To most of us, lighting a candle feels wonderfully uncomplicated. Strike a match, enjoy the fragrance and allow the room to gradually fill with scent.
As a candle maker, I experience that same moment rather differently.
When I'm testing a new candle, I'm observing far more than the fragrance alone. I'm watching the steadiness of the flame, the development of the melt pool, the way the wax responds to heat, how the fragrance unfolds as the candle warms and, ultimately, whether every element is working together harmoniously.
Everything comes back to one simple question.
Is this candle performing exactly as I intended it to?
Before an Aromachology Studios candle ever becomes part of the collection, every new formulation is extensively burn tested. Sometimes the smallest adjustment to the wick, the fragrance blend or even the wax itself can completely change the finished result. What appears effortlessly simple on the surface is, in reality, the outcome of careful formulation, patience and countless hours of testing.
If you've already read my guide, What Is the Best Candle Wax? Comparing Soy, Paraffin, Beeswax, Coconut and Rapeseed Wax, you'll know that creating a well-performing candle is about far more than choosing a good wax. The wick, fragrance, vessel and wax must all work together in harmony, and every formulation behaves slightly differently.
In this guide, I'll explain what candle tunnelling is, why it happens, how to prevent it and, perhaps most importantly, how to rescue a candle if tunnelling has already begun.
What Is Candle Tunnelling?
Candle tunnelling occurs when the flame melts only the wax immediately surrounding the wick instead of creating a full melt pool that reaches the edges of the container.
Instead of melting evenly across the surface, the flame gradually forms a narrow well through the centre of the candle. With each burn, the tunnel becomes deeper and more pronounced, leaving a ring of unmelted wax around the edge of the vessel.
Why Does Candle Tunnelling Happen?
Candles have what candle makers often refer to as a memory. During the first burn, the candle establishes the shape of the melt pool. If the wax melts all the way to the edges of the vessel, future burns will usually continue following that pattern. If the candle is extinguished too soon, however, it may continue melting only within that smaller circle each time it is lit, gradually creating the tunnel that gives the phenomenon its name.
That is why the first burn is so important.
In many ways, it teaches the candle how to burn.
The first burn, however, is only part of the story.
Candle tunnelling can occur for several different reasons. If the first burn isn't long enough, the candle may continue following that smaller initial melt pool. If the wick is too small for the diameter of the vessel, it may not generate enough heat for the wax to melt evenly across the surface. A particularly rich fragrance blend or heavier botanical ingredients, such as myrrh or patchouli, can also influence the way the wax behaves and may require a larger wick or even a second wick. The relationship between the wax, wick, fragrance and vessel determines how evenly a candle burns.
Understanding these different factors helps explain why some candles tunnel and, more importantly, how many of those problems can be prevented.
The Wick Does More Than Hold the Flame
When people choose a candle, they are naturally drawn to its fragrance or the design of the vessel. The wick is often the last thing anyone notices, yet it is one of the most important components of the entire candle.
Its role extends far beyond simply holding a flame.
As the candle burns, the wick draws liquid wax upwards through capillary action, delivering a continuous supply of fuel to the flame. At the same time, it generates the heat needed to create an even melt pool across the surface of the candle.
Selecting the right wick is one of the most important decisions I make when developing a new candle.
If the wick is too small for the diameter of the vessel, it may struggle to generate enough heat for the wax to melt all the way to the edges. If it is too large, the candle may burn too hot, shortening its burn time and affecting overall performance. The aim is always to achieve the right balance.
At Aromachology Studios, I use cotton and linen wicks because they perform exceptionally well with my rapeseed and coconut wax blend. They remain upright throughout the burn, provide reliable capillary action, produce a consistent flame and minimise afterglow once the candle has been extinguished.
The result is a candle that performs consistently from its first burn to its last.
Fragrance Influences the Burn
As a candle maker, I think about how fragrance influences the way a candle performs.
Most people think of fragrance as something we experience once a candle is lit. Yet one of the reasons I chose a blend of rapeseed and coconut wax is that it delivers an excellent cold throw, allowing the fragrance to be appreciated even before the candle is burned. You can explore this in more depth in my article, Why We Chose Rapeseed & Coconut Wax Over Soy or Paraffin.
When the candle is lit, however, fragrance becomes part of the formulation itself.
Every essential oil and fragrance composition behaves slightly differently when blended with wax. Some botanical oils are naturally lighter, whilst others are richer, denser and require more heat before the wax melts evenly across the surface.
Ingredients such as myrrh and patchouli essential oils are good examples. Their richer botanical profiles create depth within a fragrance, but they also influence the way a candle burns. That means the overall formulation often needs to change.
This is one of the reasons some Aromachology Studios candles are made with two wicks rather than one.
The second wick isn't there for appearance.
It provides the additional heat needed for certain richer essential oil blends to develop a full melt pool and burn cleanly from the first burn to the last.
These are the kinds of decisions that happen long before a candle reaches someone's home, but they have a significant influence on the experience once it is lit.
Precision Matters More Than Perfection
It is easy to imagine candle making as a straightforward process. Melt the wax, add the fragrance, pour the candle and allow it to cool.
The reality is considerably different.
Every decision influences another.
Changing the wax may require a different wick. Altering the fragrance blend may change how the candle burns. Even changing the vessel can affect the way heat moves across the surface.
That is why I never think about wax, fragrance, wick and vessel independently.
Every formulation is a balance, and achieving that balance requires careful observation, repeated testing and, occasionally, going back to the drawing board until every element works together in harmony and exactly as intended.
Perhaps that is why I still find candle making so rewarding. Every new formulation presents its own challenges, and every successful candle is the result of patience, careful observation and countless hours of testing.
Can You Rescue a Tunnelled Candle?
The answer depends on what caused the tunnelling in the first place.
If the tunnel has formed simply because the candle was extinguished too early during its first few burns, there is sometimes an opportunity to improve the way it burns going forward. The earlier the problem is identified, the better the chances of achieving a more even melt pool.
One approach is to gently warm the surface of the wax using a hairdryer or heat gun until it softens and levels out. This can help reset the surface of the candle before allowing it to cool and harden again.
It is not, however, a solution I particularly recommend.
Melting the entire surface can leave the wick sitting in more liquid wax and fragrance than it was designed to burn. In some cases, this can overwhelm or even drown the wick, making it difficult for the candle to perform as intended. Removing some of the melted wax may help, but that also means throwing away part of the candle.
More importantly, it does not address the underlying cause.
If a candle has tunnelled because the wick is undersized for the vessel, because the fragrance load is too high or because the formulation itself is not properly balanced, melting the surface of the wax is unlikely to solve the problem permanently.
That is why I always believe prevention is better than cure.
A thoughtfully formulated candle, matched to the correct wick and burned according to the care instructions, should develop a full, even melt pool without the need for corrective techniques. It is one of the reasons I spend so much time testing every new formulation before it ever becomes part of the Aromachology Studios collection.
Is It Really Tunnelling... or Just Candle Overhang?
One of the questions I'm asked most often is whether a candle is tunnelling when there is still a small ring of wax around the inside edge of the container after the first few burns.
Very often, what people are seeing is not tunnelling at all.
It is something candle makers refer to as candle overhang.
With natural waxes such as rapeseed and coconut, it is completely normal for a small lip of unmelted wax to remain around the upper edge of the vessel during the early stages of a candle's life. As the flame gradually burns lower into the container, it generates more heat around the sides, allowing this wax to melt away naturally over subsequent burns.
This is one of the characteristics of many natural waxes and is not considered a fault.
True tunnelling is different.
With tunnelling, the flame continues burning downwards through the centre of the candle, leaving a deep, narrow well surrounded by a thick wall of unused wax. Candle overhang, by contrast, is usually shallow and gradually disappears as the candle continues to burn.
Understanding the difference can save a great deal of unnecessary worry.
A small amount of overhang is perfectly normal.
A deep tunnel that becomes progressively worse is not.
A Well Formulated Candle Begins Long Before It Is Lit
Perhaps the greatest lesson I've learned as a candle maker is that the smallest details often have the greatest influence on the finished candle.
A well made candle should never ask you to think about the wick, the wax or the formulation. It should simply perform exactly as intended, allowing you to enjoy the fragrance and the atmosphere it creates.
If you're looking for candles that have been carefully developed, extensively burn tested and handcrafted using a blend of rapeseed and coconut wax, I invite you to explore the Aromachology Studios candle collection.
And if you would like to discover the philosophy that underpins everything I create, you may also enjoy reading What Is Aromachology? The Science of Scent and Emotional Wellbeing, where I explore the fascinating relationship between fragrance, emotion and everyday life.
Frequently Asked Questions
Why is my candle tunnelling?
Candle tunnelling occurs when the wax melts only around the wick instead of forming a full melt pool across the surface. It is commonly caused by extinguishing the candle too early during its first burn, although wick size, wax formulation, fragrance composition and vessel size can also influence how a candle burns.
Can a tunnelled candle be fixed?
Sometimes, but it depends on what caused the tunnelling. If the problem is noticed early, gently warming the surface of the wax with a hairdryer or heat gun may help level the wax. However, this can also overwhelm or drown the wick with more melted wax and fragrance than it was designed to burn. More importantly, it does not address the underlying cause. If the wick, fragrance, wax and vessel are not correctly balanced, the candle is likely to continue tunnelling. This is why careful formulation and thorough burn testing are so important.
What is candle overhang?
Candle overhang is the small ring of unmelted wax that can remain around the inside edge of the container during the early burns of a natural wax candle. Unlike tunnelling, it is usually temporary and melts away naturally as the flame moves lower into the vessel.
Why do some candles have two wicks?
Some fragrance blends, particularly those containing richer botanical ingredients such as myrrh and patchouli, require additional heat to create an even melt pool. A second wick helps distribute that heat more evenly, improving both burn performance and fragrance release.
Can the type of candle wax cause tunnelling?
Yes. Different waxes behave differently and require carefully matched wicks and formulations. The relationship between the wax, wick, fragrance and vessel determines how evenly a candle burns.
Why does Aromachology Studios use rapeseed and coconut wax?
I chose a blend of rapeseed and coconut wax because it offers an excellent balance of clean burning, fragrance performance, smooth appearance and sustainability. It is biodegradable, vegan and performs consistently when paired with the carefully selected wicks, essential oils and fragrance blends used throughout the collection.