Viscosity

Viscosity

Although glass has no defined softening point, there are four points in the viscosity-/temperature relation which have accepted definitions (ISO 7884-2/-3/-4):

1. Strain Point 515°C - Viscosity of the glass is 10^14.5 dPa⋅s

2. Annealing Point 565°C - Viscosity of the glass is 10^13.0 dPa⋅s

3. Softening Point 820°C - Viscosity of the glass is 10^7.6 dPa⋅s

4. Working Point 1250°C - Viscosity of the glass is 10^4.0 dPa⋅s