Prepared pigments, prepared opacifiers, prepared colours

32.07 Pre ared pigments, prepared o acitiers and an glazes, engobes (slips), liqui lustres the ceramic, enamelling or glass industry; powder, granules or flakes. 3207.10 vitrifiable enamels of a kind used in in the form of g - Prepared pigments, prepared opacifien, prepared colours and similar preparations - Vitrifiable enamels and glazes, engobes (slips) and similar preparations 3207.30 - Liquid lustres and similar preparations 3207.40 - Glass frit and other glass, in the form of powder, granules or flakes 3207.20 This heading covers a range of preparations used in the ceramic industry (china, earthenware, etc.), in the glass industry or for colouring or finishing metal articles. (1) Pre ared pigments, pre ared o acifiers and prepared colours are dry mixtyres formed by t e heat treatment o?oxidedof antimon silver, arsenic, copper, chromum, cobalt, etc.) or salts (fluorides, phosphates, etc.) wi or without fluxes or other substances, and are fired at high temperatures, generally above 300 "C,after application. The goods are used to produce a coloured or op ue surface in the course of ceramic fi+g. They may be incorporated in the glaze or ename , or be applied as a coating before glazing. it (2) Vitrifiable enamels and glazes are mixtures of silica with other products (feldspar, kaolin, alkalies, sodium carbonate, alkaline-earth metal compounds, lead oxide, boric acid, etc.) giving a smooth surface, either matt or lossy, by vitrification under heat. In most cases some of the constituents have been fuse together in a preliminary process and are present in the mixture in the form of powdered fi-it (see below). % (whether or not coloured) or rendered opaque by the addition of substances (e.g., titanium or zinc oxides) are added ecorative crystalline effects on cooling aRer the firing. These vitrifiable are generally in the form of powders or granules. (3) Engobes (slips) are semi-fluid pastes with a basis of clay, whether or not coloured, used to coat ceramic ware, either completely or in the form of a pattern. They are applied either before firing or afier a preliminary first firing. (4) Liquid lustres are solutions or suspensions of metal com ounds in spirits of turpentine or other organic solvents, used for decorating ceramics or g assware. The most widely used are gold, silver, aluminium or chromium lustres. P (5) Glass frit and all other varieties of glass (including vitrite and glass obtained from fused quartz or other fused silica) in the form of powder, granules or flakes, whether or not coloured or silvered. These roducts are used in the reparation of coatings for ceramic, glass or metal articles as we1 as for other purposes. I?% exam le, f i t is used in the pre aration of the vitrifiable products referred to in aragra h (2) a ove. Glass powder and? granules are sometimes sintered to form discs, p ates, tu es, etc, for laboratory use. f f t Vitrite is enerally used for insulating electrical parts (e.g., contact terminals for electric lamp capsf Other varieties of powdered lass are used as abrasives, for decorating postcards, Christmas tree decorations, for o taining coloured glass articles, etc. When the products referred to in other than powder, granules 0; % flakes, they are excluded, and and " enamel " glass in the rods or tubes (heading cinematograph screens, road This a plies in particular to " vitrite " g ass put up in the form of bys, grains (microspheres) used for coatmg P