Abstract: A glass frit is prepared by heating an initial glass frit in the presence of a reducing agent so as to reduce metal moiety in the glass structure of the frit and then cooling the reaction mixture. Preferably, the frit prepared is used in a method of forming electrically conducting silver tracks on enamel on glass windows, by applying to window glass an enamel composition containing the frit and on top thereof a silver composition in the shape of the tracks and firing the compositions, such that on the firing the reduced metal moiety reduces silver ions migrating through the enamel composition from the silver composition to elemental silver and thereby prevents or impairs them from interacting with the glass to form visible tracks.