There are two wicks in front of almost every UK maker at the testing stage: a braided cotton wick and a slim strip of wood. They cost pennies, they look simple, and they behave nothing alike. Swap one for the other and the same jar, wax and fragrance oil will give you a different flame height, a different melt pool, a different scent throw and a very different set of customer questions. Neither is the better wick in the abstract. The useful question is which one suits the candle you are actually making, and whether your customers will look after it.

How Each Wick Burns

A cotton wick burns with a fairly upright, pointed flame. As it burns, the tip curls back into the cooler part of the flame, which is what stops it growing endlessly — up to a point. Cotton gives you a flame you can predict, and because wick series come in small size increments, you can fine-tune the burn in a way that feels almost scientific.

A wood wick burns along its flat exposed edge. The flame is wider and lazier, often more horizontal, and it makes that soft crackle people either love or find distracting. It needs more help to get going and more wax underneath it to stay happy. Too short for the jar and the flame sits low while the candle struggles; too wide and the flame climbs, the glass gets hot and the whole thing feels out of control.

Trimming: The Habit That Decides Everything

Both wick types need trimming before every burn. This is the single biggest difference between a candle that performs and one that smokes.

For cotton, trim to around 5mm with a proper wick trimmer or sharp snips. Longer wicks give a big flame, a fast melt pool and soot. For wood, keep it to roughly 3–5mm and remove the charred, brittle tip by pinching it off with your fingers. Never cut a wood wick short to tidy it up — you will drown it on the next burn.

A cotton wick trimmed before every burn will always outperform a better wick that isn't.

A simple routine for both:

1. Let the candle cool completely before touching the wick.
2. Snap off any mushroomed cotton or charred wood with clean fingers.
3. Trim cotton to about 5mm; leave wood at roughly 3–5mm.
4. Check the wick stands upright and central before lighting.
5. Burn long enough for a full melt pool, but no more than about four hours at a time.

Soot, Smoke and Ash

Cotton gets a reputation for soot, and it earns it when the wick is too long, the jar sits in a draught, or the wick is oversized for the vessel. The classic sign is a black mushroom on the tip and a grey film on the glass. Fragrance oils and dyes make this worse, which is why a wick that behaved in a plain wax test can start sooting once you add colour and scent.

Wood wicks generally burn cleanly when they are sized correctly, but they do produce char and ash. A wood wick that is too large, or one sitting in a deep pool of unmelted wax, will smoke — and occasionally go out. Ash can drop into the melt pool, so a wood wick candle usually needs a tidy-up between burns. Neither wick is smoke-free. Ventilation, draughts and wick sizing matter more than the material itself.

Scent Throw

Cold throw — how the candle smells unlit — has nothing to do with the wick. That comes down to wax, fragrance load and cure time.

Hot throw is where the wick earns its keep, because the wick controls the melt pool. Cotton gives you a steady, controllable pool and a dependable scent release. Wood wicks produce a wider flame and often a faster, broader pool, which many makers find gives a strong throw in soy and coconut blends. Push it too far in a narrow jar, though, and the candle runs hot, the fragrance smells sharp and the glass becomes uncomfortable to handle.

Matching Wick to Wax and Vessel

Cotton wicks

• Paraffin, soy, coconut and blended container waxes — there is a cotton series for each, from CD and ECO to LX and HTP.
• Pillars and tapers — square braid and flat braid wicks are made for free-standing candles, where a wood wick has no place.
• High fragrance loads and heavy dyes — cotton is generally the more forgiving choice.
• Small and narrow vessels — fine size increments let you dial in the flame precisely.

Wood wicks

• Container candles with a flat base — wood wicks come with a clip that holds them upright, so they suit tins and straight-sided jars.
• Soy, coconut and blended container waxes — soft enough for the flame to form a pool around the wick.
• Wide vessels — use a double or triple wood wick rather than one oversized strip.
• Avoid pillars, tapers and very hard, high-melt-point waxes.

Wood wicks are a natural material, so batches vary. Expect more testing, and buy from a supplier who can give you the width and thickness rather than just "small, medium, large".

Choosing Between Them, and Testing Properly

If you sell candles, cotton is usually the practical starting point: cheaper, more consistent, easier to source in the exact size you need and far more flexible across different shapes. Wood earns its place when the crackle is part of the experience you are selling, and when you are willing to test patiently.

Whichever you pick, test like this:

1. Make two identical candles, one cotton and one wood, in the same jar with the same wax and fragrance load.
2. Cure both for the same time — a week at least, longer for soy.
3. Burn both in four-hour sessions and log flame height, time to full melt pool, soot, ash and throw.
4. Repeat once each candle is half used. Problems often show up late.
5. Retest whenever you change wax, jar, dye or fragrance oil. A wick is only right for one recipe.

Keep notes in a spreadsheet rather than in your head, and always run a fresh test batch before you list a new candle for sale. Whatever wick you choose, check that your labelling and safety information meet current UK requirements — the latest guidance from Trading Standards is the place to start, or take professional advice if you are unsure.

Photo: Yan Krukau / Pexels