Soy Candles and Their Alchemy

Long ago, candles were important for everyday life, giving a source of lighting after sunset. These days, scented candles are a luxury - using fragrance to create varied moods, while their dancing flame soothes the mind.

Candles consist of two basic elements: 1) a fuel source i.e. wax and 2) a wick. The wick is significant to the candle function as it serves as the fuel delivery system.

A naked flame is used to ignite the wick, which then melts some of the wax at the candle exterior. The liquefied wax is drawn up through the wick fibres by capillary action - this is because of the way soy wax molecules adhere to the wick fibres.

After the soy wax reaches the uppermost part of the wick, it turns to vapour upon contact with the burning flame. Combustion occurs as hot soy wax vapour combines with oxygen, producing the candle flame. Heat and light are released in this exothermic reaction.

Interestingly, a candle wick only burns at its very tip. The other parts of the wick are involved in capillary action, and are protected from burning by the vaporisation of the fuel. This has to do with a chemical property named the latent heat of vaporisation, in which the fuel takes up much of the nearby heat, allowing it to change from liquid to gas. This effect maintains the wick at a lower temperature than it would typically be.

The flame keeps burning, generating generous amounts of liquid wax, which is used as a fuel and vaporised. This creates the highly fragrant essential oils into the air.

Why are natural soy wax candles good?

Soy is a native East Asian plant that is both a renewable material and biodegradable - hence it is an eco-friendly option for the responsible consumer. The soy plant can be continually developed without harming the natural ecosystem.

To generate soy wax, the soy beans are farmed from the plant and processed into oil, which is then distilled and hydrogenated. Converting unsaturated fatty acids into saturated fat - generating a firm creamy white wax.

Soy wax has the benefit that it is slow burning due to its low melting point, this results in appreciably longer burn times for soy candles. It is also a very clean burning wax, and does not discharge dangerous chemicals such as toluene and benzene as paraffin based candles can.