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2. Causes for the degradation of books and records

2.1 Chemical agents of destruction.
2.2 Biological agents
2.3 Physical factors
2.4 The effect of light
2.5 Housekeeping problems
2.6 Storage conditions

 

An understanding of why and how library and archival materials deteriorate will help curators and administrators understand the need for, and importance of, sometimes expensive line items for preservation in the annual budgets. The enemies of books and paper records, in addition to the fire and water damage usually associated with disasters, are heat and humidity, light and ultra-violet energy, insects, rodents, fungi, oxygen, acid and the people who use (and abuse) those records. Following are brief summaries of the great deal of information that has been published in regard to each of those problems.

2.1 Chemical agents of destruction.

2.1.1 Oxidation

Oxidized paper loses its strength and durability. Oxidation is a change (invariably for the worse) in organic and inorganic substances by their reaction with oxygen in the air we breathe. Other than by isolating books and other paper records from contact with air, as has been done for the Declaration of Independence, the Constitution, and the Bill of Rights in the United States National Archives in Washington, there is little that can be done about oxidation. There is a controllable chemical reaction, chelation, that has potential for reducing damage to materials by oxidation but means for its use for the preservation of books and paper records have not been fully explored.

2.1.2 Acid

Acid is the arch enemy of librarians because it is a direct cause for hydrolysis. Hydrolysis is "a chemical product of decomposition involving splitting of a (cellulose) bond and addition of the elements of water" (Webster's Seventh New Collegiate Dictionary). As time goes by, acid contaminated paper loses its strength and becomes increasingly brown stained, and is eventually embrittled to the extent that it cannot be handled without crumbling.

The principle cause for acid stained and embrittled machine made paper is alum/rosin sizing which until recently was the only sizing used in the manufacture of that product. Alum (aluminum sulfate) reacts with the moisture that is always present in paper creating sulfuric acid (H2SO4). Hydrogen ions (H+), from the sulfuric acid, then split the cellulose bonds damaging the fibers and ultimately destroying the paper.

Air polluted by carbon aerosols and other particulate matter, and by noxious gases from industrial chimneys and automobile exhausts, is another cause for the acid contamination of library and archival materials. Sulfur dioxide from industrial chimneys is absorbed by paper as water is absorbed by a blotter. It then reacts with the water always present in paper to form sulfurous acid which in turn becomes sulfuric acid which soon discolors and ultimately embrittles the paper to the point where it is useless. Nitrous and nitric oxides from automobile exhausts when absorbed by paper and leather become nitric acid which is almost as destructive as sulfuric acid. Water scrubbing devices in air conditioning systems are an effective means for removing noxious gases from urban air but it has been learned that the problem of keeping the water scrubbing devices operable is often more than an institutions budget can stand. Activated carbon filters in the air circulation system are an alternative. They remove gaseous contaminants and when used in conjunction with glass wool filters to remove solid particulate matter from the recirculated and make-up air are a good combination.

In regard to hand made paper the acid problem is not as serious as it is for the machine made product because (a) the sizing used in it is either gelatin or starch, both of which are non-acid substances; (b) lignin (an organic acid) containing wood pulp is never used for hand made paper; and (c) alpha cellulose, which predominates in cotton and linen fibers in the pulp used for European hand made paper, is resistant to acid contamination by air pollution. For that reason the preservation of pre-19th century books and documents, all of which were made with hand made rag paper, is less of a problem than for those made in the 19th and 20th centuries.

2.2 Biological agents

Insects and rodents thrive in places where housekeeping is indifferent, and, on too many occasions, have created havoc in collections - sometimes to the point of total loss of important information. Damage by vermin is needless, because today those pests can be relatively easily controlled.

Fungi, "parasitic lower plants that lack chlorophyll and include molds, mildews, rusts, and bacteria" (Webster's Dictionary), are omnipresent. Fungus spores require three things to survive and multiply - food, warmth and moisture. Cellulose in paper, and paper and cloth book covers; collagen in leather book covers; starch and gelatin sizing in paper; vegetable and animal glue in book bindings; and even wood shelves and cabinetry all nourish fungi. When the temperature is high (above 23C), and the relative humidity is above 65%, at the same time, fungi multiply at a phenomenal rate. At first that is only a nuisance - mildew (mould) on exposed surfaces. Soon, however, the spores send roots (hyphae) down into the paper, cloth or leather fibers staining the material. The third stage is when the growing hyphae consume the fibers and disintegrate the material. Little can be done to eliminate the fungus spores always in the air around us. What can be done is to create environments in records storage areas in which mold and mildew cannot exist. That can be done by keeping the temperature below 23C and the relative humidity below 60%. Doing either will prevent mold growth but it is far preferable to do both at the same time.

Except for bibliophiles (and they are not always guiltless), people can usually be included amongst the enemies of books. Libraries have always been vulnerable to thieving and vandalism. In addition to normal wear and tear, which can only be eliminated by withdrawing books and paper records from use, patrons and even well meaning, but uninformed, staff are often the direct cause of much damage to books - while photocopying them for instance or while shelving and storing them. The answer to that is in more instruction and training.

2.3 Physical factors

High heat accelerates chemical reactions, such as oxidation and acid hydrolysis, and acerbates mould growth. Too little humidity dehydrates paper. High humidity is ideal for mold growth. In addition dimensional changes in paper and book materials, caused by constantly fluctuating temperature and humidity, over a long period of time seriously damage them. Nothing will give librarians and archivists a greater return for their investments in preservation than to stabilize the environments in their storage areas by providing close, positive, 24 hour a day, year-round, temperature and humidity control with air filtration. The recommended conditions, a compromise between what is good for the books and paper records and what is comfortable for people, are temperatures between 19-21C and relative humidity between 45-55%. Maintaining those temperatures is not too difficult in most libraries. Keeping the relative humidity between 45-55%, particularly in warm weather, is often difficult to achieve. The optimum temperatures for preservation of books and paper records are lower, in the 0 - 5 degree celcius range, but those temperatures are not realistic for libraries and archives. Books and paper records last longer at low temperatures for the same reasons that milk, butter and eggs do when they are refrigerated. It is important to know that the useful life in good condition of books and paper records, is doubled with every ten degrees celcius reduction in storage temperature.

Conflagrations, the ultimate in exposure to heat, reduce libraries and archives to ashes. Fire prevention should be included in all conservation programs because even minor fires can result in disastrous damage to collections.

Similarly means for the protection of books and records from water damage, whether it be because of great storms, ocean or river flooding, or by leaking roofs, wet basements, defective plumbing, and many other reasons, must be considered in any conservation program. Unwanted liquid water is disastrous for books and paper. In addition to its effect on inks and colors, in a very few hours it causes coated paper pages to permanently stick to each other. It also provides abundant moisture for massive fungus growth. All that in addition to the swelling and distortion of books and the disfigurement of unbound paper records. Damage by unwanted water vapor is almost as bad - it just takes a little longer.

2.4 The effect of light

Sunlight, and the ultra-violet energy always associated with it, physically destroy organic materials and probably accelerate oxidation and acid hydrolysis. Fluorescent light, the characteristics of which are similar to light from the sun, damages paper as does sunlight - it too just takes a little longer. Incandescent light on the other hand is safe artificial lighting for books and paper because there is no ultra-violet energy associated with it.

2.5 Housekeeping problems

Slipshod housekeeping is often the indirect, and sometimes the direct, cause for costly damage. Dirt from any source soils and disfigures books and paper records. Accumulations of trash and debris attract rodents. Spilled food crumbs and sugary liquids attract insects. Snacks and beverages should be strictly forbidden, except in designated staff areas, which, in addition to having their daily cleanups, should be meticulously scrubbed and cleaned regularly and frequently. Those who believe that insects are not present in these spaces are deceiving themselves. It would be even better if food and drink were completely banned in libraries and archives.

2.6 Storage conditions

Improper storage is the direct cause for much unnecessary damage to library and archival materials. On the other hand good storage will significantly extend their useful lives as well as keep them from harm.

The benefits of expensive air-conditioning systems and the most meticulous attention to housekeeping will be of little avail if the containers, shelving and cabinetry for library and archival materials are not of good quality and well designed. Containers should be made only of high quality acid-free paper and cardboard. File folders, document boxes, protective book boxes and wrappers, and portfolios for oversize materials that are made of inferior cardboard, or are lined with cheap ground wood or alum/rosin sized paper, contaminate the materials they are supposedly "protecting" because of the migration of acid from the container into the contents.

Sliding drawer vertical office files are excellent in places of business for convenient filing of correspondence, receipts, pay vouchers and other commercial records. They are not good storage for research library materials, or for archival materials and other records of permanent importance, that must be kept in good usable condition for a hundred years or more compared to an average of seven years for business paper. They are all too frequently used in libraries and archives because they are convenient, easy to obtain and compact. All unbound library and archival materials should be kept in acid-free folders in good quality boxes labeled so as to lay flat on the stack shelves. Flat storage of boxed materials eliminates the damage caused by the "slumping" of the single sheets when the boxes stand on end.

The disparity in the physical condition of large prints, maps, posters, broadsides, architectural drawings and other large items in different collections is due as much to their storage conditions as it is to damage by unstable climate, light, and chemical contamination. Oversized records are safer, and last longer, when they are kept in flat map cabinet drawers, or in large, flat, covered boxes made of acid free materials. If at all possible, each item should be in its own acid-free folder which has been cut to the inside dimensions of the map drawer or box. When, because of space limitations or other reasons, it is not possible for each oversized item to be in its own folder and several have to be put together it is best to separate the individual items in the folders with acid-free tissue. When folders in a drawer or box are cut to various sizes for economy, or any other reason, the inevitable result is that the folders slide into each other (interleaving) damaging their contents. When drawers or boxes are full of folders of odd sizes there is also a tendency for them to pile up in one part of the drawer or box causing uneven distribution of weight on the materials at the bottoms of the containers.

Altogether too much physical damage is done to framed pictures that are piled haphazardly in closets or in boxes. Careless storage of those items often results in cracked or broken glass which can, and frequently does, damage the prints or pictures in the frames. Framed materials should be kept hanging on wire storage racks when they are not on exhibition. Otherwise they should be kept in storage bins with vertical dividers between them to protect the frames from damage by contact with each other.


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