GB1092473A - Improvements relating to ceramic ware - Google Patents

Abstract

A method of making a food-receiving or supporting article of ceramic ware, e.g. casseroles, soup tureen, pie dish with a polytetrafluoroethylene coating includes the step of forming at least on a portion of the surface thereof an impervious and non-smooth base, and coating the base with polytetrafluoroethylene to form a non-stick coating thereon. The impervious, non-smooth base may comprise a glaze or frit of a particle size and given a firing time such as to form a non-smooth layer. Alternatively a smooth layer may be roughened. The polytetrafluoroethylene may be in a plurality of layers. In Example 1, the glaze comprises borax, silica, stone, calcium carbonate, china clay, bisilicate and is sprayed in liquid form on to the article. The external surfaces of the ware may be glazed and coloured. The polytetrafluoroethylene may be mixed with water and pigment, and sprayed on, or, if a flat or saucer-like article is to be coated, may be dripped or fed on to the article and distributed by centrifugal force as the article is spun. After drying at elevated temperature the complete article may be fired to cure the polytetrafluoroethylene. In Example II a conventional glaze is applied and roughened by shot-blasting. In Example III a first layer of a chromic, phosphoric acid mixture with polytetrafluoroethylene is applied by spraying to the non-smooth glaze layer, fired and a second layer comprising polytetrafluoroethylene with a stain or pigment in, say, toluene is applied and fired. missing page 184ALSO:A method of making a food receiving or supporting article of ceramic ware, e.g. casseroles, soup tureen, pie dish with a polyetetrafluoroethylene coating includes the step of forming at least on a portion of the surface thereof an impervious and non-smooth base, and coating the base with polytetrafluoroethylene to form a non-stick coating thereon. The impervious, non-smooth base may comprise a glaze or frit of a particle size and given a firing time such as to form a non smooth layer. Alternatively a smooth layer may be roughened. The polytetrafluoroethylene may be in a plurality of layers. In Example 1, the glaze comprises borax, silica, stone, calcium carbonate, china clay, bisilicate and sprayed in liquid form onto the article. The external surfaces of the ware may be glazed and coloured. The polytetrafluoroethylene may be mixed with water and pigment, and sprayed on, or, if a flat or saucer-like article is to be coated, may be dripped or fed on to the article and distributed by centrifugal force as the article is spun. After drying at elevated temperature the complete article may be fired to cure the polytetrafluoroethylene. In Example II a conventional glaze is applied and roughened by shot-blasting. In Example III a first layer of a chromic, phosphoric acid mixture with polytetrafluoroethylene is applied by spraying to the non-smooth glaze layer, fired and a second layer comprising polytetrafluoroethylene with a stain or pigment in say toluene is applied and fired.