Why cheap candles leave black marks on your ceiling and what chimney sweeps recommend instead for cosy winter light

The first time you notice it, you probably blame the shadows. That faint grey halo above the mantel, the smudgy patch over the dining table, the weird “cloud” on the ceiling where you like to light a few tealights in winter. You rub it with your thumb, it comes off on your skin, and suddenly this isn’t atmospheric – it’s dirt.

If you rent, you might immediately think about the deposit. If you own, you might think about how much it will cost to repaint the whole room. Either way, there’s an uncomfortable realisation: something in your “cosy” routine is quietly staining your house.

When chimney sweeps walk into living rooms in November, they can often tell in the first ten seconds who loves candles. The black tide above picture frames, the vertical streaks over radiators, the dark oval on the ceiling right where a big jar candle lives. People apologise for “the damp” or “the old paint”. The sweep just looks at the candles on the hearth and knows.

Because those cheap candles you grabbed in the supermarket for a bit of hygge? They may well be the reason your ceiling is wearing a grey moustache. And it’s not just about how it looks. That soot is in the air you breathe too.

Those mysterious black smudges aren’t “just dirt”

What you’re seeing on your ceiling and walls is usually a fine film of soot – microscopic carbon particles that have floated up, hit a cold surface and stuck. In the trade, some of the patterns are called “ghosting”: dark marks following the lines of joists, picture rails, radiators or even the outline of a cupboard that used to be there.

People often blame:

• condensation and mould
  
• a “dodgy” chimney
  
• traffic pollution from a main road
  

Sometimes they’re right. But chimney sweeps say a huge number of black marks they’re called out to look at are from one very ordinary source: poorly burning candles.

The giveaway is the shape. A soft oval above a coffee table. A fan-shaped patch over the mantelpiece. Black “noses” up the wall where lanterns or jars sit. If you could draw a line from the mark back down to where you burn candles in winter, you’ve probably found your culprit.

And that soot didn’t teleport to the ceiling. It passed your nose and lungs on the way.

What cheap candles are made from (and why it matters)

Not all candles are equal. The bargain multi-pack you sling in the trolley with the tinned tomatoes is usually very different from the hand-poured beeswax pillar you eye up at the craft market.

Most cheap candles are:

• Paraffin-based – derived from petroleum, it burns hot and can be quite sooty if the flame isn’t perfectly balanced.
  
• Heavily scented – packed with synthetic fragrance oils that don’t always combust cleanly.
  
• Strongly dyed – dark colours often need more pigment, which adds to the load the flame has to burn.
  
• Built to a price – wicks, wax blend and quality control are chosen to hit a cost, not to protect your paintwork.

A well-made candle – even if it’s paraffin – is designed so the wick, wax and container work together. The wick draws up just enough fuel, the flame stays steady, and the candle burns down neatly with minimal smoke.

Cheaper candles often don’t manage that balancing act. The wick might be too thick, the wax too soft, the fragrance overloaded. The result is an over-fed flame that struggles to burn everything completely, especially in real-world conditions: a draughty room, a crowded mantelpiece, someone walking past every few minutes.

Every time the flame flickers and coughs out a tiny puff of black, those particles rise with the warm air in the room. Over weeks and months, they settle on the places that catch the most air currents – usually the ceiling.

How candles actually burn: soot 101

A candle flame is a tiny chemistry lab. Wax melts, travels up the wick, vaporises and then burns in the hot zone around the wick. When everything is just right, the carbon and hydrogen in the wax combine with oxygen, and you mostly get heat, light, water vapour and carbon dioxide.

When things are not quite right, you get incomplete combustion. That’s the technical way of saying: some of the carbon didn’t finish the journey and escaped as soot.

Chimney sweeps and fire professionals see the same patterns again and again. Biggest soot-makers in a normal home?

• Wicks that are too long – a tall, dancing flame looks pretty, but it’s a soot factory.
  
• Drafts and fans – moving air makes the flame flicker and smoke as it keeps changing shape.
  
• Jar candles burned right down – as the flame drops deep into the jar, it struggles for oxygen.
  
• Over-scented and dark candles – more additives make clean burning harder.
  
• Clusters of candles – lots of flames close together heat and disturb each other, pushing more soot into the room.

You’ve probably seen it: a candle starts to “mushroom” at the tip of the wick, the glass goes black around the top, and a little plume of smoke curls upwards even while it’s burning. That’s your early warning. Keep going like that every evening all winter, and those plumes add up to the halo on your ceiling.

What chimney sweeps actually see on your ceilings

Chimney sweeps get a strange birds-eye view of modern cosiness. They see the scented candles lined along the hearth, the tealights in metal holders, the big three-wick jars on the coffee table. Then they look up.

Patterns they talk about a lot:

• A “shadow” above the TV and media unit, right where people line up jars and tealights.
  
• Black fingers rising from lanterns on the floor, especially in corners where air is still and soot just climbs straight up.
  
• A grey oval directly over the centre of the room, matching the position of a favourite coffee table candle.
  
• Ceiling fans with dark streaks on the blades, spreading soot further each time they spin.

Homeowners often assume the marks are from a “leaky” chimney or a past fire. Sweeps then do smoke tests, inspect the flue… and find nothing dramatically wrong. Instead, they watch the way air flows in the room, ask where candles are usually lit, and quietly point at the blackened glass of that bargain jar candle.

Many also raise a point people don’t love hearing: if the soot is on your ceiling, it’s been in your lungs. Fine particles from incomplete combustion are not your best friend, especially if anyone in the house has asthma or other breathing issues.

That’s why, when you ask them what to do, chimney sweeps rarely say “no more candles ever”. They say: use better ones, and burn them better.

Candles without the black halo: what sweeps recommend

Chimney sweeps are, by nature, practical. They spend their days around soot; they know what creates it and what doesn’t. When you ask how to keep the cosy light and lose the black marks, they tend to suggest a few very simple shifts.

1. Choose cleaner-burning candles

You don’t have to remortgage the house, but you may need to step up a notch from the 40-for-£3 tealights.

Look for:

• Beeswax or good-quality soy candles – they generally burn more cleanly than cheap paraffin blends.
  
• Light or natural colours – avoid very dark, heavily dyed candles for everyday use.
  
• Moderate scent – strong synthetic fragrances are the main sooters. Unscented or gently scented is kinder to your paintwork.
  
• Reputable makers – small chandleries and quality brands often test their wicks and blends so they burn properly.

A useful rule sweeps mention: if a candle blackens its own glass quickly, it will happily paint your ceiling too.

2. Burn the candles you already have… properly

If you’ve got a drawer full of gift sets and bargain jars, you don’t have to bin them all. You do, however, need to treat them like small fires – not ornaments.

Basic “burning well” checklist:

• Trim the wick to about 5 mm before every burn. Long wick = tall, sooty flame.
  
• Keep candles away from drafts – not under extractor fans, beside open windows or in narrow corridors.
  
• Don’t crowd them – give each candle at least 10 cm of space so flames don’t disturb each other.
  
• Cap the burn time – most makers suggest 3–4 hours at a time. After that, the glass can overheat and soot production rises.
  
• Extinguish with a snuffer or by dipping the wick, rather than blowing hard and sending a final puff of soot skywards.

If you notice a candle starting to smoke, “mushroom”, or blacken its container, it’s not being dramatic to blow it out. That’s prevention, not fussiness.

3. Use your fire – but respect it

If you’re lucky enough to have a working fireplace or stove, chimney sweeps will almost always tell you: a well-maintained, properly used fire is safer and often cleaner than a battlefield of cheap candles.

Their usual advice:

• Burn seasoned, dry wood or the approved fuel your stove is designed for.
  
• Get your chimney swept at least once a year (more if you burn a lot).
  
• Avoid using the hearth as a stage for candles with the flue shut – soot collects in the opening and stains the breast above.

A quiet, well-drafted fire combined with one or two good-quality candles often gives all the light and atmosphere you actually want.

4. Add light that doesn’t burn at all

Most sweeps are not anti-candle. They just see the cumulative effect. For everyday use, they often recommend soft alternatives:

• Warm-white fairy lights along the mantel or in a big glass jar.
  
• A low-wattage lamp with a fabric shade by the sofa.
  
• A salt lamp or small table lamp in the fireplace when it’s not in use.

Then keep actual flames for specific moments – a Sunday evening, a bath, a winter supper – and treat them as you would a real fire: chosen carefully, used thoughtfully, put out properly.

Fixing the marks (and when to worry)

Once you’ve tackled the cause, you may still be stuck with the evidence. Light soot on modern paint will sometimes come off with a soft cloth and sugar soap solution, but rubbing too hard can just smear it or polish a shiny patch into matte paint.

If the marks are heavy, most decorators recommend:

1. Wiping gently with sugar soap and letting the wall dry.
   
2. Using a stain-blocking primer over the marks.
   
3. Repainting the whole area, not just the patch.

It’s annoying, but cheaper than losing a rental deposit or living with a permanent grey halo.

There is one important caveat: if you see blackening specifically around gas fires, boilers or flues, or you smell fumes, that’s not a candle issue – that’s a safety issue. In that case, sweeps and gas engineers are united: stop using the appliance and get it checked. Soot can be an early sign something more serious is wrong.

A quick reference from the ceiling down

What you see	Likely cause	Simple first step
Soft oval of grey on ceiling over coffee table	Regular use of one big jar/pillar candle	Swap to cleaner candle, trim wick, limit burn time
Vertical black streak over a lantern or stove alcove	Lantern/jar burning in still corner	Move candle, use snuffer, clean glass often
Dark “ghost” lines following joists or edges of pictures	General soot from multiple sources (candles, cooking), catching on cold surfaces	Improve ventilation, reduce sooty candles, clean and repaint with stain block
Blackness around gas fire or boiler	Appliance or flue issue, not normal candle use	Stop using, call a Gas Safe engineer / sweep

Cosiness isn’t cancelled because you retire the cheap tealights. If anything, the room feels better when you know the glow on the walls isn’t hiding a grey film waiting to appear at the next spring clean.

Your ceiling is simply telling the truth about what you burn.

FAQ:

• Are all paraffin candles bad and all soy/beeswax candles good? Not automatically. A well-made paraffin candle can burn very cleanly, and a poorly made soy candle can still soot. The main thing is quality of wick, wax blend and how you burn it. That said, natural waxes tend to produce less soot when everything else is equal.
  
• Why are the marks worst near radiators and outside walls, not just above my candles? Warm air from radiators and cold patches on outside walls create little air currents where soot likes to stick. The particles drift around the whole room, then deposit where the air cools or slows – often at temperature “bridges” like corners and above heaters.
  
• My landlord says the marks are my fault because of candles. Is that fair? If you burn lots of sooty candles and there’s clear shadowing directly above them, they may have a point. However, poor ventilation, old paint and other combustion sources (like smoking indoors) also play a role. Taking photos, reducing candle use, and cleaning/repainting with their agreement is usually the most practical route.
  
• Do “soot-free” or “smokeless” candles really exist? No open flame is completely soot-free, but good-quality candles, burned correctly, can produce so little soot you never see it on your walls. Treat “smokeless” as “low smoke if used properly”, not as a magic exemption.
  
• If I only ever burn tea lights, am I safe from black marks? Not necessarily. Large numbers of cheap tealights, especially in cups or lanterns that restrict airflow, can still produce a surprising amount of soot over time. Fewer, better tealights, placed away from drafts and burned for shorter periods, make a noticeable difference.