Preservation, in library and information science, is activity concerned with maintaining or restoring access to artifacts, documents and records through the study, diagnosis, treatment and prevention of decay and damage.
While conservation is used interchangeably with preservation and their meanings overlap, some distinctions exist. Conservation concerns to counter the existing damage, preservation concerns the prevention of potential damages.
While information or knowledge are immaterial in themselves and can exist in various forms of media, the material characteristics of the media determines its life expectancy, necessary environments, and the modes of preservation. In 1933, William Barrow, an American chemist, pointed out the problem of acid paper that had been widely used in publishing industries. The life expectancy, he noted, of acid paper was only 40 to 50 years. The paper used in libraries was already showing signs of decay at that time. Since libraries hold enormous amount of books, the discovery had a tremendous effects. Both publishing and library communities set new standards and changed the paper to certified acid-free durable paper, which is still the standard today. While digital and magnetic media such as hard drive, DVD, CDs are becoming increasingly popular, they also pose new challenges.
Although preservation as a formal science in libraries and archives dates from the twentieth century, its philosophy and practice has roots in many earlier traditions. In library science, preservation is treated as an active and intentional process, as opposed to the passive sense of preservation that might be applied to paleontological or archaeological finds. The survival of these items is a matter of chance, from an information science perspective, while the preservation of them after their discovery is a matter of intentional activity.
Human record-keeping arguably dates back to the cave painting boom of the upper paleolithic, some 32,000-40,000 years ago. More direct antecedents are the writing systems that developed in the fourth millennium B.C.E. Written record keeping and information sharing practices, along with oral tradition, sustain and transmit information from one group to another. This level of preservation has been supplemented over the last century with the professional practice of preservation and conservation in the cultural heritage community.
In 1933, William Barrow introduced the field of conservation to paper deacidification when he published a paper on the acid paper problem. In later studies, Barrow tested paper from American books made between 1900 and 1949 and learned that after 40 years the books had lost on average 96 percent of their original strength; after less than ten years, they had already lost 64 percent. Barrow determined that this rapid deterioration was not the direct result of using wood-pulp fibers, since rag paper of this period also aged rapidly, but rather it was due to the residual sulfuric acid produced in both rag and wood pulp papers. Manufacturing methods used after 1870 used sulfuric acid for sizing and bleaching paper. Earlier papermaking methods left the final product only mildly alkaline or even neutral. Such paper has maintained its strength for 300 to 800 years, despite sulfur dioxide and other air pollutants. Barrow's 1933 article on the fragile state of wood pulp paper predicted the life expectancy, or "LE," of this acid paper to be approximately 40-50 years. At that point the paper would begin to show signs of natural decay, and he concluded that research for a new media on which to write and print was needed. In 1987, Terry Saunders releases the film Slow Fires: On the Preservation of the Human Record which examines paper embrittlement resulting from acid decay.
In 1989, major US print publishers convened at the New York Public Library to endorse a community-wide commitment to use ISO 9706 certified permanent durable paper in order to combat the acid paper epidemic.
The flood of the River Arno in Florence, Italy, in 1966, damaged or destroyed millions of rare books and led to the development of restoration laboratories and new methods in conservation. Instrumental in this process was conservationist Peter Waters, who lead a group of volunteers, called "mud angels," in restoring thousands of books and papers. This event awakened many historians, librarians, and other professionals to the importance of having a preservation plan. Many consider this flood to be one of the worst disasters since the burning of the Alexandria Library in ancient Rome. It spurred a resurgence in the profession of preservation and conservation worldwide.
(See main article Digital preservation)
Information technologies made remarkable developments in the late twentieth century and digital preservation emerged s a new preservation method. Cultural heritage institutions such as libraries, museums, archives, and others began to use digitization as an alternative or an additional preservation method along with traditional preservation of physical items.
Digitally produced knowledge contents such as electronic documents, digital arts, music, photo images, and others emerged as a new form of knowledge and their preservation has become another issue.
There is a longstanding tension between preservation of and access to library materials, particularly in the area of special collections. Handling materials promotes their progression to an unusable state, especially if they are handled carelessly. On the other hand, materials must be used in order to gain any benefit from them. In a collection with valuable materials, this conflict is often resolved by a number of measures which can include heightened security, requiring the use of gloves for photographs, restricting the materials researchers may bring with them into a reading room, and restricting use of materials to patrons who are not able satisfy their research needs with less valuable copies of an item. These measures can seem intimidating to less experienced researchers who might feel that these preservation measures are in place solely to keep materials out of the hands of the public.
There is also controversy surrounding preservation methods. A major controversy at the end of the twentieth century centered on the practice of discarding items that had been microfilmed. A similar concern persists over the retention of original documents reformatted by any means, analog or digital. Concerns include a scholarly needs and legal requirements for authentic or original records as well as questions about the longevity, quality and completeness of reformatted materials. Retention of originals as a source or fail-safe copy is now a fairly common practice.
Many digitized items, such as back issues of periodicals, are provided by publishers and databases on a subscription basis. If these companies were to cease providing access to their digital information, facilities that elected to discard paper copies of these periodicals could face significant difficulties in providing access to these items. Discussion as to the best ways to utilize digital technologies is therefore ongoing, and the practice continues to evolve.
Environmental controls are necessary to facilitate the preservation of organic library materials and are especially important to monitor in rare and special collections. Key environmental factors to watch include temperature, relative humidity, pollutants, and light exposure.
In general, the lower the temperature is, the better it is for the collection. However, since books and other materials are often housed in areas with people, a compromise must be struck to accommodate human comfort. A reasonable temperature to accomplish both goals is 65-68˚F however, if possible, film and photography collections should be kept in a segregated area at 55˚F. 
Books and other materials take up and give off moisture making them sensitive to relative humidity. Very high humidity encourages mold growth and insect infestations. Low humidity causes materials to lose their flexibility. Fluctuations in relative humidity are more damaging then a constant humidity in the middle or low range. Generally, the relative humidity should be between 30-50 percent with as little variation as possible, however recommendations on specific levels to maintain vary depending on the type of material, i.e. paper-based, film, etc..
The Image Permanence Institute, for example, provides a downloadable calculator to assist in determining the ideal indoor temperature when taking into account the outdoor dew point. This calculator also provides information on the risk on condensation and how many days to mold based on the entered scenario.
Particulate and gaseous pollutants, such as soot, ozone, sulfur dioxide, oxides of nitrogen, can cause dust, soiling, and irreversible molecular damage to materials. Pollutants are exceedingly small and not easily detectable or removable. A special filtration system in the building’s HVAC (heating, ventilating, and air conditioning) is a helpful defense.
Exposure to light also has a significant effect on library materials. It is not only the light visible to humans that can cause damage, but also ultraviolet light and infrared radiation. Reducing the intensity of light and length of exposure will help reduce damage.
Recent concerns about the impact of climate change on the management of cultural heritage objects as well as the historic environment has prompted research efforts to investigate alternative climate control methods and strategies that include the implementation of alternative climate control systems to replace or supplement traditional high-energy consuming HVAC systems as well as the introduction of passive preservation techniques.
Making a proper decision, taking into account the significance and value of the materials, is important before starting the preservation process. Significance is considered to be comprised of two major components: importance and quality . “Importance” relates to the collection’s role as a record, and “quality” covers comprehensiveness, depth, uniqueness, authenticity and reputation of the collection. Moreover, analyzing the significance of materials can be used to uncover more about their meaning. Assessment of significance can also aid in documenting the provenance and context to argue the case for grant funding for the object and collection.
Forms of significance can be historically, culturally, socially, or spiritually significant. In the preservation context, libraries and archives make decisions in different ways. In libraries, decision-making likely targets existing holding materials, where as in archives, decisions for preservation are often made when they acquire materials. Therefore, different criteria might be needed on different occasions. In general, for archive criteria, the points include: 1) the characteristics of a record (purpose, creator, etc.); 2) the quality of the information in the record; 3) the record in context (part of a series or not); 4) potential use and possible limitations; and 5) the cost against the benefits from its existence. For library criteria, the following are evidence of significance: 1) uniqueness, 2) irreplaceability, 3) high level of impact – over time or place, 4) high level of influence, 5) representation of a type, and 6) comparative value (rarity, completeness, integrity relative to others of its kind).
In order for the preservation of a collection to survive for a long time it is important that a systematic preservation plan is in place. The first step in planning a preservation program is to assess the institution’s existing preservation needs. This process entails identifying the general and specific needs of the collection, establishing priorities, and gathering the resources to execute the plan.
Because budget and time limitations require priorities to be set, standards have been established by the profession to determine what should be preserved in a collection. Considerations include existing condition, rarity, and evidentiary and market values. With non-paper formats, the availability of equipment to access the information will be a factor (for example, playback equipment for audio-visual materials, or microform readers). An institution should determine how many, if any, other repositories hold the material, and consider coordinating efforts with those that do. 
Institutions should establish an environment conducive to preservation changes, involve staff, and create an understanding among administration and staff. The first steps an institution should implement, according to the NEDCC, are to establish a policy that defines and charts the course of action and create a framework for carrying out goals and priorities.
There are three methods for carrying out a preservation survey: general preservation assessment, collection condition surveys, and an item-by-item survey.
Selection for treatment determines the survival of materials and should be done by a specialist, whether in relation to an established collection development policy or on an item by item basis. Once an object or collection has been chosen for preservation, the treatment must be determined that is most appropriate to the material and its repository. If the information is most important, reformatting or creation of a surrogate is a likely option. If the artifact itself is of value, it will receive conservation treatment, ideally of a reversible nature.
With old media deteriorating and new media becoming available, research remains an important practice in the field of conservation and preservation. Students and professionals in library and information science research everything from paper media preservation to the creation and maintenance of electronic resources. The two main issues that most libraries tend to face are the rapid disintegration of acidic paper and water damage (due to flooding, plumbing problems, etc). Therefore, researches tend to focus on these areas of preservation, as well as new digital technologies.
The American Library Association, for example, has many scholarly journals that publish articles on preservation topics, such as College and Research Libraries, Information Technology and Libraries, and Library Resources and Technical Services. Scholarly periodicals in this field from other publishers include International Preservation News, Journal of the American Institute for Conservation, and Collection Management among many others.
Public libraries: Limited, tax-driven funding can often interfere with the ability for public libraries to engage in extensive preservation activities. Materials, particularly books, are often much easier to replace than to repair when damaged or worn. Public libraries usually try to tailor their services to meet the needs and desires of their local communities, which could cause an emphasis on acquiring new materials over preserving old ones. Librarians working in public facilities frequently have to make complicated decisions about how to best serve their patrons. Commonly, public library systems work with each other and sometimes with more academic libraries through interlibrary loan programs. By sharing resources, they are able to expand upon what might be available to their own patrons and share the burdens of preservation across a greater array of systems.
Archival repositories and special collections: Archival facilities focus specifically on rare and fragile materials. With staff trained in appropriate techniques, archives are often available to many public and private library facilities as an alternative to destroying older materials. Items that are unique, such as photographs, or items that are out of print, can be preserved in archival facilities more easily than in many library settings.
Museums: Because so many museum holdings are unique, including print materials, art, and other objects, preservationists are often most active in this setting.
The care of cultural and sacred objects often affects the physical storage or the object. For example, sacred objects of the Native American peoples of the Western United States are supposed to be stored with sage to ensure their spiritual well being. The idea of storing an object with plant material is inherently problematic to an archival collection because of the possibility of insect infestation. When conservators have faced this problem, they have addressed it by using freeze-dried sage, thereby meeting both conservation and cultural requirements.
Furthermore, conservators are not just bound by ethics to treat cultural and religious objects with respect, but also in some cases by law. For example, in the United States, conservators must comply with the Native American Graves Protection and Repatriation Act (NAGPRA). The First Archivists Circle, a group of Native American archivists, has also created Protocols for Native American Archival Materials. The non-binding guidelines are suggestions for libraries and archives with Native American archival materials.
Preserving parchment becomes more difficult when pigments, inks, and illumination are added into the equation. Pigments do not dye parchment; instead, they lie on the surface of the parchment and so are rather fragile. The goal of restoring illuminated manuscripts should be to make them as resilient to damage while altering them as little as possible. Each individual manuscript, and even each individual page, must be considered as a separate object with different aspects that must be taken into consideration. This in turn will help determine the best course of preservation or conservation treatment.
As with CDs and computer hard drives, Magnetic media such as audio and videotapes have a very limited life span.
According to digital storage experts, media such as zip disks, CDs, or DVDs last only a definite period before the medium begins to degrade, although the fact that these media formats are recent inventions combined with a high rate of change and improvements in these technologies makes it difficult to determine how long digital media will last. Manufacturers claim minimum lifetimes of 50 years for CD-Rs and 25 years for CD-RWs. These experts suggest that digital images be transferred as new media are developed to ensure that they are preserved.
Audio and video tapes require specific care and handling to ensure that the recorded information will be preserved. For information that must be preserved indefinitely, periodic transcription from old media to new is necessary, not only because the media are unstable, but also because the recording technology may become obsolete.
Reformatting, or in any other way copying an item's contents, raises obvious copyright issues. In many cases, a library is allowed to make a limited number of copies of an item for preservation purposes.
One of the biggest challenges in the field of preservation today is educating a library's community, especially librarians and other staff, in the best ways to handle materials as well as the conditions in which particular materials will decay the least. This challenge is exacerbated by the fact that preservation is a peripheral element of most library science curricula; indeed, there are few places where one can receive a specialized education in preservation.
The University of Texas at Austin
In the U.S. for example, the primary degree granting institution for library and archival preservation is the University of Texas at Austin's School of Information Science. The conservation and preservation program is offered in partnership with the Kilgarlin Center for Preservation of the Cultural Record and trains both conservators and preservation administrators. Other conservation programs in the United States focus on Art Conservation and are considered to be more museum focused than library focused. These programs are all part of the Association of North American Graduate Programs in the Conservation of Cultural Property (ANAGPIC).
The Rutgers Preservation Management Institute
The Rutgers Preservation Management Institute provides post-graduate training in preservation administration for working librarians who have already completed a Master's degree. UT Austin also offers certificates of advanced study in conservation and preservation to librarians who already hold their MLS.
Northeast Document Conservation Center
Another educational resource available to preservationists is the Northeast Document Conservation Center or NEDCC.<ref[htp://www.nedcc.org/home.php NEDCC]. Northeast Document Conservation Center. Retrieved August 23, 2008.</ref> This institution was founded in 1973 as a reaction to the growing problem of paper deterioration occurring in repositories in the New England area. The Center provides institutions and organizations, as well as librarians, conservators, preservationists, and museum professionals, with help in learning proper care and procedures to better preserve the integrity of their collections. The institution provides a variety of services such as imaging, surveys and consultations, and digitation. They also assist with disaster planning. The educational opportunities it provides include provision of workshops, conferences, and specialized trainings. Additional online courses are also available. For instance, some of the workshops offered by the NEDCC include: Basic Preservation, Collections Care, Emergency Preparedness, Integrated Pest Management (IPM), Identification and Care of Photographs, Basic and Intermediate Book Repair, Basic Paper Repair, Preservation of Scrapbooks, Preservation Technologies, Holdings Maintenance, Creating and Maintaining Digital Collections, Scanning Training, and Grant Writing.
All links retrieved May 28, 2015.
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