This part of ISO 21306 specifies procedures and conditions for the preparation of test specimens of PVC-U materials in a specified state, and methods for measuring their properties. Any property listed in this part and referred to in combination with part 1 shall be determined by the method referred to in this part. No figures are quoted for these properties. Those required for the designation of PVC-U thermoplastics are given in part 1 of this International Standard. All properties shall be determined by the appropriate methods referred to in this part of ISO 21306 and values obtained shall be presented as laid down in ISO 10350-1. The values determined in accordance with this part of ISO 21306 will not necessarily be identical to those obtained using specimens of different dimensions and/or prepared by different procedures. The values obtained for the properties of a moulding depend on the moulding compound, the shape, the test method and the state of anisotropy. The last-mentioned depends on the gating of the mould and the moulding conditions, for example temperature, pressure and injection rate. Any subsequent treatment must also be considered, for example conditioning or annealing. The thermal history and the internal stresses of the specimens may strongly influence the thermal and mechanical properties and the resistance to environmental stress cracking, but exert less effect on the electrical properties, which depend mainly on the chemical composition of the moulding compound. In order to obtain reproducible test results, the following two conditions shall be met: a) use test specimens with the specified dimensions and conditioning; b) use test procedures as specified in this part of ISO 21306.