Phosphorescent Paint

Some fluorescent materials do not give out visible light immediately but act as light stores, giving off visible wavelengths for a period of time after the incoming light source has been turned off. This phenomenon of slow emission is called phosphorescence and is what gives us glow-in-the-dark paints. The phosphorescent pigments in such paints contain fine crystals of zinc sulphide with copper added as an activator that allows the crystals to absorb light and slowly emit it over time.