POTTERY

1539

POTTERY

king of Rome, is said to have instructed the Etruscans and Romans in this art. The Arabs seem to be entitled to the credit of having introduced the manufacture of glazed ware into modern Europe. The Italians are said first to have become acquainted with this kind of ware as it was manufactured in the Island of Majorca, and hence they gave it the name of majolica. They set up

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ETRUSCAN VASES

their first manufactory at Faenza in the 15th century. In Italy the art was improved, and a new kind of glaze was invented, probably by Luca della Robbia. (See Robbia.) The French derived their first knowledge of glazed ware from the Italian manufactory at Faenza, and on that account gave it the name of faience. About the middle of the 16 th century the manufactory of Bernard Palissy (q. v.) at Saintes in France became famous on account of the beautiful glaze and rich ornaments by which its products were distinguished. A little later the Dutch began to manufacture at Delft the more solid but less beautiful ware which thence takes its name. The principal improver of the potter's art in Britain was Josiah Wedgwood (a. v ) in the 19th century. Porcelain or chinaware first became known in Europe about the end of the 16th century through the Dutch, who brought it from the East. In the United States the manufacture of pottery and porcelain is of recent development, but has already attained considerable dimensions, the leading establishments being located at Trenton, N. J., and at Cincinnati, Akron and East Liverpool, O.

There are general principles and processes common to all kinds of pottery and porcelain. The first operations are connected with the preparation of the potter's paste, which consists of two different ingredients: an earthy substance, which is the clay 'proper, and a siliceous substance, which is necessary to increase the firmness of the ware and render it less liable to shrink and crack on exposure to heat. The clay is first finely pulverized and reduced to the consistency of cream, when it is run off through a set of wire, gauze or silk sieves into cisterns, where it is diluted with water to a standard density. The other ingredient of the potter's material is usually ground flints or flint-powder, as it is called, which, treated in much the same way as the clay, is finally passed as a creamy liquor into a separate cistern These liquors are now mixed in

such measure that the dry flint-powder bears to the clay the proportion of one sixth, one fifth or even more. The mixture is then forced into presses, lined with cloth, by means of a force-pump, the cloth retaining the clay and allowing the water to escape. The clay now forms a uniform inelastic mass, which is cut ihto cubical lumps and transferred to a damp cellar, where it remains until a process of fermentation or disintegration renders it finer in grain and not so apt to crack in the baking. It is then subject to inother operation, called slapping or wedging, which consists in repeatedly breaking the lumps across and striking them together again in another direction, dashing them on a board etc. This final process of incorporation is now most frequently performed by machinery.

In making earthenware vessels, if they are of a circular form, the first operation after the paste has been made is turning, technically called throwing them on the wheel.

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Successive Stages of Earthenware Vessel on tha Putter's Wheel.

This is an apparatus resembling an ordinary turning-lathe, except that the surface of the chuck or support for the clay is horizontal instead of vertical. The chuck in fact is a revolving, circular table, in the center of which a piece of clay is placed, which the potter begins to shape with his hands. The rotary motion of the table gives the clay a cylindrical form in the hands of the potter, who gradually works it up to the intended shape. It is then detached from the revolving table and dried, after which, if intended for finely-finished ware, it is taken to a lathe and polished. It is at this stage that the handles and other prominent parts are fitted on, which is done by means of a thin paste of clay called slip. The articles are now removed to a room in which they are dried more thoroughly at a high temperature. When they have reached what is called the green state, they are again taken to a lathe and more truly shaped as well as smoothed and burnished. When the articles are not of a circular form and, accordingly, cannot