Method for the pre-treatment of coated glasses before heat treatment

A method for treating a coated glass plate before heat treatment, the coated glass plate having an edge area parallel to the plane of the glass plate and further having a resistive, heat radiation reflecting coating layer over at least the edge area of the glass plate, the coating layer containing conduction electrons, the heat treatment including heating the glass plate to an elevated temperature ranging from 580.degree. C. to 700.degree. C., cooling the glass plate rapidly so as to produce surface compression stresses on the glass plate and interior tensile stresses in the glass plate, the method comprising removing an edge part of the coating layer from the edge area of the glass plate to produce an uncoated portion of the glass plate before the heat treatment, so as to maintain a substantially uniform resistivity across the glass plate when cooling from the elevated temperature.