The intumescent coating is a special paint anti – fire that reacts in the presence of fire releasing a carbon foam with high insulating properties. Its function is to delay the rise of temperature of a fire and the consequent collapse of the structures to facilitate the evacuation of the persons present .
The fire resistance is given by the value REI . In particular the value of REI is composed of:

• R , a factor which indicates stability, ie, ‘s aptitude to maintain the mechanical strength under the action of the fire
• And , factor which indicates tightness , or the ability to not let pass gases , vapors and fumes
• I, which demonstrates the isolation , namely ‘ ability to limit the action of heat
The value indicates REI , therefore , how many minutes an element can ensure stability , tightness and thermal insulation in case of fire .