A test specimen is mounted vertically and brought in front of a heat source, which is a vertical gas-fired ceramic panel. At definite intervals the specimen is moved closer to the heat source in a series of graded steps until ignition occurs.
During the exposure of the specimen a small gas pilot flame is held in front of the specimen to ignite gasses given off but not the surface of the specimen.
The ignitability index (representing the mean time to ignite), the spread of flame index, the heat evolved index and the smoke developed index are calculated.
Based on the calculated values the test material passes or fails the test.