What To Do If You Have Mushrooms On Your Wick

Published by Kevin Fischer on

Ever seen the top of a candle with a mysterious formation after you burn it?  They kind of look like mushrooms, but they’re actually carbon formations.  The good news is, they aren’t inherently harmful.

Some candles form mushrooms every single burn, and the users don’t even trim the wick.  If you light one of these, you’ll probably see a much larger flame until it’s burned out because the carbon burns as additional fuel for the flame.

Generally speaking, most candle makers try to avoid building candles that form excessively sized carbon balls when burning, though in some cases it can’t be avoided.  Some wicks are more prone to it than others.

Causes of Mushrooms

Candles work by balancing three components:

  • Heat, provided by the flame
  • Oxygen, provided by the air
  • Fuel, provided by vaporized wax and a little bit of the cotton/wooden wick

When all three elements work together perfectly, the combustion process completes successfully.  Think of it like cleaning your entire plate of food at a restaurant.

When carbon forms, and mushrooms appear, this means your combustion process didn’t complete!  Something is haywire with the amount of food, the size of the plate, or how fast you can eat. It’s chemistry, and the same equations for candles apply to any burning object.

Read more about combustion and other chemistry items here if you’re interested.

For the sake of candles, this issue typically happens when the wick isn’t the right size, but we’ll explore a few ideas for treating it if you think it’s a problem with your candle.

How much is too much?  Some people claim if a single mushroom ball is larger or longer than a pea or a pearl, it’s too big. There’s technically no huge risk associated with nasty mushrooms, but they burn a little bright if left untrimmed… and most consumers won’t trim.

Does that mean they’re a fire hazard? It really depends on how obnoxious the mushrooms are. Treat mushrooming like perfume: a little is okay and normal, but too much isn’t welcome by most.

Treatment

Assuming your carbon balls are out of control, you have a few major options for dealing with mushrooming.

Keep in mind that certain wick series are more prone to creating mushrooms than others, such as CD and Zinc. Don’t fret if you’re checking all the safety boxes and feel slightly alarmed by the mushrooms that show up.

Unfortunately, identifying the root cause of your particular combustion is sometimes hard, so consider looking for other signals in the candle that can help you identify which corrections to make.  Several are listed below, described in the spirit of wine tasting.

Decrease your wick size

Pairs well with deep and wide melt pools.

Candle systems run hot when your wick sends far more fuel than the flame is able to consume. You’re likely to see other symptoms from excessive heat in this case, which means you just have to wick down to reduce your fuel capacity.

Increase your wick size

Pairs well with shorter flames or tunnel-like behavior.

Sometimes the incomplete combustion occurs when there isn’t enough fuel. This happens less often.

Look for signs your candle is under-wicked and react with a wickectomy or new candle with a larger wick.

Change your wick series

Pairs well with sooting.

When your wick soots AND has mushrooms without violating much else you’re probably using a wick ill-suited for that wax or fragrance oil.

These things happen: not every material or supply gets along or behaves in the presence of others.

Change your fragrance load or fragrance type

Pairs well with disappointment, because everything else was going well.

If all else fails, you can always combine several treatments. The unfortunate truth is wicks are fairly sensitive to fragrance oils. If you practice the craft by making fragrance-less candles, you’re likely to notice the impact of fragrance on your wax.

Sometimes adding fragrance requires a larger wick than pre-fragrance, and sometimes it needs something smaller. These pairings depend on the situation and largely cannot be predicted.

Some highly experienced chandlers may anticipate a certain adjustment ahead of time, but no one at that level assumes anything without safety testing to back it up.

CD and zinc wicks are known for mushrooming more than normal, so don’t be alarmed.

Mushrooms Are (Kind Of) Okay

At the end of the day, your war against mushrooms shouldn’t disappoint you. They almost always win because candles are combustion machines in an imperfect environment.

An otherwise perfect candle will mushroom in a room with slightly more drafts than normal because too much oxygen slightly tips the chemistry equation scales.

Or perhaps that candle burns perfectly in a 72°F room, but forms extra mushrooms when it’s 80°F. In a warmer environment the candle’s thermal energy requirements are lower (it takes less heat from the flame to melt fuel) meaning there may be an excess of fuel in the equation.

Don’t stress over eliminating mushrooms from your candle design because it’s impossible to anticipate the environment your candle will burn inside of.

Instead, focus on building a candle that passes safety and performance testing. Read more about safety testing here, or visit this article to read about performance testing instead.

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