This test method may be used to determine the ability of a button to resist breaking under impact, for example in pressing the end item, which could cause the button to fail.

Note 1-In the development of this test method it was found that the following factors influenced the ability of a button to resist failure under impact conditions: resin formulation, shape ligne size, thickness, number and spacing of holes. Buttons may also pass this test but fail during the pressing of a garment due to the presence of heat during pressing.

5.1.1 If there are differences of practical significance between the reported test results for two laboratories (or more), comparative tests should be performed to determine if there is a statistical bias between them, using competent statistical assistance. As a minimum, test samples should be used that are as homogeneous as possible, that are drawn from the material from which the disparate rest results were obtained, and that are randomly assigned in equal numbers to each laboratory for testing. Other materials with established test values may be used for this purpose. The test results from the two laboratories should be compared using a statistical test for unpaired data, at a probability level chosen prior to the testing series. If a bias is found, either its cause must be found and corrected, or future test results must be adjusted in consideration of the known bias.

Test Method D 5171 for the determination of the impact resistance of buttons may be used for acceptance testing of commercial shipments of buttons but caution is advisable since information is lacking on precision.