5.1 The specific gravity or density of a solid is a property that can be measured conveniently to follow physical changes in a sample, to indicate degree of uniformity among different sampling units or specimens, or to indicate the average density of a large item.

5.2 It is possible that variations in density of a particular plastic lumber or shapes specimen will be due to changes in crystallinity, loss of plasticizer/solvent content, differences in degree of foaming, or to other causes. It is possible that portions of a sample will differ in density because of difference in crystallinity, thermal history, porosity, and composition (types or proportions of resin, plasticizer, pigment, or filler).

5.3 Density is useful for calculating strength to weight and cost to weight ratios.

5.4 If the cross-sectional area of the specimen is required for future testing on a particular sample, it is acceptable to determine it from a specific gravity measurement, see Eq 5.

1.1 This test method covers the determination of the bulk density and specific gravity of plastic lumber and shapes in their as manufactured form. As such, this is a test method for evaluating the properties of plastic lumber or shapes as a product and not a material property test method.

1.2 This test method is suitable for determining the bulk specific gravity or bulk density by immersion of the entire item or a representative cross section in water. This test method involves the weighing of a one piece specimen in water, using a sinker with plastics that are lighter than water. This test method is suitable for products that are wet by, but otherwise not affected by water for the duration of the test.

1.3 Plastic lumber and plastic shapes are currently made predominately from recycled plastics. However, this test method would also be applicable to similar manufactured plastic products made from virgin resins where the product is non-homogeneous in the cross-section.

1.4 The values stated in SI units are to be regarded as standard.

1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.