With most of the silk infilling completed (the smallest fills will be addressed later), conservators turn their attention to preparing two colors of mounting silks as well as the backing papers needed for the final stages of remounting.
The mounting silks are dyed blue and off-white, standard colors for the two-color mounting style of hanging scrolls. The blue sections, at about 120 inches long, will be used for the top and bottom borders, while off-white sections, at about 150 inches long, will surround the whole painting. Below, acrylic paints are mixed to achieve the right color, and sumi ink, a black ink used traditionally for Asian calligraphy and brush paintings, is added to get the right shade. Numerous sample mixes are made before the final colors are chosen.
The prepared dye is then brushed onto the mounting silk, and the silk is left on the table to dry.
After applying paste to the dried silk, Xuan paper is added as a lining and smoothed down with brushes. For the blue mounting silk below, blue-toned Xuan paper is used to attain a more opaque and even color.
To balance the weight and match the thickness of the painting with that of the borders, the mounting silks are lined with an additional layer using misu paper.
After the mounting silk is stretch-dried on a drying board, it is ready for use.
When the painting is later joined with the silk borders in a hanging scroll format, it will need a final backing to provide overall support. For Chinese hanging scrolls, this final layer is a complex laminate of papers, and conservators work to prepare it in advance.
The final backing is comprised of three layers of paper: two layers of Xuan paper with one layer of Taiwanese mulberry paper in between them. Sheets of each type are first joined to form ten-foot-long sections, before the sections are layered on top of each other with paste. The laminate backing is then air dried on felt.
As seen below, each layer of paper, when applied to the layer below it, was shifted about three-fourths of an inch in order to stagger the joints. A total of seven sections of this three-layer laminate are made for the scroll.
In August, when conservators removed the old lining, paint was found on the reverse of the silk in many areas. This back-coloring technique is used in traditional Chinese, Japanese, and Korean paintings; pigment is applied on the back of the painting silk to create more opaque and subtle effects when the painting is viewed from the front.
Back-coloring is recorded in Chinese literature, most notably in The Mustard Seed Garden Manual of Painting, compiled as a manual for Chinese landscape painting and first published in 1679. In the section entitled "Preparing White," the author states, "(the white) may be used in painting white flowers or may be mixed with other colors. Usually, when using white on the front on the silk, (the white) should also be applied on the back of the painting." (或着白花，或合众色。凡绢上正面用粉，后面必衬。) In the "Method of Back-Coloring with White" section, the author writes, "To paint the flowers in all pale colors, it would be more vivid with back-coloring in white. With light colors applied at the front, the white could be used at the back. With heavy colors applied at the front, these colors mixed with white could be used at the back to make the subjects." (绢上各粉色花，后必衬浓粉方显。若正面乃各种淡色，背后只衬白粉。皆系浓色，尚觉未显，则仍以色粉衬之。)
Even though back-coloring is a standard technique, because Chinese silk paintings are usually in either scroll or album formats, meaning at least two or three layers of lining papers are on the back of the paintings, it is difficult to know whether back-coloring is employed without removing their linings. Since lining removal was necessary for the remounting of Marshal Xin, conservators took advantage of the opportunity to study and document the pigments seen on the reverse.
Large areas of back-coloring are present, as illustrated below on an image of the back of the painting. White pigment was applied in the flames, eyes, inner sleeve, collar, parts of the scroll and ribbons. There is blue coloring on the face and scroll; red coloring on the hair, beard, and belt; black throughout the figure’s robe; and a small amount of green at the lower part of the inner robe.
It is rare to be able to see back-coloring, but even more rare to find that it was used so extensively throughout the painting, especially in a painting of this size. To understand how the artist decided to use the back-coloring technique for certain areas and what pigments were chosen, conservation scientists analyze samples of pigments taken from both the painting front and back. By comparing these analytical results with literature from the same period as the painting, conservators hope to understand more about the back-coloring technique.
Using analytical instruments, such as microscopy, FTIR, Raman Spectrometry, and SEM-EDS, the Scientific Research Lab is able to identify the pigment samples (see chart below), all of which are confirmed to be traditionally used Chinese pigments, supporting the Ming dynasty date of the painting.
|Sample||Compounds Identified||Possible Formula||Chinese Name|
|Red (dark)||Vermillion or cinnabar||HgS||朱砂|
|Red (orange)||Minium or red lead||2 PbO·PbO2||铅丹|
|Ground white||Calcite + talc||CaCO3, Mg3Si4O10(OH)2||石灰+滑石|
|Brown||Carbon + vermillion or cinnabar||-||墨与朱砂|