Tuesday, January 09, 2007

Relighting Candles

Here's a bit of grade school science that I learned over the holidays: Did you know you can relight a candle simply by lighting the smoke that comes off once it's extinguished? If you don't believe it, check out this video or try it yourself. The explanation is in the way a candle works. Liquid wax is absorbed by the wick where it is vaporized by the flame and it's the parrafin vapour that burns. When extinguished, the plume of smoke that is visible is condensed parrafin vapour that can then be relit, the flame traveling down and re-igniting the wick. Not exactly hard-hitting science, but a decent party trick.

Those trick relighting candles work on the same principle, only in this case, the wick is treated with a metal that combusts at low temperature (usually magnesium). The ember in the extinguished wick ignites the magnesium which provides the heat to light the parrafin vapour.


Anonymous Coward said...

My favorite party trick: bet that the circumferance of the rim of a pint of beer is greater then the hight of the glass. In fact you can stack 2 glasses one into the other and it still works as the circumferance of an average pint glass is 27cm while the height is only 15.