This test method is used to assess the dimensional stability of plastics as a function of temperature and determine the Vicat softening temperature.

The Vicat softening temperature (VST) is the temperature at which a standard indenter penetrates 1 mm into the surface of a plastic test specimen under a constant load when the temperature is increased at a uniform rate.

A distinction is made between:

Method A: 10 N load
Method B: 50 N load

as well as between temperature rise rates of 50 K/h or 120 K/h