The first mention of candles in history can be traced back to Biblical times. Even today, scientists around the world are still experimenting with candle flames. Now one interesting aspect of the candle flame is that, unlike wood or gas, it exhibits various colors when burnt. If you’ve looked closely, you already know that the base looks blue. But it changes to orange and eventually turns yellow at the top.
Now we are used to seeing yellow or light orange in things that are burning. But why is a candle blue? In short, the base of a candle flame is blue because this is where the hydrogen and carbon atoms break apart. Still confused? Below we’ve provided a detailed explanation of why a candle flame is blue.
Why Candle Flames are Blue?
The bottom part of the candle flame is blue. This is where the molecules of the fuel get heated and turn into vapor. This area has a lot of oxygen and the molecules start to break apart at very high temperatures, up to 2500°F. It’s the hottest and most concentrated part of the flame.
This disintegration of oxygen and hydrocarbon molecules separates into carbon and hydrogen atoms. Hydrogen is the first to separate in this region and combines with oxygen to create water vapor. Simultaneously, a portion of the carbon undergoes combustion, creating carbon dioxide.
Additionally, there is a visible blue “veil” that surrounds the entire flame, which you might need to take a closer look to find. This veil exists because the flame is exposed to oxygen from all sides. Similar to the blue base, this thin veil can also reach temperatures above 2500°F.
But Why Not Any Other Color?
So, we’ve already established that as the flame gets more and more saturated, it turns blue in color. But why blue though? You see, when hydrocarbon breaks down, the dominant color is blue. Therefore, as the base of the candle flame is the most saturated part. That’s why the base of a flame, in this case candle flame, is blue.
And as the condensation gets lighter going up, the blue turns into orange and eventually pale yellow.
Why It Turns Yellow at the Top?
Now as we go up, the combustion starts to get lighter. So, without complete combustion, there’s less density of heat and light, which turns the flame yellow.
So, to sum up, the blue flame is a result of complete combustion, which is smokeless and produces more heat compared to a yellow flame. In the case of the top part of a candle flame, incomplete combustion occurs, giving it a yellow color. On the other hand, in an LP (Liquefied petroleum gas) stove, complete combustion takes place, resulting in a blue flame.
FAQs (Frequently Asked Questions and Answers)
Why is candle blue in zero gravity?
On Earth, the force of gravity creates a flow of hot air in the shape of a teardrop around a candle flame. This flow carries soot to the tip of the flame, causing it to appear yellow. However, in the absence of gravity, there is no flow of hot air. As a result, the flame becomes round and does not produce soot, giving it a blue color.
Does a candle produce blue light?
No, candles generally produce warm light with a dim incandescent aura. This has little to no blue light present in it. It’s a more yellowish tone.
Is fire naturally blue?
Fire has no natural color. The color depends on the temperature. Typically, between 2,600º F and 3,000º F, it turns blue, which is rarely seen when burning wood. But when burning natural gas, this kind of temperature is easily attainable.
Final Thoughts
So, now you know why a candle is blue, especially at the base of the flame. It is simply because all the actions are happening there and therefore it’s more heated than any other part of the flame. However, lighting a match stick is easier if you hold it on the top of the flame rather than on the bottom blue part. It’s because of its condensed environment, it radiates heat less effectively than the yellow portion.
Hope you found this article interesting and informative. Thanks for reading.