Pendulum Hardness (Koenig or Persoz)

The pendulum hardness test is based on the principle that the amplitude of the pendulum’s oscillation will decrease more quickly when supported on a softer surface. There are several hardness tests which relate the damping of an oscillation motion to the hardness of surfaces.
The times taken in Persoz tests are approximately double those in Konig tests and so the Persoz has a greater degree of discrimination.