How a candle wick works

Candles may look simple but they’re remarkably ingenious. Set fire to the wick (the little string poking up at the top) and heat travels rapidly downward toward the wax body of the candle beneath.

The wax has a low melting point so it instantly turns into a hot liquid and vaporizes, funneling straight up around the wick as though it’s rushing up an invisible smokestack (chimney). The wax vapor catches light and burns, sending a flame high above the wick.

Heat from the flame travels in three directions at once by processes called conduction, convection, and radiation. Conduction carries heat down the wick to melt more wax at the top of the candlestick.

Convection draws hot wax vapors out from the wick and sucks oxygen from the surrounding air into the base of the flame. The flame also gives off invisible beams of heat in all directions by radiation. The candle continues to “feed” on the wax underneath it until it’s all burned away—until all the potential energy locked away in the wax is converted to heat, light, and chemical waste products.