Major Remedial Treatment

Major remedial treatment should be carried out only by a trained conservator armed with the appropriate tools, materials, equipment, and facilities, or by a skilled technician under a conservator's supervision. This section will be limited to a general review of major remedial treatments for the edification of untrained library and archive personnel. Untrained technicians should not attempt to apply these techniques, which are invariably carried out on rare and unique materials.

Paper treatment

Paper can be treated with aqueous solutions to remove stains/soil and to chemically stabilize it. The aqueous alkalization solutions usually consist of various preparations of calcium hydroxide and magnesium bicarbonate and sometimes both preparations are used. There are also solvent spray alkalization (de-acidification) solutions that can be applied from a pressure spray can. Testing to determine whether images (printed, written, or graphic) are water soluble is critical. Paper that has lost its original sizing or that must be strengthened can be resized with a variety of substances, principally gelatin. The removal of pressure-sensitive tape also requires paper pre-testing, as removal techniques range from the application of heat to the use of a variety of solvents. With the exception of water, all solvents should be applied in a fume adsorber or fume hood/cupboard. Repairs by hand should always be made with long-fibered paper or tissue and non-damaging, reversible adhesive. The repair of repetitive damage, such as insect damage through many sheets or leaves, can be carried out by a leaf caster.

Suction table

Some stains can be removed with a suction table. This is a mesh-covered screen surface through which air is drawn, usually with a vacuum device. The stain on the document is exposed, and the table area covered with polyester film to concentrate the suction onto the stain. The piece to be cleaned is laid on top of a blotter. The solvent is applied to the stain from the top and drawn down onto the blotter.

Leaf casting

Equipment for leaf casting is similar to the suction table. The object is to fill paper losses selectively with matching pulp. The document is placed on a screen in a tank with a prepared paper pulp. The water and pulp are drawn through the screen with a suction vacuum and deposited into the insect holes, effectively creating new paper.

Rare books

Book conservation strategy is dictated by the form of binding structure, and in particular the method of leaf attachment. Until comparatively modern times, books in the West consisted of folded sections sewn onto "slips" such as leather thongs, hemp cords, vellum strips, or linen tapes. This "through the fold" sewing allows relatively simple rebinding as the sections were sewn together using a kettle stitch and different configurations of sewing patterns. Beginning in the early nineteenth century however, a bewildering variety of leaf fastening techniques were employed involving stabbing methods whereby the entire text block was stabbed through (wire sewing, stitching, nailing, Singer sewing, post binding, plastic comb binding, spiral metal fasteners, oversewing, etc), and adhesive methods, whereby single leaves were glued together with various concoctions of rubber. All these methods were successfully mechanized and treating the large number of books constructed using these techniques is challenging and requires experienced judgment to preserve the essential nature of the books while making their contents more easily accessible.

Unless a rare book has a secondary binding to replace the original binding, the original binding should be restored to its original appearance and function.

Broken sewing

For Western style books and bindings, if the sewing is broken and the book must be resewn, the binding must be carefully removed for reapplication at the appropriate time. Usually, washing, alkalization, and resizing may be done when the book has been disbound. The book leaves are then repaired as needed, resewn in the appropriate fashion, and the original binding replaced and reinforced.

Damaged binding

If the original sewing is sound but the binding is damaged, it can usually be restored through rebacking techniques using leather, vellum, parchment, cloth, or paper. Any paper repairs can usually be accomplished in situ.

Lost binding

If the original binding has been lost, the book may be rebound. The object is to produce a sound binding appropriate to the period but without replicating the period style. There should be no elaborate gold tooling or fake antiquing.