What Is Candle Tunneling and How Do You Fix It?

You light a candle, and a few burns later there's a deep hole down the middle with a thick wall of untouched wax around the sides. That's tunneling. It wastes a big part of the candle, it weakens the scent, and eventually the wick can drown in its own hole. The good news is that most tunneled candles can be saved, and it's easy to keep it from happening again.

What Causes Tunneling

Candle wax has a memory. Each time you burn a candle, the flame melts a pool of wax around the wick. If that pool doesn't reach the edge of the jar before you put the candle out, the next burn tends to melt the same narrow circle, a little deeper each time. Within a few burns, you have a tunnel.

The most common causes:

• A short first burn. This is the big one. The first burn sets the pattern for the life of the candle.
• Short burns in general. Lighting a candle for 20 minutes at a time, over and over.
• Drafts. A flame that leans to one side melts one side faster and leaves the rest behind.
• A wick that is too small for the jar. Some candles simply can't melt all the way across. That's a design problem, not a user problem, and it's one of the things we check when we burn-test every new fragrance in our factory.

How to Tell If It's Fixable

If the tunnel is shallow, less than about half an inch, a long burn alone may fix it. Light the candle and let it burn until the pool catches up to the edges, staying with it the whole time.

If the tunnel is deeper, or the flame is getting small and weak because it's sitting down in a hole, use the foil method below.

The Foil Method, Step by Step

This is the standard fix, and it works on most jar candles. You'll need regular aluminum foil and about an hour or two.

1. Trim the wick to about 1/4 inch and clear out any debris.
2. Wrap foil around the top of the jar, folding it over the rim so the foil covers the outer ring of wax but leaves an opening in the center, about an inch or so across, over the wick.
3. Light the candle through the opening. The foil traps and reflects heat back onto the hard outer wax.
4. Stay with it. Check every 15 to 20 minutes. As the wax around the edge melts and the surface levels out, you can widen the opening.
5. Remove the foil once the whole surface is liquid and level. Use an oven mitt or tongs, because the foil and the jar will be hot.
6. Let the candle burn a little longer with the foil off so the pool stays full, then put it out and let it cool on a level surface.

From then on, treat the next burn like a first burn: let the pool reach the edge every time.

If the Wick Is Drowning

Sometimes the tunnel fills with so much melted wax that the flame shrinks or goes out. Put the candle out, let it cool slightly, and soak up a little of the liquid wax with a folded paper towel. Don't pour wax down a sink, because it hardens in the pipes. Then trim the wick and relight.

What Not to Do

• Don't use a lighter or torch on the wax. It's easy to scorch the jar or the wax and hard to control.
• Don't put a candle in the oven or microwave. Glass and wax don't handle that kind of heat well, and some jars and lids aren't heat-safe.
• Don't leave the foil method unattended. The foil concentrates heat. Stay in the room the whole time.

A hair dryer on a low setting can soften and level the top of a candle for looks, but it won't fix a deep tunnel. Burning is what resets the wax.

How to Prevent Tunneling for Good

• On the first burn, let the melted pool reach the edge of the jar. Plan on about one hour per inch of jar width.
• Keep every burn long enough for the pool to reach the sides, usually two to three hours, and stop by four.
• Keep the candle out of drafts so the flame stands straight.
• Keep the wick trimmed and centered.
• For very wide jars, choose candles with two or three wicks. One wick can only melt so far.

Those same habits also make a candle last longer overall. We walk through all of them in our guide to making any candle burn longer. And as with any candle, never leave one burning in an empty room or near anything that can catch fire.

Have a question we didn't answer? Check our candle FAQ.