Abstract: Glass-ceramic articles having compositional inhomogeneities are provided with uniformly colored gray stain decorations by heat treating a palladium-containing staining material prior to application onto glass-ceramic articles which have been crystallized by a separate heat treatment, and then subjecting the glass-ceramic articles in contact with the staining material to another heat treatment to produce the stain decorations.

Abstract: A plurality of high-temperature operating, corrosion-resistant heat pipes are employed to distribute heat transversely and longitudinally from normally hotter portions of a glass forming chamber to normally cooler portions of the same chamber in order to provide a more uniform thermal environment for the forming of flat glass. In particular, heat pipes are provided beneath the surface of a pool of glass-supporting molten metal in such a chamber to remove heat from a central and usually upstream region of such a chamber and transfer it to a marginal and preferably downstream region of the chamber. By transferring the heat in this manner, the temperature gradients within the chamber may be manipulated to be more uniform throughout a forming region so that glass of improved quality can be produced with improved efficiency, utilizing less energy than normally required for producing glass according to typical conventional float glass manufacturing methods.

Abstract: A horizontal glassmaking furnace adapted for melting glass batch materials by the application of heat to them from overhead flames within the furnace is provided with submerged electric heating electrodes in a region adjacent to where glass batch materials are charged to the furnace and, while overhead flames are reduced or eliminated above the glass batch materials in the vicinity of the electrodes, the glass batch materials are melted from below by action of the electrodes; overhead flames are maintained above exposed molten glass where the glass batch materials have already melted. Discharge of particulate batch materials from the furnace by action of overhead flames is substantially reduced while the thermal efficiency of the furnace is enhanced.

Abstract: A vertically elongated glassmaking furnace is provided with two groups of electrodes: one group is positioned in the upper portion of the furnace and is operated to melt glass batch and to establish an upward flow of hot glass along the center of the furnace; a second group is positioned in the lower portion of the furnace and operated to slow the downward flow of molten glass through the furnace, particularly near the walls of the furnace so that all the molten glass in the lower portion of the furnace flows uniformly downwardly to discharge at a rate sufficiently slow to insure the upward escape of seeds or bubbles from the discharged glass.

Abstract: A positive containment threshold for use in an apparatus for manufacturing flat glass includes a metal base with a combination of vertically disposed members for connection to a bottom casing of a glass forming chamber. Disposed adjacent a vertical member which serves as an end wall casing member in the combination is at least one refractory threshold block which provides a smooth glass contact surface over which molten glass may be delivered onto a pool of molten metal contained within the bottom portion of an enclosed forming chamber. This threshold in combination with the casing surrounding the bottom portion of an enclosed forming chamber provides an impervious barrier to prevent the inadvertent loss of molten metal from the container in the event of refractory failure.

Abstract: A novel tank-type furnace is disclosed for producing flat glass from a glass which has a high melting temperature and which contains highly volatile ingredients. The furnace has a tapered end wall construction leading from the melter into the canal. Such a construction results in the formation of better quality flat glass.