November 8, 2026, 12:04 pm | Read time: 4 minutes
Anyone who regularly uses candles has probably noticed: A few minutes after lighting, candles form a central tunnel, leaving a wax residue on the edge. But why does this happen?
A candle tunnel is annoying because it can become deeper over time, leaving some of the wax unused. To prevent this, it’s worth looking at the causes. myHOMEBOOK spoke with Constanzé Gillé, managing director, and Han Lugtmeijer, chairman of the quality committee of the RAL Quality Association Candles about this everyday problem. They explain why tunneling occurs and reveal how to avoid the issue.
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Why Does a Candle Tunnel?
When candles burn only around the wick area and leave a solid wax residue on the edge, a so-called tunnel has formed. According to RAL, one cause is a too-short burning time during the first lighting.
The experts refer to this as the memory effect. “Candles ‘remember’ how far the wax melts during the first lighting. If the candle is extinguished too early, before the entire surface is liquid, it usually only melts in this area during subsequent burnings,” explain Gillé and Lugtmeijer. In addition to a too-short burning time, low room temperatures or drafts can also cause a candle to tunnel, according to the experts.
Also interesting: How to Prevent a Candle from Sooting
How to Avoid a Tunneling Candle
To prevent a candle from tunneling, they recommend completing the first burning session. This means the candle should burn long enough during the first lighting until the top wax layer is liquid to the edge and a wax pool has formed. If a tunnel has already formed, it is much more difficult to burn down the edges evenly.
It’s different with pillar candles, often used on Advent wreaths or as decorative elements. These candles can be salvaged by trimming the wax edge. The experts explain: “It’s best to carefully cut the soft wax with a knife after extinguishing. For candles with a diameter of more than 40 mm, this should be done between 1 and 2 centimeters above the burning bowl.”
Beware of Internet Hacks
There are also tips circulating online for saving tunneling candles. Aluminum foil is particularly often recommended. The upper edge of the candle is wrapped with aluminum foil from the outside. The center remains free so the wick can burn sufficiently. The foil is supposed to store heat and ensure the wax melts more evenly.
RAL explicitly advises against such methods. “The aluminum foil can reach temperatures of several hundred degrees, posing a significant safety risk that can lead to unpredictable dangers when combined with drafts,” say the experts. RAL also advises against the oven method, where the candle is placed in the oven for five to ten minutes at 50-60 degrees Celsius. The excess wax is then poured off.
The Role of Wick Length
According to the experts, wick length is not very crucial for tunnel formation, but it does affect the candle flame. A wick that is too long can cause a candle to soot or develop a large, unsteady flame, they describe. In this case, the wick should be carefully trimmed. Conversely, if the wick is too short, the flame may be too small. “According to the guidelines of the Quality Association Candles, the ideal wick length is about 10 to 15 mm,” explain Gillé and Lugtmeijer.
Those who want to focus on quality when buying candles can look for the RAL quality seal, awarded by the Quality Association Candles. Candles with this seal do not drip, are low in soot and smoke, and are made from quality-assured raw materials.