GLOSSARY

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E

electromagnetic radiation

Radiation consisting of particles or waves of energy associated with electric and magnetic fields, produced by the acceleration of an electric charge. Electromagnetic radiation is emitted by matter in discrete quantities of energy called photons. The type of electromagnetic radiation-whether it be infrared, radio or visible light-depends upon its frequency.

The types of electromagnetic radiation of most concern in conservation are light and ultraviolet radiation. These form part of the electromagnetic spectrum. See also Electromagnetic spectrum; Frequency; Wavelength.

electromagnetic spectrum

The range of frequencies over which electromagnetic radiations are propagated. The lowest frequencies are radio waves; increases of frequency produce infrared radiation, light, ultraviolet radiation, X-rays and gamma rays. See also Electromagnetic radiation; Frequency; Light; UV radiation; Visible spectrum.

electronic media

Media which depend upon the use of electrical means to store, transmit and reproduce data or information. Electronic information may be accessed through the use of a storage device such as a sound cassette, CD-ROM or floppy disk and an electronic device for reading, processing and displaying the information such as a computer.

electroplate, electroplating

The application of a metallic coating to a surface by electrolytic action; that is, by depositing metal from a solution of one of its salts onto the surface, using an electrical current. The principal function of electroplating is to make a cheaper metal look like silver. It is used widely for domestic cutlery and plate.

electrostatic

A material which is electrically charged so that particulate matter is attracted to it and held by the charge.

emulsion

In photography, the word emulsion refers to the layer of binder containing the light-sensitive materials. The most common emulsion has been gelatine, but albumen and collodion were also used.

In scientific terms an emulsion is a suspension of one liquid in another.

When referring to paints and adhesives, emulsion means a liquid-usually water-containing small particles of synthetic materials and other chemicals. The materials and chemicals undergo chemical changes as the water dries off, and a tough, insoluble, continuous film of paint or adhesive is formed.

encapsulation

A form of protective enclosure for paper and other flat objects. It involves placing the item between two sheets of transparent polyester film and sealing some or all of the edges. The object is thus physically supported and protected from the atmosphere and during handling. Because the object is not fixed to the polyester, it can be removed by cutting one or more edges of the polyester. Note: The object may continue to deteriorate in the capsule.

enclosures

A general term for various types of protective containers constructed for temporary or permanent storage of fragile materials; also known as wrappers. Encapsulation is a form of protective enclosure, as are Solander and other boxes, dust jackets, envelopes and mounts. See also Clamshell boxes; Dust jacket; Encapsulation; Solander boxes; Mats, mounts.

environmental control

The maintenance of safe levels of light exposure, humidity, temperature, air pollution, air movement, and dirt inside a building.

equilibrium moisture content

A term applied to wood which indicates the moisture content at which the wood neither loses nor gains moisture from the surrounding atmosphere-it has reached equilibrium with the environment.

extraction unit

A piece of equipment designed to extract noxious fumes or gases from an area, often consisting of a fume hood/cupboard and a ventilation unit.