The Fluorescent Brightener 363 , with the CAS registry number 95078-19-6, is also named as Uvitex BAC . It is cation and presents light brown dispersion. It is mainly used for brightening of acrylic and its blended fabrics.

Fluorescent brightening agents (FBAs) are dyes. They can absorb light in the ultraviolet and violet region (usually 340-370 nm) of the electromagnetic spectrum, and re-emit light in the blue region (typically 420-470 nm). Phosphorescence is a delayed emission, but fluorescent activity is a short term or rapid emission response. There are approximately 400 brightener types listed in the Color Index, but less than 90 are actually produced commercially and only a handful are commercially important.

Brighteners are commonly used as whitening agents during washing and to make the clothes appear cleaner. Brighteners are also used in many papers, especially high brightness papers, resulting in their strongly fluorescent appearance under UV illumination.