Japanese tissue

Japanese tissue is a thin, strong paper made from vegetable fibers. Japanese tissue may be made from one of three plants, the kozo plant, the mitsumata shrub and the gampi tree. The long, strong fibers of the kozo plant produce very strong, dimensionally stable papers, and are the most commonly used fibers in the making of Japanese paper (washi). Tissue made from kozo, or kozogami (楮紙), comes in varying thicknesses and colors, and is an ideal paper to use in the mending of books. The majority of mending tissues are made from kozo fibers, though mitsumata and gampi papers also are used.

Forms of Japanese tissue

The kozo plant is used in the manufacture of the following papers:

How it is made

Japanese tissue paper is a hand-made paper. The inner bark of the kozo plant is harvested in the fall and spring, with material from the fall harvest being considered better quality. Bundles of kozo sticks are steamed in a cauldron, then stripped of their bark and hung in the sun to dry. At this stage in the process, it is known as kuro-kawa, or black bark.

To make paper, the black bark must be converted into white bark. The stored black bark is soaked and then scraped by hand with a knife to remove the black outer coat. At this point, it is washed in water and again placed in the sun to dry.

White bark is boiled with lye for about an hour, then left to steam for several more hours. At this point, it is rinsed with clear water to remove the lye. Then, it is stream bleached (kawa-zarashi). The fibers are placed in a stream bed around which a dam is built. Clean water is let in periodically to wash the fibers. Alternatively, the fibers may be bleached using a process called small bleaching (ko-arai). In this case, it is first placed on boards and beaten with rods before being placed in a cloth bag and rinsed in clear running water.

Impurities are removed after bleaching though a process known as chiri-tori. Any remaining pieces of bark, hard fibers or other impurities are picked out by hand or, in the case of very small pieces, by the use of pins. The remaining material is rolled into little balls and the balls are then beaten to crush the fibers.

After being beaten, it is common for the kozo fibers to be mixed with neri, which is a mucilaginous material made from the roots of the tororo plant. The neri makes the fibers float uniformly on water and also helps to "...slow the speed of drainage so that a better-formed sheet of paper will result." (Narita, p.45)

A solution of 30 percent pulp and 70 percent water is then mixed together in a vat. Neri may also be added to the vat. Nagashi-zuki, the most common technique for making sheets of paper, is then employed. The mixture is scooped on a screen and allowed to flow back and forth across the screen to interlock the fibers. This process is ideal for forming thin sheets of paper. The other technique for making paper, tame-zuki, does not use neri and forms thicker sheets of paper.

The sheet of paper is placed on a wooden board and dried overnight, then pressed the next day to remove water. After pressing, the sheets are put on a drying board and brushed to smooth them. They are dried in the sun, then removed from the drying board and trimmed.

How it is used

Japanese tissue is used in the conservation of books and manuscripts. The tissue comes in varying thicknesses and colors, and is used for a variety of mending tasks, including repairing tears, mending book hinges, and reinforcing the folds of signatures (the groups of pages gathered and folded together at the spine) or for reinforcement of an entire sheet through backing. The mender will select a piece of Japanese tissue that closely matches the color of the paper being mended, and chooses a thickness (weight) suitable to the job at hand.

Mending tears

First, Japanese tissue in a color close to that of the paper to be mended is chosen. The tear is aligned and paste may be used on any overlapping surfaces in the tear to help hold it together during the mending process.

A strip of tissue is torn away from the main sheet using a water tear. This is done by wetting the paper along the area to be torn and then pulling sideways with the fingers to separate the strip from the rest of the sheet of tissue, so that it will have feathered edges. The fibers in these feathered edges will allow the tissue to have a firmer hold on the mended paper and also to blend in with it once dried.

Paste is applied to one side of the tissue strip, from the center outward. The tissue is then placed, paste side down, on the tear, leaving a little bit of the mending tissue hanging over the edge. This bit will be trimmed off after the mend dries. A dry brush is used to smooth the tissue over the tear, again, from the center outward. The mended page is placed between layers of PET film or glass board, blotting paper, and reemay (to keep the paste from sticking to the blotting paper), then weighted and left to dry.

Mending hinges

This is another task in which Japanese tissue is often used. In some cases, the first step may be to "tip in" (that is, add with a thin strip of adhesive) a flyleaf to become the base for the attachment of the hinge mend, if the original flyleaf is not well attached. A small support the height of the spine should be placed to eliminate stress on the hinge.

Japanese tissue should be water torn in the same process as described above, in a width and length sufficient to cover the hinge of the book with about 3/8 inch extension over the sides. Paste should be brushed on to the tissue, from the center outward, transferred to the hinge and then brushed down with a dry brush.

A sheet of PET film is placed to prevent the hinge from sticking together and it is weighted until it dries.

Reattaching signatures

In the case where an entire signature (a folded sheet of paper forming several pages, or leaves, of a book) has come out, it may be reinserted by being sewn first onto a strip of Japanese paper, and then by pasting into the book along the newly-formed hinge between the Japanese paper and original signature.

References

*Ballofet, Nelly and Jenny HIlle. "Preservation and Conservation for Libraries and Archives." Chicago: American Library Association. 2005. ISBN 0-8389-0879-9
*"Conservation in the Library." Ed. by Susan Garretson Swartzburg. Westport, CT: Greenwood Press. 1983. ISBN 0-313-23267-9
*DePew, John N. with C. Lee Jones. "A Library, Media and Archival Preservation Glossary." Santa Barbara, California: ABC-CLIO. 1992. ISBN 0-87436-576-7
*DePew, John N. "A Library, Media and Archival Preservation Handbook." Santa Barbara, California: ABC-CLIO. 1991. ISBN 0-87436-543-0
*The E. Lingle Craig Preservation Laboratory Repair and Enclosure Treatment Manual. Images and text by Garry Harrison, web design by Jacob Nadal. http://www.indiana.edu/~libpres/manual/
*Narita, Kiyofusa. "Life of Ts'ai Lung and Japanese Paper Making." p. 15-70. Tokyo: The Paper Museum. 1980.
*Turner, Silvie. "The Book of Fine Paper." p. 82-101. New York, NY: Thames and Hudson, Inc. 1998. ISBN 0-500-01871-5

ee also

*
*Japanese paper
*Paper mulberry

External links

[http://www.indiana.edu/~libpres/manual/ The E. Lingle Craig Preservation Laboratory Repair and Enclosure Treatment Manual]