Why Do Candle Wicks Mushroom & How To Prevent It?
If you've ever noticed a ball of carbon forming at the tip of your wick, like a tiny mushroom cap, that's called wick mushrooming. It's a common issue in both handmade and commercial candles, but with the right adjustments, it can be managed or prevented.
What Is Wick Mushrooming?
Wick mushrooming refers to carbon buildup at the tip of the wick during burning. It usually appears as a round or lopsided bulb and may cause the flame to flicker, lean, or burn too hot. You might also see extra smoke or soot forming on the jar or around the wick.
Why Do Candle Wicks Curl or Form a Bulb?
The curled shape is often part of the wick’s design to help it self-trim. But when too much wax is pulled into the flame, especially if the wick is oversized or the burn environment isn’t ideal, more fuel is delivered than the flame can fully combust. What’s left behind is that telltale mushroom-shaped tip.
What Causes Candle Wicks to Mushroom?
A few key factors make this issue more likely, especially in highly scented or long-burning candles.
Overwicking and Fragrance Load Impact
One of the most common causes of mushrooming is using a wick that is too large for the wax, container, or fragrance load. When a large wick draws up excess wax and fragrance oil, the flame burns too hot and can’t use all the fuel efficiently. The unburned carbon collects at the wick’s tip and forms the mushroom.
Heavy fragrance loads, especially those with complex blends or vanillin, can also influence burn behavior. Be sure to test your formulation carefully and consult IFRA usage rates to ensure you are within safe, stable ranges.
How to Prevent Wick Mushrooming
While it is not always possible to eliminate mushrooming entirely, a few burn and production habits can reduce how often it happens.
Proper Wick Trimming Habits
The easiest fix is trimming your wick before every burn. A wick trimmed to ¼ inch reduces the amount of fuel feeding the flame, leading to a cleaner burn and better flame control. Never let mushroomed wicks continue burning. They can produce soot, create unstable flames, and increase the risk of container overheating.
Choosing the Right Wick Size for Your Wax
Mushrooming often signals that the wick is too thick or the wrong type for your formula. Softer waxes like soy usually require thinner wicks, while paraffin blends can support a wider range.
When testing your candle design, start with a wick recommended for your container diameter and wax type, then adjust based on burn performance. If you are unsure where to begin, TFC’s CD Wick Series is a dependable choice for smooth-burning soy and soy-paraffin blends. If you're working with a container around 3.5 to 4 inches wide and using a soy or soy-paraffin blend, the CD 18 Wick Pre-Tabbed (100 count) offers steady flame control and helps reduce carbon buildup when trimmed to ¼ inch.
Frequently Asked Questions
Q: How do I trim a candle wick properly?
A: Use scissors or wick trimmers to cut the wick to about ¼ inch before each burn. Remove any carbon buildup or mushrooming before relighting.
Q: Why does my candle wick curl at the top?
A: Some wicks are designed to curl slightly as they burn. This helps them self-trim, but excessive curling with mushrooming usually means the wick is too large or the wax is over-fueled.
Q: Can I stop candle wicks from mushrooming completely?
A: You can reduce how often it happens by choosing the right wick, managing fragrance load, and trimming before each burn. Minor mushrooming is sometimes normal, especially in richly scented candles, but should never be ignored.
Q: Is mushrooming dangerous?
A: If left untrimmed, a mushroomed wick can create a large flame, produce soot, and overheat the jar. Always trim between burns for safety.