3.1 Sward-type hardness rocker instruments have been used by the coatings industry for more than a half a century as a nondestructive test instrument to measure cure and ultimate surface hardness of organic coatings (see Refs. (1) through (2)).4 This test method is useful within laboratories to quickly screen and measure the surface hardness of candidate coatings.

Note 1: In previous task group work designed to establish an ASTM method for measuring hardness of organic coatings with Sward-type hardness rocker instruments, round-robin test results continually showed poor interlaboratory reproducibility. This lack of interlaboratory agreement could have resulted from dimensional variations among instruments, with the contact rocker rings as the most likely offender in that regard. There are several producers of Sward-type hardness rockers making instruments that differ among themselves in net weight and ring radius. Some of them exceed the measurements and net weight called for in this test method.

1.1 This test method covers the determination of the relative degree of surface hardness of organic coatings using a specific apparatus used in the coatings industry.

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 test method does not purport to address all of the safety problems, 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.