ASTM C338 – Standard Test Method for Softening Point of Glass
Description:
Significance and Use
2.1 This test method is useful to determine approximately the temperature below which the glass behaves as a rigid solid in glass-forming operations and for a control test to indicate changes in composition. It has been found useful for specification acceptance and for providing information in research and development work with glass.
Scope
1.1 This test method covers the determination of the softening point of a glass by determining the temperature at which a round fiber of the glass, nominally 0.65 mm in diameter and 235 mm long with specified tolerances, elongates under its own weight at a rate of 1 mm/min when the upper 100 mm of its length is heated in a specified furnace at the rate of 5 ± 1 °C/min.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
ASTM C349