A glass forming apparatus comprising: a molten core glass reservoir (202,222,242,252,262), extending along a length of the apparatus; a weir (204,224,244,254,264,284,294) on a first side of the molten core glass reservoir; wherein the weir comprises an inclined surface (206,226,246,256,266) that, in the intended direction of molten glass flow, slopes downward in the vertical direction while extending away from the molten core glass reservoir in the horizontal direction; wherein, along at least one cross section of the weir, the horizontal distance between the closest and farthest points of the inclined surface (206,226,246,256,266) from the molten core glass reservoir is greater than half the horizontal distance between the molten core glass reservoir and the farthest point of the inclined surface from the molten glass reservoir; a weir (205,225,245,255,265) on a second side of the molten core glass reservoir, wherein the weir on the first side of the molten core glass reservoir and the weir on the second side of the molten core glass reservoir converge to form a root (228,248,268) at a distance below the reservoir, and a source of molten clad glass configured above the molten core glass reservoir and weirs such that when molten clad glass is flowing down from the source of molten clad glass and molten core glass is flowing over the weir (204,224,244,254,264,284,294), the molten clad glass drops onto the molten core glass at a highest upstream contact point, said highest upstream contact point being located directly above the inclined surface (206,226,246,256,266) of the weir; and molten glass flowing over the weir on the first side of the molten core glass reservoir and molten glass flowing over the weir on the second side of the molten core glass reservoir converge to form a molten glass sheet below the root (228,248,268). a molten core glass reservoir (202,222,242,252,262), extending along a length of the apparatus; a weir (204,224,244,254,264,284,294) on a first side of the molten core glass reservoir; wherein the weir comprises an inclined surface (206,226,246,256,266) that, in the intended direction of molten glass flow, slopes downward in the vertical direction while extending away from the molten core glass reservoir in the horizontal direction; wherein, along at least one cross section of the weir, the horizontal distance between the closest and farthest points of the inclined surface (206,226,246,256,266) from the molten core glass reservoir is greater than half the horizontal distance between the molten core glass reservoir and the farthest point of the inclined surface from the molten glass reservoir; a weir (205,225,245,255,265) on a second side of the molten core glass reservoir, wherein the weir on the first side of the molten core glass reservoir and the weir on the second side of the molten core glass reservoir converge to form a root (228,248,268) at a distance below the reservoir, and a source of molten clad glass configured above the molten core glass reservoir and weirs such that when molten clad glass is flowing down from the source of molten clad glass and molten core glass is flowing over the weir (204,224,244,254,264,284,294), the molten clad glass drops onto the molten core glass at a highest upstream contact point, said highest upstream contact point being located directly above the inclined surface (206,226,246,256,266) of the weir; and molten glass flowing over the weir on the first side of the molten core glass reservoir and molten glass flowing over the weir on the second side of the molten core glass reservoir converge to form a molten glass sheet below the root (228,248,268).