The fire-resistant wrap itself possesses low thermal conductivity, acting as a thermal barrier that slows the transfer of heat to the underlying structure and thereby reduces the rate at which the protected object heats up.
Under sustained high temperatures, certain fire-resistant materials undergo physical or chemical changes-such as expanding to form a porous char layer, releasing water of crystallization to absorb heat, or creating a stable insulating structure. These transformations further enhance thermal insulation, effectively "self-thickening" the protective layer and extending the material's stability during a fire.
Fire-resistant wraps also serve to limit contact between oxygen and combustible materials, reducing the likelihood of fire spreading into the protected structure. For materials like steel-which can rapidly lose structural strength at high temperatures-this mechanism of delaying heat rise and blocking heat transfer is crucial, as it buys valuable time for personnel evacuation and firefighting operations.