process was complete. A newer variation on the piece mold process was put forth as a way to explain asymmetrical faces on vessels which, as a rule, should be symmetrical. It was proposed that décor was not made on a model and then transferred to the outer mold layer, but that the décor was carved into and built up on the outer, shell layer as the first step. Décor was added in a variety of ways. The first was simply carving and incising lines into the clay mold layer. The second was to stamp or press an image, inscription, or design into the wet clay. The third was a technique called tube lining. In this technique, soft, liquid clay would be put into a leather bag, and piped onto a surface through some kind of very fine tube made of metal or bone. This technique would have been quite intensive, as it was difficult to maintain constant pressure on the bag, which was needed to create even lines; however, because of certain types of décor, such as thunder or quill patterns, this would have been the most likely technique used to create low relief design in this process. Decoration Several common themes in decoration span across all types of vessel forms, from hu to pan, and guang to jia. Arguably, the most frequent, though also the most intriguing and mysterious, form of décor is the two eyed motif, often referred to as the taotie. This motif can range from something as simple as two protruding half spheres in an otherwise featureless plane, to highly detailed, mask-like faces with various animal features such as snouts, fangs and horns. In ding vessels, these taotie faces most often appear on the bowl or cauldron portion of the body, but they can also appear on the legs of the vessels. Decoration also tends to be used to fill in the background of most vessels, sometimes across the entire body of a vessel, but in other instances only a single band of décor is used. In these backgrounds, whirl or thunder pattern, a low relief spiral design, is used to fill the space and create a texture across the surface of the vessel. In later centuries, fully formed, three-dimensional animal figures, such as cows, goats, birds, dragons, and lions, were occasionally included on bronze vessels. Some of these animals were purely decorative, while others also