Fluorescent material is a type of 3D printing filament that is characterized by its ability to glow under ultraviolet (UV) light. Special pigments are added to the base plastic, such as PLA or PETG. These pigments absorb invisible UV radiation and instantly convert it into visible light, causing the print to take on an intense and bright color. This phenomenon is to be distinguished from phosphorescence, known as 'glow-in-the-dark'. While phosphorescent material continues to glow after the light source is turned off, fluorescent material only glows when directly irradiated by a UV lamp, often referred to as 'black light'. Once the UV light source is removed, the glowing effect disappears immediately. It is used for printing objects where a strong visual effect under specific lighting is desired. For example, decorations, models or functional parts that are to be easily visible under UV lighting.