GB1039996A - Enamelled cooking vessels and method of manufacturing them - Google Patents

Abstract

An enamelled cooking vessel made from sheet steel carries, on at least the outer surface of its base, a covering layer consisting of a mixture of an enamel with at least one metal powder. Specified metals are aluminium, aluminium alloys, copper and brass. The metal-containing layer may be formed directly on to the steel surface or on to a base layer of conventional enamel, or two metal-containing layers may be superimposed. The metal-containing layer may also be applied to inner and/or outer surfaces of the vessel other than its base, and is preferably applied by spraying. In one embodiment (Fig. 1, not shown) a conventional enamel base 5 is applied to the steel surface of vessel 1, dried and fired. A covering layer of metal-containing enamel 7 is then applied to those surfaces to be treated according to the invention, the remaining surfaces being covered with a further layer 6 of conventional enamel. The covering layers are dried and fired in a single operation. The metal-containing enamel may comprise feldspar, quartz, soda, borax, clay and aluminium of particle size 0.1-0.25 mm. A formulation for use when the metal-containing enamel is applied directly to the steel surface comprises the above ingredients plus quartz sand and sodium nitrite. In a further embodiment, the metal-containing enamel layer is formed by spraying a suspension of the metal on to a conventional enamel-covered steel surface. On drying and firing, a transition layer is formed so that the resulting steel vessel 1 (Fig. 6, not shown) is coated with conventional enamel 5, and a metal-containing enamel layer 71 gradually merging into a layer 711 of almost pure metal. A specified metal suspension contains aluminium powder, clay and water.