What is one notable characteristic of surfaces that are treated for fire resistance?

Surfaces that are treated for fire resistance often exhibit the characteristic of charring instead of combusting when exposed to high heat or flames. This process occurs as the material undergoes thermal decomposition, where the outer layer forms a protective char that insulates the remaining material, delaying further combustion and reducing the spread of fire. This is a desirable property in fire-resistant materials as it enhances safety by slowing down the overall combustion process and maintaining structural integrity longer than untreated surfaces.

In contrast, surfaces that are completely immune to fire do not exist in practical terms, as all materials have some point of ignition. Melting instantly when exposed to flames does not align with fire resistance characteristics, as it implies a complete failure to resist heat without any protective measure. Emitting toxic fumes during combustion is also a negative trait and contradicts the purpose of fire-resistant treatments, which aim to minimize harmful emissions. Therefore, the ability to char instead of combust ensures better protection against fire hazards.