Stove Glass Discolouration

Why has the glass in my stove gone cloudy?

You may have noticed that an area of the glass in the stove door has gone cloudy, even after cleaning it does not wipe off.

Unfortunately there is nothing that can be done, except for replacing the glass. However, the glass is not weakened and the stove can be used as normal, the damage is cosmetic.

The white cloudiness is related to the presence of sulphur. All stove manufacturers give a very detailed list of acceptable fuels that can be used on their stoves. It is important that this is adhered to. The list can vary according to manufacturer, so one fuel that is suitable for one make of stove may not be suitable for another.

During lighting of a stove a small amount of condensation will build up on the surface of the glass, this is quite normal. If sulphur is present it will mix with the water and sulphuric acid will form. Sulphuric acid is corrosive. If left for any length of time it will start to etch into the surface of the ceramic glass. As the stove heats up the moisture boils away leaving a mixture of sulphur dioxide and sulphur trioxide which is a white powder. As it is contained in the etched areas, it cannot be cleaned off, resulting in the cloudiness. When the glass is wiped with a wet cloth, it will first look as though the cloudiness has gone. But, as soon as the glass has dried, the white powder, trapped in the etched glass appears again.

Here are ways in which you can avoid any discolouration of your stove glass:

• Regularly clean the glass.

• Most modern stoves are fitted with air-wash. Make sure that your stove is set correctly for the air wash to be operating.

• Do not let your stove 'slumber burn'. This means that you should avoid letting your stove tick over gently for overly long periods. When you first light the stove let it come up to temperature and let it burn hot for at least 20 minutes. If you have a multifuel stove that is designed to stay in over night, make sure, after refuelling the stove before bed, that you open the vents and get the fire blazing, you can then close the vents and let the stove run slowly through the night.

• Use the correct fuel as stated in the user manual.