Definition - What does Intumescent mean?
An intumescent is a material that is a poor heat conductor and that increases in volume and decreases in density when it is exposed to heat. These are desirable properties for applications that require a flame retardant or fire protection. Intumescents are commonly used for coatings that provide passive fire protection.
Corrosionpedia explains Intumescent
Intumescents are good passive flame-retardants due to their ability to increase in volume, thus separating the coated material from the flame, and their insulating properties, which reduces the heat that is transferred to the coated material.
Intumescent coatings are commonly used for fire protection in structural applications. Intumescent coatings are either rolled or sprayed onto structural components. The finish of an intumescent coating is somewhat textured and not smooth.
Graphite is a popular material used to produce intumescent coatings because its carbon layers expand when heated.