Storage Methods and Handling Practices
Head of Conservation
Minnesota Historical Society
Unacceptable storage methods have a direct effect on the useful life of materials. Slovenly, haphazard, overcrowded conditions soon result in avoidable damage to collections, and poor-quality storage enclosures accelerate the deterioration of the materials they are intended to protect. Poor handling also takes its toll. Normal handling is inevitably somewhat damaging; rough handling, however, quickly leads to serious, irreparable harm. The longevity of collections will be significantly extended by observing the following basic guidelines.
In general, good air circulation should be maintained in storage areas. Books should never be stored directly against walls but should be at least three inches away from them to facilitate movement of air around the books and to avoid the occurrence of pockets of damp air. This is especially important when bookshelves are positioned against the outside walls of a building. Books stored in a closed cabinet should also be shelved a distance from the back wall of the cabinet, and the cabinet itself should be approximately three inches away from the wall. Care should be taken to ensure that humidity and stagnant air do not build up in closed cabinets, especially those against outside walls.
Books should be held upright on shelves. They should not be allowed to lean to one side or the other, because this causes strain on the binding. Books should be arranged so that shelves are full, preventing books from leaning; however, books should not be shelved so tightly that damage is incurred when they are removed from the shelf. If shelves are not full, bookends should be used to hold books upright. Bookends should be non-damaging, with smooth surfaces and broad edges to prevent bindings from being abraded or leaves from being torn or creased.
Books should not extend beyond the edges of shelves into aisles because they may be bumped or otherwise damaged. Instead, adequate oversized shelving should be provided so that large books can be stored on shelves without extending beyond the edge. Books should not be stored on the fore-edge. If books are too tall to stand upright, either the books should be moved or shelves should be rearranged so that the books fit on the shelves standing upright. Books should be stored spine down until the shelving is rearranged; storing a book spine down rather than spine up will prevent the text from pulling out of the binding due to its weight. Large books should not be stored next to small ones because they are not adequately supported by them. When possible, books should be shelved by size to prevent this. Some books are so large that they should be shelved lying down, especially if upright storage could allow heavy textbooks to sag away from their bindings.
Paper and cloth bindings should not be stored in direct contact with leather bindings. Acidity and oils in the leather migrate into paper and cloth and hasten their deterioration. Furthermore, degraded powdery leather will soil paper and cloth. When possible, books should be boxed to avoid these problems. When this is not possible, paper and cloth bindings should be shelved together, separate from leather bindings. Other alternatives to consider when the binding must remain on view, such as in a period room in a historic house, are the use of book shoes (supports that cover the sides but leave the spines of books visible) or placement of a piece of polyester film between the books.
As a rule, books should not be stacked in piles on shelves. Small, structurally sound books should be shelved upright. Oversized, heavy, structurally weak, or damaged books should be stored flat rather than upright, to give them the overall support they require. If books are stored on their sides, additional shelves may need to be inserted at narrow intervals to avoid having to stack these books. Shelves should be wide enough to support oversized books completely so that books do not protrude into the aisles. Volumes should be stacked only when absolutely necessary, and the stacks should contain only two to three books. Ideally all books that are stacked should be individually boxed. Books with bindings of special value should be stacked only if they are boxed to prevent abrasion to the bindings. Special care should be taken to insure that call number flags or titles of books that are stored flat are visible so the books can be identified without being moved.
Boxing is crucial to the preservation of certain books. Those with fragile bindings of special value that should be retained in their present condition should be boxed for protection. Damaged books that have low value or are rarely used and do not warrant treatment or repair of the binding should also be boxed. Books bound in vellum should be boxed. Vellum responds readily to changes in temperature and relative humidity by expanding and contracting. This can result in warped covers. Boxing helps restrain vellum bindings and thereby minimizes warping. Boxes should be constructed of archival-quality materials and should be custom made to fit a book’s dimensions exactly.
Both drop-spine and phase boxes are acceptable. Drop-spine boxes are preferable because they provide better support and keep books cleaner. For volumes that require structural support while being displayed, the book shoe is appropriate. The use of slipcases should be avoided because they often abrade the surface of the binding when the book is slid in and out of the slipcase. Envelopes are sometimes used for the storage of books. These generally do not provide the support books need and should be replaced with boxes. If boxes are too expensive or take up too much space on shelves, books that are infrequently used can be placed in card stock enclosures (best for small books) or wrapped in a permanent durable paper. Damaged books should never be held together with rubber bands or string. They should be boxed, wrapped in paper, or tied with a flat undyed cotton, linen, or polyester tape. Tape should be tied with knots at the top or fore-edge of the text block.
Poor handling procedures can cause irreparable damage to books. They should not be pulled off the shelves by the headcap, a practice that causes the headcap to fail, tearing the spine of the binding. Instead, books on either side of the desired book should be pushed in, and the desired book pulled out gently by grasping it on both sides with the thumb and fingers. The book should be removed, and the remaining books on the shelf and the bookends readjusted. When the book is replaced, the bookend should be loosened, the books moved on the shelf to make a space, and the book reinserted in the space. The bookend should then be readjusted. When oversized books that are stored flat are removed, the upper volumes should be transferred to an empty shelf or book truck. The desired volume should be removed by lifting it with both hands, and then the removed volumes transferred back to the shelf. Replacing the book on the shelf is done in the same way.
To minimize chances of dropping books, one should not stack them too high when they are moved or carried. Books of special value should not be stacked at all. If book trucks are used, they should be easy to maneuver and have wide shelves, protective rails, and bumpers on the corners. Books should not be stacked high on the truck, nor should they protrude beyond the edges; the center of gravity of the loaded truck should be low to help stabilize it.
Books are often unnecessarily damaged during photocopying. Photocopy machines with flat copy platens necessitate jamming the binding flat in order to get a good image. Better machines are those with edge platens or other features that allow a book page to be copied with the book open only to 90 degrees instead of 180 degrees. Photocopying of books of special value should be done only by staff members rather than by researchers, and then only if it can be done without causing damage to the books themselves. The spine of a book should never be pressed down with the hand or the cover of the copier to insure a good quality image. If a book is too brittle or tightly bound to photocopy safely, it should be microfilmed instead and a photocopy made from the film copy.
Call numbers should not be painted on books that are of special value, nor should they be typed onto labels taped to books with pressure-sensitive tape or attached with adhesive. Paint is unattractive and disfiguring; tape and adhesive may discolor and stain the binding. Ideally volumes should be boxed and the call number placed on the box. For volumes that are not boxed, call numbers should be typed onto heavy, acid-free paper flags placed inside the volume. These flags should be about two inches wide, and two to three inches longer than the book is high. An alternative is to construct polyester film jackets and place call number labels on them. Bar code labels should never be applied to books of special value because the books will almost always be damaged. If computerized codes must be used for special books, the label should be attached to a flag of alkaline paper placed in the book or onto a polyester film jacket.
For books that do not have special value, care should be taken to ensure that the label adhesive will remain effective over time. It is especially important that the adhesive does not desiccate, causing labels to come loose or fall off, and does not ooze, causing stickiness on the book, which will attract dirt and may damage other materials that touch it.
If bookplates must be used in books of special value, they should be made of low-lignin, alkaline paper, and should be attached with a stable, reversible adhesive, preferably rice- or wheat-starch paste, or methyl cellulose; or polyester film jackets should be made and the bookplates attached to them. Circulation card pockets should be treated the same way, although books of special value usually should not circulate.
All acidic inserts, such as bookmarks, scraps of paper, and pressed flowers, should be removed from books. This is to prevent acidity in the inserts from migrating into book pages and damaging them. Paper clips on book pages or on inserts into books should be removed.
Unbound Flat Paper
For paper collections, it should be kept in mind that only objects of the same size and category should be stored together. Differences in bulk and weight create a potential for physical damage, so it is not advisable to store single sheets in the same box with books or pamphlets. Generally speaking, heavy objects should be stored separately from lighter ones, as should bulky objects (which cause uneven pressure inside boxes). It should also be kept in mind that because acid migrates from paper of inferior quality to any other paper with which it comes into direct contact, it is important to separate poor-quality papers from those that are better. Newsclippings and other obviously inferior-quality papers must be removed from direct contact with historical documents and manuscripts on better-quality paper.
Documents and manuscripts should be unfolded for storage if this can be done without splitting, breaking, or otherwise damaging them. If unfolding may result in damage, a conservator should be consulted before proceeding. All damaging fasteners such as staples, paper clips, and pins should be carefully removed and replaced, only if absolutely needed, with nonrusting ones. Documents should be housed in acid-free, buffered file folders. Ideally no more than ten to fifteen sheets should be placed into each folder; the more valuable or fragile the item, the fewer the sheets that should be stored in one folder.
Folders should be kept in archival-quality document-storage boxes. All folders inside a box should be the same size and should conform to the size of the box. The boxes can be stored flat or upright. If boxes are stored flat, they should be stacked only two high to facilitate handling. Flat storage will give the documents overall support and will prevent crumbling edges, slumping, and other mechanical damage to which upright storage might subject them. Flat storage, however, causes documents on the bottom of the box to suffer from the weight of those above. Upright storage is preferable when documents and folders are well supported to prevent slumping and edge damage. Spacer boards made out of stable materials can be used to fill out boxes that are not quite full. Care should be taken not to overfill boxes because this can cause damage when items are removed, replaced, or reviewed. An alternative to boxing is storage in a file cabinet equipped with hanging racks and hanging folders. If hanging folders made of archival-quality materials cannot be found, general office hanging folders may be used, as long as the folders within them are made of acceptable materials.
Vellum documents, like vellum books, are highly susceptible to fluctuations in temperature and relative humidity and should be placed in an enclosure. Suitable enclosures include encapsulation, folders, mats, and boxes, or a combination of these.
Oversized materials — like architectural drawings, blueprints, maps, large prints, and wallpaper samples — are best stored flat in the drawers of map cases or in large covered boxes of acceptable quality. The materials should be placed in acid-free buffered folders. Until recently it was recommended that blueprints, which are alkali-sensitive, should not be stored in alkaline-buffered folders. Recent research indicates, however, that if the storage environment is maintained at an acceptable relative humidity (30–55%), unbuffered folders may not be necessary and buffered folders may be used. All folders should be cut to fit the size of the drawer or box; drawer- or box-sized folders are preferable to smaller ones, which tend to get jammed at the back of drawers or shift position as the drawers open and close or the boxes are moved. Ideally only one item should be placed in a folder, although several may be stored in a folder if necessary. If several items are placed in one folder, interleaving with acid-free tissue paper is desirable, especially if the items have colors or are of special value. There should be adequate room where oversized materials are stored so that they can be safely removed from drawers or shelves, and there should be a place to put them down once they are removed or prior to replacement in drawers or on shelves.
If they are not brittle or fragile, oversized materials can be rolled when flat storage is not possible. It is important to make sure the materials are not too brittle or fragile to sustain rolling and unrolling. Some items need to be rolled individually; others can be rolled in groups of four to six similar-sized items, the exact number depending on the size and weight of the paper. A tube several inches longer than the largest item being rolled and at least four inches in diameter (larger diameters are preferable) should be used. If the tube is not made of low-lignin, pH-neutral materials, it should be wrapped in neutral or buffered paper or polyester film. Alternatively, the items can be placed in a folder of 5-mil polyester film cut several inches larger in both dimensions than the largest item being rolled. The item or items are then rolled face out onto the tube. If a polyester film folder is used, it should be rolled so that the fold is parallel with the length of the tube. The assembly should then be wrapped with neutral or buffered paper or polyester film to protect it from abrasions. The wrapped roll should be loosely tied with flat linen, cotton, or polyester tape. This assembly may be stored inside a larger tube for added protection if desired. Tubes should be stored horizontally.
Much of the newsprint produced after the mid-nineteenth century is made of paper pulp that contains lignin and other impurities, and its long-term preservation is difficult at best. While it is possible to alkalize (deacidify) newsprint to retard its deterioration, this is often not practical because it will still continue to deteriorate at a relatively rapid rate. Also, alkalization after newsprint has become yellow and brittle will not make it white and flexible again. Most newsclippings are important because of the information they contain and not because of the value of the clippings themselves. For this reason, photocopying and microfilming are the most practical preservation options for collections of newsclippings. All photocopying should be done on low-lignin, buffered paper using an electrostatic copier with heat-fused images. Newsclippings that must be retained should be treated and then physically separated from better quality papers in a folder or in an enclosure made of polyester film.
Pamphlets can be stored in boxes or in folders. Several pamphlets of the same cover size can be stored together in a drop-spine or phase box. Pamphlets that differ in size should be stored either individually in drop-spine or phase boxes, or in file folders that are kept in document-storage boxes or in hanging files in file cabinets. If stored in folders, pamphlets should be stored spine down. If single pamphlets must be shelved between books, they should be individually boxed. Groups of pamphlets shelved between books can be boxed together according to the guidelines just given. If pamphlet binders are used, they must be of acceptable quality throughout and should be attached to pamphlets in such a way as to be non-damaging to them. Consult an experienced professional about the advantages and disadvantages of various commercially available binders. They should not be adhered directly to pamphlets. Where stitching is used to join pamphlet and binder, it should be done through the fold and through original sewing holes where possible.
Scrapbooks and Ephemera
Many historical collections include scrapbooks and ephemera (e.g., trade cards, valentines, patterns, paper dolls, etc.). These items pose challenging preservation problems because they often contain a variety of components and media. They may have raised surfaces, three-dimensional decoration, or moving parts. They are frequently unique, fragile, damaged, and of significant associational value. They should never be interfiled with other categories of library and archival materials because damage may result from the different sizes, shapes, weights, and materials represented.
Most scrapbooks and ephemera can be stored according to the general guidelines given above. Scrapbooks that are of special historic value in their original form should be individually boxed in custom-fitted boxes. Unbound ephemera should be grouped by size and type (e.g., photographs, printed material, manuscripts, etc.), individually enclosed to protect items from acid migration and mechanical damage if needed, and stored in a way that will support them structurally. Some vendors of archival supplies offer standard-sized storage boxes and sleeves for common ephemera such as postcards and stereo views. Others can produce custom-sized enclosures in quantity to meet special needs.
For photographs, it is best for each item to have its own enclosure. This reduces damage to the photograph by giving it protection and physical support. Acceptable storage materials can be made of either paper or plastic. Because paper enclosures are opaque, the photograph must be removed from the enclosure when it is viewed; clear plastic enclosures have the advantage of allowing researchers to view the image without handling it, thus reducing the possibility of scratching or abrasion. Paper enclosures should be acid and lignin free. Plastics suitable for photographic storage are polyester, polypropylene, and polyethylene. Polyvinyl-chloride should be avoided at all times. Both paper and plastic enclosures should meet the specifications provided in the American National Standards Institute (ANSI) Standard IT 9.2-1998 and should pass the Photographic activity test (PAT) as specified in ANSI NAPM IT 9.16-1993.
Once materials have been properly housed in folders, sleeves, or envelopes, they should usually be stored flat in drop-front boxes of archival quality. Glass plate negatives are an exception and should be stored vertically in order to prevent breakage of plates stored on the bottom of a pile. The boxes should be housed on metal shelves or in metal cabinets. Where possible, items of similar size should be stored together; the mixing of different sizes can cause abrasion and breakage, and can increase the risk of misplacing smaller items. Regardless of the size of the photograph, all enclosures within a box should be the same size and should be the size of the box. Boxes should not be overfilled.
Horizontal storage of photographs is usually preferable to vertical storage, since it provides overall support and avoids mechanical damage such as bending. Vertical storage, however, may make access to the collection easier and decrease handling. With vertical storage, photographs should be placed in acid-free file folders or envelopes that are themselves housed in hanging file folders or document storage boxes. Overcrowding should be avoided. The use of hanging file folders will prevent photographs from sliding down under each other and will facilitate their handling.
Special care must be given to the storage of oversized photographic prints mounted on cardboard. This board is often acidic and extremely brittle. Embrittlement of the support can endanger the image itself because the cardboard may break in storage or during handling, damaging the photograph. Such prints must be carefully stored, sometimes in specially made enclosures. They should be handled with great care.
Proper storage and handling of library and archival materials can be relatively inexpensive, with several of the measures described above costing little or nothing. In addition, it can lead to future savings by minimizing the need for repair of materials. Following these guidelines is a practical, cost-effective way to extend the useful life of collections.