Why is my candle wick mushrooming? (and how to fix it)

If your candle wick grows a little black ball on the tip while it burns, that is mushrooming. It looks like a tiny toadstool of carbon sitting on the flame, and it is one of the most common candle questions we get. The short answer: it is a build-up of carbon the flame cannot burn off fast enough, and the fix takes about five seconds.

Mushrooming is not a fault in the candle, and it is easy to keep under control. Here is what causes it, whether it is anything to worry about, and the simple habit that stops it for good.

What is candle wick mushrooming?

Mushrooming is the little ball of carbon that forms on the tip of a wick as a candle burns. The wick draws up more wax and fuel than the flame can burn cleanly, so the leftover carbon collects at the top and hardens into a mushroom shape. It is most noticeable near the end of a long burn.

Why do candle wicks mushroom?

Wicks mushroom when the flame is fed more fuel than it can burn off. A few things push it that way, and often more than one is at play.

• The wick was not trimmed. A long wick pulls up too much wax, and the extra fuel turns to carbon at the tip. This is by far the most common cause.
• Long, uninterrupted burns. The longer a candle burns in one sitting, the more time carbon has to gather on the wick.
• Draughts. A flame that flickers in moving air burns unevenly, which leaves more soot and carbon behind.
• A fragrant, richly coloured candle. Fragrance oils and pigment give the flame a little more to burn, so heavily scented candles mushroom a touch more readily. That is normal.

Is a mushrooming wick dangerous?

A mushrooming wick is not dangerous in itself, but left unchecked it can make the flame larger and flickery, throw more soot, and drop bits of carbon into the wax. That is why we trim it. A tidy wick gives a calmer flame, a cleaner burn, and less black marking on the jar.

If you are seeing black marks creep up the glass, mushrooming is usually part of the story. Our guide to keeping candles soot-free and even goes into the rest.

How do you stop a wick from mushrooming?

The fix is simple: keep the wick short. Trimming before every burn removes the carbon before it has a chance to build, which keeps the flame small and steady.

1. Wait until the candle is completely cool and the wax has set.
2. Trim the wick to about five millimetres, roughly the length of a grain of rice. Wick trimmers are ideal, but scissors or nail clippers work fine.
3. Pinch out or tip away the trimmed carbon so it does not fall into the wax.
4. Light it, and enjoy a cleaner, calmer flame.

If a wick mushrooms mid-burn, do not trim it while it is lit. Blow the candle out, let it cool, trim the tip, then relight. A few seconds of care before each burn is all it takes.

Trimming is the same small habit that helps a candle burn evenly and last longer, so it is worth making it second nature. You can see how we build our wicks to burn cleanly across our soy-blend candle collection.

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