Abstract: A method of chemically strengthening a sodium silicate glass is disclosed wherein ions from the glass are exchanged for larger ions, e.g. Na.sup.+ for K.sup.+, at a temperature above the glass strain point, subsequently the same exchange is carried out below the glass strain point, and the glass article is maintained throughout the process in a single, temperature-programmed bath containing the large exchangeable ions.

Abstract: A method for spray-decorating a low-expansion glass, glass-ceramic or ceramic article having an expansion coefficient in the range of about 0-35.times.10.sup.-7 /.degree.C. with a relatively high expansion fritted ceramic enameling composition having an expansion coefficient in the range of about 45-75.times.10.sup.-7 /.degree.C. wherein good surface coverage and color uniformity in combination with acceptable spall resistance in the applied enamel are provided by applying the enameling composition as a very thin film in the form of a non-aqueous oil-based spraying suspension.

Abstract: A method for masking selected areas of a glass, glass-ceramic, or ceramic surface against subsequently-applied coating compositions. The method contemplates three general steps: (a) a molten thermoplastic masking coating consisting essentially of about 10-60% bentonite clay, 0-40% of a refractory metal oxide, and 40-80% of a thermoplastic organic medium is applied from a heated surface onto the surface of an elastomeric or silicone-coated body; (b) the thermoplastic coating is cooled thereon to a temperature at which the coating exhibits sufficient tack and cohesiveness to permit transfer from the elastomeric or silicone-coated body; and (c) the so-coated body is brought into contact with the surface of a glass, glass-ceramic, or ceramic article to transfer the coating thereto.

Abstract: Microwave energy is utilized to energize an electroconductive film on a surface of a microwave browning apparatus to brown surface portions of foodstuff retained within said apparatus by conducting heat from said energized film through said browning apparatus to surface portions of the foodstuff. The microwave browning apparatus is provided with a recess below the electroconductive film, substantially surrounded by support portions, which function to focus or redirect the microwave energy toward central portions of the film or coating on the browning apparatus so as to provide more uniform browning temperatures across the coated surface.

Abstract: Heat-resistant masking compositions suitable for use in masking vitreous and semicrystalline ceramic surfaces from coating by liquid-sprayed coating compositions to provide permeation-resistant masks which are readily removable even after high temperature firing are described. The masking compositions comprise bentonite clay and a finely-divided refractory inorganic oxide release agent.