A flat glass manufacturing apparatus is disclosed which comprises a glass melter and molten glass conditioner connected to a forming chamber which contains molten metal on which a continuous sheet of flat glass may be formed. The molten glass conditioner is connected to the forming chamber by a molten glass delivery means which includes a convex threshold over which the molten glass flows onto the molten metal. Molten glass contact with the threshold member is minimized in that most of the glass entering the forming chamber has not contacted the threshold member and that which has moves relatively slowly in comparison to the general flow of molten glass over the threshold member.