A candle is a small, slow chemical reaction sitting in a glass on your table. When it misbehaves, it is usually telling you something specific. Here are the four complaints we are asked about most, and what each one actually means.
Why is my candle smoking?
A clean flame produces almost no visible smoke. When you see a steady ribbon of it, the flame is being fed more fuel than it can burn completely.
The usual cause is an untrimmed wick. As a wick lengthens it draws up more wax than the flame can consume, and the surplus escapes as unburnt carbon. Trim to about five millimetres before every burn and the smoke almost always stops.
The second cause is moving air. A draught makes the flame flicker, and every flicker interrupts combustion. In an air-conditioned home this is the more likely culprit of the two. Move the candle out of the airflow.
The third is blowing it out. That plume after you extinguish a candle is normal, but you can avoid it entirely by dipping the wick into the melt pool with a wick dipper and lifting it straight again, or by using a snuffer.
Why is my candle smoking black?
Black smoke is the same problem in a more advanced form - incomplete combustion producing soot rather than fine carbon. It tends to appear when a wick has both grown long and developed a mushroom of carbon on the tip.
Put it out, let the wax set, and trim the wick right back, removing the mushroom entirely. If black smoke returns within minutes of a fresh trim, the wick is oversized for the vessel or the fragrance load is too high for the wax. That is a fault in the candle, not in how you are burning it.
Is it harmful? In an ordinary room, occasional sooting from a well-made candle is not something to be anxious about. Persistent black smoke is worth acting on, mostly because it deposits on walls and ceilings, and because it means you are burning fragrance inefficiently.
Why is there soot on the inside of the glass?
Soot marks climbing the inside of the jar are the residue of the problem above. A grey shadow that appears late in a candle's life is normal, because the flame sits deeper in the vessel and the glass is closer to it.
If it appears early, look first at wick length, then at draughts, then at how long you burn it. Sessions longer than about four hours overheat the glass and the wick, and sooting increases sharply after that point.
To clean it, wait until the candle is cool, then wipe the inside of the glass above the wax with a piece of kitchen paper very lightly dampened with warm water. Dry it before relighting.
Why is my candle sweating?
Those small beads of oil on the surface are fragrance oil separating from the wax. It looks alarming and it is almost always harmless.
It happens when a candle gets warm - left in sun, stored above about 25C, or carried through a hot car. The wax softens enough to release a little of the fragrance it was holding in suspension. Soy is more prone to this than paraffin because it is softer and holds fragrance in a looser structure.
Wipe the beads away gently with kitchen paper and burn the candle as normal. The fragrance you lose is negligible. What matters more is the storage: keep candles out of direct sun and away from windows that take the afternoon, which in this part of the world is the difference between a candle that sweats constantly and one that never does.
One caveat. Heavy, repeated sweating can point to a candle over-loaded with fragrance oil beyond what the wax can bind. That candle will also throw scent unevenly and may burn with a larger flame than it should.
Why does the surface look rough or cratered after burning?
Soy sets unevenly. As the melt pool cools it contracts, and it does not always contract flat - you get a slightly pitted, matte surface, sometimes with a small crater around the wick.
This is cosmetic. It is a normal property of a natural wax and not a sign of a fault. Paraffin looks glassier because it is a more uniform material, not because it is better made. If the unevenness bothers you, a hairdryer on low for thirty seconds will re-level the top.
A quick diagnostic
- Smoke, no soot: trim the wick, check for draughts.
- Black smoke: remove the carbon mushroom; if it returns fast, the wick is oversized.
- Soot on glass, early in life: shorten your burn sessions to two to four hours.
- Beads of oil: the candle got warm. Wipe and carry on; improve storage.
- Pitted surface: normal for soy. Nothing to fix.
Most of these come back to two habits - a trimmed wick and still air. Both cost nothing, and they work on any soy candle, from Bloom to Nocturne. If you want the fuller picture of how a soy candle behaves over its life, see The Well-Kept Flame, and How to Fix Candle Tunnelling if the surface is burning down the middle rather than out to the edge.
