Kiln furniture

69.03 - Other refractory ceramic goods (for example, retorts, crucibles, muffles, nodes, plugs, supports, cupels, tubes, pipes, sheaths and rods), other than those of siliceous fossil meals or of similar siliceous earths. 6903.10 - Containin by weight more than 50 % of graphite or other carbon or of a 6903.90 - Other f 6903.20 - Containin b weight more than 50 % of alumina (A1203)or of a mixture or compoun%of'alurmna and of silica (Si02) mixture o these products This heading covers all refractory goods not specified or included in the preceding headings. These articles include : (1) Articles which, unlike the refractory products of headin 69.02, are in many cases not ermanent fixtures, such as retorts, reaction vessels, cruci les, cupels and similar articles for industrial or laboratory use, muffles, nozzles, plugs, burner jets and similar parts of furnaces; saggars, stands and other kiln furniture to support or separate pottery during firing; sheaths and rods; stands for crucibles; ingot moulds; etc. % (2) Tubing, piping (including runways in the form of half-cylinders) and angles, bends and similar tube or pipe fittings, even if intended for use as permanent fixtures in construction work. The heading does not, however, include Seger cones (ceramic firing testers) (see Explanatory Note to heading 38.24); these are not fired after shaping Sub-chapter I1 OTHER CERAMIC PRODUCTS GENERAL This sub-Cha ter covers ceramic articles other than those of siliceous fossil meals or of similar siliceous eart s and rebctory goods of sub-chapter I. R For the purpose of the Nomenclature, these articles are classified according to kind (bricks, tiles, sanitary ware, etc.), and classification is not affected by the nature of the ceramics used in their manufacture or by the presence of glazing, except in the case of: (i) Ceramic tiles, flags and mosaic cubes and the like, classified in heading 69.07 when unglazed and in heading 69.08 when glazed. (ii) Tableware, kitchenware, other household articles and toilet articles, classified in heading69.11 when of porcelain or china and in heading 69.12 if of other kinds of ceramics. (I) PORCELAIN OR CHINA Porcelain or china means hard porcelain, soft porcelain, biscuit orcelain (including parian) and bone china. All these ceramics are almost completely vitri red, hard, and are essentially impermeable (even if they are not glazed). They are white or artificially coloured, translucent (except when of considerable thickness), and resonant. F Hard porcelain is made from a body composed of kaolin (or kaolinic clays), quartz, feldspar (or feldspathoYds), and sometimes calcium carbonate. It is covered with a colourless transparent glaze fired at the same time as the body and thus fused together. Soft orcelain contains less alumina but more silica and fluxes (e.g., feldspar). Bone china, whic contains less alumina, contains calcium phosphate (e.g., in the form of bone ash); a obtained at a lower firin temperature than with hard porcelain. The firing at a ower temperature, thus permitting a greater R f Biscuit porcelain is unglazed porcelain, of which parian-ware (sometimes called Carrara porcelain) is a special, fine-grained, ellowish type containing more feldspar, and oRen resembling Paros marble in appearance, ence its name. g (11) OTHER CERAMIC PRODUCTS Ceramic products other than of porcelain or china include (A) Ceramics with a porous bod which, unlike porcelain, are opaque, ermeable to liquids, easily scratched with iron anc rwhose fracture sticks to the tongue. Suc ceramics include ; \ (1) Pottery made from common fermgineous and calcareous clay (brick earth). It has a dull earthy texture and its colour is generally brown, red or yellow. (2) A wide range of white or coloured ceramics (earthenware, majolica, delft-ware, etc.). The body is porous and must be glazed to make the articles impermeable (e.g., with transparent or opaque glazes such as white or coloured metallic oxides). Earthenware, etc., is made from finely sieved clays mixed with water. It has a fine-grained body obtained by firing to a higher temperature than in the case of pottery made from common clay; it d~ffersfrom porcelsun or china because it is not completely vitrified. (B) Stoneware which, though dense and hard enough to resist scratching by a steel point, differs from porcelain because it is opaque and normally only partiall vitrified. Stoneware may be a vitreous (impermeable) or semi-vitreous ware. It is usu ly grey or brownish because of impurities contained in the clay used for its manufacture, and is normally glazed. al (C) Certain so-called " semi-porcelains " or " imitation porcelains ", sometimes prepared, decorated and glazed to give the commercial a pearance of porcelain. Without belng really opaque like earthenware, or truly translucent 1 e porcelain, these products may be slightly translucent in the thinner arts such as the bottoms of cups. These materials can, however, be distin ished fiom rea porcelain because their fracture is rough-grained, dull and nonvitrified.%ey are therefore porous beneath the glaze and the fiacture clings to the tongue Further, they are easily scratched with a steel kn~fe,though it should be noted that oertaid soft chinas may also be scratched by steel. Products of these imitation "porcelains " are not considered as porcelain or china. S P The sub-chapter also includes certain goods made by shaping and firing powdered steatite, etc., generally mixed with clay (e.g., kaolins), feldspar, etc., but it should be noted that many articles of these materials are designed for electncal purposes and are therefore classified in Chapter 85. This sub-chapter also covers articles made by firing steatite shaped by sawing. I Certain ceramic articles made of refract0 materials e.g., sintered alumina) may also fall in sub-chapter I1 if not of a type designed or use as re ractory goods (see Explanatory Note to heading 69.09).