Place the test fixture shown in figure 1 on a horizontal plane surface. Under its own weight and in a non-compressed state apply any portion of the test sample in the most adverse orientation to the opening in the test fixture. Repeat this procedure after performing the use and abuse tests of §1500.51 (excluding the bite and flexure tests of paragraphs (c) and (d) of this section). In testing to ensure compliance with this regulation, the measurements of the opening of the Commission's test fixture will be no greater than those shown in Figure 1 and the depth of the fixture used will be no less than that shown in figure 1.