Phosphorescent material is used where it is required to remain luminous after the activating source is removed. Such material is intended for applications to be observed for as long as 8 hours, after the observer has become well dark-adapted. It is not suited for uses requiring observation before the observer has been dark-adapted less than 20 minutes.

Fluorescent material is intended for nightime applications requiring constant low intensity localized illumination. Its use requires special ultra-violet lighting equipment and practically requires custom-built installation for the specific application. Fluorescent material also is intended for daylight use where greater luminance and contrast is desired. In this case, sunlight furnishes the ultra-violet. Such materials "reflect" more than 100 percent of the incident visible light due to the conversion of ultra-violet to visible light.