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Wood burner glass still black

Updated: 22 October 2026

You cleaned the door yesterday, and this morning the glass is black again. Wood burner glass still black is usually the fire, not a weak bottle. Wet logs, an airwash that never gets hot, wood against the pane, or a flue that will not draw will lay a new film on glass you have just wiped. A cleaner can clear what you can see. It cannot season the fuel. The twelve listings are on the [fireplace glass cleaner comparison](/hub/fireplaces-and-stoves/fireplace-glass-cleaner). Peter F., 21 October 2026, from HETAS, Defra and Charnwood. A qualifying purchase can earn a commission at no extra cost to you.

You cleaned the door yesterday, and this morning the glass is black again. Wood burner glass still black is usually the fire, not a weak bottle.

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HG HG foam stove glass cleaner

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HG HG foam stove glass cleaner
9.2/10about £17.43
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HG HG stove glass cleaner twin

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HG HG stove glass cleaner twin
9.0/10about £17.98
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RAKSO RAKSO stove glass pads

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RAKSO RAKSO stove glass pads
8.6/10about £6.70
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On this page
  1. 1.Black glass is usually a burning problem
  2. 2.Airwash, log position, and slow burning
  3. 3.When the door or the flue is the fault
  4. 4.What a cleaner can still do

Black glass is usually a burning problem

HETAS ties a black stove door to wood above about 20% moisture, a starved fire, and a weak airwash. Wet wood lays tar. Defra's Burn Better guidance says that tar raises the risk of a chimney fire. In England, wood sold in volumes up to 2 m³ is meant to carry the Ready to Burn mark at 20% moisture or below. That mark does not promise clear glass, and a bottle does not change which fuel is legal in a smoke control area. If the glass blacks up on every fire, change the fuel before the bottle.

Airwash, log position, and slow burning

The airwash is a stream of air down the inside of the glass. It works when the stove is hot and that control is open. Stovax says not to shut the airwash, not to burn wet wood, and not to let flames touch the glass. Closing the vents overnight is how many doors go black by breakfast. Charnwood's Bay list adds logs piled over the front fence, slow burning and poor flue draw. A log against the pane blocks the airwash in that spot. Leave the airwash open until the stove is alight. Unseasoned pine shows up as tar. That is a fuel problem, not a reason for a stronger spray.
HG HG foam stove glass cleaner

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HG HG foam stove glass cleaner
9.2/10about £17.43
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When the door or the flue is the fault

A rope that has flattened, frayed or pulled out lets air in at the wrong place. The airwash then fails even with dry logs. A gap you can see, or a rope that powders, is a fitter's job, not a job for foam. If black deposits keep returning, look at fuel, air, the stove and the flue together. Charnwood cites at least 12.5 Pa on a warm chimney for that family of stoves. Do not measure that yourself. Smoke in the room, or a sharp soot smell, is the point you book a sweep. A cleaner does not change smoke-control fuel rules.

What a cleaner can still do

Once fuel, air, log position, rope and flue are plausible, a cleaner can clear the film you can see, on cold glass, if the manual allows it. UK pad reviews in this set say baked corners survive a dry wipe. UK HG reviews say tar from poorly seasoned pine shifted with a dwell, and one reviewer went back to ash for burnt-on marks. That is a backlog clean, not a substitute for dry wood. Several manuals tell you to leave oven cleaner in the kitchen. The dwell and the rope are on how to clean wood burner glass. Creosote in the flue is not on the glass.

Common questions

Why is the glass black the next morning?
Because the latest fire laid a new film. HETAS links that film to wood above about 20% moisture, a starved fire and a weak airwash. Stovax adds wet wood, a closed airwash and flames on the glass. Charnwood's Bay list adds logs over the front fence and slow burning. The wipe you did yesterday removed yesterday's soot. It did not change how this fire burned.
Is it the cleaner or the wood?
If the glass was clear when you lit the fire and black when you opened the door, it is the burn. A poor cleaner shows itself when a cold wipe leaves the old film in place. A returning film after a fire that hissed, or after you shut the air early, is the wood and the air. HETAS is explicit that keeping glass clean is mostly about the fire. Change the logs and the airwash before you change the bottle.
What moisture should logs be?
About 20% or below, which is the Ready to Burn line for small-volume wood sold in England and the figure HETAS uses for black glass. Measure a freshly split face if you can. Logs that hiss or weep at the ends are wetter than that line. Store them off the ground and under cover, and bring in only what you will burn, not a basket that has sat in the rain. Dry fuel reduces tar. It does not make every door permanently clear if the airwash is closed.
What is the airwash doing?
It washes a sheet of air down the inside of the glass so soot is less likely to stick, once the stove is hot. If you close that control too soon, or the stove never gets up to temperature, the wash does not happen. Stovax tells owners not to shut the airwash and not to let flames touch the glass. A log against the pane blocks the stream in that patch.
Will a stronger spray remove creosote in the flue?
No. A stove-glass spray works on the film you can see on the pane, on a cold door, if the manual allows it. Creosote in the chimney is a sweep's job. Defra links wet wood and tar with a higher chimney-fire risk, which is a reason to dry the fuel, not a reason to aim a bottle up the flue. No listing in this set is a flue cleaner. If you smell sharp soot or the stove smokes back, stop and book a sweep.

Related pages

Stove glass cleaner buying guide

Stove glass cleaner spray vs pad

Fireplace glass cleaner

Best stove glass cleaner UK: depth, not just stars

How to clean wood burner glass once the stove is cold

Sources

Public sources used for this comparison. amazon.co.uk prices, stars and review counts were taken from the listing capture, not a live check on 21 October 2026.

  1. HETAS, stove glass tips (retrieved 21 October 2026)
  2. Defra UK-Air, Burn Better (retrieved 21 October 2026)
  3. SCHOTT ROBAX (retrieved 21 October 2026)
  4. SCHOTT ROBAX dry wiper (retrieved 21 October 2026)
  5. HG UK stove glass cleaner (retrieved 21 October 2026)
  6. HG SDS code 431 ART, 15 November 2023 (retrieved 21 October 2026)
  7. Charnwood Bay instructions (retrieved 21 October 2026)
  8. HSE, COSHH for cleaning (retrieved 21 October 2026)