The Pendulum hardness is a measure of the amplitude of oscillation of a pendulum touching a surface, which decreases more rapidly the softer the surface. Differences in the hardness between samples can be evaluated by recording the number of oscillations that the pendulum makes between specified amplitudes. A digital counter counts the oscillations between these amplitudes. The test can be conducted using two different pendula, a König or Persoz pendulum, as according to standard ISO 1522:2006. CREST has a König pendula. Recommended samples consist of a glass or metal substrate, with a coating; in the case of a multi-coat system, each coating must be tested separately. The coating may be a paint, a varnish or other related product.