3.6 Emergency Salvage of Wet Books and Records

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Every cultural institution has collections of books and records, whether historic, reference, or administrative. Some of these materials may be affected by a disaster over the course of their useful lives. Leaking pipes or roofs, flooded basements, and open windows are the most common, and most easily contained, of the small water emergencies. Large events may include natural disaster such as hurricanes, flooding from heavy rains, water discharge at high pressure from fire hoses, and major construction accidents.

However small or large the event, the recovery of books and records after exposure to water can be successful and cost-effective if staff and management are prepared ahead of time and react in a timely fashion. If recovery actions and decisions are delayed more than a few hours, deterioration of materials accelerates, recovery becomes a major undertaking, funds for recovery must be diverted from other projects, service is interrupted, and public relations suffer.

The key to a successful salvage effort is disaster planning. Disaster planning consists of four elements: assessing and mitigating risks, writing a plan, the initial response, and recovery efforts. This leaflet will focus on response and recovery but will be a useful document in writing a disaster plan as well. For more information on disaster planning, see NEDCC preservation leaflets “Disaster Planning” and “Emergency Management Bibliography.”

Initial Response

The initial response to a disaster can be very stressful. If your institution is unprepared, even a small water emergency can be stressful and can spiral out of control to become a disaster. The period of initial response is a time for assessing the situation, collecting recovery materials, arranging for supplies and vendors, stabilizing the facilities, and for packing up collections. Having salvage priorities listed and mapped out ahead of time saves valuable time in the recovery stage and reduces stress from trying to decide on the spot what to save first. Advice from a preservation or conservation professional can be helpful in making decisions. If rare books or unique materials are involved, a conservator should always be consulted to best determine salvage needs.

Response to and recovery from a water disaster is most successful if collections and facilities are stabilized as soon as possible. Remove standing water, reduce and stabilize temperature and humidity, and isolate and protect dry collections. If environmental conditions are not addressed after a water problem, mold will begin to develop in as little as 72 hours, spreading rapidly thereafter. Once established, mold can be difficult to control and eradicate and may cause problems in a facility for months or even years after the recovery effort is concluded.

Before beginning any recovery efforts, the water source must be determined. Rarely is the water clean and free of debris. What has contaminated the water? Is the contamination due to pipe corrosion, mud and debris from a flood, salt water, or is sewage involved? If the water is sewage-contaminated, call in a professional recovery service immediately; do not deal with the salvage in-house. If the water is only contaminated by rust, mud, or salt water, rinsing wet books and records before freezing helps by removing debris that could be difficult to clean off after drying. If both trained labor and time are available for this step, set up three or four bins of clean water. Holding books tightly closed, dip them gently in the water. Moving each book from bin to bin will expose them to successively cleaner water and remove much of the debris. Over time, make the last two bins the first two, replace the dirty water in the first two bins, and make these the bins for final rinses. If records are mud-covered, rinse by supporting the records on a piece of plexiglass or other rigid, inert support and rinse with a gentle stream of water from a hose or pitcher. Do not rinse if the inks are soluble; freeze immediately, mud and all.

Recovery

Several drying techniques can be used for books and records that have been water damaged. For most recovery efforts, no single approach will be sufficient to cover all of the materials damaged. The selection of techniques depends upon the degree of wetness, the physical characteristics of the materials affected, expected use and retention, and available funds for recovery. Select the technique that will minimize physical damage (cockling of paper, warping of covers, and distortion of the binding) and bleeding of soluble inks and colorants. For example, in the case of a burst pipe, wet materials may be frozen and sent to a professional recovery company for vacuum freeze-drying, slightly wet materials may be air dried, the affected area is isolated, and the building, furnishings, and damp materials are dried by commercial dehumidification.
At the same time that the environment is being stabilized, wet books and records should be sorted and then treated according to degree of wetness. Degrees of wetness can be considered with these main categories in mind:

Dry materials are often overlooked in a disaster. They must be removed from the affected area if environmental conditions are not addressed immediately. Otherwise, they too will quickly become susceptible to mold growth.
Damp materials are cool to the touch. Exposed to high humidity, they can sometimes be identified after the event by mold formation.
Slightly wet materials exhibit staining to the textblock, binding, folder, or pages no more than one-half inch in from the edges. These areas will have been in immediate contact with water.
Wet materials exhibit staining more than one-half inch in from the edges, up to saturation.

It is important to understand that no drying method restores collections to their pre-damage condition. However, if stabilization and recovery occur quickly, the materials can often be dried and returned to the shelves with little discernible damage.

Air Drying

Air drying is the most common in-house method of dealing with water-damaged books and records. It is best suited for small numbers (less than 200) of damp or slightly wet books and documents. Because it requires no special equipment, it is often believed to be an inexpensive method of drying. However, air drying is labor intensive, occupies a great deal of space, diverts many hours of staff time to regularly monitor the process, and often results in a distorted finished product. Due to the time required for air drying and the potential for mold growth, it is not an option for a large-scale disaster. It is also not an option for books with coated paper. The rehabilitation costs after air drying tend to be greater than other methods because most bound materials require some form of treatment, from pressing to full rebinding; documents often need flattening and rehousing.

An additional consequence of air drying is the extra amount of shelf space required for collections when they are returned to the stacks. Depending upon how successfully wet materials are stabilized and dried, the amount of additional shelf space required after drying can be 20% or more.

Dehumidification

Drying by dehumidification with large, commercial desiccant systems allows for drying while collections, equipment, and furnishings are left in place. Temperature and humidity are carefully controlled to specifications. This drying method has the advantage of leaving damp collections in place on the shelves and in storage containers, eliminating the costly step of removal to a freezer or vacuum chamber. It is not recommended for coated papers or water-sensitive inks and pigments. The number of items that can be treated with dehumidification is limited only by the equipment and expertise of the company called in to install it. Dehumidification is most often used in conjunction with other drying methods and for stabilizing the building and environment. Home dehumidifiers are not strong enough to reduce a buliding’s humidity and thus are not a viable option.

Freezer Drying

Books and records that are damp or slightly wet may be dried quite successfully in a frost-free or blast freezer, if left there long enough. The temperature in the freezer must be maintained at or below -10° F. Books and stacks of records will dry with less distortion if they are restrained between unprinted, clean corrugated board wrapped with a strong elastic band, which will help reduce cockling. Leather and parchment/vellum bindings can be dried in this manner as well. Documents may be placed in the freezer in stacks; shorter stacks allow for faster drying. Expect this method to take from several weeks to many months, depending upon the temperature of the freezer and the extent of water damage. If items are placed in the freezer soon after becoming wet, added shelf or storage space following drying will be less than for air-dried materials.
Freeze drying will cause more harm than water for some commonly held non-book materials. Do not freeze the following:

Audio, video, and computer tapes – Air dry if just the outermost foot or two of tape is damp, or keep them wet until they can be sent to a professional recovery company no later than two days after salvage.
CDs and DVDs – Air dry in a single layer; rinse first if the water was dirty or salty.
Ambrotypes, daguerreotypes, or tintypes – Air dry in a single layer and immediately consult a photograph conservator for advice and assistance.

Vacuum Freeze-Drying

This is best suited for large numbers of wet books and records as well as for materials with water-sensitive inks and coated paper. Boxes of frozen books and records are placed in a vacuum chamber. A vacuum is pulled and a source of heat is introduced while the overall temperature remains below 32° F. The materials are dried by a process called sublimation; the water in the solid state (ice) is removed from the materials in a gaseous state without passing through the liquid state. Thus there is no additional wetting to cause distortion beyond that incurred before the materials were frozen. If materials have been stabilized quickly after becoming wet, very little extra shelf or storage space will be required when they are dry.

Although this method may initially appear to be more expensive because of the equipment required, the results are often so satisfactory that additional funds for rebinding are not necessary, and mud, dirt, and/or soot are lifted to the surface, making cleaning less time-consuming. If only a few books are dried, vacuum freeze-drying can be expensive. However, companies that offer this service are often willing to dry one client's small group of books with another client's larger group, reducing the per-book cost and making the process affordable. When dealing with commercial vendors for drying, communicate clearly from the beginning about costs, handling, and expectations.

Vacuum Thermal-Drying

It is possible to dry non-unique books and records that are slightly wet or wet in a vacuum thermal-drying chamber. A vacuum is drawn, the temperature is dropped below freezing, heat is introduced, the temperature rises above 32° F, and the materials are dried. This process removes the water from the materials in the solid state, through the liquid, to the gaseous state. Because this process occurs in cycles, it introduces considerable distortion, and items require flattening or rebinding. The freezing and heating cycle can result in a series of tidelines as well. IT IS NOT RECOMMENDED unless the materials have a short retention period.

How to Air Dry Wet Records

Air drying is most suitable for small numbers of records that are damp or slightly wet. If there are hundreds of single pages, or if the records are wet, professional dehumidification, freezing, or vacuum freeze-drying will be cost effective and result in a better end product. As explained above, stacks of documents on coated, or shiny, paper must be frozen immediately. If they cannot be frozen, separate the sheets immediately to prevent adhesion. Again, care must be taken with water-soluble inks as well. Records with running or blurred inks should be frozen immediately to prevent further loss. After the items are frozen, contact a conservator for advice and assistance.

If air drying is selected as the preferred salvage method, use the following steps. Note that wet paper is extremely fragile and easily torn or damaged, so handle these materials gently.

Identify a clean, dry, secure space where the temperature and humidity can be controlled. Reduce the relative humidity as low as you can to prevent mold and improve drying capabilities.
Keep the air moving at all times using fans in the drying area. This will accelerate the drying process and discourage mold growth. Aim fans to direct the airflow parallel to the drying records. DO NOT point the fans directly at the records!
Single leaves can be laid out on tables, floors, and other flat surfaces protected by paper towels or clean, unprinted newsprint.
If records are printed on coated paper and there is no means to freeze them, they must be separated from one another to prevent them from sticking. This is a tedious process that requires skill and patience. Place a piece of polyester film on the stack of records. Rub it down gently on the top sheet, then slowly lift the film while peeling off the top sheet at a low angle. Hang the polyester film up to dry on a clothesline. As the document dries, it will separate from the surface of the film, so it must be monitored carefully. Before it falls, remove it and allow it to finish drying on a flat surface as described in step 3.
Once dry, records may be rehoused in clean folders and boxes, or they may be photocopied or reformatted in other ways. Dried records will always occupy more space than ones that have never been water damaged.

How to Air Dry Wet Books

Air drying is most appropriate for books that are only damp or slightly wet. Books that are wet — and especially books that are saturated — should be frozen and vacuum freeze-dried to minimize cockling of the pages and distortion of the text block and binding.

Remember that books containing coated paper should be frozen while still wet and then vacuum freeze-dried, and that books with running or blurred inks or colorant must be frozen immediately to preserve the contents.

Identify a clean, dry, secure space where the temperature and humidity can be controlled. Reduce the relative humidity as low as you can to prevent mold and improve drying capabilities.
Keep the air moving at all times using fans in the drying area. This will accelerate the drying process and discourage mold growth. Aim fans to direct the airflow parallel to the drying volumes. DO NOT point the fans directly at the books!
If the book is damp or the edges of the book are only slightly wet, the book may be stood on end and fanned open slightly in a space with good air circulation, but again, do not aim fans directly at the books. To minimize distortion of the edges of the text block, place volumes in a press or press under a board with a weight just before drying is complete. Paper- or cloth-covered bricks work well for weights.
If the book is slightly wet, interleave approximately every 16 pages, starting from the back of the book, turning pages carefully. For interleaving, use paper towels or clean, unprinted newsprint. Do not interleave too much or the spine will become concave and the volume distorted. A good rule of thumb is to insert no more than one-third of the number of text pages. Complete the interleaving by placing clean blotter paper inside the front and back covers. Close the book gently and place it flat on several sheets of absorbent paper. Change the interleaving and absorbent paper frequently. Turn the book from front to back each time it is interleaved. When the book is damp, proceed as in step 3.
Dampness will persist for some time inside the book in the gutter, along the spine, and in the boards. Due to their thickness, the boards retain moisture much longer; mold is often found between the boards and flyleaves if the book is not allowed to dry completely. Check for mold growth frequently while books are drying.
When books are dry but still cool to the touch, they should be closed, laid flat on a table or other horizontal surface, gently formed into their original shape, and placed in a press or held in place with a board and weight. Press overnight and set up to dry during the day and repeat until books are dry. In no case should books be returned to the shelves until thoroughly dry; otherwise mold may develop, particularly along the gutter margin.
If you can establish an air-conditioned room capable of maintaining a constant relative humidity of 25% – 35% and temperature between 50° and 65°F, books with only wet edges can be dried successfully in approximately two weeks without interleaving. As stated earlier, exceptions are books printed on coated paper and those with water-sensitive media.

Emergency Management
3.6 Emergency Salvage of Wet Books and Records

Initial Response

Recovery

Air Drying

Dehumidification

Freezer Drying

Vacuum Freeze-Drying

Vacuum Thermal-Drying

How to Air Dry Wet Records

How to Air Dry Wet Books

Further Reading

Emergency Management3.6 Emergency Salvage of Wet Books and Records

Initial Response

Recovery

Air Drying

Dehumidification

Freezer Drying

Vacuum Freeze-Drying

Vacuum Thermal-Drying

How to Air Dry Wet Records

How to Air Dry Wet Books

Further Reading

Emergency Management
3.6 Emergency Salvage of Wet Books and Records