A wooden wick is a flat strip of wood, usually held upright in a small metal clip at the bottom of the candle. It does the same job as a cotton wick, which is to carry melted wax up to a flame, but it does that job differently enough that people who have only ever used cotton often think their first wooden wick is faulty. It usually is not. It just needs to be handled like wood.
Why it crackles
The sound is real combustion, not an additive. Wax soaks into the grain of the wood and burns off it, and the wood itself chars and pops as it goes. Because the wick is a strip rather than a braided string, it burns along a line instead of at a point, which is what gives you a low continuous crackle rather than a silent flame. It is quieter than people expect. It is closer to a fire heard from the next room than to a fireplace you are sitting in front of.
It burns wider and slower
A cotton wick makes a tall, narrow flame and a deep melt pool. A wooden wick makes a low, wide flame, which spreads the melt pool outward across the surface rather than digging down into it. Two practical consequences follow.
First, the flame will look small compared to what you are used to. A wooden wick flame that sits low and steady is working correctly. Second, because the melt pool is shallow and wide, the surface takes longer to open up. Do not judge a wooden wick in the first few minutes. Give it time to find its width.
Why it can be stubborn to light
This is the single most common complaint, and it comes from lighting it like a birthday candle. Cotton catches. Wood soaks.
Hold the flame at the base of the wick, where the wood meets the wax, not at the tip. Keep it there longer than feels reasonable, ten to twenty seconds. You are waiting for wax to climb into the grain and for the whole edge of the strip to take, not for a single point to catch.
If it still will not hold, tilt the candle gently for a few seconds so the melted wax runs down to the base of the wick, then set it upright and try again. A dry wick will not stay lit. A wax-fed one will.
The other cause is carbon. After a burn, a black crust builds along the top edge of the wood. That crust chokes the wick, and a choked wick either refuses to light or lights and then dies a minute later. It is not a defect. It is ash, and ash gets removed.
Trim it to about 3 mm
Before every lighting, with the candle completely cool, take the charred top off the wick. You can pinch it away with your fingers, or use nail clippers or a wick trimmer and cut straight across. What you want left is about three millimetres of clean wood standing above the wax.
Too long and the flame gets tall, smoky and unsteady. Too short and there is not enough wick above the wax to draw a flame at all. Three millimetres, clean edge, every time. Brush the trimmings out of the wax rather than leaving them in the pool.
The first burn decides every burn after it
Wax has memory. Whatever width the melt pool reaches on its first burn is the width it will tend to return to on every burn afterwards. If you light a fresh candle briefly and put it out while there is still a ring of solid wax around the edge, that ring becomes permanent. The candle burns down the middle in a narrowing shaft, the flame sinks below the rim, and the wax against the glass never gets used. That is tunnelling, and it is the main reason candles get thrown away with a third of them left.
So on the first burn, leave it alone until the melted wax reaches the edge of the vessel all the way round. Then you can put it out whenever you like. You are teaching it the full width once, and it will remember.
If a candle has already started to tunnel, you can sometimes recover it by burning it long enough for the pool to melt back out to the glass. Do not carve the wax out with a knife while the candle is in use, and do not push the ring inward onto the wick.
A few other things worth knowing
Keep it out of draughts. A wide, low flame is easily pushed sideways, and a flame leaning against the glass will soot it. Put the candle out with a lid or a snuffer rather than blowing, which scatters bits of charred wood across the surface. Stop using it while there is still about a centimetre of wax left in the bottom, so the vessel never gets hot enough to be a problem. And never leave a burning candle unattended, or within reach of children and pets.
Done properly, a wooden wick asks for about ten seconds of attention before each lighting. That is the whole maintenance schedule.