Patent ID: 7696113

Claim:
A method for producing glass sheets that are substantially free of alkali metal oxide by a downdraw process comprising selecting, melting, and fining batch materials so that the glass making up the sheets comprises SiO 2 , Al 2 O 3 , B 2 O 3 , MgO, CaO, and SrO, and has: (i) an iron content expressed as Fe 2 O 3 in the range of 0.010-0.033 mole percent; and (ii) a tin content expressed as SnO 2 in the range of 0.017-0.112 mole percent: wherein: (a) the fining is performed without the use of substantial amounts of either arsenic or antimony; and (b) a population of 50 sequential glass sheets produced by the downdraw process from the melted and fined batch materials has an average gaseous inclusion level of less than 0.05 gaseous inclusions/cubic centimeter, where each sheet in the population has a volume of at least 500 cubic centimeters.