Indigenous Materials

Manuscripts or original art works indigenous to a region must be treated with care and experienced judgment. Until quite recently, many cultures recopied manuscripts to preserve texts and images as the materials deteriorated. Unfortunately, many cultures have lost the ability to copy manuscripts in sufficient numbers to ensure that texts and images survive; hence the increased interest in conserving original documents.

Palm leaf manuscripts

Palm-leaf manuscripts are produced from the leaf of palms, and although long-lasting if maintained in a stable environment, they are not robust and can be easily damaged through careless use. Damage to palm leaves typically results from such things as insects, staining, splitting, cleavage (separation of the upper from the lower surface), and threaded cord cutting into the leaf. Palm leaf is more resistant than paper to mold.

Removing insects

Before treating manuscripts, it is important to kill any insects that may be infesting them. The safest and least damaging methods of killing insects is by freezing or heat. Another safe and effective method is the use of para-dichlorobenzene or naphthalene mothballs. A group of manuscripts can be placed in an airtight container, such as a plastic garbage can with a tight-fitting lid and mothballs at the bottom. The manuscripts can be placed in a smaller container with holes that rests on some sort of support to raise them above the level of chemical. They should not touch the chemical. They should be left in the container a minimum of ten days, after which they are removed and carefully examined for live insects. If there is no evidence of live insects, the leaves should be gently brushed with a soft brush to remove dust and insect parts. You should always limit your exposure to chemicals, even those considered “safe” by working in a well-ventilated area and by wearing nitrile gloves.

Removing surface soil

A number of techniques have been used for the removal of surface soil from palm leaves, including solvents that have a desiccating effect and cause leaching of some of the important leaf constituents. Dry cleaning with a soft brush and erasers can be used. If the leaves are very dry, cleaning and hydrating can be done by the direct application of water with damp cotton wool, providing that pre-treatment tests indicate that the writing is incised, and the leaf is not saturated with oil.

Old, dried oil is very difficult to remove, but it must be if effective repairs are to be carried out, as water-soluble adhesives will not adhere to the oily leaf. Soaking the leaf in a non-bleach detergent (such as a mild washing-up liquid) and warm water can be effective, but testing should be done on a blank leaf before attempting this on written text. If the leaf has surface writing, ethyl alcohol can be used to selectively clean the surface. Make sure the high water content of the solvent does not move the image in any way.

Repairing mechanical damage

Splits, broken edges, and holes may be repaired with Japanese-type tissue or thin “sa” paper, applied with a water-soluble mixture of soluble polyvinyl acetate and methyl cellulose or a conventional starch paste.

The mixture of this palm leaf repair adhesive is as follows:

Place one cup (8 ounces or 225 milliliters) of clean water (preferably distilled) in a sealable container.
Sprinkle into the water one and one half teaspoons (7.5 ml) of methyl cellulose, and stir until fully blended. After approximately one hour, the solution will assume a jelly-like consistency.
Place one-half cup (100 ml) of water into a container, such as a glass or paper cup and mix into it one teaspoon of full strength PVA adhesive and stir vigorously until completely diluted.
Gradually add the highly diluted PVA to the methyl cellulose jelly, stirring until fully integrated. It is best to use only about two thirds of the dilute PVA initially, adding the rest only if the mixture is too thick. The mixture should be the consistency of thick cream.
Allow the mixture to stand for one half hour before use. This mixture should be used promptly as mold may develop in a few days and it will have to be discarded.

Repairs to breaks can be carried out with a thin tissue such as tengujo or very fine “sa.” If a significant portion of the leaf is missing, a piece of paper only slightly thinner than the palm leaf should be carefully torn or water-cut to match the missing area. A light table is a valuable aid in this process. The repair piece is carefully tipped into place by matching the slightly overlapping edges of the leaf and the repair paper together. When dry, it is supported on both sides of the “fill” by the thin transparent tissue in the manner described above. Loose leaf fragments are secured in the same fashion.

Some conservators fill losses with matching palm leaf fragments, attaching the filler with wood glue and sanding the joint area. This has much to commend it for compatibility, but new palm leaf is quite stiff and can cause the old to break. Following repair, the leaves are re-oiled to impart flexibility. Various oils have been used for this process, and recent research on camphor, citronella, castor, lemon grass, cedar wood, mustard, neem, eucalyptus, clove, and sesame, indicates that some oils are more easily absorbed than others. The oil should be very lightly applied by laying the leaf onto a piece of glass or polyester film, and the oil applied with a soft brush. Oiled leaves should be air-dried in a constant flow of air to avoid mold forming on the surface of the oil.

Usually, it is not necessary to mix lampblack with the oil to clarify the writing after treatment, as minute amounts of surface oil and soil, washed from the leaf surface during cleaning, lodge in the incisions. If detergent is used to remove the old oil however, it may be necessary to mix a small amount of fine powdered lampblack with the oil, and apply it with a soft cloth or cotton wool. The residue can be cleaned off with ethyl alcohol.

After cleaning, repair, and oiling, the manuscript should be lightly polished with a soft dry cloth, restrung with soft cord, cased, and boxed, together with a small amount of insect repellant.

Parabaik or Concertina manuscripts

Parabaik manuscripts, common to Burma, Cambodia, Laos, and Thailand are constructed from crude, strong paper made of bamboo, bark, straw, or leaf fiber, sometimes referred to as sa. White parabaiks are written in black ink on an uncolored surface; black parabaiks are written with a limestone or chalk pencil on a black surface. Parabaiks are usually accordion-folded books, often lacking covers. The white parabaiks are sometimes richly illustrated in sumptuous colors and were obviously intended as permanent works. The black parabaiks were not intended to be permanent, as the writing may be easily erased. Research has found that black parabaiks were sometimes used to produce early drafts of palm leaf manuscripts or white parabaiks.

Parabaiks are extremely robust and stable, even when stored in adverse environments where fungus and insects are common. When insects or rodents eat the manuscript edges, leaving multiple losses on folds, repairs may be made with Japanese-type tissue and starch paste or palm leaf repair adhesive.

Some parabaiks have elaborate covers made from laminated paper, often encrusted with colored glass and precious stones. Damage to covers is usually the result of insect infiltration between the layers of paper laminate. In this case, a trained conservator should carefully separate the layers, remove insect larvae parts, strengthen the cover, and re-laminate it.

Double-leaved books

Double-leaved books (also known as “string-bound” books) originated in China and were also used in regions influenced by the Chinese, such as North Vietnam and Singapore. The technique was also commonly used in Japan even into the modern machine printing era. The soft, lightly sized paper used for these structures tends to be quite porous and translucent. Since inks tend to migrate through the paper text and graphics are applied only to one side of the sheet. The sheet is then folded in the middle with the plain surfaces together to make an apparent leaf with the text on both sides.

Wood block printing was the most common method of rendering both texts and graphics. The group of folded leaves was then assembled and stitched at the back through the unfolded edge. A simple paper (and sometimes paperboard) cover was attached at the front and back of the book and the text block fastened together by means of paper twists pushed through holes piercing the entire text block at the back and by thread stitches. The light structure and small size of these books tends to reduce the incidence of binding structure damage to broken thread and abraded covers. However, in many cases there is considerable insect damage to the leaves, no doubt because of the rice starch used to size the paper. Repair treatment is complicated by the need to retain the paper’s soft and pliable nature. If the insect damage is extensive, the book must be disbound in order to carry out the repairs.

If the conservator is not familiar with the language of the text, the leaves should be consecutively numbered in an inconspicuous place with a soft pencil to ensure that the book can be collated accurately after treatment. The sewing pattern should also be documented so that it can be reproduced.

Repairing insect damage

Each of the insect holes may be repaired with thin tissue patches or a pulp made from paste and macerated tissue. Even though the back of the text is blank, the leaf should not be simply wet laminated, as this stiffens the leaves. The small patches are applied with starch paste from the back of the leaf, which should be placed face down on a polyester film surface, preferably on a light table. Repairing the insect holes in this way is extremely time consuming, and if there are a large number of insect damaged books, the leaf caster is the best way to perform the repairs. When repairs are dry, the book should be reassembled with new twisted paper slips and the replicated sewing pattern.

Over the years, damage to individual double-leaved books or for small groups of books was minimized by protective enclosures. Replicating these enclosures is quite simple, although if new cases are needed, some consideration might be given to the use of MM cases.

Clay tablets

Clay tablets are produced from clay and molded into (usually) palm-sized shapes onto which cuneiform characters are impressed. Clay was widely used throughout Sumeria, Babylon, and Assyria, and many hundreds of thousands exist in libraries and museums today, and more are being discovered through excavations in the region where they are in generally good condition because of the dry climate.

Damage may be caused through improper/inadequate baking, the deposition of salts, and mechanical damage resulting in breakage.

Baking and Washing

It is not possible to determine the temperature or conditions under which early clay tablets were baked. In most modern museums, baking is carried in a furnace or kiln with the temperature gradually raised to 750 degrees centigrade and maintained at that temperature for some hours. The baking ensures that the clay tablets are effectively converted into brick, and they are cooled in the closed furnace at least overnight.

Any impurities in the clay are burned away or turned into a white powder that may be carefully brushed off with a dry soft brush. If soluble salts are present, the baked tablet will need to be thoroughly washed in running water for up to a month to wash them away. Only institutions with specialty equipment and trained specialists should attempt these repairs.

Repairing Breakage

When a clay tablet is broken into pieces, it is necessary to bake the fragments separately and attach them together after baking using a non-water soluble adhesive. In cases where the clay tablet is actually crumbled, it may be necessary to try to consolidate the tablet with an adhesive and clay powder mix. Consult with a specialist before attempting any repairs.

Clarifying the Image

When the cuneiform images are very faint and almost illegible, some action must take place to render it more visible. Professional guidance is needed before any action is carried out. 3-D imagery may enhance cuneiform inscriptions.

Protecting the Tablet

Various methods have been used for protecting baked tablets, including cotton bags, wrapping with fabric, and boxing. While all these methods are fairly successful, it is recommended that padded boxes be custom-made for the baked tablets, as they can be easily marked. Enclosures will protect them from dropping or careless handling.

Papyrus

Papyrus is known throughout the Middle East and was used for a wide variety of objects, from ropes, sails, boats, clothing, and to make a paper-like material for manuscripts (see Nature of Materials for method of manufacture). Papyrus was used for manuscripts from about 3000 B.C. to the ninth century A.D. when it was largely supplanted with parchment.

As manuscripts, papyrus was most successful when used in roll form, although there are many examples of codices being up of sheets of papyrus held together usually by stabbing.

Conditioning and Unrolling

Most ancient papyrus is very dry and brittle when it is discovered, and must be hydrated before it can be successfully handled. There are a number of strategies used to safely apply moisture to the papyrus, some of which are described in Basic Remedial Treatment: Paper Materials: Unrolling Materials. Three methods of hydration are described here: damp blotting paper, Gortex, and humidification chamber.

Papyrus rolls may be very gently wrapped in damp blotting paper until they have become thoroughly relaxed, usually after about one hour. When relaxed, the rolls may be unrolled carefully, inch by inch, on a glass surface, and covered in dry blotting paper held by a light weight. For long rolls, the unrolled portion of the papyrus must be kept damp until the whole process of unrolling is completed.

Gortex, or a substitute with the same qualities, is a relatively new material developed for specialized outdoor clothing. It has the advantage of allowing water vapor to pass through while retaining actual moisture. In this conditioning method, the inner felted surface of the Gortex would be sprayed with clean water and used to wrap the papyrus roll as above or used to condition flat codices of papyrus.

A humidification chamber is a closed environment in which water vapor is gradually allowed to enter though a port. The papyrus roll is left exposed to the water vapor, usually on a suction table surface or on a sheet of glass. When the roll seems sufficiently conditioned and thoroughly relaxed, it may be removed from the chamber on its glass sheet or a piece of porous screening, and laid onto, and covered with, dry blotter before being placed under a weight to dry.

It must be emphasized that all conditioning must take place in an area with strong continuous air circulation to discourage the development of mold.

Repair

Papyrus that is broken or fragmented may be repaired prior to stabilization by thin strips of Japanese tissue. The strips are used to line the losses in the papyrus, and are carefully pasted with a rice starch or wheat starch paste, then laid into position along the loss, taking care not to stretch the pasted tissue. A suitable Japanese tissue is tengujo, thin but strong tissue which becomes almost transparent when pasted.

Consolidation

It was formerly the practice to seal sheets of papyrus or unrolled papyrus manuscripts between sheets of glass sealed around the edge with passé-partout, a black paper tape. The problems with this method is that glass breaks when dropped and can scatter the pieces of released papyrus widely. A safer method is the use of sheets of Perspex or Plexi-Glass that are cut larger than the manuscript and sealed with a cloth tape glued with polyvinyl acetate. Smaller fragments of papyrus may be encapsulated in polyester film with double-sided tape or with an ultra-sonic welder.

An alternative method is to use two sheets of polyester film that is spot welded with either an ultra-sonic welder or by use of a judiciously applied a hot soldering iron to seal the film in strategic spots, then matting the final product in strong matt board form use.

Library Preservation and Conservation Tutorial