Purple lavender soy candle sits on a tabletop with vases behind it

How does a candle work and where does the wax go?

How does a candle work?

A candle works through the process of combustion, where the wick and wax play essential roles. When a candle is lit, the heat emitted from the flame melts the solid wax near the wick. The wick then absorbs the liquid wax, drawing it upward due to capillary action.

As the flame settles on the wick, it begins to heat the liquid wax. Through a chemical reaction, the heat breaks down the wax molecules, releasing carbon atoms. These carbon atoms combine with oxygen in the air, forming carbon dioxide gas.

The wax acts as the fuel for the candle. As the wax near the wick is transformed into a gas, it combines with oxygen molecules present in the air. This combustion process provides the necessary heat to sustain the flame.

Why do candle flames have different colours?

Candle flames exhibit a mesmerising display of colours, each representing a different zone within the flame. Understanding these variations can provide insight into the chemistry and physics of candle burning.

At the base of the candle flame, there is a blue zone. This area occurs when hydrocarbon molecules from the vaporised wax break apart and react with oxygen. This reaction results in the formation of water vapour and carbon dioxide, producing a blue glow.

Moving upwards, we reach a dark orange-brown region. Here, carbon continues to break down, forming small, hardened carbon particles. These particles emit light as they heat up, resulting in the characteristic dark orange-brown colour.

Further up the flame, we find the yellow zone. In this area, carbon particles increase in number and size. These particles become hot enough to ignite, emitting a dominant yellow light. The yellow zone is responsible for providing the majority of the light emitted by a candle flame.

Finally, there is the veil, which appears as a faint blue edge. This part of the flame is the hottest and emits the highest energy radiation. The veil represents the presence of complete combustion, where carbon molecules are fully transformed into carbon dioxide gas.

Does the type of candle wax matter?

The science of candle wax does matter. It can affect how well the candle burns. The type of candle wax used - out of the wide range available - can have a significant impact on the performance and characteristics of a candle. Different wax types, such as paraffin, soy, beeswax, and coconut wax, have unique properties that can affect factors such as burn time, scent throw, and appearance.

Paraffin wax is commonly used in traditional scented candles due to it being cheaper, it's made from petroleum.

Vegan soy wax is a popular choice for environmentally conscious consumers, as it is derived from renewable resources and has a cleaner burn than paraffin wax. It's also vegan.

Non-vegan Beeswax is known for its natural, subtle honey-like fragrance and long burn time. Coconut wax offers a smooth and creamy texture, as well as excellent fragrance diffusion.

Ultimately, the type of wax used in a candle can impact both the overall experience and environmental considerations for the user.

Try our Lemongrass and Persian soy candle for a zesty experience.

What chemicals are in candles?

Candles are commonly made from paraffin wax, which is a petroleum byproduct. Paraffin wax contains various hydrocarbons, such as alkanes, alkenes, and alkynes. These hydrocarbons provide the fuel source for the candle to burn. When a candle is lit, the heat from the flame melts the solid wax and turns it into a liquid. This liquid wax is drawn up the wick through a process called capillary action.

As the liquid wax reaches the top of the wick, it vaporises and turns into a gas. This gas then reacts with oxygen from the air to undergo combustion. During the combustion process, the hydrocarbon molecules in the wax break apart, releasing energy in the form of heat and light. The carbon atoms from the hydrocarbons combine with oxygen to form carbon dioxide gas (CO2), while the hydrogen atoms combine with oxygen to form water vapour (H2O).

Harmful chemicals in candles typically refer to the soot they leave behind, if the flame is unstable, wick is not centered, or burns too greatly. It the jar gets too hot, or you accidentally heat the side of the container while lighting the candle, you may see the black residue. Soot, black smoke and excessively hot jars are not common for normal candle burns.

Non-toxic candles typically burn cleaner and produce less soot.

Is it the wick or wax that burns?

What actually burns in a candle container? When you light a luxury candle, it is the wick that burns, not the wax. The role of the wax is to provide the fuel source for the flame.

The candle wick and the wax work together in a coordinated process to create a flame. The wick is usually made of cotton and serves as a channel for the melted wax to travel up to the flame. This is where capillary action comes into play. Capillary action is the ability of a liquid to flow against gravity in a narrow passage, such as through the tiny fibres of the wick.

When the flame is ignited, it generates intense heat. This heat melts the wax surrounding the wick. Through capillary action, the liquid wax is drawn up into the wick, where it is then vaporised and turned into a gas.

The flame continues to burn because the vapourised wax combines with oxygen from the air and undergoes a combustion reaction. This reaction releases energy in the form of heat and light. The wax serves as the fuel source for the flame, while the wick acts as the conduit that delivers the melted wax to the flame.

How does a candle relight?

Once a candle has been blown out, it may seem impossible for it to relight on its own. However, a unique process allows a candle to relight after being extinguished, where you'll see white smoke.

When a candle is blown out, a stream of white wisp of smoke can be observed rising from the wick. This white smoke is vaporised wax that is still hot enough to ignite.

If a fire source, such as a lighter or a match, is introduced to this stream of white smoke, the vaporised wax will ignite and relight the wick.

This phenomenon occurs because even though the flame has been extinguished, the wax around the wick remains hot and continues to produce vapour. When exposed to a fire source, this vaporised wax ignites, leading to the candle's relighting.

Why does candle wax harden?

Candle wax hardens due to a process called solidification. Paraffin wax, specifically, is naturally solid at room temperature because the carbon atoms in its molecular structure form a tight, organised pattern. This arrangement allows the wax molecules to stack closely together, creating a solid substance.

This is the same for other types, such as soy, coconut or beeswax.

When a candle is lit, the heat from the flame melts the solid wax. As the temperature rises, the heat energy breaks the organised pattern of the wax molecules, causing them to move more freely and take on a liquid form. This is why the melted wax becomes a melt pool of liquid around the candle wick.

However, when the temperature drops, the heat source is removed, and the surrounding environment cools down. As a result, the wax molecules lose their energy and start to slow down. They gradually rearrange themselves into the original pattern, forming solid wax once again. This process is known as solidification or hardening.

For a soft and creamy fragrance, try our Goji Berry & Blood Orange soy candle.

Where does the wax go when you burn a candle?

When you burn a candle, the wax gradually disappears. But where does it go? The answer lies in the intricate process of combustion.

As the flame heats the wax, it melts and turns into a liquid. Capillary action, similar to how water rises in a straw, draws the liquid wax up the candle wick. The wooden or cotton wicks act as a fuel source, continuously supplying the liquid wax to the flame.

Once the liquid wax reaches the flame, it undergoes a chemical reaction. The heat from the flame breaks down the wax molecules into smaller carbon atoms. These carbon atoms then react with oxygen molecules in the air, forming carbon dioxide gas.

Some wax molecules aren't fully burned, resulting in the release of unburned carbon particles. When these particles cool, they become the soot you see on the candle wick and jar.

The majority of the wax, however, is vaporised during combustion. The vaporised wax combines with oxygen to create water vapour, which escapes into the air as invisible gas.

So, while you may not see the wax disappearing, it's transforming into carbon dioxide gas and water vapour. This process, along with the release of extreme heat and light, is what creates the mesmerising glow and atmosphere of a burning candle jar.

Why does the candle flame stutter or smoke?

The stuttering or smoking of a candle flame can be attributed to the fuel not completely burning down. This can occur due to a variety of factors.

One possible reason for a stuttering flame is when there is too much fuel available for the flame to have a clean burn. In this case, an excess of wax is drawn up the wick, overwhelming the flame and causing it to sputter. Similarly, if the wick is not correctly trimmed, an overly long wick can result in too much fuel reaching the flame, leading to a stuttering or uneven burn.

On the other hand, if there is insufficient air supply or oxygen reaching the flame, incomplete combustion can also occur. A draft or gust of wind can disrupt the steady flow of oxygen, causing the flame to flicker, stutter, or produce smoke. Additionally, the presence of impurities in the wax or wick can contribute to incomplete combustion, resulting in a less clean-burning flame.

To promote even candles and clean burns and minimise stuttering or smoking, it is crucial to trim the wick to the recommended length before lighting the candle jar. This helps control the amount of fuel reaching the flame. If your wick is gradually reducing in size as you burn the candle, then you won't need to trim it. Aim between 1/4 to 1/2 an inch for the length of wick, from the top of the candle wax, to the top of the wick.

Furthermore, ensuring the candle container is placed in a draft-free area can help maintain a consistent supply of oxygen and prevent disruptions to the combustion process.

MOREHow to get wax out of a candle jar

Do candles burn in space?

Wax candles in the burning process in space face different conditions compared to those on Earth due to microgravity and the absence of oxygen. In a microgravity environment, candles do not burn the same way as they do on Earth.

In the absence of gravity, the process of capillary action, which draws liquid wax up the wick, becomes ineffective. Without gravity providing a downward force, the liquid wax disperses and can't reach the flame. This prevents wax candles from burning properly in microgravity.

Additionally, the absence of oxygen in space prevents combustion from occurring. Container candles rely on oxygen to sustain the chemical reaction that creates the larger flame. Without oxygen, candles cannot burn.

However, in controlled environments like a spaceship, scented candles can burn if provided with an artificial air supply. By introducing oxygen into the environment, the combustion process can be sustained.

Instead of the typical teardrop shape seen on Earth, the flame is spherical due to a lack of buoyancy. The absence of convection also results in a lack of flickering or dancing flames. Instead, the flame forms a steady, blue-coloured orb.

For the ultimate fruity indulgence, light our Watermelon Mojito soy candle.

Signs your candle has expired

When a candle expires, there are several visual and olfactory cues to look out for. Firstly, the colour of the candle may start to fade or change, indicating it has passed its prime. Additionally, the texture of the wax may become dry and brittle, losing its smooth and creamy appearance. It's also important to note, soy wax candles made from 100% vegetable wax won't have a smooth top after burning due to its nature. There is nothing wrong with the candle.

Another sign your candle has expired is a change in fragrance. Over time, the scent of the candle may become weaker or completely diminish. This is especially true for candles made with natural wax and essential oils, as these ingredients are more prone to degradation.

It's important to note dust particles can also affect the scent of a candle. If your candle is exposed to dust or other debris, it can alter the fragrance and diminish its overall quality. Wipe down the top of the product before lighting.

Lastly, changes in burn performance can also indicate a candle is no longer usable. If you notice the candle is burning unevenly, forming a tunnel, or if the wick is consistently flickering or producing excessive smoke, these are signs the candle has expired.

Shop our full range of soy wax candles, which are vegan, cruelty-free and handmade right here in the UK.

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our handmade soap bars are vegan, homemade in the UK and cruelty-free. there's no palm oil, parabens or SLS in our products and they're designed with you and the earth in mind. soaps have added shea butter for nourishment, whereas lip scrubs are infused with vitamin E and sweet almond oil to help nourish the skin. when it comes to our soy wax candles, they're made up of vegetable wax, eco-friendly cotton wicks and recyclable glass jars which can be re-used or re-purposed to prevent waste.

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