What is the science behind a burning candle?

Putting aside all bias, let's focus on the science of burning candles!

A burning candle is a classic example of a chemical reaction between three major elements: oxygen, hydrogen, and carbon. The wax in a candle is composed of atoms of hydrogen and carbon. When the wick is lit, wax begins to melt and the carbon and hydrogen atoms move up the wick to react with the oxygen atoms in the flame.

Over the past decade, there has been a steady climb in the sales of soy wax candles - with many claims being made that soy candles are somehow "better" for us. Putting aside all bias and focussing on science alone, the following conclusions were made by scientists and they make for interesting reading!

  • All waxes are primarily hydrocarbons, whether the wax is of animal, vegetable or petroleum origin. The chemical composition of all waxes used for candle making is similar.
  • All waxes produce a yellow flame due to the presence of carbon.
  • No specific type of wax or wax blend is considered "best" for candle making. All candle waxes, when provided in a high-quality format, have been shown to burn cleanly and safely.
  • No candle wax has ever been shown to be toxic or harmful to human health.
  • There is no such thing as a soot-free wax. All organic compounds when burned will emit some carbon (soot) due to incomplete combustion. (

Scientists in universities and research laboratories around the world will no doubt continue to conduct experiments with candles to learn more about candle flames, emissions, and combustion, and of course thousands of students every year investigate the principles of heat, light, and combustion in school science projects involving candles.