Specifies a method of test for determining the flexural strength and the apparent flexural modulus of elasticity of rigid cellular plastics. A load is applied at a uniform rate by means of a cylindrical loading edge to a test specimen supported at two positions. The load is applied perpendicularly to the specimen at a position midway between the supporting positions. The values of the load and the deformation are recorded. The flexural properties are calculated from these values. A universal mechanical-testing machine is used for the test. Cancels and replaces ISO 1209:1976.