Patent ID: 8007913

Claim:
A laminated glass sheet comprising a central core that comprises a core glass and an external skin that comprises a skin glass wherein: (a) the skin glass has a strain point greater than or equal to 700° C. and a melting temperature that is less than or equal to 1,665° C.; (b) when measured by a gradient boat technique, the skin glass has a liquidus viscosity that is in the range of 15,000-80,000 poise and the core glass has a liquidus viscosity that is greater than 100,000 poise so that the core glass is more stable with respect to devitrification during formation by a fusion overflow downdraw process than the skin glass; and (c) the laminated glass sheet is formed by a double fusion overflow downdraw process so that the central core has a rejoin surface and the external skin has a fire-polished surface.