Common Candle Problems and Solutions
Have you ever wondered how long a candle should burn before extinguishing it? How about why there is black smoke coming from the flames or black dust accumulating on the candle's container? Maybe you’ve wondered why wicks look like they're turning into mushroom heads? Well, this post has the answers!
Burn Cycles
All candles, containing natural or unnatural waxes alike, have a limited amount of time they should be burned. This is called a Burn Cycle, which is the duration of time a candle is burning. A proper and safe Burn Cycle is 4 hours, regardless of a candle’s size, container, fragrance, wax type, or wick type.
Why 4 hours?
To put it simply, 4 hours of burning allows a candle to safely achieve a full Melt Pool. A Melt Pool is the amount of melted wax surrounding the candle’s wick(s) while it burns. Burning candles for 4 hours allows the wax enough time to melt all the way to the edges of the container, achieving a “Full” Melt Pool, and allowing it to maintain a smooth, flat surface of wax as it cools.
What is Tunneling?
Burning a candle for less than 4 hours usually results in Tunneling - when candle wax primarily melts down the center of the candle close to the wick(s), leaving hard, unused wax built up around the edges.
Let’s say you have a candle that is 3 inches in diameter and you decide to burn it for 1 hour. Its Melt Pool may only achieve a diameter of 1 - 1.5 inches after 1 hour of burning, leaving 2 - 2.5 inches of unmelted wax around the edges of the container.
Because candle wax has “memory”, candles maintain their shape every time they are lit. Meaning that in every future burn cycle, your hypothetical candle would only achieve a 1 - 1.5 inch melt pool every time it burns. This will result in tunneling, or wax creating a tunnel around the wick, and leaving you with unused wax on the edges of the container.
Below is an example of a candle that has been through two less-than-4-hour burn cycles and shows slight tunneling. The wax touching the edges of the container is staying unmelted due to candle wax having a “memory.”
Continuous tunneling over time will begin to melt some of the built-up wax, resulting in the Melt Pool rising higher than the wick and snuffing out the flame. This would result in any exposed wick being lower than the unmelted wax, and the candle would no longer be usable. Below is an example of a candle that would no longer stay lit because the wax built up on the sides would melt down on top of the flame.
A little side note - any candle that is not paired with a thick enough wick may not be strong enough to create a full melt pool regardless of how long each burn cycle is. Therefore, that type of candle would always tunnel. Additionally, if a candle is paired with too large of a wick, it can create a melt pool too quickly and burn too strongly, evaporating the wax faster than it should. Knowing what size and type of wick you need is determined by the candle container size and the type of wax you are using. That is a whole other discussion for people who want to get into candle making, so I am going to leave it at that!
What happens if you burn a candle for longer than 4 hours?
The candle will explode!
Ha, just kidding! Burning a candle for longer than 4 hours causes outcomes like excess Mushrooming, Soot, Muddy/Dirty Wax, and puts glass containers at risk of cracking or breaking due to excessive heat exposure.
Let’s talk a little more about these adverse outcomes!
What is Mushrooming?
Mushrooming is an excessive build up of carbon that collects at the tip of the wick. Whenever you light a candle, you are causing combustion, and that 1 simple action releases carbon. Regardless of the wax or wick types, carbon is being released as soon as you light a candle. It’s the nature of the product!
However, too much of anything is just too much. Candle wicks are designed and manufactured to burn for extended periods of time, but burning them too long (over 4 hours) makes it harder to maintain an even carbon release. Therefore, when you exceed 4 hours of burning, you will see a mushroom-shaped build up of carbon form at the tip of the wick. This build up can also happen if the candle wax and wick combination are not properly paired, or if there is too much fragrance oil in the wax and it overloads the wick(s). Always cut the “mushrooms” off before lighting the wicks again.
Please note - combustion and carbon release are normal aspects of candle burning. It is not “good” or “bad” for candles to release carbon; it is just the nature of the product. However, excessive carbon buildup that creates mushrooms on wicks can alter the candle’s fragrance, dirty the wax, become heavy and bend the wicks down into the wax, and/or produce soot.
What is Soot?
Soot is a fine black or white/clear powder made up of unburned carbon particles. Soot can form when a candle’s wax and fragrance oils undergo incomplete combustion. This means the flame is taking in too much fuel and not enough oxygen to burn cleanly, leaving fine black or clear residue on the inside walls of a candle container or producing a stream of black or clear smoke from the flames.
Additionally, soot can be clear or undetectable to the eye. Most commonly, black soot appears in wax blends containing paraffin wax, while clear or white soot appears in all-natural blends containing beeswax, sunflower, or coconut waxes (for example). Just because the wax is “all natural”, does not mean it isn’t producing soot! If the natural waxes are not paired with the correct fragrance load, or the correct wick, it will produce more soot than their correctly crafted counterparts. Soot is produced no matter what, but the amount of soot that is produced depends on how the candle was made and how long it is left burning.
What is Muddy/Dirty Wax?
This is pretty self-explanatory! When a candle produces too much soot, the wax begins to capture floating soot particles, which alters the wax's original color to a duller/muddier version of it.
If a candle was not crafted correctly, there is not much you can do to reduce this outcome. However, if a candle was created correctly, the best way to ensure the wax doesn’t get muddy or dirty is by trimming your wicks between each use, keeping burn cycles at 4 hours, and keeping candles away from drafts or circulating air (like under a fan) while lit.
Below is an example of one of my mini candles and the progression of its life from beginning to end. You will notice the wax did not get dirty or muddy throughout the entirety of its life because I paired the right wick with the wax and container size, did not exceed 4-hour burn cycles, and kept my wicks trimmed to ⅛ to ¼ of an inch.
In summary…
Every “adverse” outcome is largely due to how a candle is made. Some candles just won't stop tunneling, producing soot, or muddying the wax, regardless of what you try to do!
The good news is that you can maintain a cleaner and more efficient candle experience by:
Timing burns to no longer than 4 hours
Trimming long wicks
Trimming mushroom heads
Keeping candles away from drafts and fans, and
Burning candles on even, heat-resistant surfaces.
The craft of candle making is not a one-size-fits-all system. There are hundreds of wax blends, container sizes, and wick types to choose from - and that's before getting into all the different fragrances out there! As a candle crafter myself, it has taken me several months to find the right combination of components before I was able to produce successful candles. Even the best candle companies and crafters make mistakes due to how scientific and finicky a candle system can be. All that said, sometimes it really is just the candle!
My goal with this post was to give you an educational resource and instructions on how to get the most out of your candles! Hopefully I was able to accomplish that. As always, if you have any questions, feel free to comment on this post or contact me through a submission on my contact page!