 Although black lights date to 1903 with the development of Wood's glass, fluorescent ink was not developed until 1932 when the Switzer brothers were inspired by a "Popular Science" article to experiment in their father's pharmacy.Their Day-Glo Color Corp. marketed the ink chiefly to the military before a counterculture emerged to embrace the aesthetic.The 1960s saw the pervasive use of illegal drugs, especially mass use of hallucinogenics such as LSD (lysergic acid diethylamide), mescaline, and marijuana for the first time.