CONSERVATION OF CHINESE SHADOW FIGURES: INVESTIGATIONS INTO THEIR MANUFACTURE, STORAGE, AND TREATMENT
3 TECHNOLOGY: MATERIALS AND MANUFACTURE
The construction of a shadow figure of the East City type begins with soaking a hide in water and then stretching it on a frame. The wet skin, traditionally donkey, is rubbed and scraped, first with a stone, then with bamboo, until it is thinned to translucency. Often, the hide of a young animal or a hide that has been split or skived is used for parts of the figures that require greater translucency. When thicker skins were needed, sheep or cow was used (Erda 1979; Jilin 1988).
The outline of the figure is traced or drawn freehand onto the skin, usually by incising, and is cut out using specialized chisels and knives (fig. 6). Most of the puppets depict human figures and are composed of 11 parts. For less important figures, the legs, torso, and even head may be cut from one solid piece of hide. These characters are not required to express multiple personalities and therefore do not need to make the range of movements obtained with the more complex articulated puppets.
As mentioned, different parts of the puppet body are made from different sections of the hide. Traditionally, the skin from the belly of the donkey is employed for faces and upper body parts, while thicker sections are more appropriate for the feet, legs, and torso. The thinner skins of the faces transmit more light, creating a sense of illumination, while the weight and rigidity of the thicker skins in the lower body keep the puppet balanced and stable. Often tiny lead plates are attached to the bottom of the pant legs to obtain greater balance and to allow the legs to swing back and forth, simulating a walking stride.
The puppet maker cuts joints between the legs, arms, and torso into shapes resembling wheels with spokes. These radial cuts prevent a large dark spot from appearing on the screen where parts inevitably overlap, creating two layers for the light to penetrate. This technique can be seen in the puppet shown in figure 1 at the elbow junctures, at the tops of the legs, and through the center of the figure. Silk, cotton string, or flaps of rawhide hold the parts together, and occasionally metal wire is used to reinforce separate elements. The heads are not attached permanently. Instead, they fit into a collar of parchment, allowing the character to change costume or persona in the course of a performance. Often many heads are needed to show the changing status and emotions of a single character in the course of a play. This construction also allows decapitation, a frequent mode of execution, to be convincingly portrayed. The puppeteer attached iron alloy wires with bamboo handles to the figures for manipulation.
Traditionally, the skin was painted on both sides with vegetable dyes. Later, synthetic dyes and paints were used. An application of oil, usually tung oil, was applied in order to saturate the colors, resulting in a more vivid projection as well as greater transparency. Periodically, as part of the regular maintenance of his collection, the puppeteer reapplied the coating.
3.1 CONDITION: INHERENT INSTABILITIES
Structural instabilities throughout the collection are mostly related to the manufacture of the puppets, specifically their thinness and intricately cut designs. Common damage resulting from this inherent disadvantage include tearing of the skin, distortion, and detached elements. It was common for the puppet master to manufacture his own figures and to regularly restore damaged figures. Therefore, before any treatment is accomplished, a clear distinction must be made between ethnographic and modern interventions. Ethnographic repairs in the Laufer collection include sewing, pinning, and patching with skin. These repairs have historic importance and should be preserved if possible. Modern attempts at restoration include applying transparent, pressure-sensitive tape to tears and using paper clips to connect detached elements. In most cases, it is appropriate to remove and redo these repairs using more appropriate materials or techniques.
3.2 THE TUNG OIL COATING
The tung oil coating is the main culprit in creating condition and preservation issues in many shadow puppet collections. In the AMNH collection, old storage facilities in non-climate-controlled environments aggravated these issues. Puppets piled into shallow trays were found stuck to adjacent puppets, to storage materials like brown Kraft paper, or to plastic bag enclosures. Correspondence with other institutions and private collectors indicates that this sticking problem was widespread.3 A 1974 letter to AMNH restorers from a restorer working in a large American museum reads:
We own a large collection of shadow puppets made of traditional “parchment,” dyed with bright colors, and then coated with a shellac-like substance. The problem lies with the latter material which in time has become tacky and sticky and adheres to whatever guard sheet we lay between the images. We've not been able to find a solvent which can remove the sticky material without removing the color.” (AMNH 1974)
The AMNH response to this inquiry suggested either complete removal of the coating using methyl ethyl ketone solvent (MEK) or “if one wanted to preserve the coating then application of Butcher's wax would act to prevent sticking.” The collection from the corresponding museum was treated by soaking the artifacts in baths of MEK, removing the coating entirely along with much of the originally applied color.
Another letter in the AMNH archives describes a different approach. In this case, removal of the coating would cause irreparable changes. Instead, paraffin was applied directly to the surfaces in an attempt to reduce the sticking. When conservators were unsatisfied with the results, the surfaces were rubbed with Vaseline (AMNH 1974).
These approaches to the problematic coating either attempted to cover it with another material or to remove it altogether. At the AMNH, we consider both of these options unacceptable. Instead, a lessintrusive treatment involving upgrading storage conditions and developing treatment procedures compatible with these inherently fragile and sticky artifacts needed to be developed.
3.3 TUNG OIL: CHEMICAL AND PHYSICAL CHARACTERISTICS
An investigation into tung oil and its drying properties offered some help in understanding the troublesome surface treatment. Most references concerning Beijing shadow figures describe tung oil as the primary coating material. Several oil samples were removed from puppets in the collection. These represented the range of oil types found on the puppets as distinguished by their surface characteristics. All samples were positively identified as tung oil by using Fourier transform infrared spectroscopy (FTIR) and gas chromatography–mass spectrometry (GC-MS). George Wheeler accomplished the analysis at the Metropolitan Museum of Art Conservation Laboratory.
Tung oil, also known as Chinese wood oil, is obtained from the seeds of the fruit of Aleurites fordii, a tree that has grown in China for centuries (Gettens and Stout 1942). The native method for separating the oil involves roasting the seeds over a flame and grinding them with stones or wooden presses. A coldpressed version of the oil called “white tung oil” is light in color and is mostly exported. The hot pressed oil has a very dark color and is called “black tung oil.”
Tung oil contains a large proportion (75-85%) of eleostearic acid, a stereo-isomeride of linoleic acid, which is found in linseed oil. These acids contain two unsaturated double bonds, a property that gives an oil its drying property. However, under normal temperature and humidity conditions, tung oil takes approximately 30 days for a full gain in weight or for drying to be complete, distinguishing it as a slow-drying oil. In fact, tung oil is not recommended as an artist's material since it requires extensive processing to dry to a satisfactory level (Gettens and Stout 1942).
Under humid conditions the oil will dry more rapidly, with a resulting film that is wrinkled, cracked, or reticulated. This drying-rate increase in moist air is not “drying” in the usual sense through oxidation and polymerization. Instead it is thought that the oil is coagulating from the high moisture exposure and is therefore thicker and more viscous but not necessarily drier (Gettens and Stout 1942). The reticulated surface texture of the coatings on the puppets is common and could have resulted from application and “drying” in a humid environment.