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alumina applied barium Berlin bituminous coal blue boracic acid brown burning burnt calcium calcium carbonate carbonate cent chemical clay substance cobalt cobalt oxide colored glazes colorless glaze composition cones contains continuous kiln crazing decoration drying enamel engobe especially exhibit face-brick factory faience feldspar ferric oxide fire fire-gases fluxes frit furnace fused fusible gases German glass gray green Grossalmerode ground heat industry latter layer lead oxide lignite lime Limoges machine majolica manufacture means melting melting-point metallic oxides mixture mold obtained ordinary ornaments oxygen painting pieces pipes plastic clay porcelain body porcelain glaze potash pottery Professor Seger quantity quartz quartz sand raw materials red color reducing refractory roofing tile Royal Porcelain saggars silica silicic acid soda stoneware stove sulphates sulphuric acid surface temperature terra cotta tion underglaze colors vitrified ware washed whiteware body yellow color yellowish
Page 832 - The plates or panels are apparently white faience or biscuit, on which the ornamentations are in harmony with the use to which the article is to be put, and consist of figures pressed to form a low relief.
Page 571 - By raising the silica content and thereby lowering the content of the basic fluxes. A limit must be observed in this respect, in the fact that the acidity of the glaze must never exceed a trisilicate, and never fall below a bisilicate. In the first case, an inclination to devitrification ensues, and in the last case, a tendency to running off from the ware, which is the more marked the lower the glaze is in alumina.
Page 656 - Chromium oxide with tin oxide and lime produces red tints. The red colors show many peculiarities which must be considered. They are obtained, when to a mixture of marble and tin oxide a small addition of potassium chromate is made, and the mixture strongly ignited. Outside of the potassium chromate, quite a number of substances produce the same effect, but it is safest to work with potassium chromate. However, if too...
Page 601 - If the coefficient of expansion of the glaze is greater than that of the body, the glaze will craze.
Page 562 - ... elements indicated are present in certain proportions, and it does this in a simple and graphic manner, from facts which can only be deduced from an analysis of the material.
Page 656 - However, if too mtich of the latter is used (over 3 to 4 per cent) the resisting power of the underglaze color is decreased considerably. If silica is added to the mixture the color turns towards red...
Page 581 - B. By increase of the boric acid at the expense of the silica, leaving the other ingredients of the glaze unaltered. By this, a lowering of the melting-point of the glaze is accomplished. C. By substitution of one of the fluxes with a high equivalent weight (and therefore a low percentage of silica) by one having a lower equivalent weight (and therefore a higher percentage of silica). An elevation of the melting-point of the glaze is coincident with this change.
Page 1138 - Per cent. in. IV. Per cent. V. Per cent. VI. Per cent. Per cent. Per cent. SiO, 54-51 56.09 59.58 66.05 38.40 79-58 (0.39...
Page 583 - The thinner the layer of glaze, and the longer the duration of the glost fire, and the higher temperature it attains, the more completely will this enriching of the glaze in silica and alumina from the ware take place, and if on account of thicker layers of the glaze this action should not permeate clear through its substance, it forms at least, immediately on the ware, a silicious transition layer, which is in position to mediate between the tension existing between the glaze and body.