fluorescent brighteners are now widely used in textiles, paper production, detergents, and plastics. They work by emitting light, making the material seem whiter than it would appear with just bleaching. This phenomenon is a form of fluorescence, where atoms are excited and emit light almost instantaneously.23