ISO 306:2022

This document specifies four methods for the determination of the Vicat softening temperature (VST) of thermoplastic materials:
—    Method A50 using a force of 10 N and a heating rate of 50 °C/h;
—    Method B50 using a force of 50 N and a heating rate of 50 °C/h;
—    Method A120 using a force of 10 N and a heating rate of 120 °C/h;
—    Method B120 using a force of 50 N and a heating rate of 120 °C/h.
The methods specified are applicable only to thermoplastics, for which they give a measure of the temperature at which the thermoplastics start to soften rapidly.