The temperature at which a thermoplastic material reaches a specific degree of softness, as measured by a standardized indentation test. The exact value is only meaningful for comparison purposes (comparing two materials or quality control of different material batches).
The ASTM D1525 test for this property is largely equivalent to the ISO 306 test. Vinyl-based plastics are poorly suited for this test because they tend to have a wide Vicat softening range.
Also called Vicat hardness or Vicat softening point.
For additional information, see Material Properties Explained.