Conservation in Action: Preserving Nirvana, September 2016

Conservation and Collections Management

With the painting relined with two layers of handmade usu-mino paper, supplementary linings need to be applied to the painting and to the various sections of mounting silk. These secondary linings use a unique paper called misu, which is made in the Yoshino area of Nara prefecture in Japan. Misu paper is made from the same bast fiber (kozo) of the paper mulberry bush, as the other lining papers, but with the addition of ground oyster shell to the fiber vat. Each formed sheet is laid directly onto a drying board as opposed to the usual method of layering and pressing the wet stack overnight before drying. The shell loading and the direct drying method yields a soft, supple paper with a textile-like quality that is ideal for the inner layers of a hanging scroll. This paper is used to balance out the different elements of the scroll, which all vary in texture, weight, and flexibility, in order to achieve a uniform structure that hangs straight and rolls smoothly. Below, conservators organize the misu paper to be used.

conservators organizing misu paper
Conservators organizing misu paper

Misu paper is made in very small sheets, so in order to use the paper efficiently for lining this oversized scroll, conservators join the sheets into large continuous rolls using dilute wheat starch paste. Sheets are graded (sorted) by weight, thickness, and the amount of shell white loading, so that appropriate linings may be chosen to balance out the different characteristics of the border sections and the painting. Long strips are measured and cut from these rolls to accommodate the size of the various sections.

conservator cutting misu paper
Conservator joining misu paper

Misu paper is applied using aged wheat starch paste. The aged paste is prepared by storing cooked wheat starch in earthen jars in a cool cellar to age naturally for seven to ten years. The resulting paste is soft and supple, and is used only in the supplementary linings of a hanging scroll. Because aged paste is of relatively low adhesive strength, it is used in combination with a pounding brush (uchi-bake) to mesh the paper fibers together, creating a strong but supple laminate structure ideal for a hanging scroll.

Watch the pounding brush in action

One of the most significant conservation issues for this painting is the presence of numerous creases and cracks. Many of these are the natural result of the rolling and unrolling of the scroll, delamination of the lining papers, and the stress of hanging such a large, heavy scroll. The cracks and creases are reinforced using narrow strips of usu-mino paper, applied to the reverse of the painting using fresh wheat starch paste. If these weakened areas are left unsupported, they could cause pigment loss and tearing.

conservator reinforcing cracks on back of scroll using usu-mino paper
Conservator reinforcing cracks on back of scroll using usu-mino paper

The painting is executed on paper made from the bark of a plant called gampi (Wikstroemia sikokiana), which is characterized by short fibers and a silky, glossy texture. The lustrous appearance of the scroll comes from the deep mineral pigments applied to this smooth, shiny paper. However, gampi paper also has the unfortunate characteristic of delaminating within the paper structure itself. During past restorations, these areas blistered, creased and wrinkled, and sometimes split apart, resulting in delicately thinned areas in the painting where the blisters have been stripped away. These thinned areas are reinforced by applying patches of soft paper onto the back of the lined painting.

conservator reinforcing thinned areas using patches of soft paper
Conservator reinforcing thinned areas using patches of soft paper

The relatively thick and stiff gold brocades of the border mounting, the thinner and softer damask satin silk custom-woven to reproduce the outermost soberi lining, and the gampi paper painting all have very different characteristics. In order for the hanging scroll structure to operate as a balanced whole, several supplementary layers of paper are applied to the painting and each section of mounting silk.

conservators applying supplementary layers of paper to painting
Conservators applying supplementary layers of paper to painting

Each section is stretch dried on a drying board to pull it flat and square prior to reassembly of all the sections back into the hanging scroll format.

sections of mounting silk stretch drying on drying board
Sections of mounting silk stretch drying on drying board