Porcelain--Forms and Surfaces
Much that has been said of the forms and surfaces of stoneware applies equally to porcelain. In this chapter, the points of difference will be stressed, as well as those qualities of form and glaze which are peculiarly suitable to porcelain.
The range of forms which can be achieved in porcelain by plastic shaping is rather severely limited by the nonplastic character of porcelain bodies. Yet within that range, pottery of a sensitive beauty of shape can be made. As described in an earlier section, the preparation of porcelain bodies must be done with a great deal of care. And especially if the body is to be used on the wheel, it must be carefully aged and wedged.
The potter who is throwing with a porcelain clay must be reconciled to the fact that only forms of modest size can be made on the wheel. It is extremely difficult to pull up any cylinder higher than about 8 inches. It may be wondered how the large porcelain jars originating in China during Ming times were made. The clay from which they were made was, no doubt, unusually plastic, perhaps better for wheel work than any porcelain body available to us. The jars were made in parts, and probably a combination of coiling and throwing was used. However, much as we may admire the skill which went into the making of these monumental porcelain pots, they do seem out of scale for the material used, and porcelain by its nature is more suitable for small forms. It is refined, smooth, dense, transparent, and glasslike, and its semiprecious feel is not very adaptable to great size.
Not only is the size of porcelain pieces limited by the material, but the shapes are also limited by both the lack of plasticity in the clay and by the inability of the clay to withstand beyond a certain point the tendency toward slumping and deformation when it is softened by the maturing fire. Porcelain must adhere to a rather strict architecture of form to survive the process which makes it what it is. Porcelain bowls or plates cannot be thrown with extreme overhangs. Pieces with widely swelling bellies are difficult to make, and the clay cannot be collared in easily to form very narrow necks on wide bottle shapes. The clay resists all of these maneuvers on the wheel by slumping down into a heap. For this reason, the free, and sometimes exaggerated shapes of stoneware, are not for porcelain. But what can be made is still considerable--bowls of all sorts, jars, plates, covered pieces, closed-in bottle-like forms (on a modest scale), cylindrical forms, and functional things like pitchers or teapots. But the beauty of the forms must reside in grace, proportion, and refinement, rather than in strength, ruggedness, or extremes of conformation.
Since porcelain is difficult to throw, more is usually left to the trimming than is usual in stoneware making. Thus bowls are made with considerable clay left about