What are char blisters primarily formed on?

Char blisters are primarily formed on carbonized materials, which include organic substances such as wood, cloth, or plastics that have undergone pyrolysis during a fire. When these materials burn, they experience chemical decomposition and the release of volatile gases, leading to the formation of char. As the heat from the fire impacts these materials, bubbles can form within the char, creating blisters that are indicative of the heat exposure and its effects on the original material.

The presence of char blisters can provide valuable evidence during fire investigations, pointing to areas with the most severe heat exposure and assisting investigators in understanding fire dynamics and material behavior under extreme conditions. This characteristic helps distinguish charred materials from other surfaces that do not undergo the same transformation when exposed to similar thermal conditions.

In contrast, while metal, concrete, and glass surfaces can exhibit various forms of damage from heat and flames, they do not develop char blisters. Metal might melt or warp, concrete can spall, and glass may crack or shatter, but these phenomena do not produce the blistering typical of charred organic materials. Understanding the formation of char blisters is crucial for accurately assessing fire damage and the conditions that caused it.