||Using a testing device called a cone calorimeter, NIST researchers measure the heat-release rate and other flammability properties of materials. Above, untreated polyurethane foam "catches fire" from a nearby heat source. Below, foam treated with a novel clay-filled coating did not ignite when exposed to the same heat source. Instead, a fast-growing protective layer-called char-forms on the surface.
See also http://www.nist.gov/el/fire_research/clay-062712.cfm.