In general, with materials of this type, softening does not take place at a definite temperature. As the temperature rises, these materials gradually and imperceptibly change from brittle solids to soft, viscous liquids. For this reason, the determination of the softening point must be made by a fixed, arbitrary, and closely defined methods if the results are to be comparable.

1.1 This test method covers the determination of the softening point of certain alkali-soluble resins having uniform plastic flow characteristics as the melting point is approached.

1.2 The resin manufacturer should specify whether or not this test method may be used for his product(s).

1.3 This test method is not suitable for styrene-maleic anhydride resins.

Note 1—For testing rosin and other resins, see Test Method E 28. For testing asphalts, tars, and pitches, see Test Method D 2398.

1.4 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 and health practices and determine the applicability of regulatory limitations prior to use.