healthmedicinet

Some initial thoughts on the preparation of Hexi painting

Given the multiple layers revealed on cross sections of investigated golden–dragon
Hexi painting fragments and fiber/phase identification and compositional analysis carried out on each layer (Table 1 summarizes the main findings for material use in golden–dragon Hexi painting), the primary procedures that explains Hexi painting and its application upon the Qing imperial architecture can be summarized as follows:

Step 1: 

Preparation of the ground layer (including a fiber layer and coat layers). Surfaces of the wooden materials are fully leveled and polished to produce a smooth surface. A layer of ramie fibers, probably mixed or covered with wet paste prepared from brick powder, is then applied. The ground coat layer uses brick powder as the main (if not the only) coating pigment, and it is prepared by several rounds of coating. Chinese wood oil or other organic materials might be used to mix with fibers and/or brick powder.

Step 2: 

Preparation of the background layer. The indigo-blue and atacamite-green serve as two major background colors on Hexi painting. A usual practice is to apply indigo to paint the blue layer, and then atacamite to paint a green layer upon the blue one wherever necessary. Based on our visual inspection of Hexi painting on Xitian Fanjing, we believe that an inverse order, although not noticed in our samples, could also be true (i.e., painting the atacamite-green layer as the main background first and then overlapping it by indigo-blue layer).

Step 3: 

Preparation of the embossed dragon and cloud patterns. These patterns are embossed by squeezing and shaping soft, wet chalk-white paste out of a container’s opening, following the lifen tiejin technique. The fine particles of chalk must have been mixed and diluted with water and/or oily materials.

Step 4: 

Preparation of the gold-colored layer. The application of hand-hammered gold-silver (quite possibly 76 Au:24Ag, wt%) foils makes sure that the dragon and cloud patterns look prestigious with a yellow gold color, a color highly valued and reserved only for the Qing emperor and his association. Plant or animal glues should be used to glue the foils onto the patterns.

Step 5: 

Application of lead white and other pigments on Hexi painting, the last few steps for painting and decoration. Lead white is applied on the corner of curved surfaces of the dragon and cloud patterns to make sure that a bright white color can always be noticed. Carbon black is used to draw black boarder lines, and hematite to paint the red color.

Clearly, the preparation of Hexi painting follows a few standardized steps (surface leveling, the preparation of ground layer, coloring, embossing, etc.), which have been especially widely noticed on architecture from the Ming and Qing periods onward in many parts of China [e.g., 11, 13, 34, 35], therefore revealing no uniquely special treatment in the painting and decorating procedure. Regarding the use of materials in Hexi painting, a few findings attract our attention, which include: (1) using ramie fibers, rather than wheat/rice straw or cotton fibers [34, 35], for preparing the ground fiber layer; (2) using brick powder, in contrast to chalk or unfired loess [34, 35], for coating the ground layer; (3) using chalk, rather than talcum powder and others [28], for creating embossed patterns; (4) using indigo, rather than inorganic blue pigments [20, 34, 36], to dye blue; and (5) using substantial gold-silver (chijin) foils to decorate the outermost surface of dragon and cloud patterns. However, it is soon realized, upon further consideration, that none of these ‘features’ was exclusively restricted to Hexi painting. That is to say, ramie fibers and pigments used on Hexi painting (such as brick powder, chalk, lead white, atacamite, hematite, and carbon black) can also be noticed on other forms (folk art, for example) of Qing architectural decoration [e.g., 13, 34–36], although they rarely are incorporated into one single package as the case with Hexi painting. Indigo, indeed, is barely reported as blue color on the Qing imperial architecture, but case studies do exist [19, 20]. The extensive use of chijin on golden–dragon Hexi painting is remarkable and undoubtedly a distinctive feature of Hexi painting, considering the substantial amount of gold-silver foils needed. But we do not know whether or not this assumption still holds true when more samples (from other Qing imperial and non-imperial architectural paintings) are included and analyzed for comparison. Given all findings made so far, we propose that neither the kinds of (inorganic) materials nor the painting and decorating process makes Hexi painting uniquely distinguishable from many (if not all) other Qing imperial or folk architectural paintings and decorations. Instead, it is the combination of material use and the painting/decorating process that seems to make Hexi painting special. Considering this possibility, the interpretation that Hexi is a decorative art that “incorporates all the best-known technical skills” seems to make some sense, even though more analytical studies are needed to test whether each feature really is technologically “the best” compared to other contemporaneous techniques and methods of the same kind.