Candles have been used since the olden ages for illumination. In fact, if you trace the history of candles all the way back, you will find that they were being used as far back as 3,000 B.C.
The first candle was made by the Egyptians using beeswax, and they were also responsible for the creation of the first true candle holder, which they made using clay.
Today, candles are used for a variety of purposes. Ever since the introduction of electricity thanks to Nikola Tesla, candles have become all but redundant for use in the night.
However, people still use them for a more warming effect in their house. On top of that, candles are very useful when there is a blackout and no access to electricity.
Almost all of us have lit a candle in our lives. When you do light it up, you notice that the wax begins to melt, until the candle gets smaller and smaller. The wick eventually falls down and the candle is extinguished. But, have you ever wondered where all the wax goes?
To understand this answer, you need to go into a bit of detail. Let’s talk about how a candle works, and the principles that it uses.
Candles Use Combustion
Candles generate light by generating heat. So, in a way, you could say that the candle is a pretty crude and basic example of an incandescent lamp. The light generated by the candle is because of the process of combustion.
The wax, which is usually made from chemicals that include a carbon base and are derived primarily from petroleum, reacts with the oxygen in the air.
This leads to the creation of a colorless gas otherwise known as carbon dioxide. A small amount of water is also generated as a byproduct of the reaction, though in its gaseous form; steam. In almost all situations, the wax never burns in a perfectly clean manner. As a result of that, a little bit of smoke is also produced.
The smoke produced by the candle is usually an aerosol, and often leaves a bit of charring on the walls or a black carbon deposit on the ceiling. If you look at the flame burning in the candle, you will notice a few things.
First of all, you will see that the steam being generated by the flame usually emanates from the blue part of the flame.
The flame is divided into several colors. At the center, it’s completely blue. Then, you have the slightly more orange shade, and finally, the yellow part of the flame.
Where the flame burns perfectly (the blue section), the wax is able to burn cleanly, and as a result creates steam. On the outer areas, where there’s an imperfect burn, the wax generates smoke.
Now, most people just think that wax is wax, and don’t think too much about it. However, if you want to know where it goes during the combustion, you need to understand its composition.
Wax is a bit like plastic in the sense that it is made using a series of different substances. It’s very similar to plastics, because it contains a series of different chemicals that combine together to create the material.
When you light up the candle, the wax is what actually burns into the air. Thanks to the principles of capillary action, the wax is drawn up the wick (the wick usually runs the entire length of the candle), and it evaporates as the flame reaches around 200 degrees Celsius.
In the simplest of terms, the wax is used to feed the flame and keep it lit. There are paraffins, which are simply long-chained hydrocarbons that react with the oxygen in the air to create carbon monoxide.
This combines with the oxygen to create carbon dioxide which is the source of the blue light at the bottom of the candle flame.
At the edges of the flame, the amount of oxygen is lower, as the environment becomes hotter, and ultimately, the carbon entropy is reversed. This leads to the creation of unsaturated acetylenes, which polymerize and turn into nanoparticles that are rich in carbon.
As the black body emissions fill up the air, these particles tend to glow yellow, which is why the outer part of the flame is completely yellow. As it goes up, the flame continues to get hotter and hotter.
That is why the wax continues to melt and the candle continues to get smaller and smaller as it burns up.
Why Does the Flame Point up?
Another common question that many people have in mind is why the candle flame always points up when it’s burning. When you burn the candle, the flame heats up the nearby air and begins to rise.
Hot air always rises up, so when the air around the candle begins to rise, the oxygen rushes to take its place at the bottom (thus the blue flame at the bottom).
Again, when the cooler air also heats up, it is replaced by the cooler air around it. This is a process that continues to repeat itself for as long as the candle is burning.
It creates a continuous cycle where the air generates an upward movement and ultimately leads to the formation of a convection current around the flame.
That is what gives the flame its teardrop appearance or the elongated shape. Scientists actually conducted an experiment whereas they lit a candle flame in microgravity, and instead of having an elongated, teardrop appearance, the flame was actually spherical in nature.
The candle radiates heat and light all around its surroundings. At least one quarter of the energy that is generated from the combustion created by the paraffin is released as heat, so candles aren’t really a very efficient form of illumination.
However, the heat is important because it vaporizes the wax and continues to support the reaction.
This allows the candle to burn for as long as there is wax inside. This creates a steady supply of fuel. The reaction comes to an end when the wax is all melted, and that is when the flame withers and dies.
It’s also interesting to note that even though a small amount of steam is released by the candle as it burns, the air around it usually feels quite dry.
That’s because the temperature around the candle allows the air to hold more water vapor. Now, a question that arises in most people’s minds is whether they can inhale the wax from the candle. Thankfully, the chances of that happening are incredibly low.
When a candle burns steadily with its teardrop shape, it’s relatively efficient and only releases water and carbon dioxide. If the flame begins to flicker, it usually indicates a lack of heat for the candle to burn properly. These are just a few things that you should know about burning candles and the wax.
It’s important to note that the wax is much more efficient than what was used in the past. Today, you can easily find candles that can burn for days on end without melting into nothing, so you might as well choose a more efficient one.
I have a bachelor’s degree in construction engineering. When I’m not constructing or remodeling X-Ray Rooms, Cardiovascular Labs, and Pharmacies…I’m at home with my wife, two daughters and a dog. Outside of family, I love grilling and barbequing on my Big Green Egg and working on projects around the house.