Candle Barn Guide

Wicks

Candle wicks: materials, sizing and trimming

The wick is the engine of a candle. It pulls melted wax up to the flame, and its size decides how wide the melt pool gets and how tall the flame burns.

How a wick works

When you light a candle, the flame melts the wax around the wick. The liquid wax travels up the wick by capillary action, the same way water creeps up a paper towel. Near the flame, the heat turns that wax into vapor, and the vapor is what burns. A wick that is the right size keeps this cycle steady: enough fuel for a calm flame, and enough heat to melt the wax out to the edge.

What wicks are made of

  • Braided or knitted cotton. The most common type. The braid helps the wick curl slightly as it burns, so the tip burns away and the wick trims itself a little.
  • Cotton with a paper core. A paper thread runs through the center to keep the wick upright in soft wax.
  • Wood. Flat strips of wood, sometimes layered, that give a wide flame and a soft crackle. They need a shorter trim than cotton.
  • Cored wicks. Some wicks have a thin core of another material for stiffness. Wicks with lead cores have been banned in the United States since 2003.

Why size matters

Wick size is matched to the diameter of the candle and to the wax, fragrance and dye in it. A wick that is too small makes a narrow melt pool and leaves a wall of wax, which leads to tunneling. A wick that is too large gives a tall flame, soot, and a container that can get too hot.

Fix

Tunneling

Short burns left a well down the middle and a wall of hard wax around it. The wall wastes wax and can drown the wick.

Good

Full melt pool

A shallow pool runs edge to edge. This is the shape to aim for on the first burn and on every burn after it.

Fix

Wick too long

A tall, flickering flame gives off dark smoke and blackens the glass. Put it out, let it cool and trim the wick.

Wick makers publish sizing charts by diameter and wax type, but they are only a starting point. Candle makers test-burn each new combination of jar, wax and fragrance, because a change in any one of them can change the right wick. Wider containers often use two or three wicks instead of one very large one.

How to trim a wick

  1. Let the candle cool completely and the wax harden.
  2. Remove any black, mushroom-shaped tip and any loose bits of wick from the wax.
  3. Cut a cotton wick to about 1/4 inch. Cut a wood wick shorter, about 1/8 inch, unless the label says otherwise.
  4. Check that the wick stands near the center. If it leans, nudge it upright while the wax is still slightly soft on the next burn.

Wick trimmers have an angled head that reaches into deep jars and catches the trimmed piece. Nail clippers or small scissors work for open pillars. Don't trim while the candle is lit or the wax is liquid, because the bit you cut off can drop into the pool and act as a second wick.

What wick mushrooming means

A carbon ball on the tip of the wick, often called mushrooming, forms when the wick takes up more wax than the flame can burn. It is common in long burns and with heavily scented candles. It makes the flame larger and smokier, and the ball can drop off still glowing. Trim it away before the next burn.

When a new candle smokes right away, the wick may simply be too long from the factory. Trim it before you blame the wax. If a trimmed wick still flares, the candle may be over-wicked for its jar, and it is safer to stop using it.