Patent ID: 7842631

Claim:
A glass composition having comprising: about 55.0-62.2 weight % SiO 2 about 12.9-15.5 weight % Na 2 O; about 8.0-11.2 weight % B 2 O 3 about 4.0-8.0 weight % CaO; about 0.9-5.6 weight % Al 2 O 3 about 3.0-5.0 weight % MgO; about 0.2-1.4 weight % K 2 O; and about 0.0-1.0 weight % F 2 . a softening point in the range of about 1230-1276° F.; a log-3 viscosity temperature in the range of about 1802-1879° F.; and a liquidus temperature in the range of about 1635-1780° F.