Conservation Treatment of a Japanese Pillar Print
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By Cyntia Karnes and Gwenanne Edwards
Background
"Two Beauties under a Cherry Tree" (1782-83), a color woodblock print by Torii Kiyonaga, required conservation treatment for the Library’s 2012 exhibit Sakura: Cherry Blossoms as Living Symbols of Friendship, celebrating 100 years since the city of Tokyo gave Washington, D.C. its famous cherry trees.
“Two Beauties” is an example of a pillar print, or hashira-e, a long and narrow format designed for display on architectural pillars within traditional Japanese buildings. The design is printed on a single sheet of thin handmade kozo paper, made from the inner bark of the mulberry tree.
At some point in the early twentieth century, before the establishment of the Library’s Conservation Division, the print had been glued overall onto two poor-quality boards hinged together with paper tape (Fig. 1). The mount and the adhered print were folded in half for smaller storage. Over time, the boards had become acidic, brittle, and discolored, and the print was breaking along the center fold. In addition, the print was also faded and discolored, likely from exposure to light and pollutants.
"Two Beauties" was printed in five colors using the woodblock technique, a relief printing process in which the image is carved into a block of wood and the ink is applied to the raised areas of the block for printing. To make a print, a dampened sheet of kozo paper is placed onto the inked block, rubbed with a baren – a soft, round pad covered with bamboo fiber – then carefully peeled off the block and allowed to dry.
In traditional Japanese printmaking, the black lines in the design − often including publisher and censor seals − are carved and printed to make a keyblock print. Specific areas of color are noted on the keyblock print, which is then used as a guide to create separate printing blocks for each color. Guide marks cut into each block ensured that the color ink areas were printed in registration.
The Kiyonaga print may have been executed with as many as seven separate blocks: the black line keyblock; a block each for printing in pink (beni, or safflower), deep orange (tan, or red lead), blue (bero-ai, or indigo), and yellow (shio, or orpiment); and finally, a block for printing fields of black (sumi, or lampblack). This last step may have involved repeated printings with additional ink binder to create a deep, lustrous black. "Two Beauties" also exhibits a special printing technique known as karazuri, in which a design is embossed into the paper using a separate block to suggest textile patterns or other textural elements.
Traditional Japanese printing inks were made from finely ground minerals or extracted plant dyes mixed with a small amount of rice starch paste or animal glue. Many of these traditional colorants are vulnerable to fading from light exposure and are sensitive to environmental pollutants, pH extremes, water, and other solvents. In addition to improving the physical condition of the print by removing it from the acidic mount, conservation treatment revealed that the colors were indeed much more vibrant when the print was created approximately 230 years ago. This can be seen by comparing the front and back of the print; for example, the pattern in the robe appears warm gray on the front, but the better-preserved back side – exposed after treatment to remove the mount – reveals a deep blue.
Conservation Treatment: Removing the Old Mount
The colorants were tested to ensure that the solutions needed to soften the mounting adhesive would not adversely affect the printing inks. The boards were thinned down from the back using a surgical scalpel. An ethanol and water solution was applied to what remained of the thinned mount, which quickly penetrated to the adhesive layer and allowed the remaining layer of mount board to be lifted off in one piece. An additional layer of machine-made western paper that had been glued to the back of the print was also removed. The western paper wa removed on a light table to ensure that the back of the print was not inadvertently thisnned.
Residual adhesive on the back of the print was then reduced in a bath of calcium-adjusted deionized water. This also reduced the yellow discoloration and improved the strength of the paper. The tear through the center of the print, caused by the folding mount, was mended on the back with Japanese tissue while the print was still damp. The print was dried between thick felts to bring the sheet into plane without flattening the karazuri embossing.
When dry, the paper appeared less yellow, the colorants appeared brighter, and some of the grime that had accumulated along creases running across the print appeared slightly diminished.
Conservation Treatment: Reverting Blackened Red Lead
When exposed to poor quality housing materials or atmospheric pollutants, the pigment red lead (tan) can darken. However, conservation research has revealed that black discoloration in tan can also result from an intentional manipulation by the printer, in which the tan is altered with an acidic compound to create a silvery, mirror-like effect. This silvery compound of tan will degrade upon exposure to sulfur (present in poor quality housing materials and atmospheric pollution) to form a black compound chemically indistinguishable from the black compound created by environmentally-induced degradation of red tan.
In the Kiyonaga print, areas printed in tan, including the hair combs and the obi (the sash wrapped around the robes worn by the figure on the left), had turned partially black. In addition, the black discoloration obscured the pattern of the obi. To determine whether the blackening was a discoloration of red tan or discoloration of intentionally silvered tan, the conservators and curator considered the uniformity and shape of the discoloration, iconography, printing characteristics, and degree of aesthetic disfigurement. Since the irregularly-shaped, partial blackening in the obi worn by the left figure obscured the pattern printed in indigo, only this area could be determined with confidence to be the result of unaltered red tan degradation. As it was unclear whether the darkening in other areas of the print, such as in the hair combs, resulted from discoloration of intentionally silvered tan, these areas were not treated.
The black compund obscuring the pattern in the obi was selectively reverted to its original red color by precisely applying -- under magnification -- an extremely dilute oxidizing agent to the discolored areas. Oxidizing residue was rinsed from the print with a mixture of deionized water and ethanol.
Left: Before selective reversion of blackened red lead.
Right: After selective reversion of blackened red lead.
Conservation treatment reduced the visual disfigurement caused by unintentional blackening of red lead, reduced surface dirt and the overall yellow discoloration of the paper, improved the physical integrity of the paper, and removed a damaging storage mount. After treatment, the back of the print is also now accessible, which can provide additional information about the print and traditional printing processes, important clues about the identity of the artist and printer, and other areas of research. After exhibition, the print will be housed in a window mat made from acid-free, non-buffered cotton rag board and stored in stable environmental conditions to promote its longevity.
References:
Hirano, C. 1939. Kiyonaga: A Study of His Life and Works. Boston: Museum of Fine Arts, Boston.
Kanada, M. 1995. Color Woodblock Printmaking: The Traditional Method of Ukiyo-e. Tokyo: Shufunotomo Co.
Kanada, M. 1995. Color Woodblock Printmaking: The Traditional Method of Ukiyo-e. Tokyo: Shufunotomo Co.
Walsh, J., B. Berrie, and M. Palmer. 1998. The Connoisseurship Problem of Discolored Lead Pigments in Japanese Woodblock Prints. In IPC Conference Papers London, 1997: Proceedings of the Fourth International Conference of the Institute of Paper Conservation, 6-9 April 1997, ed. J. Eagan. 118-124.
Prepared by:
Gwenanne Edwards, Harper-Inglis Fellow in Paper Conservation, Library of Congress Cyntia Karnes, Senior Paper Conservator, Library of Congress
Acknowledgements:
Katherine Blood, Curator of Fine Prints, Prints and Photographs Division, Library of Congress Holly Krueger, Head of Paper Conservation, Conservation Division, Library of Congress Mary Oey, Preservation Education Specialist, Conservation Division, Library of Congress Diane Vogt-O’Connor, Chief, Conservation Division, Library of Congress Colleagues of the Conservation Division