Why Do Candles Get Smaller As They Burn?

People have been using candles since ancient times for lighting up their houses. Today, along with lighting, candles are also used for various purposes like décor and fragrance. Hence, all of us have lit a candle at least once. When a candle is lit up, you notice that it gets smaller and smaller in size. The wick eventually blows off while the candle extinguishes. Have you ever wondered what is the reason behind it?

When we burn a candle, it ends with less wax than it started with. This is because the wax burns or oxidizes in the flame to produce carbon dioxide and water as by-products, which dissipate in the atmosphere around the candle, emitting light and heat.

A Candle Uses Combustion

The candle wax consists hydrogen atoms with surrounding chains of connected carbon atoms. When a candle is lit up, these hydrocarbons are burnt, melting the wax near the wick into a liquid form. The wax molecules are vaporized by the flame’s heat, reacting with the oxygen in the air. As this wax is consumed, the flame takes in more of it, leaving no ash or residue behind.

The combustion reaction gives off 25% of its energy as heat, which is more than enough to melt more wax from the burning candle. This cycle of combustion reaction continues till the whole of the candle wick burns down, or until the candle is blown off. This is the reason why the size of the candle gets smaller and smaller as long as it burns. 

This video would explain the burning process and why the burning candle decreases in size.

Why Does The Flame Smoke Or Stutter?

Sometimes, the combustion reaction of a burning candle does not go perfectly, resulting in either much or too little melted wax, leaving the combustion reaction incomplete. This incomplete combustion causes the candle flame to form soot or stutter. This stuttering of a flame is more common right after the candle has been lit, while the combustion reaction is still stabilizing. After the stabilization, the candle flame would continue to burn steadily. 

Can You Breathe In The Vaporized Candle Wax?

There is no need to worry about breathing in the vaporized candle wax because it exists only around the burning flame and instantly dissipates as soon as the flame is blown off. However, you should take a few measures to prevent your candle from stuttering or producing too much soot, which can be unpleasant to inhale.

You can do the following things to avoid the candle flame from producing soot:

  • Trim the candle’s wick if it is too long, as it might take in too much melted wax, resulting in more soot. 
  • Keep your candle away from gusts and drafts that can cause the candle to burn unevenly. 

Parting Ways

Candles are very simple items, but the science behind their operation is quite fascinating. However, today you can even buy candles that can burn for days without melting down a single inch. How cool is that? So, go get yourself one today!

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