4.1 Since some potentially adhesive materials are both thermoplastic and hygroscopic, this test method provides means for estimating, on the same material, both thermoplastic and hygroscopic blocking. Because some requirements are more strict than others, two varying degrees of blocking are recognized and defined: (1) First degree blocking, and (2) Second degree blocking. Two types of blocking are covered: (1) Cohesive blocking, and (2) Adhesive blocking.

1.1 This test method covers the determination of the blocking point of a thermoplastic or a hygroscopic layer or coating of potentially adhesive material. Potentially adhesive materials comprise those materials in a substantially nonadhesive state which may be activated to an adhesive state by application of heat or solvents.

1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.

1.3 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.