Why Does My Candle Crackle?

Candle crackling refers to the popping and sizzling noises produced by a burning candle. This common phenomenon is the result of multiple factors coming together around the candle’s flame.

Most candles will make some subtle crackling sounds here and there as they burn. But occasionally, a candle will produce loud, frequent crackles throughout the burn time. When this happens, it’s usually an indication that something about the candle composition or the burning environment is amiss.

In this article, we’ll take a closer look at the reasons why candles crackle during burning. By understanding what conditions lead to excessive candle crackling, we can learn how to set up our candles for the most pleasant, soothing burn.

Wick Issues

One common reason for candle crackling is having a wick that is too large or too small for the size of the candle. The wick size needs to be properly matched to the diameter of the candle in order to get a flame that burns cleanly and evenly. If the wick is too small for the candle, it will not be able to draw up enough wax which can cause the flame to sputter and crackle. On the other end of the spectrum, a wick that is too large can overload the melted wax pool and cause the excess fuel to burst and pop.

To prevent wick issues, always trim the wick to 1⁄4 inch before lighting and make sure to use the wick size recommended by the candle manufacturer for that particular candle width and wax type. The product labeling or website will indicate the proper wick-to-width ratio. Standard wick sizing guides are also available to help determine the right wick diameter and thread style.

Wax Composition

The type of wax used to make a candle can impact cracking and popping sounds. Paraffin wax, derived from petroleum, is the most commonly used candle wax. It is inexpensive and easy to work with, but can produce more soot and smoke. Soy wax and beeswax are natural alternatives that burn cleaner.

Paraffin wax has a low melting point, allowing candles to liquefy quickly and pool deeply as they burn. This rapid melting can lead to an uneven candle surface, triggering wick issues and popping sounds from air pockets. Soy and beeswax have higher melting points, causing candles to burn slower and more evenly.

Additionally, paraffin wax tends to shrink more than natural waxes as it cools after being poured into a candle mold. This shrinkage can create gaps between the wax and the container, allowing air bubbles to form and crackle as they ignite.

Thus, switching to a natural soy, beeswax, or blended candle wax can help reduce cracking and popping by promoting steadier, residue-free burning. However, no wax is crackle proof, as many other factors impact the phenomenon.

Flame Size

One factor that impacts candle crackling is the size of the flame. If the flame is large, the candle wax will melt more quickly. This causes air pockets to form in the melted wax pool. When these air pockets get heated up by the flame, they will expand, pop, and crackle audibly.

In comparison, a smaller flame melts the wax at a slower pace. This allows the melted wax to cool and resettle smoothly, without forming bubbles and empty spaces for air pockets. With less opportunity for air pockets, a smaller flame will create a quieter, more peaceful burn.

To reduce crackling, trim your wick before lighting to create a smaller flame. You can also periodically extinguish the candle and re-trim the wick when the flame starts to grow too large. Aim for a flame about 1/2 inch in size for most standard candles. The smaller the flame, the less popping and crackling you’ll hear.

Air Pockets

One common cause of candle crackling is air pockets trapped in the wax. As the candle burns, tiny bubbles of air get trapped in the melted wax. When these air bubbles are heated by the flame, they rapidly expand. This expansion creates pressure in the bubble, which leads to a popping or crackling sound when the bubble bursts.

Air can get introduced into the candle wax in several ways during the manufacturing process. If the wax is not properly de-aerated during production, small air bubbles will remain suspended in the solid wax. Air pockets can also form if the wax shrinks or pulls away from the container walls as it cools after being poured into the candle mold. This leaves empty spaces where air is trapped against the container surface.

While most manufacturers try to minimize air pockets in their candles, some small bubbles inevitably end up embedded in the wax. When you light the candle, these bubbles expand and pop, creating the familiar crackling noises. So some minor candle crackling is normal due to trapped air pockets in the wax.

Altitude Affects Flame and Candle Lifespan

The altitude where a candle is burned impacts how it performs. As altitude increases, the atmospheric pressure decreases. This lower air pressure provides less oxygen to the candle flame. With less oxygen available, the flame gets smaller and cooler. The decreased flame means the candle wax melts and pools more slowly. This can make the candle last longer before the wax pool reaches the edges.

However, the smaller flame may also prevent the candle from reaching its ideal burn temperature. This can increase issues like candle tunneling. The cooler flame struggles to maintain the wax pool temperature needed for an even burn.

A smaller flame at high altitudes can also lead to more unburned soot. With less oxygen, the flame cannot fully combust the wax and wick as designed. This leaves more unburned carbon behind, which can make the candle smoke more.

If you live or travel to high altitude locations, be aware the change in air pressure impacts candle performance. You may need to trim wicks more often to account for the smaller flame size and maintain an even burn.

Drafts

As the candle burns, air currents in a room can cause the flame to flicker and jump around. These gusts and drafts disrupt the even burning of the wax and wick. When the flame moves from side to side or jumps sporadically, it creates small explosions or crackling sounds. This happens more frequently if a window or door is open, a fan or vent is on, or there are fluctuations in indoor air currents. The crackling tends to increase when the flame is disturbed by these drafts or air pockets moving around the room.

Burning Too Fast

If your candle burns too hot, it can cause the wax to pop and crackle. When a candle burns, the wax closest to the flame melts and turns to liquid. This liquid wax then travels up the wick to fuel the flame. If the flame gets too large, it will overheat the surrounding wax. The wax can then go from solid to liquid extremely quickly, boiling and popping in the process. This rapid expansion of wax causes audible crackling noises.

Burning the candle too quickly can also lead to overheating. If you let the flame get too large, it will melt wax faster than normal. The wick gets overloaded with liquid wax, making the flame grow even bigger. This continues in a dangerous cycle, quickly overheating the wax and making it pop and hiss.

To prevent this, carefully monitor flame size and trim wicks as needed. Smaller flames burn at cooler temperatures and help wax melt slowly and smoothly. Proper wick length also helps regulate wax melting. With a little care, you can enjoy your candle’s glow and fragrance without noisy crackling.

Wick Trimming

Neglecting to trim the wick can lead to increased crackling sounds from your candle. As the candle burns down, the wick gets longer and longer. This exposes more wick material to the flame, resulting in a larger flame. Larger flames mean more rapid wax melting and an increase in little pops and sizzles coming from the candle.

To minimize crackling, be sure to trim your wick to 1⁄4 inch before each lighting. Use wick trimmers designed specifically for candle care. Trim the wick perpendicular to its length for the most even burn. This allows the proper amount of wick to absorb wax and prevent mushrooming at the tip. With a neatly trimmed wick, your candle will burn slower and more quietly.

Conclusion

In summary, there are several reasons why candles may crackle while burning. The most common causes have to do with the wick being too large or improperly trimmed, the wax composition being too soft, the flame being too big, air pockets in the wax, and environmental factors like high altitude or drafts. Cracking and popping happens when the candle burns unevenly or too quickly, allowing excess air to mix with the flame. While some crackling is normal, excessive noise can be minimized by using a properly trimmed wick suited for the wax type, avoiding drafts, and trimming the wick as needed to control the flame size and rate of burning.