Why Do Candles Sink in the Middle: Reasons, Solutions, and Prevention

Candles can sometimes develop a troubling phenomenon where they sink in the middle, creating a depression or a 'sinkhole' that can be unsightly and even affect their burn quality. This issue can be attributed to several factors, primarily related to the way the candle burns and the materials used in its construction. In this article, we explore the main reasons behind this problem and provide practical solutions to prevent it.

Uneven Heat Distribution and Wax Mixture

The primary cause of candles sinking in the middle is uneven heat distribution. As a candle burns, the heat generated can cause the wax to melt unevenly. This uneven melting can be exacerbated by the size and placement of the wick. If the wick is too large or positioned improperly, it can create a larger flame that heats the wax around it more than the wax further away, leading to a depression in the center of the candle. In contrast, a wick that is too small may not produce enough heat to melt the wax evenly, resulting in a tunnel where the wax burns down the sides but leaves a central column of unburned wax.

Wick Issues

The type and quality of the wick can also play a significant role in whether a candle sinks in the middle. A wick that is either too thick or too long can burn too hot, causing the wax to melt rapidly around it. Conversely, a wick that is too small may not produce enough heat to melt the wax evenly, leading to tunneling. Additionally, drafty environments can cause uneven melting, leading to sinking in the middle.

Wax Quality

The type of wax used can also affect how a candle burns. Softer waxes tend to melt and set more easily, which can lead to sinking. Harder waxes are more resistant to melting and sinking. Impurities in the wax can also affect its burning characteristics, further contributing to the issue.

Cooling and Shrinking

As the melted wax cools, it can shrink, leading to a depression in the center. If the wax cools too quickly or unevenly, it can create a sinkhole or sunken dip in the middle of the candle. Proper temperature control during the manufacturing process is crucial to prevent this from happening.

Preventing Candles from Sinking in the Middle

To prevent candles from sinking in the middle, it's essential to:

Ensure proper wick sizing: Choose a wick that is appropriately sized for the diameter of your candle. Use high-quality wax: High-quality wax can help maintain a consistent burn and prevent sinking. Burn the candle in a stable environment free from drafts: This ensures even melting and a consistent burn.

Common Issues and Solutions

The problem of homemade candles sinking in the middle has a relatively simple answer and an even simpler fix. Wax can sink when it sets because as the wax cools, it slowly contracts, leaving a 'sinkhole' in the middle of your candles. The flame is giving off various forms of radiation, with thermal radiation only being sufficient to melt wax up to a certain distance, which for a candle flame is only a few centimeters. This limitation can cause uneven melting and sinking if the wick is either too large or too small.

Using a deteriorating wick made of materials like cotton can help maintain a consistent burn time, as the wick will degrade gradually, allowing the wax to flow evenly around the flame. However, a wick that is too large can result in excessive heat, causing the wick to deteriorate faster than it can melt the wax, leading to a sinkhole. To avoid this, it's best to find a balance that allows the wick to melt just enough wax without burning out too quickly.

By understanding the reasons behind candle sinking and implementing the appropriate solutions, you can enjoy perfectly shaped candles that burn evenly and beautifully.

In Conclusion

Preventing candles from sinking in the middle is not just about aesthetics; it's about the quality and longevity of the burn. By paying attention to wick size, wax quality, and environmental factors, you can ensure that your candles burn evenly and provide the best possible experience. Whether you're a candle enthusiast or a hobbyist, these tips will help you achieve the perfect burn every time.