In 1933, a student at the University of California named Bob Switzer fell and hit his head. He had been removing boxes from a freight car for a summer job when he tumbled off the loading dock and was knocked unconscious.

Months later, Switzer awoke from a coma with blurred vision. To continue his recuperation, his doctor recommended avoiding bright light. His father, a pharmacist, turned his shop's basement into a darkroom for Bob's recovery.

That sparked Bob’s interest in ultraviolet, or black, light. Bob's younger brother, Joe, was a chemistry student and an amateur magician who was also interested in the black arts—playing with ultraviolet light and fluorescence (not sorcery) to create the illusion of objects appearing and disappearing on a darkened stage. Hoping to find chemical compounds that would glow in UV light, the brothers mixed the pharmacy’s supply of Murine eye wash with alcohol and white shellac, which created a fluorescent yellow substance under black lights.

The Switzer brothers’ breakthrough would eventually lead to their development of a dazzling fluorescent rainbow of pigments, which they trademarked as DayGlo colors. From traffic-cone orange to Pepto Bismol pink to yellow the shade of Mountain Dew, DayGlo’s colors have been used in industrial machinery, safety equipment, and psychedelic posters. The eye-popping palette has been saving lives and expanding consciousness for more than eight decades.

At first, Joe put the yellow dye to work in his magic show. In his signature act, a woman appeared on a darkened stage wearing a costume and headdress of fluorescent painted paper. Lit only by UV light, Joe would take the woman’s headdress off in one direction while the woman danced in the opposite direction, so her head appeared to separate from her body. With this trick, Joe won the prize at the Pacific Coast Association of Magicians in 1934 and created a fan base willing to spend $10 a pint for fluorescent paints. Bob and Joe thus established their first company, Fluor-S-Art Co.

By the summer of 1935 the Switzers had moved to Cleveland, where they worked for a subsidiary of Warner Brothers, creating dramatic special-effects scenes called “midnight paintings” for movie theater lobbies. The glowing tableaux appeared to transform when a black spotlight switched to a white light. This effect worked well in the darkness of theaters. But when the brothers tried to branch out to painting traditional billboards and store advertisements, regular white light sources faded the colors.

Bob and Joe continued to experiment, hoping to create a luminous paint that shined in daylight. In 1936 they created their first batch of pigments that reflected visible color from the spectrum, while also absorbing and transforming UV wavelengths of colors lower in the spectrum. As a result, viewers perceived a more intense, dazzling color. The first products were patented in 1937 as DayGlo fluorescents.

Initially, DayGlo colors were used for commercial advertisements. But when World War II erupted, the dyes found a new niche. The military spent $12 million on DayGlo dyes for safety applications like flags or painted signals that could be seen by airplanes 10,000 feet in the air, buoys that marked where underwater mines had been cleared, and suits worn by aircraft carrier crew to guide nighttime plane landings. Thanks to the colors’ use in safety fabrics, Joe and Bob Switzer became very rich.

During this time, the Switzers also developed black light penetrants, a type of pigment that reveals flaws in machinery when painted on the metal parts and exposed to UV light. Patented as Magnaglo and Zyglo, they became widely used by the U.S. Air Force for ensuring the integrity of airplane parts.

Justin Sullivan/Getty Images

After World War II, Bob and Joe founded Switzer Brothers, Inc., later renamed the DayGlo Color Corporation. The company continued its production of flaw-revealing pigments, but now began to experiment with producing daylight fluorescent colors for consumer product packaging. In 1957, the company patented a process that combined fluorescent dye with a polymer, which gave the dye greater light stability for use as outdoor paints as well as in traditional printing applications.

The company convinced advertisers to adopt its super-fluorescent inks and papers, and in 1959, Proctor & Gamble opted to package its Tide laundry detergent, the first heavy-duty synthetic soap, in the Switzers' Blaze Orange hue. Soon, the DayGlo fad expanded from supermarket shelves to clothing, toys, and rock n’ roll posters in the 1960s. Pop artists like Peter Max and Andy Warhol incorporated psychedelic colors into trippy paintings and lithographs.

DayGlo eventually reached the zenith of pop culture relevance when the Beatles wore military-style suits in DayGlo colors on the cover of Sgt. Pepper’s Lonely Hearts Club Band in 1967.

The Switzer brothers’ legacy shines on in their rainbow of trademark high-visibility tones—Saturn Yellow, Blaze Orange, Aurora Pink, Neon Red, Corona Magenta, Signal Green and many more—that are found on everything from food wrappers to public safety workers today.

In 2012, the American Chemical Society awarded DayGlo Color Corporation a national historic chemical landmark designation for the development of its pigments, citing the Switzer brothers' inventions as a “symbol of safety and protection that improve our daily lives.”