Outline for a Flood Preparedness Exercise

Walter Henry
Stanford University Libraries
February, 1988
I. Introduction

A. Water itself is not inherently damaging to paper; in fact, washing paper is a common conservation treatment. The problems in a flood arise because a book is not simply paper, but is a complex composite object, composed of varying materials that react differently to water. These materials swell, curl, stretch or shrink, at different rates and to different degrees. A system that, under normal circumstances, functions as an integral machine, becomes, when wet, a network of conflicting forces, pushing and pulling against one another until one component or the other gives way.

  1. Dry Paper has a normal water content equal to 5 - 7% of its weight. However, the water content can increase to as much as 30% and the paper still feel reasonably dry to the touch. Therefore, it can be very misleading to base your actions on whether something 'feels dry'.
  2. In theory early papers (before the mid-nineteenth century, when modern sizing techniques came into force) are capable of retaining up to 80% of their weight in water and modern papers up to 60%. In practice the retention rates seem to be substantially higher, perhaps because a great deal of water can be retained on the surfaces between the pages.
  3. Many books, especially art books and books with photographs, are printed on coated paper stock. These papers have a surface layer of an adhesive material and one of several pigments or powdery substances, such as Kaolin (china clay). When a textblock printed on such paper gets wet, the adhesive softens and the coatings on adjacent leaves bond together. When this effect, which is known as 'blocking' occurs, it is virtually impossible to reverse. If the textblock is promptly frozen at very cold temperatures (which promotes the formation of smaller ice crystals) and then vacuum freeze dried, sometimes blocking can be prevented. Under no circumstances should coated stock books be allowed to dry; if freezing must be postponed and the paper is wet (i.e. not merely damp), it is better to leave the book under water. However, in such cases the chances for successful recovery are severely reduced.
  4. Leather, when wet will shrink severely and often undergo extreme darkening. Both of these effects ought to be considered irreversible.
  5. Book cloth is fairly stable when wet. It neither expands nor shrinks dramatically. Because other components of the book, such as the boards, do expand when wet, this stability can result in board warpage. Dyes in many book cloths will run, and can permanently stain other materials with which it comes in contact. Many cloths are sized with starch which will dissolve and form a slimy mess, that in addition to being rather unpleasant to work with, provides a good medium for mold growth.
  6. Sewing thread may be dimensionally stable, or may stretch. More often, however, it will shrink slightly. Coupled with the swelling of the textblock paper, this encourages the development of a concave spine. For those that care about such things, the tendency of the thread to shrink or stretch is a function of its twist structure.

B. General considerations.

1. The principle enemy is mold, which can set in quickly if conditions are favourable, as they frequently are at a flood site. Although this is a somewhat inadequate characterization, it is a common and reasonable rule of thumb that mold may establish itself within 48 hours in a warm, damp environment. It is important to remember that if conditions are more severe, mold can develop within a shorter period; nevertheless, if the material is dealt with within that period and if the ambient conditions are brought quickly under control, the likelihood of a successful recovery is good.

2. Floods may reasonably, if arbitrarily, categorized according to a three-step scale of severity. Their assignment with respect to this scale will to a great degree determine the nature and extent of intervention.

a. Minor Emergency. In this category, there are few enough items that it is practical to air dry them on-site immediately. Within our institution, this category applies to emergencies involving less than 100 items. In practice, moreover, many of the materials affected are likely not to be very wet, but merely damp. Such emergencies are handled by the Preservation Office staff. The Collections Emergency Response Team is not called and assistance from outside the institution is not requested.

b. Moderate Emergency. This category applies to emergencies in which as many as 1000 items are affected. In such instances, we are likely to need outside resources, such as large freezers, etc. An event in this category may invoke a pre-planned organizational response, such as calling upon the Collections Emergency Response Team or implementing a phone tree.

c. Major Emergency. Generally, if more than 1000 items are involved, and damage is severe, than the event is assigned this classification. All available resources, both within and outside the institution, are called upon.

3. In any flood, but especially in a large scale flood, damage and loss is inevitable. Some material will be permanently disfigured, whether cosmetically or structurally. The object of a salvage effort is to recover the collection as a whole, while minimizing damage. Under emergency conditions there is sometimes a tendency either to spend too much attention on single items or small groups of items at the expense of the collection or, on the other hand, to become somewhat callous to the damage being caused by, say, handling or packing. Both extremes are to be avoided but the former is probably the more dangerous.

C. Damage Assessment and Intervention Priorities. Items of the highest priority (greatest value, greatest significance to the collections) should be removed from the flood site, as should the wettest items. An adequate disaster plan will have identified such materials ahead of time.

1. How wet is the material? The wettest items are not only likely to be the ones most in need of attention, but, since they hold substantial quantities of water, their removal will help a great deal to lower the ambient humidity at the flood site.

a. Visual clues are good indicators of water content.

i. Swelling, cockling (undulation of sheets), darkened colour of paper or cloth and deformation of binding all indicate absorption. The longer the books have been exposed to water, the more pronounced these indicators will be.

ii. Swelling, especially, is an indicator of length of exposure. As the book sits in water, it continues to absorb water and the various parts swell at different rates. The textblock will swell the most and push out against the less expansive case and the sewing thread, which may even shrink. This results in a tendency for the spine to assume a concave configuration and the longer the book sits the more concave it becomes.

Some books, when they have been sitting in a pool of water for a few days swell to such an extent that the spine forms a tight backwards circle and the front board actually comes around to touch the rear board. Some tightly shelved books may swell to such a degree that they 'walk' themselves off the shelves. In most cases the swelling will reach a maximum after a few days.

2. If mold has already developed, there is little likelihood that the material can be air dried, and it should normally be frozen immediately.

3. Either the uppermost or lowermost shelves will be the wettest, depending on the source of the water.

D. Immediate action (all levels of damage)

  1. Eliminate the source of water.
  2. Turn off the heat. If possible turn air conditioning on and leave it on around the clock. Turn on fans and dehumidifiers. The aim is to keep the air as cold and dry as possible and to keep it moving. This will discourage the development of mold.
  3. Vacuum out (with wet-dry vacuums) any standing water. If there are carpets or curtains that are holding water, they may need to be removed.
  4. Be aware of potential electrical hazards. It is often necessary to turn off the main power and run the fans from generators to avoid fire or danger to personnel.
II. Books and Paper

A. General handling.

  1. The paper will have very little wet strength and is subject to tearing. Although this sounds rather obvious, the degree of weakness comes as quite a surprise to many people at their first flood.
  2. Do not attempt to open a fully wet book. The pages of a wet book cling together quite aggressively and an attempt to open it often results in serious tears. Moreover damage to the binding can also occur. There are exceptions to this rule. If the book is only damp, it is usually safe to open it, though it is rarely necessary unless it is to be air dried.

    In most situations, it is also unwise to close a wet book that has been lying open, as often happens when books 'walk' off the shelves and fall into standing water. Such books are usually badly swollen and the pages are temporarily fused together. If you observe the motion of the pages as you open a dry book, you will notice that the pages slide easily over one another. When paper is wet, it loses this slipperiness and clings to adjacent sheets. If you close a book in this condition, severe distortion and tearing can result. There are rare exceptions to this rule.

  3. Mud, silt, dirt, etc. As a general rule it is advisable not to attempt to remove such accretions at the flood site, but rather to allow them to dry and brush them off later. However, if the materials are extremely dirty or if the nature of the contaminant is particularly noxious or toxic, as, for example, sewage, it may be necessary to wash off at least the covers of the book before further treatment. The book is held gently closed and a slow stream of water run over the spine, with the fore edge pointed down so that the water runs off the case without further wetting the paper. On occasion it may be necessary to wash contaminant from the paper itself, in which case extreme care should be taken and the task should be performed as quickly as possible. Books that have been so washed, should normally be frozen immediately and dried very carefully after the emergency has passed. Rare materials, art on paper, and other unusual materials may need to be treated in a different fashion; these are not dealt with here.
  4. Disbinding. In a small-scale emergency when attention can be paid to individual items, it is, on occasion, appropriate to remove the textblock from its case (by slitting through the hinging material). This may be appropriate when the textblock is swelling severely and is being distorted by the less expansive case, or when mold has begun to grow in the case. In a large scale emergency, such action is rarely warranted.

B. Minor Emergency.

Air Drying.

a. Materials. Large tables or, if necessary large areas of floor. White, unprinted paper towels (generic are best, because you will need a lot). Fans. Towels or blotting paper.

b. Line the table with towels, paper towels or blotting paper. These will absorb water dripping from the books and prevent their sitting in standing pools.

c. Place a sheet of paper towel between the leaves every 20 pages or so. The paper should not be placed all the way into the fold, because this will lead to a buildup at the spine, which will cause the case to fail. If the book is to be set on its tail (normal shelving position) arrange the interleaving such that it extends past the edges of the book at the fore edge and the head edge but not at the tail edge. This will provide an exposed area of interleaving paper while still allowing the book to stand safely. This interleaving paper serves as wick to draw water out of the book. Water will evaporate at the exposed edges of the interleaving, and, as it does so, water from the interior of the book will move, by capillary action through the interleaving toward the exposed edges.

d. The boards of each book should be fanned open and and the volume stood upright on the table. Often it is possible to place the books in such a position that they help to prop each other up. Frequently either the tail or the head of the book has absorbed more water (depending upon the source of the water). If so, turn the book so that the least weight is placed on the swollen area.

e. Place fans such that they keep air moving gently over all of the volumes without blowing them over. Sometimes this can be best accomplished by using large powerful fans and placing them at a considerable distance from the table. The fans must be left on around the clock until the drying is complete. If possible, air conditioning should also be left on continually.

f. As the interleaving papers become saturated with water, replace them with fresh interleaving. Try to place them between different pages than you did the last time. That is if the first interleaving was between pages [20-21, 40-41, 60-61 ...], the second should be between [30-31, 50-51, 70-71 ...], the third between [25-26, 45-46, 65-66 ...] and so forth. When the books are very wet, the interleaving will become saturated almost immediately and as soon as you finish interleaving a small group of books, it will be time to start all over again.

g. As the drying progresses, a stage will be reached at which the interleaving papers cease to wet out but merely become damp. At this stage, it is no longer necessary to replace the interleaving.

h. After the books feel dry to the touch, a condition that may take several days if the books were quite wet, remove the interleaving papers and leave the books fanned open, with the fans still running continually for several days. Paper can hold substantial quantities of water and still feel dry to the touch.

Line Drying.ed as either an alternative or a supplement to interleaving and air drying, this process, in which the volume is suspended from three thin monofilament lines strung between two walls, tables, etc., line drying can help to avoid spine distortion caused by extreme swelling or excessive interleaving. It is only rarely necessary.

C. Moderate Emergency. Events in this category usually involve some combination of actions associated with both minor and major emergencies. In many ways, these are the most difficult sorts of emergencies to deal with.

D. Major Emergency. In the case of a large scale flood, one in which so many items have been affected that it is not possible to dry them on-site, the objective is to freeze the materials as quickly and safely as possible. Again, the principle enemy is mold, and the (somewhat misleading) limit of 48 hours applies. Proper freezing at very low temperatures, as in a large commercial food locker, will stabilize the objects, preventing the development of mold, the further swelling of the paper and boards, the bleeding of inks and, if we are lucky, the blocking of pages. More importantly, however, freezing buys us time. Because the books can remain frozen indefinitely without danger (for years, if necessary), we gain the leisure to plan the salvage effort sensibly, without having to operate under crisis conditions. In a major flood, recovery will almost certainly involve vacuum freeze drying and a aggressive program of rebinding and repair, both of which impose significant logistical difficulties.

1. Packing books for freezing.

a. Books can be packed either in cardboard cartons or egg crates. If egg crates are used, they can be stacked higher than cartons. However, as wet books are very heavy even egg crates should usually not be stacked more than three high. In one flood here, a pallet loaded with egg crates three high was so heavy that a forklift couldn't lift it.

b. Each volume should be very simply wrapped in freezer wrap. This prevents the volumes from sticking together and facilitates unpacking and rearrangement or manipulation inside the freezer and vacuum chamber. A piece of freezer wrap is rough-cut to approximate size and simply folded in a U-shape around the case. An assembly line should be set up at the flood site. Cutting freezer wrap from the roll (Zippy (tm) cutters are great for this), assembling cartons, and wrapping and packing the volumes are operations that need to be done as efficiently as possible.

c. Whenever possible, books should be packed in a single row with the spine down. If that is not possible, then they may be packed flat. In this case it is important that a large book never be placed on top of a smaller one, because the larger one will sag and become permanently deformed. It is important never to box wet books in a normal standing position or with the fore edge down because the weight of the wet paper will pull the textblock out of the case. Similarly, with books boxed spine down, one should never try to save box space by adding a second row of books; the second row will crush the bottom row, resulting in permanently misshapen volumes.

d. Books will tend to take on permanently their shape at time of freezing. One can think of the book as a malleable material, like wet clay; a little care and common sense in molding and packing will go a long way toward recovery. On the other hand, because wet paper has very little strength and because the wet sheets do not slide against one another but cling to each other, an excessive attempt to bend or mold the volume may cause great damage and result in a volume that is neither usable nor repairable.

e. Books packed for local freezing in a Wei To (tm) blast freezer can be handled in largely the same manner as books sent to a larger food locker, although it is usually more efficient not to box the books but simply to lay them flat in small piles. Again, common sense must be the principle guide.

It is possible to dry books in the freezer and if this is envisioned it may be best to leave the material unboxed. Although it is possible to dry books inside cartons, leaving the materials unboxed allows freer air movement resulting in quicker, more efficient drying. In many cases it will be desirable to insert a sheet of non-woven polyester web in between the boards and the textblock to facilitate the movement of water vapour from the book to the air. If the books are very wet or are of leather, there is a danger of impressing the image of the freezer's wire racks into the covering material. Often this can be prevented by placing the most vulnerable books on the top of the pile or by placing the volume on a small stack of non-woven polyester web.

f. Books that have been swollen open should not be closed. Instead they should be packed in their own carton. Similarly, books that have stuck together should not be separated, but wrapped as a unit and packed together.

E. Flat Paper. Flat materials, such as manuscripts, typescripts, prints, drawings, blueprints, photocopies, etc. exhibit somewhat wider variability of materials and production methods than printed books. As a result problems with soluble media (bleeding inks, etc.) and blocking of paper are common. Inks may dissolve and offset onto adjacent materials. Such staining will frequently be permanent and irreversible.

In most instances, it will be desirable to freeze the material and dry it sometime in the future. Improper drying or uneven drying may result in additional damage In general the material should be frozen in stacks. Cartons of manuscripts in file folders can be frozen in the cartons with not further preparation. At this institution, it will often be possible to freeze and freeze-dry up to 9 cartons of flat material on site, in the Preservation Office blast freezer.

If it is not going to interfere with the rest of the salvage effort, it is advisable to keep labels, folders, etc. with the objects, but frequently this is unwise. Time and efficiency take precedence under emergency conditions.

In some instances, as when it is not possible to freeze the materials, it may be necessary to separate the sheets of paper from a block of wet material. The material can then be air-dried or dried between blotters under light weight, and at a later stage, flattened. Either drying method involves a great deal of time and space, both of which are usually in short supply at the flood site.

1. Procedure. (The following procedure can potentially cause a great deal of damage and should normally be done under the supervision of a conservator). A team of several workers, working with adequate table space, can separate a blocked stack of sheets quickly.

a. Materials. Polyester film (mylar (tm)). Hollytex (tm), or other non-woven, spun bonded polyester web. Clean, smooth, undyed blotters.

The polyester film is moistened slightly with a sprayer or sponge and laid on top of the stack. The polyester film will cling to the top sheet. With extreme caution, the film can be rolled back, and with it a small stack of paper (10-20 sheets), which is passed to another worker. In this way the large stack is broken down into smaller more manageable piles and the work of separation can proceed quickly.

Each person then repeats the following process for each sheet in the smaller stack: a moistened sheet of mylar is placed on the top of the stack and a single sheet of paper gently rolled off. The mylar support is placed on the table with the paper up, a sheet of hollytex is laid on top (this can take a bit of practice) and a blotter pressed gently on the hollytex to take up any standing water. The whole unit is turned upside down so that the mylar is on top, the mylar very carefully rolled off the paper and a second sheet of hollytex laid onto the paper and blotted. Removing the mylar is the most difficult and dangerous operation, as the wet paper will have very little strength and will tear easily.

III. Non-Print Materials

A. Photographic Materials. In general, the best approach will be to keep the material wet and arrange for professional salvage (e.g. Kodak) immediately. If delay is unavoidable, the material can be frozen, but some materials may be damaged by this.

1. Slides and Negatives. These can be placed in zip-lock bags filled with cold clean water. Ideally, distilled or deionized water should be used. At this institution the cleansed water is (in descending order): a) a small stock of DI water kept in the conservation lab b) conservation lab tap water, which is charcoal filtered c) Alhambra drinking water from the water coolers. Ordinary tap water should only be used as a last resort. The water should be kept as cold as possible. Refrigeration is ideal but if it is unavailable ice (not dry ice) can be added to the packages if cooling is necessary.

The adhesives in the slide binders will swell and dissolve with prolonged immersion in water. As these adhesives are coloured, they may stain adjacent material. Periodic water changes may be necessary to prevent this.

a. Black and White slides and negatives. In theory these may be kept wet for up to 72 hours, after which time the emulsion may be expected to lift. If the material can not be sent to Kodak within this time, it should be frozen. In practice, we have kept materials wet for longer periods without significant damage.

b. Colour slides and negatives. In theory these may be kept wet for up to 48 hours, after which time the dye layers may begin to dissolve. If the material can not be sent to Kodak within this time, it should be frozen. In practice, we have kept materials wet for longer periods without significant damage.

2. Microforms and Motion Picture Film. Roll films wet in a different manner than sheet films and prints. Because they are tightly wound, it is not at all unlikely that the interior of the rolls may not be significantly wet. If they are it is possible that the film is only wet along the edges, near the sprocket holes. However if it is wet, then the softened emulsion may cause the tightly wound film to fuse together. Film cans, microfilm boxes etc. can offer substantial protection against water damage; materials in such containers have been found to be dry even after floating in water for long periods.

Normally these materials should be kept wet and sent to Kodak or a film processing lab as soon as possible. The salvage operation will probably involve reprocessing the film. It is essential that the film not be allowed to dry because it will fuse. Plastic (not metal) garbage cans and buckets filled with clean cold water make appropriate storage containers.

In rare instances, roll film may be dried in-house be rolling it slowly with a pair of film rewinds and cleaning it with film cleaner, a solvent which will encourage even drying. This procedure is too time consuming to consider unless only a very few items are affected.

a. Microfiche. This is difficult to reprocess. If possible it should be frozen and vacuum freeze dried.

3. Photographic Prints

a. Assessment. If negative are available, it may be best to discard the prints and devote your attention to other materials. In some cases, the prints themselves may be of artistic or historic significance. Normally these materials should be kept wet and sent to a photographic conservator, Kodak or a film processing lab as soon as possible. In minor emergencies, if trained staff is available, prints may be dried in house.

b. Procedure. (The following should normally be done under the supervision of a conservator).

i. Materials. High quality, smooth surfaced, acid-free blotters. Hollytex, a non-woven, spun bonded polyester web.

The print should be immersed in distilled or deionized water to remove dirt, accretions, and impurities deposited by the flood water. Standing water is removed with blotters, the print is placed between two sheets of polyester web, placed between blotters, and allowed to dry under very light weight. After a few minutes the blotters must be changed, because they will cockle. The blotters should be changed a second time after another fifteen minutes, and perhaps a fourth time after an hour.

When wet, the film emulsion, which is a hardened gelatin, will become very soft. Any contact with the surface can cause permanent and irreversible marking. If the blotter has any texture, that texture will be transferred to the print surface. The polyester web will prevent the print from adhering to the blotters, but great care must be taken.

B. Electronic Storage Media.

1. Floppy Disks. Disks consist of iron oxide bonded to polyester film, housed in plastic sleeves lined with Tyvek (tm). If they get wet and are allowed to remain damp, the rust, which carries the encoded information, may become disturbed (rusty rust). The goal, then is either to achieve fast, even drying or to keep the disks wet until they can be dried properly.

If time is available and the floppies are merely damp, it may be possible to air dry them with hair dryers set on low temperature. If the disks are wet, muddy, etc. or if treatment must be postponed (e.g. if there are many of them), then they should be kept wet in cold, clean water, in plastic trays, garbage cans, buckets, etc. In the case of significant material, get in touch with any of the major disk manufacturers, several of which can provide salvage services and technical advice.

In some instances, the information on floppies can be recovered. Any salvage work on floppies is going to entail a significant expenditure of time, effort, and perhaps money, so locating backup or replacement copies and discarding all but essential disks is wise.

a. Procedure. The wet floppy is kept wet until treatment. Two edges of the sleeve are slit open, being careful not to cut the disk itself (the disk floats freely within the sleeve and can be pushed to the opposite end of the sleeve).

A blank sleeve is prepared by slicing two edges from the sleeve of a new diskette and discarding the disk itself. The old disk is inserted in the new sleeve, and the information copied to a new disk. After several disks have been copied, the sleeve should be replaced, as debris from the damaged disks may build up on the Tyvek surface.

i. If the medium has been damaged, high level copy utilities (such as DOS copy and diskcopy commands) may not work and lower level sector editors may be necessary.

ii. As disks may have information recorded on both sides,it may be advisable to mark the top surface of the disk in a non-information carrying area (e.g. the area at the large round spindle hole at the center of the disk).

iii. An expendable disk drive should be used for this procedure and it should be cleaned frequently.

2. Videotapes. In most cases, replacement will be the most appropriate action. In very rare instances, it may be possible to dismantle the cassette and dry the tape chemically in a manner similar to the procedure for roll film (see III.A.2). Consultation with a recording engineer is advised.

3. Videodiscs, Optical discs, etc. Normally these can be washed in clean water and air dried without problems.

This text, previously distributed under the name disprep.txt, is an outline for an inhous staff-training Exercise at Stanford University Libraries in 1988. It was marked up in HTML in Nov, 1998 but the content was not changed.


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