“For a magical time in the 1960s and ’70s, your wood-paneled basement hideaway wasn’t worth its weight in cheap weed and questionable acid without a collection of psychedelic blacklight posters. Combining Art Nouveau, Surrealism, Pop Art, and countless other artistic styles with the relatively new (commercially anyway) phenomenon of fluorescence, these glow-in-the-dark posters became an icon of the Summer of Love and its youth culture. Here’s where they came from and how they worked.”