Reaction is part of all those safety and prevention measures taken to reduce the probability of fire when it starts, while we talk of resistance when fire has already broken out and we must make sure that the structures resist for the time necessary to evacuate the building and put out the fire. For example, if must fireproof chairs, we talk about reaction to the fire because the purpose of the paint is to prevent the chair from catching fire. While, if we must fireproof load-bearing beams, we have to guarantee that the beam will hold for the time necessary to activate the fire-fighting teams and save lives.

At temperatures above 200-250 °C, surfaces of steel, wood and cement elements protected with intumescent paints form a very compact layer of carbonaceous foam whose volume is many times greater than the dry coat of paint applied. It has the function of blocking the passage of heat for a period of time (expressed in minutes of fire-resistance) to prevent the heat of the fire from reaching the core of the element, causing deformation and the consequent collapse of the structure. A fundamental characteristic of Stufex intumescent paints is the excellent ratio between the thickness of the applied paint and the intumescence it develops

The symbol “R” = stability (the ability of a construction element to maintain its mechanical resistance under the action of the fire. The last state is collapse) • The “E” = seal (ability to prevent the passage of fumes, vapors and hot gases from the side exposed to the fire to the side that is not exposed) • The “I” = thermal insulation (the ability to limit the transmission of heat) When a certain resistance class is required, it will typically be: ü An “R” class for just the load-bearing elements (such as beams) must, in fact, guarantee that the beams will maintain their static stability. ü An “REI” class for the separating elements (such as a firebreak wall) must guarantee the stability, seal and thermal insulation for a certain time.