Earthenware is of soft body, is opaque--that is, it cannot be seen through. Its thinness or its thickness has nothing to do with its title. Stoneware is equally opaque, but it is as hard as porcelain. It may be as thick and heavy as a German beer-mug or a stone ginger-beer bottle, or it may be cream in colour, and thin as a Passover cake, as in salt-glazed Staffordshire ware, or white and heavy, as in later stone china. Porcelain may be hard or soft and possesses properties equally its own, but is outside the scope of this volume.
Practically earthenware is of such porous clay that when fired in the kiln it is unfit for use, as it is still too porous until it receives a coating of glaze. Unglazed stoneware, Egyptian black, and Wedgwood's jasper ware differ from earthenware in this respect, as they do not receive any glaze, since they are of dense enough body to be used in "biscuit" or unglazed state.
_Its appearance._ In colour earthenware may be brown or white in exterior, or brown or white in body as shown when broken. At its best its style to the beginner may not be suggestive of great difference between earthenware and porcelain. Similar figures were attempted in the one material as in the other. In France at Niderviller, at Marseilles, and at Scieux the potters deliberately set themselves to make objects in earthenware as delicate and fanciful as were produced in hard porcelain at Dresden or in soft porcelain at Vincennes. Clocks, vases, sweetmeat-boxes, and elaborate dinner services lavishly decorated in over-glaze enamels and gilded, emulated the best work of the porcelain factories. In Staffordshire the story has been repeated. So that form is no guide as to what kind of ware a piece may be. In weight earthenware is lighter than porcelain as a general rule, though variations in the body make this rule an elastic one. In stoneware, and ware approximating to this in character, the weight is heavier than porcelain. All ironstone ware is exceedingly heavy.
_Reasons for its appearance._ The earlier earthenware was brown in body. The Dutch potters in the seventeenth century covered their ware with an opaque white tin enamel to conceal the dark earthen body and to enable them to paint on its surface in imitation of Chinese porcelain. Stoneware, such as the jugs of early type known as Bellarmines, is of very vitreous earthenware fired so hard as to resist acids or the use of a file when applied to the surface. When glazed this class of ware has salt glaze. Dwight, of Fulham, introduced white, or nearly white, stoneware into England in his statuettes, which induced him to claim that he had discovered the secret of making porcelain. Cream ware followed later, and, perfected by Wedgwood, it was adopted as the standard earthenware of Staffordshire. It was the last note in earthenware till the beginning of the nineteenth century, when the Staffordshire potters invented an earthenware with a white body more nearly approaching porcelain in appearance. For fifty years experiments had been carried on, and this cream ware was whitened by a process called "blueing" by the use of cobalt to whiten the lead glaze. But the final invention was by Mason with his patent ironstone china, in which he produced a hard, white body.