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.
The so-called black light comes from ultraviolet rays that are invisible to the human eye. However, when they shine on various chemical substances they glow with an eerie assortment of colours.
The ultraviolet rays are called black light because we do not see them – but we do see their lighting effects.
In the late 60s and early 1970s, special blacklight posters – painted and printed with Day-Glo paint which intensified the colours – were extremely popular.
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 😉