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How Do Wood Wick Candles Work? The Science Behind Their Signature Crackling Sound

Wood wick candles have become increasingly popular in recent years thanks to their unique and satisfying crackling sound as they burn. But what exactly causes this distinctive noise that sets wood wicks apart from regular cotton wicks?

In this article, we’ll explore the science behind wood wick candles and reveal what makes them crackle.

What Is A Wood Wick Candle?

A wood wick candle contains a wick that is made of wood instead of cotton. The wick is made from natural wood fibers that are pressed and braided together to create a stiff wicking material that looks like twisted rope or twine.

Wooden wicks are often made from bamboo, but other woods like maple or birch can be used as well. When the wick is lit, the wood fibers burn slowly and evenly, maximizing the candle’s burn time.

The key difference between wood wicks and regular wicks is that wood wicks have a wider, flat profile compared to the narrow shape of cotton wicks. This flat profile is what allows wood wicks to produce their signature crackling sound.

Why Do Wood Wicks Crackle When Burning?

When a wood wick candle is lit, the flat wooden fibers stacked on top of each other begin burning slowly from the top down. As the flames consume the wood fibers, tiny pockets of air get trapped between the burning pieces of wood.

When these air pockets reach a certain temperature, the oxygen and hydrogen molecules within them ignite and create small explosions – which we hear as little “pops” or cracks.

The unique flat shape of the wood wick allows more air to get trapped within the stacked fibers, creating more pops as the candle burns. With a narrow cotton wick, there is less room for air pockets to form within the tightly spun fibers, so no crackling occurs.

The Science Of Fire And Combustion

To truly understand why wood wicks crackle, we need to take a quick look at the basic science of fire and how combustion works.

Fire occurs when three elements are present: heat, fuel, and an oxidizing agent (usually oxygen). This is commonly referred to as the “fire triangle.” For combustion to happen, the right mixture of these three ingredients must come together.

As the wooden wick burns, the primary fuel source is the carbon contained within the wood fibers. Oxygen from the air provides the oxidizing agent. The heat source comes from the flame itself.

When the wood fibers reach around 300-400°C, the carbon within them reacts with the oxygen to produce heat, light, and carbon dioxide. This chemical reaction is called oxidation.

The heat from this exothermic reaction keeps the wood fibers next in line hot enough to keep the fire triangle functioning, allowing the wood to continue burning slowly down the wick.

Now, back to those popping air pockets…

The Role Of Hydrogen And Oxygen

Within the trapped air pockets in the wood wick, the main components are hydrogen and oxygen (78% and 21% of air, respectively). When the temperature of the air pockets reaches around 500°C, the conditions are right to ignite the hydrogen and oxygen within through a combustion reaction.

When hydrogen and oxygen combust, they form water vapor and release energy. This rapid release of energy causes the “pop” as it turns water vapor into a gas state very quickly. The higher the temperature, the louder the pop.

So essentially, the characteristic crackling and popping happens because the unique structure of wood wicks allows tiny air pockets to get trapped between the fibers. As the temperature rises, the oxygen and hydrogen within these pockets combust, creating miniature explosions we hear as cracks and pops.

How The Type Of Wood Affects The Crackling

Not all wood wick candles crackle equally. The frequency and volume of the cracking depends on a few factors:

  • Thickness – Thicker wood wicks allow larger air pockets to form, creating louder cracks. Thinner wicks have softer, smaller pops.
  • Wood density – Dense woods like maple make very loud, sharp cracking sounds. Softer woods like pine create quieter, more muted pops.
  • Wood composition – Some woods contain more flammable extractives, such as pine sap and oils. These increase the intensity and rate of combustion, resulting in more frequent, louder cracks.
  • Wax composition – Harder waxes burn hotter, allowing the wooden wicks to reach higher temperatures and produce louder cracking.

So a thick maple wood wick burning in a hard soy wax will create a noticeable increase in crackling volume compared to a thin pine wick in a softer paraffin wax. Candle makers can fine-tune their wood wick formulations to achieve the ideal crackling volume for their brand.

The Benefits Of Wood Wicks

There are a few key benefits that make wood wicks popular for both candle makers and consumers:

They Burn Longer

The wide, rigid shape of wood wicks allows them to burn slower and resist curls or bends as they burn. This results in a longer burn time compared to soft, malleable cotton wicks.

They Don’t Release Soot

Regular cotton wicks can release a small amount of soot into the air as they burn, resulting in black smoke and carbon buildup on jar walls and ceilings.

Wood wicks produce almost no soot thanks to their lower combustion temperature and steady burn rate. This keeps candles and homes cleaner.

They Enhance Fragrance

The popping cracks help diffuse and distribute the candle’s fragrance by agitating the wax pool as the candle burns. This leads to better fragrance throw and allows you to fully enjoy the candle’s scent.

They Provide A Soothing Experience

The pleasing, rhythmic crackling sounds create a comforting ambiance that many people find therapeutic and soothing. The pops and snaps make wood wick candles extra engaging for the senses.

How Are Wooden Wicks Made?

Producing wood wicks takes precision and skill to achieve the right thickness, flatness, and consistency required to make them crackle properly.

It starts with natural wood fibers, usually bamboo, maple, cedar or pine. The fibers are pressed into thin sheets and carefully braided or twisted into wick cords. No glues or binding agents are used – just the wood fibers themselves intertwined tightly.

The key is keeping the braid flat, which provides enough surface area for air pockets to form between the fibers. The width of the braid as well as the tightness of the twist allows manufacturers to calibrate the wick’s thickness and adjust the rate of combustion.

After braiding, wooden wicks go through a specialized treatment process to carbonize the outer layer of fibers. This carbon layer provides two benefits: it helps anchor the wood wick into the wax, and it gives the wooden wick an initial black color that is visually pleasing against the candle wax.

The carbonized wicks are then cut to size to fit various jar diameters and wax depths. Quality control steps help ensure each wick has an optimal flatness, tightness, and consistency that will enable the signature crackling sound.

Common Questions About Wood Wick Candles

Wood wick candles generate a lot of curiosity among consumers. Here are answers to some frequently asked questions:

Are wood wick candles safe?

Yes, when used properly according to the manufacturer’s instructions, wood wick candles are safe. The wooden wicks meet current candle-safety standards for wick composition and length. Like any open flame, basic precautions should be taken, such as avoiding drafts, not burning unattended, and keeping wicks trimmed.

How do you put out a wood wick candle?

Wood wick candles can be safely extinguished like regular candles by simply blowing out the flame. Avoid extinguishing candles by submerging them in water, as this can cause the wood wick to expand and crack. Trimming the wick will help the candle relight evenly on the next burn.

Why is my wood wick not crackling or popping?

If a wood wick candle fails to crackle, it’s usually because the wick has curled over into the wax pool. Use a wick dipper tool to gently straighten and center the wick, which will allow air pockets to form properly within the fibers. If centering doesn’t help, trim the wick to refresh the tip.

How do I clean soot off a burning wood wick?

While wood wicks produce very little soot, some black carbon dust can build up on the wick tip after burning for a while. Use candle tongs to gently wipe and remove any carbon dust to restore the flame. Avoid trimming the wick each time, as this can shorten the life of the candle.

Can I burn a wood wick candle all the way down?

It’s best not to burn a wood wick candle to the very bottom. The wick can fall over into the wax pool as it gets very short, preventing it from burning properly. Stop usage when there is 1⁄2 inch of wax remaining. Burning all the way down can also scorch your candle vessel.

Discover The Crackling Joy Of Wood Wicks

Wood wick candles provide a uniquely enjoyable experience thanks to their mesmerizing pops and cracks. The next time you want to add some auditory ambiance to your space, light up a wood wick candle and enjoy the show! Just be prepared for your guests to be fascinated and ask lots of questions about the science behind your crackling candle.

Laura Kassovic

Laura Kassovic, a former engineer at Intel SOC, now dedicates her efforts to mentoring startups in the realms of Wearables and AI. As a co-founder of New Tech Brake, she spearheads a wireless sensing solution enterprise catering to diverse applications including product development, research, location tracking, and people monitoring, as well as asset and cargo supervision. The platform empowers developers to craft an array of innovations such as fitness trackers, temperature-monitored cargo systems, medical trial tools, smart running garments, or even straightforward transmission of unprocessed accelerometer data to cloud-based repositories.

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