Wicks Unlimited, a division of Stimpson Company, Inc.

Common Burn Issues

The proper wick for any given candle provides a correctly sized burn pool, does not extinguish before its wax is exhausted, and has a safe, pleasant flame height.

When observing the characteristics of a proper burn, it is important to achieve a properly sized burn pool, minimal sooting and a well-sized flame throughout the length of the entire candle. Container candles may entrap an increasing amount of heat as they burn, so the way a candle burns in the first half of its life may not indicate how it will burn toward the end.

That's why Wicks Unlimited tests each candle to its completion. There are no shortcuts in the pursuit of a quality candle.

The Burn Pool

The burn pool serves two main functions for a candle. It provides the liquid fuel required by the flame and it regulates the "scent throw."

too large wick    too small wick

In general, choosing too large a wick will result in excessive flame size and hence a large burn pool, causing too large a portion of the candle to liquify, and, in the case of pillar candles, collapse the walls.

Too much heat will also cause the fragrance to break down, reducing the disbursement of scent and requiring a greater flow of oxygen which, in turn, causes burning inconsistency and "sooting."

Too small a wick will either cause the wick to drown in its burn pool or to create too small a pool resulting in "tunneling" and reduction of burn time.

In both cases, the customer will almost certainly feel disappointed by his or her purchase. The choice of the proper wick for a particular candle's composition will determine the success of the burn pool and ultimately, the customer's satisfaction.

Flame Height

Flame height is another determining factor in judging the overall burn of the candle and it is also ultimately determined by the wick choice.

sooting and incorrect flame height

After all, the wick is the candle's sole conduit for fuel. Too high a flame not only will cause "sooting" but can also become quite dangerous.

Soot is the black substance found in smoke. It is comprised of tiny particles of unburned fuel and its excessive presence indicates incomplete combustion and the improper wick choice.

Mushroom Capping

Mushrooming occurs when there is an overabundance of wax fuel to be combusted, creating a collection of partially reduced molecules which are unable to reach the flame, combine with oxygen and complete the burning process.

mushroom capping

As a result, the incompletely combusted material falls back onto the wick, and through molecular attraction, builds up as a carbon cap on the end of the wick.

This excess fuel can be caused by an oversized wick providing more wax to the flame than can be burned; or the wrong type of wick in general.


Afterglow occurs when an individual manually extinguishes the flame but the charcoaled mass of wick at the end continues to throw off soot. All wicks do this to some extent when they are blown out, but it becomes "afterglow" when it continues for minutes.


This condition most often occurs as a direct result of mushroom capping during the burn.

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