Black Lights

In the late 60s and early 70s, the Black Light brought a new dimension to our world. White T-shirts and teeth suddenly would glow in the dark, and gaudy fluorescent hippy posters would come alive with secret symbols and slogans.

These days you will only see black lights in night clubs (where you can always tell at a glance which girls are wearing white panties or bra under their dancing clobber ;)