Flame resistance is the characteristic of a fabric that causes it to self-extinguish when the source of ignition is removed.

 

Fabrics that self-extinguish after the source of ignition is removed can dramatically reduce body burn percentage and increase the chance of survival. However Char length measurements by themselves have no correlation to the protection afforded by flame resistant fabric. True protection to thermal events is better measured by testing the thermal resistance of fabrics against exposures to simulated hazards, such as the flash fire manikin test or the arc thermal performance test.