What occurs as temperatures rise in Stage II of wood combustion?

As temperatures rise in Stage II of wood combustion, the primary process that occurs is the breakdown of the chemical structure of the wood. This stage, often referred to as the volatiles stage, involves the thermal decomposition of cellulose, hemicellulose, and lignin present in the wood. As the heat increases, these components break down into smaller molecules, leading to the release of gases and vapors.

This breakdown is essential because it transforms the solid wood into volatile compounds, which are ultimately responsible for producing flame and contributing to the overall combustion process. During this stage, the wood is not yet burning completely; that process occurs in later stages where the released gases ignite and further contribute to the combustion process. Therefore, understanding the chemical changes happening during Stage II is crucial in grasping the overall dynamics of wood combustion.

The production of smoke, generation of ash, and complete burning of wood all relate to different aspects of combustion that occur in the later phases or as a result of the combustion process; they are not the primary focus of Stage II.