Black lights are used in stage productions for special effects and to show off items that might first appear invisible. Black lights are also used at clubs and other entertainment venues as a means of detecting those who have already paid an entrance fee. A UV stamp is applied to a portion of the body upon entering. If the patron leaves and returns, a black light device is used to detect the stamp.
Black light devices are used in modern pest control. This device can make certain pests, such as rodents and scorpions, easily visible. The black light can also be used to illuminate the urine trails and feces of rodents. This helps the pest control agent see the path of movement around an area. Pest control also uses black lights to attract insects to an electrical rod. The insects are attracted by the light but hit the rod and are killed.
U.S. currency can be detected as false by using a black light. Each treasury note has a phosphorous strip implanted that can be easily detected under black light. Counterfeit debit and credit cards can also be easily detected. Modern cards are stamped with a small UV symbol that is illuminated under a black light device. Counterfeit cards are easily detectable when the stamp is not illuminated
A black light device can be used to easily detect automotive leaks. The mechanic can flush an engine with a florescent UV dye. When passing a black light device over the engine, the source of the leak is illuminated. Leaks that might otherwise be hard to detect are easy to see. This same process can be used in other areas to detect leaks, such as running an luminescent dye through an air-conditioning system.