6.1 The resistance of plastic lumber and shapes to direct withdrawal of nails, staples, or screws is a measure of its ability to hold or be held to an adjoining object by means of such fasteners. Factors that affect this withdrawal resistance include the physical and mechanical properties of the plastic lumber and shapes; the size, shape, and surface condition of the fasteners; the speed of withdrawal; physical changes to plastic lumber and shapes or fasteners between time of driving and time of withdrawal; orientation of fiber axis; the occurrence and nature of prebored lead holes; and the temperatures during insertion and withdrawal. These factors will be as circumstances dictate, and representative of the normal manufacturing process.

6.2 By using a standard size and type of nail, staple, or screw, withdrawal resistance of plastic lumber and shapes can be determined. Throughout the method this is referred to as the basic withdrawal test. Similarly, comparative performances of different sizes or types of nail, staple, or screw can be determined by using a standard procedure with a particular plastic lumber and shape, which eliminates the plastic lumber and shapes product as a variable. Since differences in test methods can have considerable influence on results, it is important that a standard procedure be specified and adhered to, if test values are to be related to other test results.