Published by Kevin Fischer on
Candle tunneling is the phenomenon of a lit candle melting through the center of the candle without melting all the surrounding wax, leaving a ledge of solid wax around the edge of the container.
The flame on the wick creates a vertical “tunnel” towards the bottom as it burns, leaving a lot of wax around the sides.
There are a few tricks you can use to fix any candles that have tunneled, but the best medicine is prevention!
If you leave a candle that tunnels by itself, sometimes it will correct and melt the remaining wax, but most of the time it won’t, leaving you with a permanent ring of solid wax around the perimeter of the container.
You need to act quick to avoid wasting any wax! The longer you wait, the harder it becomes to fix.
If a candle continues to tunnel:
- It may stop burning on its own if it runs out of oxygen or the surrounding wax melts and drowns the flame or,
- It will finish burning, but without consuming all the wax which leads to a dramatically shorter burn time for the candle.
The easiest way to stop tunneling is to prevent it from happening in the first place, but it’s possible to fix it if it gets out of hand.
In this guide you’ll learn:
- What causes tunneling
- How to prevent tunneling from starting
- How you can fix tunneling on your favorite candles
What causes candle tunneling?
It’s easy to identify candle tunneling because of the characteristic “ledge” it leaves behind.
There are two main culprits for tunneling candles.
- Wax memory
- Wick size
Wax memory
To understand wax memory, we need to talk about what happens during the lifecycle of a candle.
When candle wax melts, it becomes a liquid.
Duh.
But when it cools back into a solid, it’s not as “hard” as it was before lighting the wick. Depending on the wax, it could take a few days or even two weeks before it’s as “hard” as it was before you lit the wick.
This means freshly melted wax is softer, and takes much less heat to re-melt into a liquid again.
When you re-light the wick, the previously-melted area will melt first, and much quicker than the rest of the wax.
Wax memory is the area of the candle that melts much quicker than the rest of the candle because it hasn’t cooled back the original hardness.
If you don’t allow the candle enough time to melt more of the outer ring of wax, and increase its memory, the wick will begin to tunnel downwards until it’s impossible for the flame to melt the outer ring at all (because the heat is too low).
The candle will keep melting the softest part of the wax until it:
- Runs out of oxygen or,
- Reaches the bottom while leaving a large ring of unmelted wax in your jar.
Candle tunneling from wax memory is caused by poor burn behaviors of the candle owner.
Wick size
Candle makers know that choosing the right wick is the most critical element of a candle’s design.
Everything else in the candle can hum along, but if the wick isn’t the right size it won’t matter.
Wax memory stops the wick from having the chance to melt the outer wax, but bad wick size makes it impossible.
When a candle wick is too small it can’t generate enough heat to melt a large enough area of wax. In this case it will burn downwards in a hole as wide as the wick is capable of melting.
Cold rooms also make it more challenging to melt the right amount of wax.
For example, if you burned a candle outside during the winter you’d find that almost every single candle tunnels. The solid wax needs reach its melting point which takes even longer when it’s resting in a cold room.
There’s no substitute for having the wrong wick size in a candle.
Candle tunneling from improper wick sizing is caused by poor candle design.
How to prevent candle tunneling
There are two main strategies for preventing tunneling from happening.
1. Burn the candle for at least 3 hours
Not a hard and fast rule, but you want to make sure the candle has time to start melting. If it burns too deep before melting anything else, the flame won’t have the opportunity to properly melt the surface and it will become a problem.
Make sure you allow the candle to burn for at least 3 to 4 hours in its first few “sessions.”
If you don’t let it burn long enough, wax memory will remain small and your candle will probably start tunneling.
2. Use the right wick size
The other main cause of tunneling is improper wick size.
If you’re a candle maker, make sure you’re testing your candles to choose the right wick size and series for your wax and container.
Nobody likes a crappy candle.
If your candle design is tunneling, increase the size of your wick for the next one. This typically addresses undersized wick problems. There are many testing tricks for candles to quickly find the right wick size.
How to fix tunneling on your favorite candles
Before doing anything make sure tunneling is the real problem. Some candles that look like they’re tunneling are actually suffering from craters.
You can usually tell the problem is from CRATERS and not TUNNELING when two things happen:
- The wick rapidly tunnels in a matter of minutes
- The diameter (width) of the melted area is very small
If so, use the “Severe tunneling” steps outlined below to fix your candle.
When tunneling is the real problem, you can use any of the following methods to fix it, ordered by difficulty and severity of the tunneling.
Barely tunneling: burn the candle for a long time
If the candle is barely tunneling, it might just fix itself if you give the candle enough time to burn.
Theoretically, a well-designed candle will eventually melt, or “clean” all the wax off the sides. When your candle shows a minimal sign of tunneling, it’s worth just letting it burn for an extended period of time to see if it eventually burns.
The remedy? Burn the candle for 3-4 hours at least twice.
If that doesn’t help, move on to the next step.
Normal tunneling: place tinfoil around the edge and let it burn for a few hours
When your candle has the right size wick but you ended up with tunneling because you didn’t burn it long enough it’s time to move to more… creatively aggressive maneuvers.
Not too long ago, the internet presented a viral hack for addressing candle tunnels that only requires a bit of tin foil and some extra time.
The theory goes, you can melt down the “shelf” of wax with heat from the candle by redirecting that heat BACK to the wax instead of out of the container using tinfoil!
- BEFORE lighting the candle, trim the wick to remove any mushrooms down to a 1/4″ height.
- Cover the top of the candle with tinfoil (aluminum foil).
- Cut an opening on the top roughly 1″ wide, or small enough that tinfoil remains above the wax shelf.
- Carefully light the candle and allow it to burn for 3-4 hours.
Once the burn completes, the tunneling should be smaller than before.
You may need to repeat this a few times to completely restore the candle.
Alternatively, you can melt the surface of the candle down with a heat gun to level out the top. This requires no tinfoil and works much faster.
The downside? Most people don’t have a heat gun.
If you used tinfoil or a heat gun and the tunneling continues, or the wick is covered up, proceed to the next option.
Severe tunneling: wick replacement
If your wick is swallowed up in wax, or the tunneling is far too tall to be corrected using any of the earlier methods, your only option is to replace the wick completely.
The catch?
This operation is like candle surgery and comes with a risk of failure. The alternative is a wasted candle, so it’s usually worth the risk!
Gather the following before starting:
- New wick
- Oven (or heat gun, as shown).
- Apple corer
You can usually buy wicks from your local hobby store, though there’s no guarantee they’ll be the right size for your candle. Apple corers are pretty easy to find. Many grocery stores carry them too.
1. Push the apple corer through the wax around the wick
2. Twist apple corer and carefully pull upwards until the wax plug comes out with the wick
If the wick is still stuck to the bottom of the candle jar, use a needle nose pliers to pull out the wick tab and wick.
Throw the old wick away. Keep as much wax as possible,
3. Place wax back in the empty area of the candle
Don’t worry about this being perfect – you’re just going to melt all the wax down again anyways.
4. With a heat gun, melt the surface of the candle until the entire surface is liquid and it appears flat
Alternatively, place the container in the oven on low (usually about 200°F or 93°C) for 20 minutes or until the entire surface of the candle is liquid and appears flat.
5. After the surface has dried, use a toothpick or skewer to make a hole for the replacement wick
You may have to cut off the wick tab if the wick is too long
Don’t worry about gaps between the wick and the wax. After the candle is re-lit, the areas will fill back in with liquid wax right away.
Since your replacement wick doesn’t have a tab, it may eventually tip over when the candle reaches the end of its life. Typically this doesn’t take much time off the life of the candle, but it’s better than never burning the candle again!
Final recommendations
Candle tunneling is a pretty common problem and usually doesn’t take too much effort to fix. Even though wax has memory, candles that are well-designed can usually correct the problem but sometimes things happen and you need to take drastic action!
Instead of crying or discarding the candle, consider making a small craft project out of it and restore it with the tricks above.
However, the best medicine is prevention, so make sure you burn new candles for at least 3 to 4 hours for the first few burns to make sure the wax melts consistently.
If you’re interested in accelerating your candle making technique, check out our beginner’s candle making course!
