成型工艺部分

[Page 553] # Yixing Pottery Manufacturing Techniques ## Lesson Two: Forming Process Section (December 12, 1981) In current production, the practice of free-form operation (following one's whims) is a relatively common phenomenon. This lesson will cover the basic operational standards. 1. **Moisture content**: This refers to what is colloquially called "hardness and softness." Since there are no instruments yet to measure the moisture level of clay, we must rely on feel for the time being. How to determine the proper hardness and softness? Generally speaking, when beating clay slabs and coils, it should feel crisp, not sticking to the paddle or clay board. Before opening the clay, one must first prepare the square edges of the clay block. The opening should be just right—generally, the rough material should be about 1/4 larger than what is actually needed. The length of the clay strips should be cut approximately the same as the length of the clay coils. 2. **Speed**: Working the clay requires attention to speed. When beating slabs, one should develop the habit of using one hand to hold the paddle. For slabs within 10 centimeters, one must be able to beat them holding the paddle with one hand. For clay slabs over 15 centimeters, both hands may be used to grip the paddle and flatten evenly. For small slabs, the requirement is to achieve 3-4 pieces per minute. 3. **Clay coils**: When beating clay coils, the left hand should be capable, with the right hand gripping the paddle to beat the clay strips. When beating clay coils, the force should land evenly. Beat until it approaches the required thickness of the coil, then use the paddle to smooth it. In short, thinning clay coils does not rely solely on flat beating with the paddle—otherwise, the effort yields poor results, wasting time and labor. Clay coils must be turned over; turning is done to correct errors. Sometimes, to correct errors, the coil must be reversed end-to-end for beating (this generally relates to factors such as one's sitting posture, the height of the clay board, and the bearing surface of the paddle). 4. **Method of cutting clay coils and precautions**: The hand position and grip for cutting clay coils must be correct. The cutting tool handle should face forward, with the left hand's three fingers holding the straight ruler, and the right hand moving the cutting tool. The smooth side of the clay coil should face the clay board; when wrapping the coil, the smooth side will be on the outside. This is because the molecular density of the clay coil becomes loosened when forming the cylinder body, which facilitates beating the cylinder. Conversely, if turned back and forth with uneven loosening on both sides, the cylinder beating will not be harmonious. When wrapping the clay coil, since the blade at the base of the cutting tool's gauge is slightly higher than the blade at the top, the outer gauge portion of the cutting tool should be placed against the turntable. [Page 554] # Developing Proper Habits in Yixing Pottery Technique It is essential to develop proper habits and absolutely avoid putting the cart before the horse. ## 5. Beating the Body Cylinder Beating the body cylinder (*da shen tong*) is one of the most difficult fundamental techniques in Yixing clay forming. When beating the body cylinder, both hands must work in close coordination, but they should not deliberately assist in rotation. The force applied must be even and consistent—absolutely not heavy one moment and light the next. The speed should neither be too fast nor too slow, but maintained at a moderate pace. Relatively speaking, small body cylinders can be worked faster, while large body cylinders should be worked more slowly. The paddle should not intentionally lift upward or press downward. After the body cylinder is properly beaten, the bottom coil should be attached. Generally, the bottom coil of a body cylinder should be attached to the inside of the clay strip. Take care that the boundary between the bottom coil and clay strip remains distinct—they must not become muddled together and entangled. When wheel-throwing the bottom coil, pay attention to placing the smooth surface (that is, the side smoothed with the clay rib) against the wheel. After throwing, flip it over to attach, so that the smooth surface faces outward (or in other words, the small eye of the foot rim faces up and the large eye faces down), achieving the effect of tight on the inside and loose on the outside. Nowadays, fully handmade forming has become less common. Generally, plaster molds are used for pressing or squeezing the clay. Even when using plaster molds to squeeze the form, attention must be paid to beating the body cylinder. When placing it into the plaster mold, one must have a good sense of the difficult shape, so that when expanding the form, only slight adjustments are needed—merely adequate and nothing more. Currently, there is a widespread reaction that the mold quality is poor. The qualification of molds must be verified by ourselves, and any incorrect areas must be corrected by ourselves. When inspecting and repairing molds, it is better for the mold to be slightly concave rather than protruding, as this facilitates trimming. After demolding, one should develop the habit of immediately trimming the mold seam lines. Because our Yixing pottery products have countless variations in form, the technical methods employed in production change accordingly with the craft requirements. For example, consider the two forms shown in Figures 1 and 2 below: Figure 1 has a relatively short neck, which is handled by applying a large rib and adding slip (indicated by the arrow). Figure 2 has a relatively tall neck (indicated by the arrow), where it is impossible to use the method of applying a large rib and adding slip. Instead, one must employ a technique we call "collaring inward" (*sha ao*) to handle it. To use the collaring technique, one must first beat the body cylinder as shown in Figure 3, then perform the collaring at the location indicated by the arrow, shaping it into Figure 2. [Figures 2 and 3 referenced in text] --- *Page 59*