**2. Fire retardant vs. fire resistant**

There is always misconception about inhibition of fire by using coating of either fire retardant or fire resistance. **Figure 1** shows the development of fire in a compartment, which distinguishes the usage of coating in a particular stage of fire. For instance, the material properties play an important role in prior to flashover, which will be controlled by fire retardant coatings (ignition, flame spread, release of heat, smoke, and gases), whereas fire resistant coatings are mainly predominated in protection of structures that occur after flashover, that is, phase of fully developed fire. Post-flashover fires (temperature above 600°C) are considered as hazardous fires for structures [4]. Fire retardant coatings are mainly involved for reaction-to-fire to retard or inhibit the combustion of flammable materials (wood, foam, textile fabrics, electric cables, and fiber reinforced composites) whereas fire resistant or fire protective coating for resistance-to-fire to protect the non-flammable materials. Different test parameters, such as oxygen index (OI), flame spread rate, ignition time, heat intensity, smoke generation, and

**Figure 1.** Phases of fire development in an enclosure.

release of toxic gases, are to be considered for assessing the flammable materials. On the other hand, thermal insulation, integrity, and load-bearing capacity are paramount important for the fire resistance of non-flammable materials. Depending on the types of material and intended application, specific fire performance properties of building materials are to be tested by use of different test methods. The relevant test standards for both coatings are different that also depend on the region of countries.
