Candle Care: 5 Rules to Prevent Tunnelling and Soot
A quality candle lasts much longer and stays more enjoyable when used correctly. Here are 5 golden rules to get the best performance from your Studio Craftisan candle.
1. The First Burn Matters Most (Memory Effect)
When you light the candle for the first time, wait until the top surface has fully liquefied to the edges. A candle forms a "memory"; if it does not melt fully on the first burn, a tunnel forms in the middle and the edges never melt. This step is especially critical for concrete-vessel candles.
2. Trim the Wick
Before each burn, clean the burnt tip of the wooden or cotton wick and trim it to about 5 mm. This prevents soot and an uncontrolled flame, giving you a cleaner burn.
3. Don't Burn More Than 4 Hours at Once
To prevent overheating and damage to the vessel, don't burn the candle for more than 4 hours at a time. Let it cool completely before relighting.
4. Choose a Safe Surface
Never leave a candle unattended; keep it away from children, pets and flammable objects. Always place a heat-resistant plate under sculptural (uncontained) candles.
5. Extinguish Properly
Instead of blowing the candle out, use a snuffer or dip the wick into the melted wax and lift it back — this reduces soot and smoke. Reposition the wick upright after extinguishing.
With these simple steps, your candle lasts longer and delivers the same calming experience every time.
Fixing a Tunnel Once It's Started
A candle that has already started tunnelling won't fix itself — you need to change how you burn it. The most reliable method is the aluminium foil trick. Here's how to do it.
- Cut a piece of foil slightly wider than the top of the candle.
- Poke a small hole in the centre, just big enough for the wick to pass through.
- Tent the foil over the candle like a dome and fold the edges down over the sides of the vessel.
- Let the candle burn like this for 1-2 hours.
- Remove the foil and check the surface once the wax has fully cooled.
The foil traps heat and reflects it back onto the colder wax at the edges, so the whole surface melts more evenly. If the tunnel is deep, repeat the process 2-3 times. Levelling the surface first also helps: once the wax has fully hardened, use a clean spoon to push the raised centre outward toward the walls, widening the melt pool for the next burn. This only works on shallow tunnels, though — if more than a centimetre of solid wax remains above the container wall, go straight to the foil method. Don't rush the fix; blowing the candle out early during the repair just resets the problem. Once the tunnel is gone, letting the wax pool reach the edges on every burn keeps it from coming back.
Soot and Blackening: Causes and Fixes
That thin black smoke rising off the flame eventually leaves a dark film on the inside of the jar and under the lid. There are three usual culprits.
- Wick length: once the wick grows past 6-7 mm, the flame gets too big and unburned carbon particles rise as visible smoke.
- Drafts: an open window, air conditioning, or a fan makes the flame flicker constantly, and uneven burning produces more soot.
- Fragrance load: cheaply made candles often carry more fragrance oil than the wax can fully combust, and the excess turns to smoke.
The fix is straightforward. Trim the wick to 5-6 mm before every burn, keep the candle away from drafts, and if the flame keeps flickering, blow it out and move it somewhere calmer. A well-made candle burns with a small, steady flame and produces almost no visible smoke — if soot keeps showing up, look at the burning conditions before blaming the candle itself. To clean soot off the inside of the jar, wait until the candle is completely cool, then wipe with a damp cloth and a small amount of dish soap; avoid abrasive scrubbers or sharp scrapers, since they can scratch the glass. For stubborn marks, let a damp cloth sit against the glass for a few minutes to soften the residue before wiping it away. The same method works for soot on the underside of the lid — just check for metal parts before getting them wet.
Wick Troubles: Mushrooming, Drowning, and Leaning
Mushrooming is the small, carbonised clump that forms at the tip of a cotton wick as it burns. Left unchecked, it grows, destabilises the flame, and increases soot. Trimming the wick before every burn prevents most of it. A wick that drowns and goes out is usually the result of not letting the first burn melt the wax long enough — as the wax re-hardens, it pulls the wick down with it. If this happens, watch the candle closely on the next burn and don't extinguish it until the surface has fully melted. If the wick is already buried, gently work it free with a warmed pin or toothpick to expose the tip again.
A leaning wick usually shows up when there's a steady draft on one side of the container, or when the wick wasn't held straight during pouring. A wick that leans toward the glass causes uneven melting and can overheat the container wall. If you catch it while the wax is still liquid, nudge the wick gently back toward the centre with a clean toothpick or wick centring tool; it sets in place as the wax hardens. Wooden wicks need slightly different care: they crackle as they burn and leave a thicker charred tip than cotton wicks do, so that tip should be snapped off by hand or trimmed by about 3-4 mm before each burn — breaking it by hand keeps the wood fibres from splitting unevenly. Wooden wicks also need a bit longer to catch, around 5-10 seconds of direct flame contact; if it won't light, tilt the flame slightly and try again.
Storing Candles and Recognising the End of Life
Store unused candles somewhere cool and dark, ideally between 15-20°C. Direct sunlight fades the colour of soy wax and can cause a whitish surface haze known as bloom — harmless, but it dulls the look of the candle. Keeping the lid on between burns slows the evaporation of fragrance oil; a candle left uncovered for a few months will noticeably lose scent strength. In summer, avoid hot spots like a car interior or a sunny windowsill — with concrete-topped candles, high heat can even cause discolouration where the concrete meets the wax. In winter, moving a candle straight from a cold room into a warm one can cause fine surface cracks, so it's worth letting it sit at room temperature for a couple of hours before lighting.
The most reliable sign that a candle has reached the end of its life is the remaining wax height: stop burning once less than 1 cm of wax is left at the base, since the container overheats at that point and both glass and concrete vessels risk cracking. To clean out the last bit of wax, set the container in warm water for a few minutes, or soften it in a low oven at around 90°C, then wipe it out with paper towel once it's soft. Never pour melted wax down the sink — it can harden inside the pipes and cause blockages, so throw it in the bin instead. Once it's clean, the container works well as a new candle vessel, a pen holder, or a small planter.
Frequently Asked Questions
Why does a candle tunnel?
Tunnelling almost always starts on the first burn, when the candle is extinguished before the wax has melted edge to edge. Wax has a kind of memory — on every burn after that, it tends to melt only as wide as that first pool, leaving a narrow well in the middle and a solid ring around the edge. The wrong wick size or repeated short burns speed this up.
How much should I trim the wick?
Trim it to about 5-6 mm before every burn, roughly the length of a fingernail. A longer wick produces a large, smoky flame, while an overly short one can smother itself or barely stay lit. A proper wick trimmer instead of scissors also keeps trimmed ash from falling into the wax pool.
Is it okay to blow out a candle?
You can, but it's not ideal — blowing can splatter melted wax and send up a thick puff of smoke from the wick. A candle snuffer is a cleaner option, or you can dip the wick briefly into the wax pool and immediately set it upright again; this puts out the flame without smoke and leaves the wick ready for the next burn.
How do I remove the leftover wax at the bottom of the jar?
Set the jar in warm water for a few minutes, or warm it in the oven at around 90°C for a short while. Once the wax softens, it wipes out easily with paper towel or a plastic scraper. Never pour the leftover wax down the drain — it can solidify and clog the pipes as it cools.
Why is my candle producing soot?
The most common cause is an overgrown wick — once it passes 6-7 mm, the flame grows too large and unburned carbon rises as smoke. Burning in a drafty spot and using lower-quality candles with a heavy fragrance load also add to it. Trimming the wick regularly and burning in a steady, draft-free spot resolves most of the problem.