Conservation of Marshal Xin of Thunder, Ming dynasty, 16th century:
Cleaning continues after the painting is moved into the gallery. Two layers of blackless papers, made from chemically processed pulp and rayon fibers, are placed underneath the painting to absorb discoloration and provide temporary cushioned protection. Overall cleaning is undertaken by first spraying filtered water onto the painting, then gently applying paper blotting squares to the surface to absorb any water soluble discoloration. At the same time, simple gravity moves some of the filtered water and discoloration through the scroll to be absorbed by the blackless papers.
After cleaning, Xuan paper, made with tree bark and rice straw fibers, is applied with water on the painting to protect the surface and also to absorb more discoloration. Below, more blotting paper squares are used on top of the Xuan paper to pick up discolorations.
Due to its large size, conservators work on relining the painting one section at a time. The painting is turned face down and a section of the old lining is removed using tweezers.
Once one section of lining is removed, new lining for the same section is added. Below, conservators apply wheat starch paste to the new lining.
The new lining paper is then moved into position and smoothed down with brushes.
This process is repeated many times until the painting is completely relined with new papers. Relining is highly labor intensive, and only one section can be relined in a day. Below, conservators remove the final old lining layer from the reverse.
After the new lining is in place, the painting is turned face up and the protective layer of Xuan paper is removed. With the paste still wet, conservators take the opportunity to align any silk fragments that are misaligned. These fragments were shifted either from previous restoration or handling before treatment.
During lining removal, painting on the reverse is found in many areas. Applying pigment to the back of the painting silk to create more opaque and subtle effects is a technique traditionally used in Chinese, Japanese, and Korean paintings. For Marshal Xin, painting is located in the areas behind the flames (white, as seen below), face (blue), hair (red), robe (black) and belt (red). Colors found on the reverse are not necessarily the colors seen on the surface of the painting.
Pigment samples from the front and back of the painting are taken and will be analyzed by the Scientific Research Lab. Some of the pigments on the reverse had become attached to the old lining paper. In order to preserve the painting on the reverse, the old lining paper in these areas was not replaced. Instead, conservators carefully peeled back the old lining paper, applied new paste, and reattached it to prevent further or future delamination.
During removal of the old lining, some crude repairs of gray paper were seen along areas of tears and cracks (see below), indicating that the painting was previously remounted at least once. Pigments that are not from this painting appear on these repair papers; it is clear that when Marshal Xin was remounted, scraps of paper from another painting was reused for the repair.
Below, the green pigment on the old repairs does not correspond to the painted image. The repairs were removed from damaged areas in the figure’s robe, which is comprised of mostly black pigment.
Conservators theorize that the previous remounting was carried out during or after the Qianlong period (1736–95) in the Qing Dynasty because the old backing/lining paper looks like Qianlong Korean paper, a popularly used paper for mounting during this time. Qianlong Korean paper has distinct chain lines and is well known for its strength. In the Qing court, imperial mounters routinely used this type of paper for backing and lining scroll paintings, wall papers, and paintings.
Paper samples will be taken for fiber identification and comparison with known examples of Qianlong Korean paper. Pictured below is the removed backing paper at left and Qianlong Korean paper at right.
To further support this oversized painting, a second lining is needed. Pieces of handmade Japanese misu paper, chosen for its thinness and clay contents, are joined together to form a length long enough to cover the back of the painting. The papers are water cut, a technique different from knife cut, as the paper is moistened with water along the cutting line and torn by hand to create feather-like edges. The feather edges help to ensure that the joins are even and smooth in both thickness and texture.
For application of the second lining, the painting is turned face down and sprayed with water. Conservators apply paste on the misu lining paper and lay it onto the back of the first lining.
Below, pounding with brushes secures good contact between the two paper layers.