Additives for lead-free frits.

摘要

This invention is drawn to a method for eliminating the grayish discoloration which customarily develops when lead-free and cadmium-free glass frits are applied to substrates employing an organic vehicle and which are thereafter fired to fuse the frit particles into a glaze. The grayish hue results from a carbonaceous residue left upon thermally decomposing the organic vehicle. The inventive method comprises five general elements: (a) glass frit particles of a desired composition are prepared; (b) a coating of an organic compound containing at least one sulfur oxide group as an oxidizing agent is adsorbed on the surface of the particles; (c) the coated particles are mixed with an organic vehicle; (d) that mixture is coated onto a surface of a substrate; and (e) that coated substrate is fired to fuse the frit particles into a glaze, the oxidizing agent eliminating the carbonaceous residue left upon thermal decomposition of the organic vehicle.