When a wick doesn’t self-trim sufficiently as the candle burns, the extended length of the wick may curl up to the point where the end of the wick touches the melt pool. This situation is referred to as bridging since the curved-up wick loosely resembles a bridge.

Sometimes a bridging wick can curl into the melt pool to such an extent that the wick becomes submerged in the liquid wax and self-extinguishes. However, bridging can occasionally create a hazard. Bridging itself will not cause a candle to fail a fire safety test but if a wick bridges and remains above the melt pool, the flame can increase in size and the rate of wax consumption may increase. In extreme cases, the flame height could be greater than 75mm and the candle would fail to meet the safety standard. A larger flame could also make the container so hot that it cracks. A larger flame will also generate more soot.