Why the glass turns black – and how to keep it clean

Anyone who chooses a stove with a large glass wants to see the fire. All the more annoying when the glass is grey after two evenings. The good news: in the vast majority of cases it is not the stove but the way it is fired. ## How a stove keeps the glass clear Modern stoves guide part of the combustion air from above along the inside of the glass. This air curtain keeps soot particles away from the glass. But it only works if enough air flows and the fire is hot enough. ## The most common causes - Damp wood: The classic. The fire stays cool and produces a lot of soot and tar. - Air throttled too early: If the air supply is reduced before all the logs are burning properly, the air curtain collapses. - Too little wood for the stove: A single log in a large combustion chamber never brings the stove up to temperature. - Logs too close to the glass: Wood leaning against the glass almost always blackens it at that spot. - Weak chimney draught: For example in mild weather, see our article on weather and chimney draught. A light film after several evenings is normal. But if the glass darkens after just one burn, it is worth going through the points above. ## Cleaning gently Only clean the glass when the stove has cooled down completely. 1. Dab a damp kitchen towel or newspaper briefly into the fine, light ash. 2. Wipe it over the glass in circular movements. The ash acts like a very fine polish. 3. Wipe again with a clean, damp cloth and rub dry. For stubborn deposits there are special cleaners for fireplace glass. Spray them onto the cloth, not directly onto the glass, so that nothing gets onto the seals or painted parts. Scouring cream, steel wool and abrasive sponges are off limits; they leave fine scratches where soot will stick even better in future. ## When nothing helps If the glass still turns black quickly despite dry wood and correct operation, a seal may be leaking or the stove may not match the chimney. Talk to us and we will take a look.