High volume production of display quality glass sheets having low zirconia levels

A method for making display quality glass sheets comprising:

• (I) melting batch materials in a furnace to produce molten glass;
• (II) fining the melted batch materials in a finer;
• (III) forming a glass ribbon from the fined, molten glass;
• and
• (IV) separating glass sheets from the ribbon;
• wherein:
• (a) the furnace has an internal surface, a portion of which contacts molten glass;
• (b) said portion of the internal surface that contacts molten glass comprises ZrO2 as its major constituent;
• (c) the melting of step (I) comprises employing a plurality of electrodes to pass electrical current through the molten glass;
• (d) each of the plurality of electrodes comprises molybdenum as its major constituent;
• (e) molten glass leaves the furnace and enters the finer at a rate R, where at steady state, R satisfies the relationship:
• R≧2,000 pounds/hour;
• and
• (f) at steady state, the glass sheets produced in step (IV) are characterized by:
• (i) the glass making up the glass sheets is an alumina-silicate glass;
• (ii) the average content of ZrO2 in the glass sheets satisfies the relationship:
• [ZrO2]≦0.1,
• where [ZrO2] is in weight percent on an oxide basis;
• (iii) the average content of MoO3 in the glass sheets satisfies the relationship:
• 0<[MoO3]≦0.002,
• where [MoO3] is in weight percent on an oxide basis;
• and
• (iv) prior to removal of any unacceptable glass sheets, a population of 50 sequential sheets has an average level of solid defects plus gaseous defects of a size greater than 100 microns that is less than or equal to 0.012 defects per pound of glass, where each of the glass sheets has a thickness that is less than or equal to 2.0 millimeters and a weight of at least 10 pounds.