Page:The New International Encyclopædia 1st ed. v. 16.djvu/383

* POTTERY. 323 POTTERY. vrare vessels, called seggars, or saggars, which are so shaped that they can be piled one upon another to a great height. The seggars are often made large enough to hold each a number of pieces of the unbaked pottery, and as these would adhere if they touched one another, a number of curiously shaped pieces of baked clay are used, upon which they rest : these are called watches, cock-spurs, triangles, stilts, etc. Thus, each seg- gar forms a small oven by itself, and by this means the unequal heating of the pieces is pre- vented, and they are also protected from smoke. A pile of seggars is called a bung, and there may be forty-eight or fifty bungs in the charge of a kiln. When all this is arranged, the furnaces, of which there are several to each kiln, are lighted. The firing requires from twenty-four to fifty hours, after which the ware is allowed to cool verj" slowly. See Kilx. The articles are now in the state called biscuit, and still require glazing, and perhaps decorative painting and gilding. ( For the various kinds of glazing see the articles 8toxew.re; Faience; iI..JOLiCA, etc.) Many mixtures are used, the essential thing being that the glaze and the body shall be of the same general nature in order that . they may contract evenly during the liring. The result of uneven shrinking is seen in the cracking of the surface, called 'crazing;' and the crackle of Oriental porcelain and pottery is deliberately produced in the same Avay. The difl'erent glazes are composed of litharge, tlint, feldspar, Paris white, and white clay, applied in the form of 'slip.' The glazing materials are triturated with water, with the same care and by similar means to those employed in forming paste, and are reduced with water to the same milk-like liquidity. Each workman has a tub of the glaze before him ; and as the articles of biscuit-ware, either with or without decorations, are brought to him, he dips them in the glaze, so as to insure a uniform coating over them ; and, by nice management, he prevents any large drops or accumulations on one part more than another. The porous biscuit-ware rapidly ab- sorbs the moisture, and dries up the thin film of glaze on the surface of the articles, which are again placed in seggars, and carried to the glaze- kiln, where they undergo another firing, which melts the glaze, and converts it into a perfectly transparent glass, all over the surface, and renders any pattern previously printed upon it very plain. The temperature in the glaze or enamel kiln is increased very gradually, and is kept up for about fourteen hours, after which it is allowed to cool slowly, and the articles are taken out completed. So far, this description has applied to the manufacture of pottery and porce- lain on a large scale, for general purposes : but when it is applied to more costly and artistic works, very special arrangements are required. Decoration by means of painting may be ap- plied to pottery on the biscuit, or on the unfired enamel, or on the already fired enamel, or glaze, of whatever nature. The method is limited in its scope, but very permanent. The difficulty is to find colors that will stand the great heat required for firing the glaze. Practically the only color used for a hard glazed ware is cobalt blue : but for the softer glazes the oxides of many metals, as copper, iron, and nickel, may be used. The above applies especially to porcelain. Painting on the unfired enamel is used in some of the brilliant modern varieties of faience. Painting upon the glaze, allowing of almost any combination of colors, is the more common prac- tice in ceramic art generally. Painting under glaze requires great skill and experience, for the appearance of the pigments as they are laid by t!ie painter is altogether difl'erent from the resulting efTect after the firing. The decora- tion may be applied with a brush-or by a transfer of printing. In the latter process the designs are engraved on copper plates ; the colors are specially prepared with a printing oil, and the designs printed on a wet tissue paper, which in turn is laid upon the ware and transfers its pat- tern to the surface of the clay. After the paper has been washed off, the decoration may be touched up with a brush, if necessary. When it is desired to avoid sharpness of outline in painted or transferred designs, the process called 'flowing' is sometimes used. Sups of more volatile liquid are placed in the seggars, and the vapor of this, partially combining with the metallic colors, softens their outlines. Some- times the glaze itself is colored, and brilliant and very much admired effects are produced in this way. In general the term earthenw'are is used for common pottery, and this carries with it the gen- eral idea of a coarser, a softer, and a less care- 'fully made ware than those specified under dif- ferent names. Primitive Ware. In general, primitive pot- tery is made from surface soil, sometimes of most unpromising appearance, rather than from the finer and purer grades of clay. Naturally the ware produced from such material is coarse and thick-walled. Some of the crudest types of ware ' are molded in baskets — indeed, archaeologists find good reason for supposing that the earliest pottery was nothing more than an earthen lining for a basket in which corn or other grains were parched by shaking them with live coals until the material was more or less completely baked. Sometimes the frames of wicker or basketry were burnt off in the firing, in such manner as to leave permanent impressions of the framework. This type abounds in mounds and on other prehis- toric sites in the Central and Southeastern United States. In the arid regions, not only in the United States and Mexico, but in South America and on other continents, the early ware was im- proved far beyond this primitive type, in form and finish as well as in material and manufac- ture. Some of the aboriginal American ware is graceful in form, elaborate in decoration, and perhaps finished with a more or less siliceous slip; though neither the true clays nor the potter's wheel were known to the pre-Columbian natives. Frequently the forms were fantastic, the utensils grading into elaborate symbolic moldings and votive effigies ; while the decorations in color were also largely emblematic. ( See !M.^', Science OF, pijragraph Esthetolofii/.) In beauty of form and color effects, as well as in elaborateness and delicacy of the svmbolic designs, aboriginal American pottery may be said to have culminated in the Pueblo region in the Southwestern United States and Xorthern Mexico : some of the pieces from this region (as shown in the accompanying plate) attest a fairly advanced stage in artistic development. The primitive methods of firing are extremely simple. Ordinarily either a single piece or a small lot is fired outdoors in a shallow