ASTM D61-15(2019)

5.1 Pitch does not go through a solid-liquid phase change when heated, and therefore it does not have a true melting point. As the temperature rises, pitch softens and becomes less viscous. The softening point is arbitrarily defined and shall be established by a closely controlled method which shall be carefully followed if test results are to be reproducible.

5.2 This test is useful in determining the consistency of pitch as one element in establishing the uniformity of shipments or sources of supply.

1.1 This test method covers the determination of the softening point of pitches below 176 °F (80 °C). Pitches of higher softening point should be tested by Test Method D2319 or Test Method D3104.

1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.

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.