Why Does Firewood Pop and Crackle?

16th November 2023

The procedure Moisture Content of The Wood

1) The noises created by fireplaces can be a very relaxing experience, but these traditional fireplace sounds can vary in type and frequency between fires, so what causes wood to pop and crackle when burning?

2) When firewood is burnt a chemical reaction known as combustion occurs in which the solid state of the wood is converted to heat and waste gases.

3) As the cellulose matter within the firewood turns to heat and gas, some of these gases can become trapped within the pores of the wood.

4) Combined with steam created from the evaporation of moisture within the firewood, the waste gases from combustion expand due to the heat and must find their way out of the wood.

5) The process of steam and gases forcing their way out of the firewood creates the noises you hear in the form of pops and crackles.

• The moisture content level of firewood can also influence how much firewood will crackle and pop in a fire.

• Firewood higher in moisture content will typically produce more noises compared to firewood that is lower in moisture.

• Moisture within the wood will evaporate and expand due to the temperature of the fire, and the fire can make pops and crackles when the moisture forces its way out of the wood in the form of steam.

• Firewood higher in moisture content can produce more popping and crackling noises because there is more moisture contained within the wood.

• This can lead to more pockets of steam escaping the wood and making pops and crackles.

• Unseasoned 'green' wood will typically be much higher in moisture content compared to properly seasoned or kiln dried firewood.