How does the Life Saver spark trick work and what causes it?

One of the three best in-the-dark revelations of adolescence is that if you crack a Wint-O-Green Life Saver between your teeth, tiny blue and green sparks will flash in your mouth.

If you’ve never seen it happen, pick up a pack of Wint-0-Greens and wait until after dark. Turn out the lights and crunch one between your teeth while standing in front of a mirror.

Besides feeling silly for going to this much trouble, you’ll see a blue-green spark.

But how does it happen? Nabisco says it gets about fifty to a hundred queries about this phenomenon every year, —enough to have a canned answer: “Triboluminescence resulting from crystal fracture” at work.

Huh? Simply put, when crystalline molecules are smashed, the free electrons collide with the plentiful molecules of nitrogen in the air. The nitrogen molecules become excited and vibrate.

They emit this extra energy in the form of mostly invisible ultraviolet light, but a small bit of visible light is emitted as well. This is the spark you see in the mirror.

All hard candies that contain sugar create triboluminescence when cracked. So why do Wint-O-Greens produce a visible result when other flavors don’t?

Because oil of wintergreen has the special ability to take in light with short wavelengths (invisible ultraviolet) and then spit out light with longer wavelengths (visible blue-white light), thanks to fluorescence.