The candle flame: scientific reasons for enduring romantic fashion and appeal

I would not know of a better invention than a smoke and carbonless burning candle."
Johann Wolfgang von Goethe (1749-1832)

"All the natural forces encountered in space can be found in the chemical history of a candle."
Michael Faraday (1791-1867)

"How far that little candle throws his beams - so shines a good deed in a naughty world."
The Merchant of Venice,
William Shakespeare (1564-1616)

In our age of high technology, let us examine the candle flame in a purely scientific way. When we light the wick of a candle, the heat from the flame causes the wax to melt. The liquid wax then rises by means of the capillary attraction up along the wick and evaporates when it reaches the end of the wick. This releases hydrocarbon molecules.

The hydrocarbon molecules are then split in smaller molecules, which chemically react among each other and with the oxygen from surrounding air. Solid carbon particles become incandescent as a result of the hot gases and heat radiation from the reaction zone. This incandescent glow gives us the warm red-orange-yellow candle light.

Since the combustion of all carbon particles is not always 100% guaranteed, this causes uncombusted carbon particles to escape. The result is smoke (small uncombusted carbon particles) or carbon soot residues, also known as "mushrooms" (large uncombusted carbon particles).

Therefore, although a candle flame can never be entirely "smoke-less", the amount of uncombusted carbon particles can be minimized through the use of the best raw materials for the candles and a wick which is constructed and/or treated to bend slightly in order to reach the outside of the flame, which has the highest temperature zone.