Over Firing a Clay Chimenea
Over firing clay chimeneas is not only likely to cause damage to the chimenea; it can also be hazardous to your health and safety. The most common cause of over firing a chimenea is adding to much fuel to a fire or using an accelerant when starting a fire.
It is clear that a chimenea is being over fired when the flames protrude from the top or mouth of the chimenea. When this occurs it is highly likely that the chimenea will damage or crack as a result of the intense heat from the large roaring fire.
The body of a clay chimenea will retain and radiate heat so it is not necessary to create a large roaring fire as this is only likely to cause damage or cracks. Due to the radiating properties of clay you will find that a small or medium fire will be more than sufficient to create the warmth and ambience you require.
Results of Over Firing a Clay Chimenea
Although the most likely consequence of over firing a clay chimenea is for it to crack under the intense heat, it can cause more subtle, aesthetic and structural damage.
If your chimenea has a paint finish and it has been over fired, it is possible that the paint will begin to bubble and peel around the bowl region where the fire is contained.
Over firing your chimenea will also lead to black 'soot' forming around the mouth and top of the flue which may later weaken and crack.