a lit candle

How Do Candles Work: The Fascinating Science Behind Wax and Wick

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Introduction: Candle Magic or Candle Science?

There’s something incredibly enchanting about lighting a candle—the flickering flame, the soothing scent, and the warm ambiance it creates. But have you ever paused to wonder how a candle works? Far from mere magic, there’s intricate science at play every time you strike a match to a candle wick. Whether you’re a candle newbie or a seasoned aficionado, come along on this illuminating journey into the world of candles, from paraffin wax to wick burns, combustion, and everything in between.

a burning candle

What Makes Up a Candle? The Essential Parts

A candle mainly consists of two parts: the wax and the wick.

  • Wax: This is the fuel for your candle. The most common types of waxes used in candle making are paraffin, beeswax, and various plant-based waxes.
  • Wick: Acting as a fuel pump of sorts, the wick absorbs the liquid wax and pulls it upward, allowing the candle to burn and produce light.

Types of Candle Waxes

  • Paraffin Wax: Made from petroleum, paraffin wax is the most commonly used type of candle wax.
  • Beeswax: A natural alternative made from, well, bees.
  • Plant-based Waxes: These can include soy or palm waxes and are praised for being eco-friendly.

The type of wax can affect how a candle burns, its scent throw, and even its environmental impact.

The Combustion Saga: How Do Candles Actually Work?

Wick and Wax: A Symbiotic Relationship

When you first light a candle, the heat of the flame melts the wax near the wick. This melted wax is then drawn up the wick thanks to capillary action. As it reaches the heat of the flame, the liquid wax vaporizes and becomes hot gas.

Capillary Action: This is the science behind how a wick absorbs the liquid wax and pulls it upward. Basically, liquid flows against gravity through small pores in the wick, similar to how plants draw water from their roots.

Wax Never Burns, It Vaporizes

Yeah, you read that right. The wax never actually burns. It’s the vaporized wax—now a hot gas—that reacts with oxygen in the air to produce light, heat, carbon dioxide, and water vapor.

The Flame of a Candle: A Colorful Tale

You’ve probably noticed that a candle flame isn’t just one color. That’s because different parts of the flame are doing different things:

  • Blue Color at the Base of the Flame: Here, the hydrocarbon molecules from the vaporizing wax are breaking down due to the heat, producing hydrogen and carbon atoms.
  • Yellow Part of the Flame: This is where the carbon particles are glowing as they burn to produce carbon dioxide.

What Happens to the Byproducts?

When a candle burns, it produces water vapor and carbon dioxide through a chemical reaction. In a well-ventilated area, these are safely dispersed into the atmosphere.

Soot and You

If you burn a lot of candles, especially those made from paraffin, you might notice soot—those little black carbon particles—around the base of the wick or even on the side of the candle. Soot occurs when there’s incomplete combustion, meaning not all the carbon atoms were converted into carbon dioxide.

Scented Candles: An Olfactory Bonus

Ever wondered how scented candles work? When the wax melts and vaporizes, volatile organic compounds in the scent are also released into the air.

Why Do We Love Candles?

candles burning for too long

Candles can also serve as symbols of peace, are part of many religious rituals, and are just plain amazing lighting systems!

Pro Tips: Making Your Candles Last Longer

  • Keep the Wick Trimmed: A shorter wick produces a smaller flame, which will melt less wax and make your candle last longer.
  • Avoid Drafts: Wind can cause the wax to melt unevenly, affecting the candle’s burn time.
  • Invest in Quality: Higher-quality waxes and wicks will result in a more efficient candle that burns longer.

Conclusion: The Endless Fascination with How Candles Work

The next time you light a candle, you’ll know that it’s not just about setting a mood or filling a room with fragrance. It’s a science experiment happening right before your eyes, from the moment the wick first absorbs the liquid wax to the heat of the flame vaporizing it. It’s about understanding the unique chemical reactions that produce light and heat, and the complex interplay of elements like hydrogen and carbon atoms, oxygen in the air, and even the various types of waxes. Now, isn’t that just illuminating?


Q: What is the science behind how a candle burns?

A: The science of candles revolves around the principles of combustion. When you light a candle, the heat of the flame melts the wax near the wick. This liquid wax is drawn up the wick where the heat of the flame vaporizes the liquid wax, creating a wax vapor. This vapor is then drawn up into the flame, wherein it reacts with oxygen in the air to create heat, light, water vapor, and carbon dioxide. So, the candle wick works essentially as a fuel delivery system.

Q: How does the candle wax contribute to the burning process?

A: When a candle is lit, the heat melts the wax around the base of the wick. This molten wax is then drawn up the wick where it vaporizes and breaks down into molecules of hydrogen and carbon. These molecules react with oxygen in the candle flame to produce heat, light, water vapor, and carbon dioxide. The heat from this reaction keeps the process going, vaporizing more wax to keep the candle burning for as long as the wick and the available wax lasts.

Q: What part of a candle flame actually burns?

A: It may surprise you, but it’s not just the wick of the candle that burns, the wax also burns. The part of a candle flame that actually burns is the wax vapor. The heat of the flame vaporizes the wax that has been drawn up the wick, and this wax vapor burns, providing the light and heat we associate with a candle flame.

Q: What role does the wick play in how a candle burns?

A: The wick is a crucial part of a candle. It works as a fuel delivery system, drawing up the molten wax to the flame where it is vaporized and burned. The burning process creates a cycle where the heat produced by the flame melts more wax, which is then drawn up the wick to keep the candle burning.

Q: How does a wax pool form and what is its role?

A: A wax pool forms when the heat of the flame melts the wax near the wick. This pool of hot, liquid wax allows the wick to draw up fuel (molten wax), which is then evaporated and burned in the flame. The pool of wax helps regulate the amount of fuel that reaches the flame and aids in prolonging the burning process of the candle.

Q: Can a candle burn without a wick?

A: No, a candle cannot properly burn without a wick. The wick serves the critical purpose of bringing the candle wax to the flame where it can be vaporized and burned. Without a wick, the flame would have no way of accessing the wax, and so the candle wouldn’t be able to keep burning for long.

Q: What type of candle wax burns the longest?

A: Various types of waxes are used to make candles, each with its burning properties. However, beeswax and soy wax are known to burn longer compared to the commonly used paraffin wax. Beeswax burns the cleanest and longest as it is denser and harder. Soy wax also burns slower and cooler, helping to create a longer burning candle.

Q: How does the heat from a candle flame melt more wax?

A: The heat generated from a candle flame primarily radiates outwards, but some of it also travels downwards into the body of the candle, melting the wax directly around the wick. The outer wax stays solid, forming a sort of ring or shell that helps to contain the hot, liquid wax near the wick.

Q: Why does my candle wick turn to carbon?

A: The carbon build-up on a candle wick is called “mushrooming” due to the shape and colour it takes after burning for a while. When the flame burns the wick without enough wax vapor, the exposed wick also burns, creating carbon, which collects at the tip of the wick. Trimming the wick before each burn can help reduce carbon build-up.

Q: How many different types of waxes are used in candle making, and what are they?

A: There are several different types of waxes used in candle making. The most common ones include paraffin, soy, beeswax, palm and coconut wax. Each wax has different properties – paraffin wax provides a high scent throw, but burns fairly quickly. Soy and beeswax burn slower and cleaner, making them popular choices for those wanting a longer-lasting, more environmentally friendly candle.

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