We use candles almost daily, but do you ever wonder what happens when they’re burned? Sure it disappears- but why does this happen, and is burning a candle safe for your house in general or just certain materials with special care requirements. This article will discuss these questions more thoroughly by focusing on chemical reactions that cause them as well as how much flame affects the wax itself.
Most of the candle wax evaporates in the air. A small amount remains on top before sinking. Some spilled wax also forms puddles around the base. If the flame is flickering, a lot of wax is melted too quickly. As a result, it accumulates and starts dripping off the candle edges.
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The chemical reaction of a candle explained.
Understanding what exactly happens when burning a candle is not as simple as just burning the wick because many different compounds react differently.
Wax is made of long chains of carbon and hydrogen. That’s why it is classed as a hydrocarbon. Lighting a candle involves using candle wax as a fuel for combustion.
Combustion is a reaction between hydrocarbons and oxygen that yields carbon dioxide and water. This reaction is exothermic in nature, meaning that it releases a lot of energy in the form of heat and light.
This energy is produced when the complex bonds between hydrogen and carbon are broken. Candles produce light by producing heat first. They are quite similar to incandescent lamps in their mechanism.
Candles utilize the oxygen that is present in the surrounding air. This oxygen supports the flame and lets it be lit until all the wax is exhausted or the candle is extinguished intentionally.
The wax is melted by the heat and mobilized. It reaches the top of the wick through capillary action and provides the fuel for burning the candle. Wick is not a fuel itself, but it helps in the effective utilization of fuel that is wax.
This mechanism is common for all types of candles. However, different waxes have different melting points. They all burn at their own unique pace.
During this burning reaction, wax is evaporated in the form of soot and smoke. Therefore all the particles present in the wax become a part of the air surrounding the candle.
Which part of the candle flame is the hottest?
Have you ever wondered how a candle’s flame can become when it’s burning? It’s not really something that can easily be calculated, but we can roughly guess the temperature in most cases. However, there is something you can do to get the exact temperature. And this will depend on the type of wax the candle is made of, the surrounding temperature, and the amount of oxygen available for this reaction.
- Wick – 400 C or 750 F
- Blue/ white outer edge of the flame – 1400 C or 2550 F
- The yellow central region still need to brightest part – 1200 C or 2190 F
- The dark brown or red inner part of the flame – 1000 C or 1830 F
- The red-orange still inner part of the flame – 800 C or 1470 F
- Body of the candle – 40 – 50 C or 104 – 122 F
- The melted pool of wax on top of the candle – 60 C or 140 F
Here you can see that the brightest part of the flame is not the hottest one. The blazing part of the flame of a candle gives only one-fourth of its part as heat. The rest three quarts are given off as light.
The hottest part is the invisible blue area near the base, where oxygen reacts with the wax. The flame is cooler in the insides as compared with the outer edges. Most of the heat is directed toward the tip of the flame because the convection pushes hot gases towards the edge.
What Burns In a Candle?
Candles may seem small, but they have a complex burning mechanism. When you set the wick on fire, the heat quickly travels downwards and reaches the wax body of the candle.
Wax has a low melting point, and when it receives heat from the flame of an open wick, there is enough vapor to make some go all the way up. This vapor then burns to produce a flame high above the wick.
The heat from a burning candle is transferred in three directions through the following heat transfer mechanisms.
Conduction: It takes the heat down to the wick, and as a result, more wax gets melted at the upper surface of a candle. The heat is also transferred to the bottom of the wick, which you can easily notice as the whole candle becomes warmer when it is burning.
Convection: Hot wax vapors are transmitted from the wick into the surrounding air, and oxygen present in the air is absorbed by the base of the flame.
Radiation: The burning candle emits beams of invisible light in all directions.
The flame of a candle feeds itself on the wax until all the wax is used up. In this way, all the potential energy present in the wax is converted to light, heat, and smoke.
What does Candle Combustion mean?
A candle produces light as a result of a chemical reaction called combustion. During this reaction, wax that comprises carbon-based chemicals (often the by-products of petroleum) reacts with oxygen present in the air to form a colorless gas, carbon dioxide.
At the same time, water is also produced, and it is released as steam as the combustion is not a perfectly clean reaction. As a result, you will see smoke coming out from the candle.
Smoke is an aerosol that consists of tiny particles of unburned carbon dissolved in the steam. That is why it leaves a black carbon deposit on nearby walls or any other nearby surface.
The blue part of the candle flame produces the steam when the wax burns cleanly with oxygen in the air. The smoke is produced in the yellow flame. Smoke is produced when a flame is flickering due to the lack of oxygen, and therefore, the combustion is not perfect here.
To kick-start, the combustion reaction in a candle will require some extra energy. This energy is called activation energy. Using a burning match stick is the best way to provide activation energy to a candle.
The heat from a burning match stick or lighter is enough to melt and mobilize some of the wax that is present on the wick and the upper surface of the candle.
Where does Candle Wax disappear to when burned?
When you light a candle, most of its matter will evaporate in the air. A small amount remains on top for a while before sinking down to become part of your flam,e’s respiratory system – this is known as moratorium wax. The burnt polymers from which it came are still there, too; they’re just not producing heat any longer because their atoms have all left by now (evaporated).
Sometimes the spilled wax also forms puddles around the base. It happens when the melted wax is more than the capacity of the wick. If the flame is flickering, a lot of wax is melted quickly. So it is not efficiently transported to the upper part of the candle.
As a result, it accumulates and starts dripping off the candle edges. It may also make the candle irregular in shape and will decrease its lifespan of the candle. You can collect this wax and reuse it again. However, you can not use the evaporated wax again.
Do all Candle Waxes Evaporate the Same Way?
Have you experienced different burning waxes? You must have noticed that some waxes last longer than others. Or some candles just stop burning or maybe even don’t light up at all.
Maybe you’ve also noticed how some candles have a waxy film on the inside of their jars? This is because candle waxes evaporate differently. Some types of wax are better suited for outdoor use, while others will burn for hours in your home.
Many people are surprised to learn that not all waxes evaporate the same way. The type of candle you use, how it’s made, where it’s used, and what materials are in the wick can all impact how effectively or quickly your candle will evaporate. For example, soy candles take much longer to burn through because they have a higher melting temperature than paraffin waxes.
Due to their higher melting point, natural waxes have a slower burn rate. They melt and evaporate at a slower speed. That is why the candles made from natural waxes are much more long-lasting than paraffin wax candles.
How long does it take wax to evaporate?
Well, we already mentioned earlier that many factors play a role in how long it would take for the wax to evaporate. But when we talk about evaporating, we actually talk about burning time. The time an express wax takes for evaporation will depend on its melting temperature, where it’s used, or what other outside factors impact its burning. But if we were to try to guestimate it, most of the candle wax will melt somewhere between 75 and 180 degrees Fahrenheit. The additives used in a candle wax also alter its melting point.
To understand the melting time, you must know the melting point of wax you are using in your candles.
Melting Point for Different Types of Wax
| Type of Wax | Melting Point |
| Paraffin Wax | 122 – 158 F |
| Beeswax | 143 – 151 F |
| Soy Wax | 120 – 180 F |
| Rapeseed Wax | 125 – 136 F |
| Coconut Wax | 75 – 100 F |
Apart from the melting point, the shape of the candle and the quality and size of the wick also influence the evaporation time of a given wax.
Would wax melt also evaporate?
The answer is no! wax melts don’t evaporate. The wax warmer does not produce sufficient heat to burn the wax in the wax melts. Therefore you don’t need to worry about the smoke and soot that is produced by lighting the candles.
The heat produced by the wax warmer is just sufficient to disperse the fragrance of wax melts. Consequently, you will have scentless wax lying in your wax warmer after a certain time.
If you are left with many wax melts that do not give fragrance anymore, you can easily renew them. You just need to add fragrance oil or essential oil to make them work like new. As they do not evaporate, they can be used multiple times before you decide to throw them away.
Where Do Wax Goes When a Candle Burns?
Well, we already discussed how candles burn and how waxes evaporate. But what happens after? Well, nothing much. In fact, once it’s evaporated, it’s gone. It may have a scent that comes from the fragrance you’ve added, but other than that, it’s gone.
When it comes to health concerns which is something we all are concerned about. The answer would be it depends. I know it’s not the answer you were expecting. Paraffin is the only one I can give. If you go for all-natural candles and waxes, you’ll be fine. But once you start using Paraffin or a mix with Paraffin, this would be hazardous to your health in the long run.
As when it comes to the technical part, as the heat increases, the candle starts evaporating the wax in the atmosphere of your home. To understand this process, you still need to use the scientific process called ‘combustion.’
During the process of combustion,.’ the wax is split into hydrogen and carbon molecules producing various hydrocarbons. Then these hydrocarbons react with atmospheric oxygen to produce carbon dioxide, water vapors, heat, and light.
So we can say that your wax breaks down into its components for evaporation, and its stored energy from the molecular bonding is released in the form of heat and light.
The burning candle releases these compounds, and they are greater in density near the burning candle. Then they slowly disperse in the surrounding air.
You must have noticed that when you blow out a candle, black smoke comes out. This smoke emitted by the extinguished wick is actually your evaporated candle wax.
Is candle wax safe to breathe?
I briefly talked about this previously but let’s dig in a little deeper since this topic is something that is discussed a lot, and there is also a lot of confusion surrounding it.
Most of the candle wax is made from a petroleum-derived compound called Paraffin. When the paraffin wax is burned, it releases various toxic compounds into the air. Acetone, Toluene, and Benzene are even known as potential carcinogens, meaning that they may cause cancers if inhaled for prolonged periods.
Additionally, paraffin wax candles produce a lot of soot. They are black fumes released in the surrounding air by flickering flames. When they are mixed with air, they are inhaled easily. These toxic particles can reach and accumulate in the deepest parts of your lungs, alveoli and lower respiratory tract.
These small particles can enter your bloodstream and cause short and long-term health hazards. Despite all these dangers, people still use paraffin wax candles because they are cheaper and easily available everywhere.
Most people prefer Paraffin wax candles because of their strong scents and eye-catching dyes. However, as the dyes and fragrances are also synthetic in nature, they further add to the problem.
So should you quit using candles?
If you have made up your mind about completely quitting the use of candles, here is good news for you.
You can choose healthier alternatives to the paraffin wax too!
Soy wax candles don’t produce toxic compounds when they burn. And the good thing is that they do not give off the soot. They burn slowly and will last 30 – 50 % longer than paraffin wax candles.
Some people are concerned that excessive use of soy candles may lead to deforestation. As soy wax is a by-product of the soybean industry, it may contain few pesticides and fertilizers.
Another viable option is the use of beeswax candles. Beeswax is an amazing natural ingredient that is sourced from honey bees. That is why beeswax is the most expensive wax. But it also promises a long-lasting product as beeswax burns slowly.
Beeswax candles are claimed to have a beneficial effect on your home environment. According to studies, beeswax candles release negative ions in the surroundings when they are burning. These negative ions tend to neutralize pollutants and other hazardous particles present in your home environment.
Apart from the choice of wax, it is essential to use candles that contain all-natural ingredients. Artificial synthetic fragrances and dyes also release dangerous toxins and may be harmful to health.
Why does the Flame Point up?
Sometimes when you start looking at a candle’s flame, you can not look away from it for minutes. Yes, watching a beautiful candle burning is mesmerizing. But have you ever wondered why the flame is constantly pointing upwards? Let’s explore the science behind it!
When you light a candle, its flame increases the temperature of the nearby air. The flame also releases some hot gases that are lesser in density than the air. This hot air and emitted gas move up and send the cool air down towards the bottom of the flame. Then this cooler air is also heated, and it moves upward, again making space for cooler air.
This constant flow of warm and cool air gives the candle flame the shape of a teardrop. It is the reason that you see the candle flame always points up.