What term is used for the fuel that is first ignited by the heat source?

The term "Material First Ignited" is the most accurate descriptor for the fuel that is first ignited by the heat source during a fire event. This term emphasizes the sequence of events in the combustion process, identifying it as the specific material that encounters sufficient heat to ignite initially. Understanding this concept is crucial in fire investigations as it helps in tracing the origins of the fire, assessing how the fire spread, and determining the overall cause of the incident.

In fire science, knowing which material ignites first can provide clues about the factors leading to the ignition, including the heat source and the combustibility of the materials present. This term encapsulates this critical aspect of fire dynamics and helps investigators categorize and analyze the details of fire incidents effectively.