This practice covers the basic test procedures for the determination of the physical properties and the reporting of data for high-density rigid cellular plastics. Samples shall be prepared by either processing samples directly into proper size specimens, or by preparing samples from larger sections as specified in each individual test. Since cellular plastics are often nonuniform in density distribution, a minimum of five specimens shall, therefore, be tested per testing method to obtain representative values. The test methods covered here are to examine the following material properties: apparent density; compressive strength; tensile properties; coefficient of linear thermal expansion; apparent flexural properties; deflection temperature; dielectric breakdown voltage and dielectric strength; thermal conductivity; and water absorption rate.