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| In chemistry, a substance capable of forming hydrogen ions when dissolved in water. Acids can damage cellulose in paper ,board and cloth, by weakening or breaking their molecular bonds leading to embrittlement. Acids may be introduced during the manufacture of library materials, or may be present in the raw material. Acids may also be introduced by migration or from atmospheric pollution. They can be neatralised by an alkali to form a salt |
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| The weakening of paper structure by an acid through hydrolysis or other means, resulting in a breaking down of the chain length of the material, and a subsequent loss of strength. This can become so severe that the paper has almost no residual strength and is said to be brittle. |
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| In chemistry, material that have a pH of 7(neutral) or higher(alkaline). Acid free paper is often alkaline buffered. Since cellulose is da,aged by acids, acid free materials are desirable in library preservation. |
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| The transfer of acid from an acidic material to a less acidic, neutral, or alkaline material. This may occur when two materials are in direct contact or indirectly by vapour transfer. It can cause staining, weakening and embrittlement. The actual mechanisms of acid migration are not well undersood, and the term is sometimes erroneously applied to any transfer of staining. |
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| In chemistry, a substance capable of forming hydroxyl ions when dissolved in water. Alkaline materials may be added to materials to neutralise acids or as an alkaline reserve or buffer for the purpose of counteracting acids which may form in the future. While a number of chemicals may be used as alkaline buffers, the most common used in paper conservation are magnesium carbonate or calcium carbonate. Alkalis can be neutralised by an acid to form a salt. |
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| An imprecise term suggesting that a material, product or process is durable, and/or chemically stable, that it has a long life and can therefore can be used for preservation purposes. The phrase is not quantifiable; no standrads exists that describe how long an 'archival' material will last. The word permanent is sometimes used to mean the same thing. |
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| A process sometimes used in conjunction with deacidificationor during manufacture when an alkaline material is deposited in paper in order to neutralise future potential acidity. |
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| Active intervention to physically stablilize and/or repair the physical structure of an item. Ideally, all techniques should be reversible. |
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| A common term for a chemical treatment that neutralises acid in a material such as paper, and that may deposit an alkaline buffer to counteract future acid attack. While deacidification may increase the chemical stability of paper, it does not restore strength or flexibility to brittle materials. |
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| The managed activities necessary for ensuring the long-term retention and usability of digital objects |
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| A document setting out procedures to be followed by an organization to prevent or minimize the reisk of a disaster occurring, and to describe actions to be taken should a disaster occur. Such a plan should include provisions for the prevention of a disaster, salvage procedures in case a disaster should occur, and replacement/restoration measures to be taken. More correctly should be called a disaster preparedness plan. |
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| A form of protective enclosure for paper and other flat objects. It involves placing the item between two sheets (or one folded sheet) of clear plastic film(usually polyester), that are subsequently sealed with adhesive tape or by heat welding or sewing around the edges. The object is thus physically supported ad protected from the atmospher, although it may continue to deteriorate within the package. A sheet of buffered paper or a board is sometimes included. The object can simply be removed by cutting one or more edges of the plastic film. |
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| The maintenance of safe levels of light exposure, humidity, temperature, air pollution, air movement, dirt inside a building |
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| A reproduction or copy of an original work that is similar in appearance to the original. |
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| Discoloration on paper, generally in the form of random rust colored spots. Believed to be caused by one or more of the following: fungus or mold, impurities in manufacture, high humidity or dampness, airborne acids. The removal of foxing is not generally recommended in library preservation since methods of removing foxing almost always will cause further damage to the object |
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| In machine made paper and board, the direction in which the fibres predominantly lie. Paper tears and folds more redily along the grain than across the grain. Grain direction needs careful consideration in bookbinding and paper conservation treatments. Grain direction should be parallel to the spine of a book |
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| Items have intrinsic value or not, depending upon such factors as uniqueness or value of informational content, age, physical format, artistic or aesthetic qualities, and scarcity. Materials having intrinsic value generally warrant preservation in their original form. |
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| Leaf attachment is the structural method used to hold the pages of a volume together - creating a textblock. Some leaf attachment methods only employ adhesive to hold the pages together. Other methods employ thread that is used to sew together the pages of the text block. |
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| Commercial library binding is the binding and rebinding of volumes in a largely automated commercial facility. In general, journal issues are bound together to collocate them and to prevent damage and loss; paperbacks are bound to make them more sturdy for library use; hardcover books are rebound because they are damaged and do not merit conservation treatment. |
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A component of the cell walls of plants, along with cellulose. Lignin is largely responsible for the strength and rigidity of plants, but its presence in paper and board is believed to contribute to chemical degradation. There can be large amounts of lignin present in pulp made form wood. It is not removed in the production of mechanical pulp, but using chemical processes, it can be optimally removed.
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| The transfer of digital objects from one hardware or software configuration to another, or from one generation of computer technology to a subsequent generation. The purpose of migration is to preserve the integrity of digital objects and to retain the ability for clients to retrieve, display, and use them in the face of constantly changing technology. Migration includes refreshing as a means of digital preservation, however, it is not always possible to make an exact digital copy of a database or other information object and still maintain the compatibility of the object with a new generation of technology. |
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| Fungi with a filamentous growth form, producing cotton-like or powdery colonies. Mold spores are ever-present in the air, and generally grow on moist surfaces in the absence of circulating air. Because paper is hygroscopic (i.e. capable of absorbing moisture), mold can become embedded. Many molds are dangerous to health. Mold cause staining and weakening of most library materials. Keeping the relative humidity below 70-80% and providing good air movement is the best way to control the growth of mold. |
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| Measure of the extent to which an item is acidic or alkaline. The pH scale ranges from 0 (acid) to 14 (alkaline). |
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| Filament tape consisting of an adhesive layer and a filament carrier (e.g. Scotch tape, Sellotape). Generally not recommended for permanent paper repair. |
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| A simple, economical box designed to provide a good degree of protection to its contents without undertaking full conservation treatment. Initially developed to provide intermediate protection to materials awaiting further treatment. |
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| Activities associated with maintaining library, archival or museum materials for use, either in original physical form or in some other format. Preservation is a broader term than conservation: conservation activities form part of a total preservation program. Preservation includes both activities taken to repair or treat damaged materials and activities taken to prevent or delay material becoming damaged. |
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| Reformatting is the copying of library materials. Deteriorated objects such as brittle books are copied onto more stable materials (silver halide microfilm, alkaline paper) to preserve information. Decaying nitrate negatives are copied onto stable film; motion picture film is copied to new film to protect the original from the wear and tear of repeated use; photographs may be re-photographed using analog or digital means in order to protect originals from handling; sound recordings are transferred, now almost exclusively to digital form, to ensure that audio remains playable and usable. |
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The percentage of moisture contained in air as compared with that required to completely saturate it at a given temperature. A low relative humidity of around 40% is considered ideal for paper storage, but is very difficult to achieve in the humid tropics. Mould growth becomes a serious problem above 70% relative humidity.
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| Ability to undo a process or treatment with no or minimal change to the object. Reversibility is an important goal of conservation treatments, but it must be balanced against other treatment goals or options. Full and total reversibility is an ideal which is impossible to achieve. |
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| A copy of the information content of an original item in another medium, usually one which is more durable. See also: Reproduction and Facsimile. |
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| Light having a shorter wavelength and higher energy than visible light. Ultraviolet light is potentially damaging to library, archive and museum objects. Removing UV light can reduce the rate of deterioration. Certain acrylic sheets have UV filtering chemicals built into them. |
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