Glass Surface Tension Tester (Contracted Filament Method)

This instrument employs the contracted filament method to determine the surface tension of glass at its softening temperature range. By using a vertical tubular furnace where a glass filament is freely suspended and heated, the filament initially extends due to thermal expansion, then contracts in the high-temperature region under surface tension effects, forming an olive-shaped node.

The instrument calculates the surface tension at a specific temperature by balancing the tension against the weight of the filament's lower end. This device finds applications in both research and educational settings to test and analyze the surface tension of glass and fiber yarns.