ASTM D4366-16

5.1 The pendulum damping test has been found to have good sensitivity in detecting differences in coating hardness, where hardness is defined as resistance to deformation.

5.2 The two procedures given in these test methods embody the principle that the amplitude of oscillation of a pendulum touching a surface decreases more rapidly the softer the surface. However, these test methods differ in respect to pendulum dimensions, and period and amplitude of oscillation.

5.3 In general, the damping time of the König pendulum is approximately half that of the Persoz pendulum.

5.4 The Persoz pendulum has a greater degree of discrimination than the König for measuring the hardness of soft coatings, but it may not be as suitable for testing hard, slippery films because of its tendency to skid on surfaces with a low coefficient of friction.

5.5 The interaction between the pendulum and the paint film is complex, depending on both elastic and viscoelastic properties, and it may not be possible to establish a precise relationship between the two types of pendulum tests.

1.1 These test methods cover the use of pendulum damping testers in the determination of hardness of organic coatings that have been applied to acceptably plane rigid surfaces, such as a metal or glass panel.

1.2 Two test methods based on different pendulum types are covered as follows:

1.3 This standard is similar in content (but not technically equivalent) to ISO 1522.

1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.5 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.