ISO 4625:1980

Specifies a method of test for resins (including rosin) and similar materials by means of the ring-and-ball apparatus. In general, with materials of this type, softening does not take place at a definite temperature. As the temperature rises, these materials gradually and imperceptibly change from brittle or exceedingly thick and slow-flowing materials to softer and less viscous liquids. For this reason, the determination must be made by a fixed, arbirary, and closely defined method.