The re-ignition potential of multi-species soot clouds in building fires were investigated based on their extinction characteristics. The investigation was carried out theoretically using an adaptation of Semenov’s thermal explosion theory. The critical sizes of soot particles in the cloud were found to be strongly affected by the particle temperature, shape, and reactivity, as well as the mass fraction of each species, and ambient conditions. The cloud shape, cloud particle number density, fuel mass fraction, and soot reactivity were identified as the major parameters impacting upon the cloud extinction potential. Our analysis indicate that blending of a base soot with a less reactive soot generally increases the extinction potential of the cloud (i.e. likelihood of extinction) while addition of a more reactive secondary soot to the base one minimises the probability of cloud extinction
