Candle Burn Troubleshooting for Manufacturers


Candle manufacturers sometimes focus on appearance, scent, and aesthetics during the formulation process rather than performance and functionality to meet customers’ initial demands at the point-of-purchase. It is only after several burn cycles that customers begin to encounter entirely avoidable combustion issues. More often than not, candle combustion issues are caused by the incorrect wick size or family used in a particular candle since each wick and candle type has unique burn characteristics. Let’s explore some observable candle combustion issues often encountered and remedied in Wicks Unlimited’s in-house combustion workshop during the formulation process.

Mushroom Capping


An oversized wick providing too much fuel (wax) to the flame or using an incorrect wick size/type for a particular candle system can cause mushroom capping. If the candle wick is too large, the flame starts to consume more wax (fuel), resulting in carbon buildup on the wick’s tip of partially reduced molecules unable to reach the flame. The buildup of partially combusted material then falls back onto the wick. It forms a mushroom shape on the wick’s end, known as mushroom capping.

Mushroom capping can be avoided with thorough testing of your candle to determine the perfect wick for your individual candle formulation.



Mushroom capping often causes wick afterglow, whereby the carbon mass on the tip of the wick continues to throw off a gentle glow for a considerable amount of time once extinguished. Not only is this unsafe, but it can also damage the candle brand’s reputation.

Like most combustion issues, afterglow is entirely avoidable. To prevent this phenomenon, candle manufacturers should partner with combustion specialists like Wicks Unlimited early in the formulation process. Once we understand your burn objectives, we will perform test burns to ensure that the appropriate wick size and type meet the particular candle system’s needs.

Excessive Flame Height 


An excessive flame causes “sooting” consisting of tiny particles of unburned fuel. This indicates not only incomplete combustion but also improper wick selection for this particular candle system. In other words, the candle wick is delivering more fuel to the flame than it can burn.

To prevent excessive flame, manufacturers should work with candle combustion specialists to complete burn tests and identify the appropriate wick size and type for their specific candle application to refine their manufacturing specs.

Excessive/Long Wick


Excessive or long wick modifies the candle’s overall combustion process and causes mushrooming, sooting, and an uneven burn. The soot sticks to the candle jar, surrounding walls, and potentially the ceiling resulting in an unhappy customer and damage to the brand’s image and reputation.

For an optimized burn and to protect the brand’s reputation, working with experienced candle combustion specialists can prevent excessive wick through test burns.

Oversized Wick 

An oversized wick generates a larger than the average flame size that causes a deep burn pool liquifying a large portion of the candle. This type of wick causes sub-optimal combustion causing the wick to mushroom. An oversized wick also increases the candle’s surface temperature resulting in fragrance destruction, which greatly reduces the intended scent profile of your candle. A properly sized wick creates an appropriate burn pool according to the candle’s width with the correct flame height. Wicks Unlimited combustion specialists can identify an oversized wick during controlled burn testing. Once complete, our combustion technicians make appropriate wick recommendations based on various criteria, including the container’s width and scent combinations.

Undersized Wick

An undersized wick is a wick that is too small for a particular candle system and does not generate enough combustion (heat) to melt the wax, causing tunneling. While tunneling is most common in a large container and votive candles, it can also happen with other candle types and sizes. It is indicated by the burn pool not forming edge-to-edge and forming a circular “tunnel” around the wick down to the core of the candle. Candle tunneling and an unhappy end user are entirely avoidable by selecting the appropriate wick size to generate optimal candle combustion.

Partnering with experienced candle combustion specialists like Wicks Unlimited during the formulation process can prevent combustion issues from happening in the first place. Even if the formulation phase has passed and a candle is experiencing combustion issues during real-world applications, our candle technicians can perform a complimentary troubleshooting burn analysis. Once completed, we confidentially report our findings and make product recommendations, including the appropriate wick size and sustainer type to produce an optimized burn. With over 450 different wicks stocked on-site, 26 candle sustainers, and an assortment of wick clip assemblies, Wicks Unlimited is the ultimate destination for all of your combustion needs. Use the form below to contact Wicks Unlimited and schedule your confidential candle combustion troubleshooting or optimization test since testing and observation are vital in the candle formulation process.

Schedule Your Candle Optimization Today!

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