This International Standard specifies a small-scale laboratory screening procedure for comparing the relative horizontal burning characteristics of small test pieces of flexible cellular polymeric material exposed to a low-energy source of heat. It is intended only for the purpose of assessing quickly and simply the horizontal burning characteristics of small test pieces of the material as such, i.e. considered without reference to the environmental conditions under which the material, or products made from it, may be used. As a consequence, it is not possible to establish a correlation between the results of this test and the performance of such materials or products under actual service conditions. The test is restricted to test pieces of thickness greater than 5 mm. Results of tests on test pieces of different thicknesses are not comparable. This test method is not intended to be used to assess the potential fire hazard in use.