What Does It Mean When A Candle Only Burns On One Side?

Candles that only burn on one side, with the wax around the wick melting while the rest of the candle remains largely untouched, is a phenomenon known as “tunneling.” This occurs when the melted wax surrounding the wick creates a tunnel that gets deeper over time as the candle continues to burn. The end result is a candle that appears hollowed out on one side, sometimes resembling a volcano or cone shape. Though tunneling may seem harmless at first glance, it can actually lead to issues like soot buildup, wick drowning, and uneven or dangerously accelerated burning later on. Understanding why tunneling happens and how to prevent or fix it is important for safety and maximizing candle life.

Wick Issues

One potential cause for a candle only burning on one side is an improperly sized or off-center wick. As candles burn, the wax melts and is absorbed into the wick, fueling the flame. If the wick is too short or not centered in the wax pool, it can create an uneven burn and only melt wax from one section of the candle. This can occur especially with handmade or natural candles that tend to have more variance in wicking.

According to candle experts Harlem Candle Co., “If your wick is too short or too far over to one side, the flame will naturally burn towards the wick, leaving wax unmelted on the opposite side.”¹ This uneven melting around the wick causes the candle tunnel described in the question.

The solution is to center the wick properly in the candle wax so it has access to melt the wax evenly across the top. Trimming the wick or using a longer wick style can also help create an even burn. If the wick position cannot be fixed, it’s best to stop burning a candle that only melts from one side to prevent tunneling.

Wax Makeup

The makeup of the wax itself can cause uneven candle burning. High quality candle wax has an even density and melt point throughout (Harlem Candle Company). Lower quality waxes can contain pockets of higher density that resist melting, or additives that alter the melt point. Wax additives like fragrance oils and dyes can change the wax density. High concentrations of additives end up sinking to the bottom as the wax cools, creating dense areas that resist melting and tunneling up the sides instead. The overall quality and purity of the wax impacts how evenly it melts across the entire candle surface.

Air Currents

One of the most common causes of a candle only burning on one side is air currents around the candle.[1] Drafts from open windows or air vents can cause the flame to flicker inconsistently, making it difficult for the wax to melt evenly. This results in more wax melting on one side compared to the other.

Candles burning near sources of moving air like fans or air conditioning vents are also prone to one-sided burning. The constant air blowing on the flame causes it to bend toward one side, making that side hotter and melting more wax there.

To prevent drafts from impacting candle burn, avoid placing candles near open windows, doors, or vents. Make sure the area is free from fans or air currents. A candleholder that shields the flame can also help block drafts on one side.

[1] https://www.purcellandwoodcock.com/blog/burn-candles-evenly.html

Candle Placement

The placement and positioning of a candle can significantly impact how evenly or unevenly it burns. According to Nomad Noë in their blog post “How To Fix Uneven Candle Burn,” if a candle is placed in a drafty area or where it can catch air currents from fans, air conditioning vents, or open windows, the flame will flicker and bend, causing uneven melting and tunneling (https://nomadnoe.com/blogs/the-blog/how-to-fix-uneven-candle-burn). The uneven airflow causes the candle to burn faster on the side exposed to the most air movement. Similarly, if the candle is placed too close to a wall or corner, the flame will burn brighter and hotter on the more exposed side, melting that wax more quickly. Proper placement in a draft-free spot allows the flame to burn straight up in the center without bending, promoting an even burn.

Tunneling

Tunneling is a phenomenon where a candle burns downwards, creating a hole or tunnel within the wax directly around the wick. This leads to only a portion of the wax surrounding the wick being melted, while the rest of the candle remains untouched. Tunneling is the primary culprit behind why a candle will only burn on one side.

When a candle exhibits tunneling and uneven burning on just one side, this is caused by the flame only reaching the wax in the tunnel, leaving the outer wax solid. According to Properity Candle (source), the wick then burns straight down into the wax, creating a deep center hole. As the tunnel deepens, it becomes impossible to light the parts of the wick that are buried in the hole. This in turn causes the candle to only burn and melt wax on the one side closest to the flame.

Solutions

The most common solution to fix an unevenly burning candle is to trim the wick(s). Using scissors, carefully trim the long wick(s) down to be equal in length with the short/unburnt wick(s) (source: https://nomadnoe.com/blogs/the-blog/how-to-fix-uneven-candle-burn). This helps ensure even burning across all wicks.

You can also fix tunneling candles by placing a foil tent over the top, leaving just a small hole for oxygen. The foil traps heat and melts wax pools evenly again (source: https://homesick.com/blogs/news/how-to-fix-candle-tunneling). Poke holes in the foil if needed so it doesn’t fully snuff out the flame.

Gently warming a tunneled candle in the oven at 175°F for 5 minutes can re-melt wax and fix uneven burning. Let it cool and test again before warming longer (source: https://nomadnoe.com/blogs/the-blog/how-to-fix-uneven-candle-burn).

Using a blow dryer on a low heat setting, gently re-melt sunken wax and coax it back out to the edges. Cool before testing the burn again (source: https://nomadnoe.com/blogs/the-blog/how-to-fix-uneven-candle-burn).

When to Discard

There comes a point when a candle with one-sided burning issues becomes unsalvageable and needs to be discarded. Some signs that indicate a candle should be thrown away include:

• The wick is completely consumed and no longer accessible.
• The wax has hardened into a thick, uneven surface that the wick can no longer penetrate.
• Soot has built up on the glass, indicating improper burning.
• An unpleasant or strong odor is emitted when burning.
• The candle can no longer remain lit even after multiple attempts to fix tunneling.
• Wax has leaked down the side of the glass, making it unstable.

Generally, if the one-sided burning and tunneling persists after multiple attempts at troubleshooting, it’s best to discard the candle. Continuing to burn a severely tunneled candle that can’t be fixed poses safety risks with excess soot and smoke production. It’s not worth the time and effort to salvage a candle that’s clearly reached the end of its safe usage.

Preventative Measures

There are some ways to avoid uneven burning when purchasing and setting up candles to help prevent the issue of tunneling:

When purchasing a new candle, check that the wick is centered and trim the wick to 1⁄4 inch before lighting to avoid an uneven flame (https://nomadnoe.com/blogs/the-blog/how-to-fix-uneven-candle-burn). Make sure the candle wax is level and uniform across the top as an uneven surface can cause uneven melting.

Place the candle on a stable, level surface away from drafts to allow for an even burn. Trim the wick to 1⁄4 inch each time before lighting. Allow the candle to burn all the way to the edges on the first burn to create a melt pool across the entire surface (https://www.harlemcandlecompany.com/blogs/journal/candle-care-101-how-to-fix-prevent-candle-tunneling).

Burn the candle for at least 1 hour the first time to form an even melt pool and 2-4 hours each time after that. Allow the wax to fully solidify between burns. These steps can help prevent tunneling and uneven burning.

Conclusion

Candles that only burn on one side can be caused by a few different issues. The most common causes are problems with the wick being off-center or too short, wax makeup being improper for the candle design, and air currents around the candle.

To fix a one-sided burning candle, you can try centering the wick, moving the candle to avoid drafts, or using a candle lamp or votive holder to shield it from air currents. Discard candles if tunneling or melting on one side is very deep or extreme. To prevent one-sided burning in the future, look for high quality, smooth candles with centered wicks and burn candles away from drafts.