Absolute Humidity
Humidity is the amount of water held as vapor in air. It is expressed as the weight of water in a given volume of air. This measurement is called the absolute humidity and is usually given as the number of grams of water vapor in a cubic meter of air. (Wilks, 23)

Conservation
The profession devoted to the preservation of cultural property for the future. Conservation activities include examination, documentation, treatment, and preventive care, supported by research and education. (AIC Directory 1999)

Documentation
The recording in a permanent format of information derived from conservation activities.

Examination
The investigation of the structure, materials, and condition of cultural property including the identification of the extent and causes of alteration and deterioration.

Integrated Pest Management
Preservation professionals increasingly recommend a strategy called integrated pest management (IPM). This approach relies primarily on non-chemical means (such as controlling climate, food sources, and building entry points) to prevent and manage pest infestation. Chemical treatments are used only in a crisis situation threatening rapid losses or when pests fail to succumb to more conservative methods. (Patkus, 1999)

LE Designation
Rating for the "life expectancy" (length of time that information is predicted to be retrievable) of recording materials and associated retrieval systems. The number following the LE symbol is a prediction of the minimum life expectancy in years for which the information can be retrieved without significant loss when properly stored under extended-term storage conditions. (ANSI/AIMMTR-2-R)

Lignin
natural aromatic polymer that is found in the cell walls of grasses and woody plants. Lignin and hemicellulose cement the fiber cells together. Lignin composes 17-30% of wood. In the destructive distillation of wood, it decomposes to produce methanol. In the manufacture of paper pulp by the chemical processes, the lignin is removed by reaction with alkaline or sulfur compounds. The presence of lignin in paper shortens its overall lifetime as lignin can photo-oxidize to form acidic products which can then attack the cellulose. - from: Boston MFA Conservation and Art Materials Dictionary (May 3, 2001)

Lumen
A measure of the amount of luminous flux or light energy, such as the light output of a lamp. (Lull, 91)

Lux
The density of light striking an object; the result of one lumen striking one square meter; a metric system measure of illuminance at a point on a surface, equivalent to about 0.09 footcandle. (Lull, 91)

Microclimate
A microclimate, or a microenvironment, refers to the isolated environment within a small enclosed space such as an exhibit case, closed cabinet, drawer, box, or other container. Depending on the construction materials and quality of the seal, a cabinet or container can isolate the collections from short-term temperature and humidity fluctuations within a room. (Weintraub and Wolf, 123)

Preservation
The protection of cultural property through activities that minimize chemical and physical deterioration and damage and that prevent loss of informational content. The primary goal of preservation is to prolong the existence of cultural property. (AIC Directory, 1999)

Preventive Conservation
The mitigation of deterioration and damage to cultural property through the formulation and implementation of policies and procedures for the following: appropriate environmental conditions; handling and maintenance procedures for storage, exhibition, packing, transport, and use; integrated pest management; emergency preparedness and response; and reformatting/duplication. (AIC Directory, 1999)

Provenance
1) The organization or individual that created, accumulated, and/or maintained and used records in the conduct of business prior to their transfer to an archives; 2) information regarding the origin and custodial history of documents; 3) the principle that records/archives of the same provenance should not be mingled with those of any other provenance. (SAA Glossary)

Relative Humidity
The relative amount of moisture in air expressed as a percentage of the total amount of moisture the air can hold, varies with the temperature and air pressure. (Lull, 92)

Restoration
Treatment procedures intended to return cultural property to a known or assumed state, often through the addition of non-original materials. (AIC Directory, 1999)

Stabilization
Treatment procedures intended to maintain the integrity of cultural property and to minimize deterioration.(NEDCC)

Treatment
The deliberate alteration of the chemical and/or physical aspects of cultural property, aimed primarily at prolonging its existence. Treatment may consist of stabilization and or restoration.

References:

AIC. "AIC Definitions of Conservation Terminology," in Directory, 1999.

ANSI/AIIMTR-2-R, Glossary of Document Technologies. The LE designation is used in all photographic standards produced by ANSI.

ANSI/NISO Z39.48-1992, American National Standard for Permanence of Paper for Publciations and Documents in Libraries and Archives.

Lull, William P. Conservation Environment Guidelines for Libraries and Archives (Ottawa, ON: CCA, 1995).

NEDCC (Northeast Document Conservation Center), Andover, Massachusetts.

Patkus, Beth. "Integrated Pest Management," in Preservation of Library and Archival Matierals, 3rd ed., ed. S. Ogden (Andover, MA: NEDCC, 1999).

Patkus, Beth. "Protection From Light Damage," in Preservation of Library and Archival Materials, 3rd ed., ed. S. Ogden (Andover, MA: NEDCC, 1999).

SAA. A Glossary for Archivists, Manuscript Curators, and Records Managers.

Weintraub, Steven and Sara J. Wolf. "Macro- and Microenvironments," in Storage of Natural History Collections: A Preventive Conservation Approach, Vol. I, eds. Carolyn L. Rose, Catharine A. Hawks, and Hugh H. Genoways (Iowa City, Iowa: Society for the Preservation of Natural History Collections, 1995).