Colorfully glowing phosphorescent materials are often neutral in color under normal light
Phosphorescent, or glow-in-the-dark, materials are widely and commonly used in novelty items. However, they have other, potentially more important uses, largely as safety equipment or signage.
Definition
Phosphorescent lighting is a lighting system that functions by absorbing light energy during the day or when other nearby lights are shining, then releasing it gradually at night or in other dark conditions.
Uses
Phosphorescent lighting is useful for marking object edges, pathways and stairs that might otherwise be hazards for anyone moving around in the dark (during power outages, for example). They are also used to make glowing signs, such as exit signs, that can be read without any other light source or a power supply in the event of an outage.
Limitations
Phosphorescent light sources do not shine as brightly as traditional incandescent bulbs and are of limited use as general light sources. They can also only release what light energy they have previously stored, after which they will cease glowing until exposed to light again. Phosphorescence is also dependent on thermal energy for the release of stored light and as such is not useful for cold-weather applications. Because of this, it is largely restricted to indoor use.
