What is Crazed Stove Glass and What Causes It?

Crazing refers to fine hairline cracks that develop on the surface of ceramic stove glass over time. This happens due to acidic residues from unburned fuel interacting with the glass. While this is not a defect in the glass itself, it is a result of how the stove is used and the type of fuel burned.

Certain fuels, particularly those with high sulphur content—such as petroleum coke (petcoke) or manufactured fuels containing it—are especially harmful and should be avoided.

When a stove is operated at low temperatures for extended periods—whether to conserve fuel, because the stove is too powerful for the space, or to maintain an overnight burn—incomplete combustion can occur. This can also happen when using less fuel than recommended by the manufacturer.

Restricting airflow prevents the stove and airwash system from reaching optimal temperatures, leading to the production of sulphuric acid. Over time, this acid can damage both the glass and the flue liner.

How to Prevent Crazing in Stove Glass

While your stove manufacturer will provide specific guidance on proper use, here are some key tips to help keep your stove glass clear and prevent crazing:

✔ Keep the glass clean and dry before lighting the stove.
✔ Only use fuels recommended by the stove manufacturer.
✔ Avoid high-sulphur fuels, such as petcoke and certain processed fuels.
✔ Don’t burn at low temperatures for long periods—after running the stove at a reduced setting, operate it at maximum heat for at least 30 minutes.
✔ Ensure proper airflow—avoid fully closing the secondary air control.
✔ Burn only dry, seasoned wood—never use wet, unseasoned, or processed wood.
✔ Prevent ash buildup on the lower part of the glass.

Following these steps will help extend the life of your stove glass and keep it free from hazing, crazing, and damage.