thumb|Luminous ink under ultraviolet light
thumb|Fluorescent paintings lit by black light
Black light paint or black light fluorescent paint is luminous paint that glows under a black light. It is based on pigments that respond to light in the ultraviolet segment of the electromagnetic spectrum. The paint may or may not be colorful under ordinary light. Black light paint should not be confused with phosphorescent (glow-in-the-dark) or daylight fluorescent paint.
History
The invention of black light paint is attributed to brothers Joseph and Robert Switzer in the 1930s. After a fall, Robert suffered a severe head injury that resulted in a severed optic nerve. His doctor confined him to a dark room while he waited for his sight to recover. Joseph, who was a chemistry major at the University of California, Berkeley, worked with Robert to investigate fluorescent compounds. They brought a black light into the storeroom of their father's drugstore looking for naturally fluorescing organic compounds and mixed those compounds with shellac to develop the first black light fluorescent paints. The first use of these paints was for Joseph's amateur magic shows.
The brothers founded the Fluor-S-Art Company, later named Day-Glo Color Corp., to develop and sell their products. The first commercial uses of black light fluorescent paints were for store displays and movie theaters. During World War II, black light fluorescent paints were used on U.S. naval carriers to allow planes to land at night.