A method of modifying glass frit involves treating the frit with a grain-boundary-healing compound. The method increases transmission and clarity, and reduces haze of a fired enamel coating made from such modified glass frit as compared to a coating not made from such modified glass frit. The grain-boundary-healing compound influences the chemistry at the grain boundaries to prevent haze. The compound burns out to yield a fluxing material that dissolves alkaline carbonates or bicarbonates on the surface of the glass frit. The dissolved species are incorporated into the enamel coating, thereby promoting the fusion of the glass frit and reducing the amount of haze in the enamel coating. The additives also function to prevent the formation of seed crystals on the surface of the glass frit that may inhibit the fusion of the glass frit.