Rubber properties – Standard test method for Hardness 1- Test method involves A, B, C, D, DO, E, M, O, OO, OOO, OOO-S and R 12 (Diauroch) hardness tests and procedures for determining the indentation hardness of substances according to the classification of rubber, net materials, elastic materials, thermoplastic materials and certain hard plastics.
Meaning and Purpose
4.1 The test method is based on the penetration of a specific type of indentation when forced into the material under specific conditions. Indentation hardness is inversely proportional to penetration and depends on the elastic modulus and viscoelastic behavior of the material. The geometry of the indenter and the forces applied can affect the measurements, so there is no simple relationship between the measurements obtained using one hardness tester and those obtained using another hardness tester or other instruments used to measure hardness. The test method is an empirical test primarily used for control purposes. There is no simple relationship between the indentation hardness determined by this test method and any basic characteristics of the tested material. For specification purposes, it is recommended that test method D785 be used for materials other than those described in 1.1.

Scope of
1.1 The test method covers twelve types of rubber hardness measuring equipment called durometers: type A, B, C, D, DO, E, M, O, OO, OOO, OOO-S and R. Procedures for determining the indentation hardness of substances classified as thermoplastic elastomers, vulcanized (thermoset) rubber, elastomeric materials, porous materials, gel-like materials and certain plastics are also described.

1.2 This test method is not equivalent to other indentation hardness methods and instrument types, in particular those described in Test Method D1415.

1.3 This test method is not applicable to the test of coated fabrics.

1.4 All materials, instruments or equipment used to determine mass, force or size shall be traceable to the National Institute of Standards and Technology or other internationally recognized organization of a similar nature.

ASTM D 2240-2021 “Rubber Properties – Standard Test Method for Hardness 1- (Diauroc) Hardness Tester”

1.5 Values expressed in SI units should be considered standard values. The values given in parentheses are for reference only. Many of the stated dimensions in SI were translated directly from the US customary system to fit instruments, practices, and procedures that existed prior to the 1975 Metric Conversion Act.

1.6 This standard is not intended to address all safety issues, 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 to determine the applicability of regulatory restrictions prior to use.

1.7 This international Standard has been developed in accordance with the internationally recognized standardization principles established in the Decision on Principles for the Development of International Standards, Guidelines and Recommendations issued by the Committee on Technical Barriers to Trade of the World Trade Organization.