The Candle Flame

The candle flame is the whole reason for the existence of the candle. The light given off by a candle allows us to see through the darkness; it creates romantic or nostalgic ambience for our living spaces. In our holy places the candle flame symbolizes our faith and devotion. We find calm or vigor from aromatic essences released by the heat of the flame in scented candles.

One might find oneself mesmerized by the intoxicating glow of the flame of a candle. A fascinating thing is a flame, dancing on the end of the wick of a candle, beckoning us to wonder and marvel at its existence. What is it? How does it give off its light?

Fire is a strange thing. It may be difficult to understand, but what we perceive as the flame of a candle is not truly fire at all, rather it is an effect of fire. Actual fire is virtually invisible to the naked eye. It is intense heat created by a chemical reaction. The light we see, as what we call a flame, is the luminescence of substances which are super heated but not burned. Like a when a blacksmith works a horseshoe made of iron he has removed from hot coals, the iron glows bright orange but is not on fire. Elements passing through the flame of a candle glow brightly in the heat of an invisible fire.

A perfect example of the incandescence in an invisible fire is "limelight". You may have heard of limelight in reference to the 19th century stage or theater. At the time limelight was the brightest, most natural color of artificial light available. The light was produced by placing a block of lime (calcium oxide) within the combustion area of a hydrogen/oxygen jet flame. The flame from the combustion of hydrogen and oxygen gives off no light even though it is one of the highest temperature flames man can produce. Lime is not chemically affected by either hydrogen or oxygen, and has a very high melt point (2600 degrees). When a block of lime is placed within the flame it gives off light.

The reason that limelight is a perfect example to compare with a candle flame is that in limelight, calcium oxide is a non-combustible substance which gives off light when exposed to high temperatures. Its counterpart in the candle flame is carbon. When a substance is exposed to extreme heat its molecular structure may break apart. In the case of a candle flame, hydrocarbons are broken apart. While the hydrogen atoms from the hydrocarbon combine with free oxygen to create water, the non-combustible carbon atoms are released. Driven upward on a column of hot air the carbon atoms become incandescent as they pass through the invisible fire. This is what we perceive as the candles flame, the glow of floating carbon atoms.

How does a candle burn?

An interesting thing about a candle is that it is a very good example of the four states of matter. The four states of matter are Solid, Liquid, Gas, and Plasma. Wax, the fuel source of a candle goes through all four of these states of matter.

Let's see what happens when we light a candle. We need a catalyst to start the whole thing going, so we touch a flame to the end of the wick. At first the wick itself starts to burn. The flame creeps down the sides of the wick and usually diminishes until it touches the wax. This is when the mechanism starts to work. The heat from the flame melts the wax surrounding the base of the wick directly beneath it. By the principle of capillary action the melted wax is drawn into the wick providing fuel for the flame which bursts to life.

The candle continues to burn through an ongoing cycle. Wax in a solid state of matter is melted by the heat of the flame and converts it to a liquid state of matter. The liquid wax is drawn up to the tip of the wick inside the flame. At this stage the liquid wax is heated even more and it vaporizes changing into a gaseous state of matter. The gaseous wax enters the combustion area of the flame and is converted to energy. The energy conversion gives off heat, which melts more of the solid wax. The cycle repeats itself until the wick no longer functions due to consumption or lack of fuel for the flame.

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