For examples and and more in-depth descriptions of paper, book, photographic, and audiovisual formats/processes, please check out our Collection ID Guide.


1-layer print
An early era photographic print with no binder or baryta layer—simply image material on a paper support—is given this designation (popularized by James Reilly). Examples include the Salt Print, Cyanotype, and Platinum/Palladium Print.
2-layer print
An early era photographic print with no baryta layer—simply image material in a binder layer on a paper support—is given this designation (popularized by James Reilly). Examples include the Albumen Print, Carbon Print, and Woodburytype (also regarded as a Photomechanical process).
3-layer print
An early era photographic print with a baryta layer, binder, and image material on a paper support—is given this designation (popularized by James Reilly). Examples include the glossy Collodion Print, Matte Collodion Print, Gelatin POP Print, and Silver Gelatin Print.


The process of damaging or wearing away something by rubbing, grinding, or scraping. In some cases, this can lead to the loss of information on the surface of an item.
Access copy, or Reference copy
A restored copy of an item, or a clone, imitation, or duplicate copy of an item that is available for public use.
Access restriction
A limitation on the access to or use of materials. Access restrictions may be determined by a period of time or by a class of individual as to protect national security, personal privacy, or to preserve materials.
1.) Materials physically and legally transferred to a repository as a unit at a single time; an acquisition.
2.) To take legal and physical custody of a group of records or other materials and to formally document their receipt.
3.) To document the transfer of records or materials in a register, database, or other log of the repository's holdings (Pearce-Moses, 2005).
Accession number
A number or code assigned to uniquely identify a group of records or materials acquired by a repository and used to link the materials to associated records (Pearce-Moses, 2005).
A transparent plastic base for photographic film made by treating cellulose with acetic acid. This term is used for various modifications of cellulose acetate, e.g., cellulose diacetate, cellulose triacetate, cellulose acetate propionate, and cellulose acetate butyrate. Also referred to as "safety" film, because, as opposed to nitrate film, acetate is nonflammable. That said, acetate suffers from its own form of chemical deterioration (see Acetate decay).
Acetate decay (vinegar syndrome)
Chemical degradation of cellulose acetate film base that may cause distortion, shrinkage, and brittleness. Accelerated by high humidity and temperature, it is often detected by a vinegar odor. The severity of decomposition can be determined using A-D Strips.
Acetate disc
See Lacquer disc.
Acetic Acid
An acid released by unpainted wood that can cause metal corrosion.
Property of an item with a pH below 7.0. Some paper materials may become acidic as they age. Acidity is often a characteristic of older papers made from wood-based pulp that has not had its lignin removed. Acidic material will yellow over time, become brittle, and cause the pH of items in proximity to shift toward acidic pH levels. Exposure to light or heat hastens deterioration.
Acid Etching
Type of decoration on glass which is produced through exposure of the surface of the glass to hydrofluoric acid. The glass item is first covered in an acid-resistant material, sometimes a wax, before the acid is used to scratch through that material. The item is then immersed in hydrofluoric acid. A patent for the acid-etching process was filed in 1857 by Richardson's, an English glass company.
Term used to describe paper and plastic products (and archival storage and display materials) with pH equal to 7.0 (neutral) or greater than 7.0 (alkaline). Slightly acidic paper (6.0 - 7.0 pH) is also sometimes called "acid-free." It was the creation of alkaline sizing in the 1950s that ultimately led to acid-free wood-based pulp papers. Acid-free enclosure products must be free of acid, lignin, alum, and sulfur. "Acid-free" does not necessarily mean that the material will maintain this pH over time.
A-D Strips
Indicator papers, manufactured by Image Permanence Institute (IPI), which change color when acetic acid is produced by degrading cellulose acetate base.
A substance, either organic or synthetic, which bonds the surfaces of two other materials through chemical and/or mechanical means. The term "adhesive" may be used interchangeably with glue, cement, or paste. Pressure-sensitive tape adhesives are of particular concern when it comes to paper, book, and photo collections.
A clay mixture that has been dried to harden, but is not fired.
An extremely soft, wax-like type of stone.
A protein obtained from egg whites. Used as a binder for the image layer of photographic materials, especially from the 19th century.
Property of an item to produce a basic pH (pH >7.0). An alkaline reserve is added to some paper materials (called buffered papers) during manufacture intended to neutralize acid compounds contained in older papers.
A metal made by combining two or more metallic elements. Often used to improve a metal's strength or resistance to corrosion.
A type of metal that is silver-white in color and has a very reflective, flat sheen. Aluminum is easily formed and manipulated.
Alum-rosin sizing
Method of sizing papers, rendering them more suitable for printing/writing by reducing liquid absorption capacity (no ink bleed/run). Alum-rosin was commonly used from the 1850s through the 1980s. Though effective, it is considered an "inherent vice" of papers of this era, as it lowered the paper's pH and set the stage for browning/yellowing and embrittlement.
Alveoles are symmetrical cavities that can form in soft stones such as limestone, usually as the result of weathering. Alveolization sometimes occurs in an interconnected "honeycomb" pattern.
A noncrystalline solid having neither a definite form nor an apparent structure.
An electrical signal that varies continuously; comes from the word "analogous," which means "similar to." All early AV recordings were analog (National Film and Sound Archive, 2007).
Analog recording
1.) A method of recording in which a characteristic of the recorded current, such as amplitude or frequency, is continuously varied in a manner analogous to the variations of the original signal.
2.) A logging of an event by one of various methods of capturing and storing a continuous replica of the source sound pattern by tracing an analogous pattern into another medium. The most commonly used storage methods have been engraved or embossed modulated grooves in a disc, magnetic particle patterns in tape, and optical patterns in film (Miliano & IASA, 1999).
3.) A recording in which continuous magnetic signals, which are representations of the voltage signals from the video camera or microphone, are written to tape. Analog signals stored on tape deteriorate with each copy or generation (in contrast, see Digital) (Bay Area Video Coalition, 2009).
The process in which a continuous analog signal is quantized and converted to a series of binary integers (Bay Area Video Coalition, 2009). Also referred to as A-D.
Aniline dye
Type of dye used in colored inks. Aniline dye was invented in 1856 and is derived from coal tar. Aniline ink is light sensitive and water-soluble. Aniline ink will commonly be violet or blue, but may be assumed to be in any color ink for documents and copies produced after the mid-1800s.
Archival quality
A generic term used by the paper industry to indicate that a product (usually a housing or display material) is durable and will not cause harm to original collection materials. "Archival" often means acid-free, but that is not an absolute. Note that the term "archival" may be used indiscriminately by manufacturers to describe their products and does not necessarily guarantee that the product meets ISO or ANSI guidelines.
Audiovisual artifact
An undesirable picture element in a video image, which may naturally occur in the recording process and must be eliminated in order to achieve a high quality image. Most common artifacts include cross-color and cross-luminance. Not to be confused with artifact as a cultural product (Bay Area Video Coalition, 2009).
Audiovisual item
Any recorded sound or moving or still image item (Miliano & IASA, 1999).
Authority control
The process of establishing the preferred form of a heading, such as proper name or subject, for use in a catalog, and ensuring that all catalog records use such headings (Pearce-Moses, 2005).
Authority file, or Authority list
A compilation of records that describe the preferred form of headings for use in a catalog, along with cross-references for other forms of headings. Examples include Library of Congress Subject Headings (LCSH) and Art and Architecture Thesaurus (AAT), among others (Pearce-Moses, 2005).


Backing film, or Substrate
The layer that supports the magnetic layer in a magnetic tape, most commonly made of polyethylene terephthalate (PET) (Bay Area Video Coalition, 2009).
An inked logo or manufacturer/brand information on the back side of a photo paper. Though there are exceptions, backprinting was a common practice for some manufacturers (Agfa, Kodak) and today provide clues about the print's origin.
Baking (videotape)
The process of gently heating damaged videotape in an oven in order to enable playback. The polymer of the magnetic tape's binder deteriorates by hydrolysis, resulting in sticky shed syndrome. Archivists have reported success in baking tapes that are suffering from severe sticky shed syndrome; however, scientific research has not been conducted to explain this. The temperature and humidity of the oven must be tightly controlled, as well as the time in which a tape is baked. This process is not recommended except in extreme circumstances, as it may accelerate the deterioration of the tape. When a tape is baked successfully, it can usually be played back one time for remastering (Bay Area Video Coalition, 2009).
A coating of barium sulfate in gelatin applied to the surface of photographic paper base to provide opacity, smoothness, and brightness. Barium sulfate is a chemically stable white pigment. Part of the weight and stiffness of a photo paper is due to the baryta undercoating, which is primarily intended to provide a smooth, pure white, inert base for the emulsion.
A support on which something is applied or built; a carrier; a substrate (Pearce-Moses, 2005).
The polymer that contains recording or imaging particles. For example, gelatin is the binder for silver image particles in photographic media.
Binder hydrolysis
See Sticky shed syndrome.
Bit (Binary digit)
The smallest unit of information in a binary system. A number in base 2, which can be represented using only two numeric symbols: a zero and one (National Film and Sound Archive, 2007). Eight bits equals one byte. There are 256 possible combinations for eight binary digits; thus, the color depth of eight bits represents 256 possible colors (2×2×2×2×2×2×2×2). Because each pixel of a video picture contains 3 samples (Y', R-Y', B-Y'), there are 16.7 million (256×256×256) possible colors in an 8-bit system (Bay Area Video Coalition, 2009).
Black-and-white, or B&W
See Monochrome.
A type of deterioration that can occur on the surface of ceramics when air or fluid on the surface becomes trapped between the glaze layer and the clay body, or when the glaze is too thick.
When a seed occurs at the surface of the glass, it causes a visible and often fragile bubble called a "blister". When a blister bursts, it leaves behind a divot in the glass that is especially sensitive to weathering.
Blocking (AV media)
The sticking together or adhesion of successive windings in a tape pack. Blocking can result from deterioration of the binder, storage of tape reels at high temperatures, and/or excessive tape pack stresses (Bay Area Video Coalition, 2009).
Blocking (Paper/book material)
Adhesion of paper leaves to one another. This occurs as a result of water or moisture on glossy pigment-coated papers.
Used during glass construction, it is a long tube by means of which molten glass is blown into the required shape.
Blue wool test
Scale used to measure the permanence of colouring dyes. The test was initially developed for textiles but has been adopted by printers as measure of lightfastness of ink colourants, and it now often used in exhibition environments to monitor UV levels in a given zone or display.
Bound object
Form that contains a number of individual documents or sections that were once separate and were sewn or bound together as a book or pamphlet.
A metal alloy of copper and zinc. It is often yellow or red in color.
A metal alloy of tin, antimony, and copper.
A metal alloy of copper and tin that is yellow in color. It often has a tarnish or patina.
A type of glass damage that can result from impact, when a ring of cracks stemming from a central "impact cone" occurs.
Distortion or lack of flatness. This may be caused by chemical degradation, shrinkage, or flow. (See Distortion).
A stiff cotton (or linen) cloth used to cover and protect books. Today buckrams are stiffened by soaking in a substance, usually pyroxylin, to fill gaps between the cloth fibers.
Buffered is a term for paper enclosure products and interleaving sheets with an alkaline reserve, meant to absorb excess acidity from materials within. Alkaline buffers can damage some items. Items that should NOT be stored in buffered enclosures include: hand-tinted materials, Diazotypes, Blueprints/Cyanotypes, and additional photographic materials.
Bulk dates
The earliest and latest dates of the majority of materials being described. Bulk dates indicate the chronological or period strength of a collection, especially when the inclusive dates may be misleading (Pearce-Moses, SAA, 2012).
Term referring to the darkening on the back side of an inked area caused by ink corrosion rather than ink's intended penetration.


Refers to two similar finishing processes for cloth and machine-made papers producing more smooth and glossy surfaces. This was achieved through pressure, heat, and/or friction of rollers.
Carbon black
Highly stable, black pigment derived from elemental carbon. Carbon black pigment is often used to achieve black in most printing inks.
A stiff piece of cardstock measuring about 4 ½" × 2" on which a photograph of nearly the same size is mounted. These photographs were primarily albumen prints. The carte-de-visite was gradually succeeded by the cabinet card in the late 1870s.
A container used to store and facilitate access to a roll of tape or film on a single core (Pearce-Moses, 2005). Used for insertion of the medium into recorders, readers/printers, and retrieval devices, and requires no threading or rewinding. Most audio tape cartridges contain two-channel, 8-track stereo recordings (Miliano & IASA, 1999).
Case (book)
Outer enclosure of a book; its primary function is to protect the text block. The case might also be referred to as the book's cover.
Cased photograph
Decorative case in which daguerreotypes, ambrotypes, and tintypes will often be found displayed in. Cases are usually hinged and will be made of wood, covered in embossed leather or some imitation of it. Image is often protected by a brass mat and glass cover, which are bound with a tape obscured by a decorative brass foil along the edges.
An enclosed container holding a roll of tape, film, or wire stored on two cores. Common forms today include compact audio cassettes, audio mini-cassettes, and videocassettes (Miliano & IASA, 1999).
NOTE: A cassette is distinguished from a cartridge, the latter having one hub instead of two.
Cast Iron
A type of metal. An iron alloy that is similar to steel but has a higher carbon content, which makes cast iron harder than steel or pure iron. Cast iron is typically silver-grey in color and is highly reactive with water.
CD standard specification
The technical specifications for CD and CD-ROM formats that are outlined in a set of color-bound books. These standards are licensed by Philips.
Cellulose acetate
See Acetate.
Cellulose nitrate
See Nitrate.
Ceramics are made from natural materials/clay mixtures that are pliable when wet and shaped into particular forms that are then dried and/or fired to become hard/solid objects.
Buckling of the emulsion caused by base shrinkage.
See Flint.
Chipped stone
Made from cutting or chipping away edges of hard/brittle stones, like flint, chert, or obsidian, to create an intentional shape that can be used as a tool. "Arrowheads" or projectile points, knives, and other cutting or drilling implements are made from some type of chipped stone.
Chromogenic photographic processes work by first forming a conventional silver image and then replacing that image with colored dye. Most conventional films and prints from the 20th century are chromogenic. See Chromogenic Color Print in the Collection ID Guide.
Chunkey Stone
See Discoidals
Cire perdue
See Lost-wax casting.
Coarse groove
The channel size found in two minute cylinders and most shellac recordings (generically called 78 rpm discs), as opposed to the microgroove used in 33? rpm LP sound recordings (Miliano & IASA, 1999).
Coated paper (photos)
A support which has an emulsion layer on its surface consisting of either albumen, gelatin, or collodion. This layer holds the light-sensitive photographic salts. A three layer structure has as its third layer barium sulfate, (a.k.a. baryta layer). This layer occurs between the paper and the image layer.
Wrinkled or puckered quality, usually occurs as a result of exposure to high humidity or water damage, though it also refers to manufactured paper surfaces.
Cold flow
Viscous flow of a solid under stress or at ordinary temperatures.
An aggregation of items. In the PSAP, a collection and item may be referred to as a resource.
Collection development
The policies and procedures of a collecting institution used to select materials, typically identifying the scope of the creators, subjects, formats, and other characteristics that influence the selection process (Pearce-Moses, 2005).
Color balance shift
A change in the overall tone of color images.
Color bleeding
Movement of the colorant in color images, either laterally into adjacent areas in the image plane or outside the image plane to a contacting sheet.
Color book standard
See CD standard specification.
Color image decay
Can be manifested as color fading, color balance shift, yellowing, or color bleeding.
Compact disc (CD)
A recording medium, introduced commercially in 1983, consisting of a 12 cm/4.72 inch disc made principally of plastic coated with a reflective metal, commonly aluminum in commercial discs, and a protective layer of lacquer. Presently used primarily for audio and CD-ROM recordings. Normally recorded and played on one side only, the medium can yield up to 78 minutes of audio signal (Miliano & IASA, 1999).
Compact disc-extra (CD-Extra)
A format developed in the mid 1990s by Philips, Sony, and Microsoft, designed either for the playback of music with access to the audio session only on CD audio playback equipment, or for simultaneous access to audio titles and complementary multimedia applications (lyrics, images, etc.) where a CD-Extra compatible CD-ROM drive is installed on a computer system (Miliano & IASA, 1999).
Compact disc-interactive (CD-I)
A compact disc format developed by Philips and Sony that stores electronic resources, including sound, text, still images and full-motion video in optical form, used with a CD-I player (Miliano & IASA, 1999).
Compact disc-read only memory (CD-ROM)
A compact disc format that stores electronic resources, including sound, text, still images and full-motion video in optical form, used with a CD-ROM player (Miliano & IASA, 1999).
A technique that provides for the transmission or storage, without noticeable information loss, of fewer data bits than were originally used when the data was created (Bay Area Video Coalition, 2009). The reduction of the size of a fixed file. Compression may be "lossless" where redundant information is removed in a way that allows the original file to be reconstructed (e.g. a Winzip file), or "lossy" where data or information that is considered to be less important or less perceptible is removed, and may not be completely or accurately reinstated (e.g. JPEG) (Miliano & IASA, 1999).
Continuous form paper
Paper designed for use with dot-matrix/impact printers, line printers, often associated with desktop publishing from the 1980s to 1990s. It can be single ply (usually woodfree uncoated paper) or multi-ply (with a carbon paper layer, or multiple carbonless copy paper). Also known as continuous stationary, fan-fold paper, sprocket feed paper, burst paper, tractor-feed paper, or pin feed paper. Common sizes: 9.5" × 11" or 15" × 11".
Continuous tone
Quality of an image that describes a large range of shades from light to dark, with a capacity to represent fine detail in low or high contrast image areas. Most photography produces continuous tone images, while most photomechanical processes produce half-tone or other patterned images.
A non-magnetic metal that is red or pink when pure and whose alloys are shades of red, yellow, and orange. Copper is used to make coins, roofing, cookware, pipes, and other utilitarian items.
Copper corrosion
Form of damage caused by cupriferous (copper-containing) pigments, which was once popular for use in illuminated manuscripts and maps. Over time, the blue or green pigment darkens, turns brown, and begins to bleed through and off-set onto adjoining pages. It will also embrittle and weaken paper or vellum supports.
Copy paper
Paper typically used for modern copying and laser printers. It is optimized for smooth runs in a copying machine or printer: no curling or cockling. Copy paper has strict specifications; basis weight is 70-90 g/m², ISO brightness 80-96%, made of 90-100% virgin chemical pulp or 100% deinked pulp (recycled) with total pigment content of 10-15%.
Copying (process)
In terms of reprography, copying refers to the production of a small batch of copies from an original. The format of the original does not matter, and there is no need for the creation of a master.
A form of protection provided by law to the creators of "original works of authorship," including literary, dramatic, musical, artistic, and certain other intellectual works. This protection is available to both published and unpublished works (U.S. Copyright Office, 2008). It gives copyright holders the ability to control the reproduction, publication, adaptation, exhibition, or performance of their works.
NOTE: In the United States, copyright is provided for by the Constitution (Article I, Section 8) and is codified by the Copyright Act of 1976, 17 USC 101-1332. Internationally, copyright is defined by the Berne Convention, which the United States joined in 1989. Copyright protects the owner's interests in the intellectual property (content), rather than in the physical property that serves as a container for the content. For example, an archives may own a collection of papers, but the author retains copyright. As property, copyright can be transferred or inherited; hence, the owner of a work's copyright may not be the work's creator. These works may be in a wide range of media, including literary works; musical works, including any accompanying words; dramatic works, including any accompanying music; pantomimes and choreographic works; pictorial, graphic, and sculptural works; motion pictures and other audiovisual works; sound recordings; and architectural works. Copyright does not protect any idea, procedure, process, system, method of operation, concept, principle, or discovery in such works; it only protects their tangible manifestation (Pearce-Moses, 2005).
A cylinder on which film or tape is wound to form a spool (Pearce-Moses, 2005).
Core dipping/winding
The oldest technique for glass shaping. A core of straw or dung is dipped into molten glass. The core and glass are then rolled over a smooth surface to shape the item. When the item is formed and glass is cooled, the core is removed leaving only the glass outer shell.
Gradual destruction caused by chemical action.
A gradual process of destruction in which a solid, especially a metal, is deteriorated and changed by a chemical action, as in the oxidation of iron in the presence of water by an electrolytic process.
Cotton paper
Paper made from cotton fibers, using cotton linters or cotton cloth. Cotton paper is more structurally durable and more archival than acidic wood pulp-based papers. Today, cotton office paper typically will contain 25%, 50%, or 100% cotton (check watermark). Also referred to as rag paper.
A type of deterioration or damage that occurs with ceramics when the glaze shrinks into independent blobs, leaving behind "holes" or bare, unglazed areas on the clay surface. Crawling can happen when dirt or oils on the clay's surface prevent the glaze from sticking evenly.
A type of deterioration that occurs with ceramics when the glaze surface contracts or shrinks at a rate faster than the clay body, forming a network of fine cracks may appear on the the surface of the glaze layer.
Earthenware whose body has a opaque tin glaze applied to it. Can also be referred to as tin-enameled, tin-glazed, majolica, faience, or delft.
Crizzling (Crisseling)
A network of fine cracks/fissures and flaking (sometimes called "surface crazing") that creates decreased transparency on the surface of glass. When crizzling is severe, the glass appears cloudy and damaged areas may crack away from the body of the item entirely.
An undesired signal that interferes with the desired signal, usually caused by unintentional capacitive (AC) coupling. Can result in several types of picture distortion, mistracking, and/or noisy picture. Also refers to signal interference from one part of a videotape to another (Bay Area Video Coalition, 2009).
A hard layer formed on the outside of something. On museum objects, the surface of an item may develop hard and discolored outer layer as the result of a chemical reaction to air pollution, water, or other damaging elements.
Cupriferous pigment/ink
Pigment that contains copper, commonly blues and greens. Conventionally used as a coloring agent in illuminated manuscripts and maps.


Daisy wheel printing
Impact printing technology used in electronic typewriters, word processors and computers from the early 1970s-1980s. Daisy wheel printers were regarded for their crisp, high-quality text. Like other impact printing technology, though, daisy wheel printers were superseded by the laser printer.
Data logger
Electronic or battery-powered instruments that record environmental conditions such as temperature, relative humidity, and light levels over periods of time. Data loggers are connected to a computer terminal and proprietary software is used to download the recorded data and produce needed reports (Nebraska State Historical Society, n.d.).
The process by which an archives, museum, or library permanently removes accessioned materials from its holdings.
NOTE: Materials may be deaccessioned because the repository has changed its collections policy and the material is no longer within its scope. Materials may also be deaccessioned because they have been reappraised and found to be no longer suitable for continuing preservation. Materials that are badly decomposed and beyond repair may be deaccessioned. Deaccessioned material may be offered back to its donor, offered to another institution, or destroyed. Also called permanent withdrawal (Pearce-Moses, 2005).
Deed of gift
An agreement transferring the title to property without an exchange of monetary compensation.
Separation of individual layers, a flaking or peeling away of component layers e.g., separation of emulsion from the glass base in photographic plates.
Deterioration (of tape)
The degradation of tape, most typically with the binder, which is responsible for holding the magnetic particles on the tape and facilitating tape transport. If the binder loses integrity—through softening, embrittlement, loss of cohesiveness, or loss of lubrication—the tape may become unplayable. Sticky tape and sticky shed syndrome are commonly used terms to describe the phenomenon associated with the deterioration of the magnetic tape binder (Bay Area Video Coalition, 2009).
Developing-out paper (DOP)
A photographic paper which forms a visible image through the use of a chemical developer to reveal the latent image made by exposure to light. DOP prints are cool in color—blue, neutral, or black—unless they have been toned. They may be either contact-printed or enlarged from a negative.
Diazo (microform)
A microfilm duplication process intended for service copies. Unlike silver-gelatin microfilm, diazo is not regarded as preservation quality, though it is capable of producing color. Diazonium salts in the film emulsion combine with dye couplers to produce strong, dense colors. May be on either an acetate or polyester base.
Representing information through a sequence of discrete units, especially binary code.
NOTE: "Digital" is distinguished from "analog," the latter representing information as a continuous signal. Often used as a synonym of automated, computerized, electronic, or the prefix e-. "Digital" and "electronic" are often used synonymously, although "electronic" may include analog as well as digital formats (Pearce-Moses, 2005).
Digital preservation
The process of maintaining, in a condition suitable for use, materials produced in digital formats, including preservation of the bit stream and the continued ability to render or display the content represented by the bit stream. The task is compounded by the fact that some digital storage media deteriorate quickly ("bit rot"), and the digital object is inextricably entwined with its access environment (software and hardware), which is evolving in a continuous cycle of innovation and obsolescence. Also refers to the practice of digitizing materials originally produced in non-digital formats (print, film, etc.) to prevent permanent loss due to deterioration of the physical medium (Reitz, 2007).
The process of transforming analog material into binary electronic (digital) form, especially for storage and use in a computer. The word "digitized" distinguishes materials that have been transformed from the media in which they were created from materials that are born digital. Digitization is distinguished from "data entry," which is the process of typing textual records, often in forms designed to facilitate the process, into a computer system.
Digitization may start with information that is in electronic or physical form, for example magnetic audio tape or phonograph discs. Digitization of textual documents typically produces an image of the words, which must be transformed into character data through a process of optical character recognition (OCR). In some instances, the OCR process may preserve text and page formatting (Pearce-Moses, 2005).
Direct positive
A class of photographic materials that are one-of-a-kind objects, developed directly onto support material with no separate negative. Direct positives include Daguerreotypes, Ambrotypes, and Tintypes.
A term used to signify the resolution of ambiguity existing between related subjects in a given category.
Disaster plan (Disaster recovery plan)
The policies, procedures, and information that direct the appropriate actions to recover from and mitigate the impact of an unexpected interruption of operations, whether natural or man-made (Pearce-Moses, 2005).
Are round "game stones" that were used in the ancient Native American game known as chungke or chunkey.
A shift in the original or desired color. This may be a localized or uniform change, a fading, darkening, yellowing effect.
Alteration of the original or desired shape of an object. In the case of 2-dimensional items (paper, photo), the uniform flatness has been altered by warping, bending, twisting.
A written, drawn, or printed archival material.
Drafting cloth
Support material commonly found in architectural collections. A flexible, durable alternative to wood pulp and rag paper used primarily by architects and engineers for working drawings and reprographic prints (e.g. blueprints, diazotypes). The fabric is typically cotton or linen, starched and calendered to create a smooth drawing surface.
Drafting film
Plastic drafting film was the preferred support for large-scale technical drawings from the 1980s-2000s (Lowell & Nelb, 2006). Drafting films will have a matte finish on one or both sides, which gives the surface "teeth" to accept media (pencil, ink) or emulsion. Like other translucent supports, drafting film may be used alternately for original drawings or as a reproductive intermediate. Film composition maybe either acetate or polyester (or Mylar).
Dub (noun)
A copy of a video recording; (verb) to make a copy (Bay Area Video Coalition, 2009).
The copy of a master used for making additional copies (Bay Area Video Coalition, 2009).
A form of glass deterioration or weathering in which the previously transparent surface layer becomes cloudy. Weathered glass is extremely fragile and should be not be handled unless completely necessary.
Dummy tape
A test item that has no value to your collections, which can be used to test playback equipment.
Duplication (process)
In terms of reprography, duplication refers to the reproduction of virtually limitless copies from a master. This includes printing processes. Since the emergence of digital printing, the distinction between a duplicate and copy has become less clear as hardware and software utilize and blend both.
DVD (abbreviation for Digital Versatile Disc)
There are a number of different types of DVDs, which include DVD-R, DVD-ROM, DVD-RAM, DVD+RW, and DVD-RW. DVD is not a suitable archival format for video, mainly because it uses a lossy form of compression (MPEG2). It is also a format that is likely to see rapid changes in technology, which makes the risk of its obsolescence very high. DVDs are made up of a reflective aluminum layer, a polycarbonate substrate, a dye layer, and a clear lacquer layer. While the aluminum layer is highly susceptible to pollution, the lacquer layer does not sufficiently protect it from oxidizing. Double sided DVDs are bonded using an adhesive—the life expectancy of which is unknown. A DVD is the same diameter as a CD (120cm) but cannot be read by the same equipment. DVDs and CDs both encode data as tiny pits in tracks that correspond to the zeros and ones of binary digits. A laser reads and plays back the information encoded on the pits. DVDs are able to store more data than CDs by making the pits smaller, the tracks closer together, and by compressing the data using MPEG2. DVD-R discs were introduced in 1997 with a 3.95 GB capacity and a track pitch of 0.8 microns; the capacity was later increased to 4.7 GB by reducing the track pitch to 0.74 microns.
Many artists now use DVD-R as an exhibition format, which has replaced laser disc as a popular display format for many museums and galleries. However, because of the way the data is encoded, it cannot achieve frame accurate control to reference the picture content (as it can with laser disc). Where external control is needed for display, it is important clarify any specific requirements of the control system before having the disc(s) made.
There are two types of DVD-R discs: "General" and "Authoring." This has caused some compatibility issues, as the lasers in the discs' players need to be angled differently. Professional DVD players will have both lasers; however if you are using a domestic model, it is important to check which discs your player is compatible with. This is also true for all other types of discs. DVD is a rapidly developing technology and there is a continued push to increase the amount of data that can be stored on a disc (Bay Area Video Coalition, 2009).


A type of low-fired ceramic that is generally fired between 1742-2012?, earthenware is not vitrified and is the most porous of fired ceramics.
A wave which has been reflected at one or more points in the transmission medium. Echoes may lead or lag the primary signal, and appear in the picture monitor as reflections or double images, commonly known as ghosts (Bay Area Video Coalition, 2009). Related Terms: Pre-echo; Post-echo.
Edge curl
The curling of the edges of videotape, usually on the outside one-sixteenth inch. If the tape is sufficiently deformed, it will not make proper contact with the playback heads. An upper curl (audio edge) may affect sound quality. A lower curl (control track) may result in poor picture quality (Bay Area Video Coalition, 2009).
A powdery white film or hard white crust that can form on the surface of porous materials that have been buried. Porous stone or ceramics will absorb soluble salts when buried or exposed to the elements. Those salts can rise to the surface of the item, leaving behind salts (in the form of a white film or crust) once water evaporates.
Elastic substance, occurring as natural rubber, or produced synthetically as butyl rubber or neoprene.
Electrostatic printing
Printing and copying method in which the image is carried electrostatically. Examples include Xerography, Laser printing, and Electrofax.
Structural degradation of a support material, making it brittle or fragile. This is usually a result of fiber decomposition (as a result of acidic components), aging, or oxidation.
The image-forming layer of photographic films, papers, and plates. For most photographic processes, this refers to both the image material (e.g. silver particles) and the binder in which it is suspended (e.g. albumen, collodion, or gelatin). Throughout the 20th century, the most common was the silver halide emulsion.
A treatment or display method in which a single sheet or thin pamphlet item is sealed between two sheets of polyethylene polyester film, which helps to protect and structurally support objects.
See Slip.
Electro Plated Britannia Metal
Electro Plated Nickel Silver
Epoxy Resin
An adhesive, plastic, paint, or other material made from a class of synthetic thermosetting polymers used chiefly in strong adhesives and coatings and laminates.
Exercise (a tape)
The periodic rewinding and fast-forwarding of tapes in good condition for preservation purposes.


Fading (image)
A decrease in image density resulting in overall loss of tonal value. Most photographic materials are subject to image fading due to a number of factors. Light exposure, chemical reaction between compositional elements (hurried by poor storage conditions) external chemicals or atmospheric pollutants. The destructive results of these factors may be partial or evident all over the photograph. Usually the tone of the image will be lightened and there may also be a change of color, but not a uniform color shift.
Fair Use
A provision in copyright law that allows the limited use of copyrighted materials without permission of the copyright holder for noncommercial teaching, research, scholarship, or news reporting purposes (Pearce-Moses, 2005).
A rock-forming mineral that usually appears as a colorless or pale-colored crystals and consisting of aluminosilicates of potassium, sodium, and calcium.
Ferric salts
Iron salts that, in combination with tannic acids, comprise iron gall inks.
Ferriferous ink
See Iron gall ink.
When gelatin absorbs moisture and touched against another material, the gelatin surface will take on its surface characteristics. This effect was often implemented to deliberately smooth or finish photo print surfaces but might also cause gelatin emulsions to lift and adhere to other materials.
Fiber-based print
Designation for photographic paper supports "carrying" photographic gelatin emulsion. This is the classical paper support, as opposed to the later resin-coated photo paper. May be directly sensitized or baryta coated; baryta is more common—generally smoother and more chemically stable. The term "fiber-based" became common only after the late 1960s, when it became useful to distinguish between it and the new resin-coated paper.
A substance added to paper during time of manufacture intended to create a smooth and shiny surface. Today, paper fillers are typically used in high quality photo or art book applications.
A generic term for a flexible strip of cellulose (usually nitrate, acetate or polyester) that contains audiovisual material that can be played back on a projector. Motion picture film has perforations along its length by which it is driven through a camera, projector, or other apparatus. One side of the film is coated with a layer of light sensitive emulsion or a magnetic coat. The record on the film may be a photographic image, sound image, magnetic sound, or a combination of these (National Film and Sound Archive, 2008).
Finding aid
1.) A tool that facilitates discovery of information within a collection of records.
2.) A description of records that gives the repository physical and intellectual control over the materials and that assists users to gain access to and understand the materials (Pearce-Moses, 2005).
The act of baking ceramics, often in a kiln (See Kiln) .
A horizontal displacement of the upper portion of a picture. Also called skewing (Bay Area Video Coalition, 2009).
A sedimentary rock that is tough and hard (difficult to break or scratch), and very resistant to weathering. Flint and chert are often used for weaponry and tools because they have sharp edges when broken.
Quality of a material that, when exposed to light, radiates light of another color. For instance, mold may radiate light in a wide range of colors when viewed under UV radiation; some magenta dyes will also fluoresce orange under UV; transparentizers in some tracing papers also cause a fluorescent surface quality.
Flux Material
Fluxes, such as soda, mica, potash, and lime, are used in glazes to lower the temperature at which a ceramic needs to be fired.
Measurement of the light cast on a surface by a one-candela source one foot away. As a light measurement, the foot-candle has been used primarily by U.S. lighting industry and is often criticized as imprecise.
The physical presentation of an item (Miliano & IASA, 1999). For examples of formats, please use our Collection ID Guide.
Formic Acids
A type of acid that can cause corrosion on lead and lead alloys.
A type of paper staining characterized by blotchy, reddish-brown (rusty) flecks. They may appear uniformly over the surface, or will be situated in clusters. There are two subcategories of foxing: "bullseye" (small and round, dark center) and "snowflake" (larger, irregularly shaped blotches). The exact cause(s) are not well understood, but is associated with metal impurities in paper and is precipitated by high humidity (Reilly, 1986). Other forms are categorized as a form of mold staining.
Frame package
Complete display frame package may include the item displayed, mounting board, backing board, dust cover, window mat, glazing (i.e. glass), and frame itself.
Insect droppings consisting of undigested paper fibers.
Friable media
Refers to writing/drawing materials that are made up of small particles which may easily come loose from the paper or other support material. Examples of friable media include pastels and flaking paint.
A powdery mixture of granulated silica and fluxes that is fused at high temperature to make glass and glazes for ceramics.
A network of small cracks on the surface of glass that look like frost on a window pane. When frosting is advanced, moisture in the cracks may be the only material holding the glass together. Glass with frosting deterioration is very susceptible to cracking and breaks.


The width of motion picture film from edge to edge, expressed in millimeters (e.g. 35mm, 16mm, 8mm) (NFPF, 2004).
A protein obtained from naturally occurring collagen. Used as a binder for the image layer of photographic materials.
A precious or semiprecious stone, especially one cut, polished, and used in a piece of jewelry.
A copy of the original media. The original tape or film (source footage) is the first generation. A copy of the original is the second generation, and so on. Generally, the edited master tape is a second generation tape. In analog systems, extensive effort is made to keep generations to a minimum, since each copy or process adds noise and other artifacts, resulting in diminished quality (Bay Area Video Coalition, 2009).
Generational loss
Degradation caused by tape duplication (Bay Area Video Coalition, 2009).
A shadowy or weak image in the received picture, offset either to the right or to the left of the primary image. It is the result of transmission conditions where secondary signals are created and received earlier or later than the primary signal and is caused by a reflected RF signal (Bay Area Video Coalition, 2009).
An inorganic, amorphous solid material. The primary component of glass is called a former (most often silica), which is then combined with a flux material (such as soda or potash), stabilizer material (like calcium carbonate), and modifier material (like magnesium). Glass is found in many forms, both utilitarian and decorative, and while it is generally transparent, it can also be translucent, opaque, and/or colored.
Glass deterioration
Degradation of glass supports caused by exposure to high humidity. May result in a hazy appearance or layer separation in photographic glass plates.
Glass Pressing
A glass construction method during which a blob of molten glass is placed into a mold and pressed into the correct shape by a plunger or "follower".
Glassine paper enclosures/sheets are commonly found in archives, though are effectively banned due to the high probability of their containing rosin sizing (causing acidification), volatile adhesives (fading), and plasticizers. Water exposure will cause the glassine paper to adhere to photo emulsions. Glassine has a very glossy surface and is produced through the imitation parchment process.
Glazes are thin, glassy, vitrified layers on the surface of a ceramic object.
Glossy (photo)
Gloss, or high surface sheen, defines the print density scale. The higher the surface gloss, the greater possible range of tones in the print.
Glue Chipping
A surface treatment for glass in which fern- or frost-like patterns are created by applying hot animal glue to the sandblasted surface of clear glass. As the glue dries, it shrinks, which removes or "chips" flakes of glass from the surface.
When pure, gold is yellow, non-magnetic, and soft, making it easy to manipulate. Gold does not tarnish, however some gold alloys can tarnish. Pure gold is also resistant to corrosion. Gold and its alloys are used in jewelry, ornaments, coins, gilding/goldleaf, dental repairs, circuit boards, architecture, engineering, and medicine. The kind of metal sulphide produced in the corrosion and the extent to which the object will corrode is dependent upon how much gold is present in the mixture and what the other metal in the mixture is. Alloys are typically produced to increase gold's durability.
An igneous rock ranging in color from light pink to dark grey, with visible grains.Granite is hard, but it can be susceptible to blistering, spalling, staining, fracturing, and efflorescence if exposed to detrimental conditions.
Green Gold
Anatural alloy of gold and silver. Also called "electrum".
The cut, embossed, or pressed channel in a recording medium (i.e. cylinder, disc, film) that carries the encoded signal. Such a groove may be blank (unmodulated), recorded (modulated), or a combination of both. A cut recording contains only one groove cut or embossing, spirally from the beginning to the end of the item, but it is more common to refer to this groove in the plural: grooves. See also Coarse groove; Microgroove (Miliano & IASA, 1999).
Grooved-disc audio
An analog recording format composed of a disc of varying material (shellac-type resins, plastics, etc.) that contain information encoded in grooves. The grooves are channel cut, embossed, or pressed into a recording medium (i.e. cylinder, disc, film) that carries the encoded signal. Such a groove may be blank (unmodulated), recorded (modulated), or a combination of both. A cut recording contains only one groove cut, or embossed, spirally from the beginning to the end of the item, but it is more common to refer to this groove in the plural: grooves (Pearce-Moses, 2005). Discs may be of the older coarse groove type or microgroove. See also Coarse groove; Microgroove.
In architectural drawings this refers to the background color of the image. Often this is not the same color as the paper support, but instead is a layer of pigment, paper coating, or a color change from chemical reactions as a result of the printing process. For example, in one of the most common types of architectural prints, Blueprints have a Prussian blue ground.
Ground stone
A common type of archaeological stone, ground stone tools are usually made of basalt, rhyolite, granite, or other cryptocrystalline igneous or granitic rocks whose structure makes them ideal grinding tools. They were commonly used for making stone axes, manos, metates, and gaming pieces called discoidals or chunkey stones.
Form of paper characterized as low-quality due to at least 10% of the pulp content being composed of short-fibered mechanically-ground wood. Lignin and acidic resins are not removed and ultimately cause the paper product to yellow and become brittle. Along with alum-rosin, groundwood is identified as a primary culprit in structurally weak paper structures of the early 20th century.
Gum Arabic Binder
Gum arabic, also known as acacia gum, is a natural gum made of the hardened sap of various species of the acacia tree.
Gummed adhesive
Adhesives activated, i.e. rendered sticky, through the application of moisture, typically with water or saliva. Moisture can often reactivate adhesive and allow for the removal of the carrier (e.g. cloth or paper tape). Water-based adhesives are typically starch-based or animal glue-based and include "gummed" tape and some postage stamp adhesives.
In terms of a book, this refers to the inner margin, or the white space between the printed matter of the two pages.
A soft white or gray mineral consisting of hydrated calcium sulfate. It occurs chiefly in sedimentary deposits.


Quality of a photomechanical image produced through a screen. Half-tones simulate a range of tones by breaking an image into a pattern of some kind (lines, dots, grid).
Additive color method commonly used to "enhance" monochrome images. Hand-coloring meant the manual application of water colors, paints, or aniline dyes to the surface of a B&W photograph, slides/transparencies, even direct positives. Hand-colored images can be identified by their saturated, unnaturally bold colors, and sometimes selective coloring. Not to be confused with tinted paper.
Hardbound (or Hardcover, Hardback)
Type of book bound with a rigid protective cover/case. The cover is typically paper board (or wood), covered with cloth, treated cloth (e.g. buckram), leather, or heavy paper. Hardbound volumes may have sewn spines or glued spines. See the Bound/Book profile in the Collection ID Guide for more.
Harmful enclosure
Folder, envelope, sleeve, box, or other container that contributes to collection material degradation.
Acronym for Hazardous Material.
Magnetic pickup device in a magnetic tape player (audio or video) used to record, erase, or reproduce video and audio signals (Bay Area Video Coalition, 2009).
Head clogging
The accumulation of debris on one or more heads, usually causing poor picture quality during playback. Clogging causes dropout (Bay Area Video Coalition, 2009).
Helical scan
A method of recording video information on a tape resulting in recorded parallel tracks that run diagonally across the tape from one edge to the other (Bay Area Video Coalition, 2009).
Hollow Cast
A molded method of construction for ceramics where a plaster mold is allowed to absorb the slip and once the cast is dry, it is trimmed and allowed to dry.
Acronym for Heating, Ventilation and Air Conditioning.
Damaging chemical reaction of a compound with water. Acid hydrolysis plays a large role in the degradation of paper. Acid within paper reacts with moisture (from humidity in the environment or water exposure), causing fiber molecules to break, weakening and embrittling the paper. In leather, sulphuric acid forms and catalyzes hydrolysis of the collagen, weakening the leather by breaking down the molecular chains within it (NEDCC, 2006).
Ability of a material/substance to attract, absorb, retain, and release water molecules to/from the environment.
Ability of a material/substance to attract, absorb, retain, and release water molecules to/from the environment.
A device for recording atmospheric humidity and temperature over time (Pearce-Moses, 2005).


Igneous rocks
One of the three geological classifications of stone, igneous rock is formed from cooled/hardened molten magma or lava. Igneous rocks are typically hard. They can be intrusive (forming underneath the surface of the earth; larger grains) or extrusive (forming above the surface of the earth; smaller grains). Examples: granite, basalt, and obsidian (volcanic glass).
Visible light incident on a surface.
Image fading
See Fading.
Inclusive dates
The dates of the oldest and most recent items in a collection, series, or folder (Pearce-Moses, SAA, 2012).
In terms of enclosure products, "inert" refers to materials that will not react chemically with your collection materials, e.g. uncoated polyester film and acrylic sheets.
Inert plastic (container)
An archival quality container generally composed of chemically stable plastic, typically polypropylene.
Inherent vice
The tendency of material to deteriorate due to the essential instability of the components or interaction among components (Pearce-Moses, 2005).
Ink corrosion
Form of damage associated with iron gall ink. Iron gall contains sulfuric acid that causes a paper or vellum support to disintegrate, and renders ink documents illegible over time by causing text loss, bleeding, fading, burn-through, strike-through, and acid migration. Corrosion is very difficult to stop without further loss or change to the appearance of the ink.
Ink jet printing
Printing method in which the image is transferred through tiny ink droplets. This is a digital printing method.
Intaglio printing
Printing method in which the inked image is transferred from a recessed surface onto the print surface. Examples include Gravures (Rotogravures, Photogravures).
Intellectual right
May be divided into industrial rights, which include patents, trademarks, industrial designs, and geographical indications, as well as copyright and related rights, which include the rights of reproduction, adaptation, distribution, exhibition, and performance, and moral rights (Pearce-Moses, 2005).
A rainbow-colored, shiny surface layer or layers, sometimes called a "degradation layer," resulting from exposure to moisture and often seen on archaeological/buried glass. When advanced, the iridescent layer(s) may flake off, along with the surface layer of glass.
Iron gall ink
Ink containing iron salts and tannic acids. Iron gall ink was the standard writing and drawing ink of the western world from the 5th to 19th century. There were innumerable recipes for iron gall ink, as it was often homemade, but the four basic ingredients include galls, vitriol, gum, and water. When fresh, ink appears purple-black or brown-black. As it ages (and corrodes), it browns further. Also known as iron gall nut ink or oak gall ink.
The International Standards Organization, in Geneva, Switzerland, which publishes internationally agreed-upon norms and best practices for a variety of industrial products and processes.
A physical resource that, in part, constitutes a collection. Often used interchangeably with "object."
The act of repeating; a repetition.


A furnace or oven for burning, baking, or drying, especially firing pottery
Kraft paper
Form of paper or paperboard (cardboard) produced from chemical pulp that is almost entirely cellulose fibers. This is a low-grade, utility paper; think packaging and base papers, e.g. brown paper sacks.


A common form of iron gall ink deterioration in which "the inked areas become so weak and brittle that they crack, crumble and fall out" resulting in a lace-like appearance (n.d., Iron gall ink).
Lacquer disc
A glass, metal, or fiber disk coated with acetate or cellulose nitrate (lacquer) used to make instantaneous sound recordings (Pearce-Moses, 2005).
Laid paper
Form of paper having a ribbed texture imparted by its manufacturing process. From the 12th century into the 19th century, laid paper was the predominant type of paper produced, until wove paper rose in popularity.
Most common black pigment used in oil-based printing inks; derived from soot, essentially. See Carbon black.
Lapis Lazuli
A richly colored, blue metamorphic rock often used as a gemstone. Often used in sculpture, jewelry, and decoration and, in a powdered form, as a pigment. Lapis Lazuli is typically soft, although it can be much harder depending on its precise mineral composition.
Layer separation
The partial or complete separation of a laminate into its constituent layers (See also Delamination).
It is a dull silver-grey metal that cannot be polished. It is non-magnetic and very heavy. It is soft and easily cast with a low melting point. Lead is toxic to humans when absorbed through the skin, when lead fumes are inhaled, and when it is ingested.
Lead glazed
A type of earthenware upon which a transparent lead glaze has been applied.
Blank film attached to the beginning and end of film rolls to facilitate handling. Sometimes used to separate short films or shots on a single film roll (NFPF, 2004).
The transfer of rights from the rights holder to another party, generally for a specific use, duration, and territory (NFPF, 2004).
A simple slow-growing plant that typically forms a low crustlike, leaflike, or branching growth on rocks, walls, and trees.
Life expectancy (LE)
A rating for the expected longevity of recording materials and associated retrieval systems.
A chemical polymer that, along with cellulose fibers, forms plants' cell walls and provides rigidity. Lignin is also the inherent vice substance left in wood-based (or straw) paper that causes yellowing and embrittlement. In archival paper products, the lignin has been removed through use of chemical solvents.
A term used to describe manufactured papers, boxes, and cardboards which are made from wood-pulp fibers that remain after lignin has been chemically removed.
A sedimentary rock often found with visible fossilized fragments and debris. It is typically grey but can also be white, yellow, or brown. A soft stone that is relatively easy to carve, limestone is easily scratched and not often seen in items or sculpture, but frequently used as a sculptural base. Particularly susceptible to weathering, erosion, cracking, chipping, efflorescence, and crumbling.
Lost-wax casting
It is a glass-making technique borrowed from metalworking. A model is created with wax and then encased in plaster or clay. When heated, the wax melts through vents in the plaster/clay. Once dry, this becomes a mold into which molten glass can be poured, pressed, or blown. Also called cire perdue.
A magnifying eyepiece used to identify materials (i.e. film, photos).
Lubricant loss
The loss of a component added to the magnetic layer of a tape to decrease the friction between the head and the tape (Bay Area Video Coalition, 2009).
Unit of luminous flux; measures total visible light emitted from a source.
Luminous emittance
The amount of light emitted from a source.
Unit of illuminance and luminous emittance; measures total illuminance or emission figured with the area over which the luminous flux is spread, luminous flux per unit area. This is equal to one lumen per square meter.


Magnetic media
Tape and discs that store information on a magnetized surface, such as videotape, audiotape or computer floppy discs (Bay Area Video Coalition, 2009). Related terms: Magnetic Audio, Magnetic Video.
Magnetic particles
The elements incorporated in the binder to form the magnetic layer (top coat) on a magnetic tape. The signal is recorded on these particles (Bay Area Video Coalition, 2009). Iron oxide, chromium dioxide, barium ferrite, and metal particulate are various examples of magnetic pigment used in commercial tapes (National Film and Sound Archive, 2008).
Magnetic shedding
Degradation of the binder of magnetic tape, which results in loss of magnetic oxide particles during storage or playback.
Magnetic sound track
Motion picture sound track in which the sound information is carried by magnetic oxide. Magnetic sound track can be affixed as a stripe along the film edge or exist as a separate element (full-coat mag). Often shortened to magnetic track, mag track or magnetic (mag) stock (NFPF, 2004).
Magnetic tape
A flat, thin strip of material either capable of being magnetically charged, or coated with particles capable of being magnetically charged. Used for recording analog or digital data. Magnetic tape is stored on reels, cassettes, and cartridges (Miliano & IASA, 1999).
Manifold copy paper
Lightweight paper used with carbon copy paper to make multiple copies.
Item that has been written by hand, as opposed to printed or reproduced in some other way. In a publishing or academic context, a manuscript is the text submitted for publication, regardless of format.
A hard and heavy metamorphic stone with limited porosity. Found in a wide range of colors, from white to black, including green, red, and gray. Often polished and used in sculpture and for decoration.
A fiberboard composed of wood chips or other cellulose fibers bonded with glues/resins and compressed into thick, rigid sheets. Masonite (or hardboard) was often used to mount presentation prints, drawings, and photographs. These items were often mounted with volatile adhesives.
Source (document, record) by which multiple copies can be reproduced. In many cases, the master document must be of a specific format in order to be duplicated.
Master (tape)
The earliest generation of a finished tape, which should also be of the best quality. Masters should not be used as exhibition tapes, i.e., not for repeated playback. See also Dubmaster (Bay Area Video Coalition, 2009).
Master disc
A finished disc recording in edited or approved form from which copies can be made in the recording production process. It is used to produce a reverse copy or metal matrix, which has ridges instead of grooves that are then used to stamp copies in the single-step process, or to produce a metal mother in the three-step process (Miliano & IASA, 1999).
Mat burn
"Burned-in" discoloration of paper/image edges that have been in contact with an acidic mat.
Matte (photo)
Matte papers are characterized by an absence of surface sheen, reflecting no light, and have a relatively limited scale of image densities. Photographs with neither an intermediate or binder layer (1-layered), and digital prints on uncoated paper, will possess a matte surface.
Mechanical adhesion
Form of damage characterized by torn or frayed parts of an object are stuck together as a result of mechanical damage or wear.
Metals are naturally occurring elements found in the Earth's crust. They typically are not found in their pure forms, but rather as sulfides and oxides. Their distinct properties have made them useful for a variety of purposes. The term "metal" is used to describe any material with metallic properties. In their use by humans, metals have been mixed into alloys in order to make them better suited to particular uses. As such, many alloys are typically called "metals," even though they may also contain non-metal elements.
Metamorphic rock
One of the three geological classifications of stone, metamorphic rock forms when sedimentary or igneous rocks have undergone transformation through heat or pressure, or both. Metamorphic stone can be hard or soft; largely dependent on the "parent" structure (whether it come from sedimentary or igneous rock). It has low porosity and is resistant to weathering. Examples: marble and slate.
1.) A generic term indicating any form of small grooved item.
2.) A groove, usually on a disc or a cylinder, with nominal width at the top, or widest part of the groove, of 3mm.
3.) A type of disc audio recording having 200 to 300 or more grooves per inch, suitable for reproduction by a stylus having a tip radius of 1 mm or less. Four minute cylinders and LP recordings are microgroove, as opposed to coarse groove for two minute cylinders and discs replayed at the generic 78 rpm speed (Miliano & IASA, 1999). See also Coarse groove; Groove.
See Redox blemishing.
Migration, or Re-mastering, Transferring
Refers to the process of copying the content of an existing videotape to new media (Bay Area Video Coalition, 2009).
Italian for "thousand flowers," this method of glass construction involves the rolling together of long, thin (and typically multi-colored) rods of molten glass. These multi-colored rods or canes are then cut into small, round pieces called "murrine." Murrine are sometimes used as beads in jewelry or melted together to achieve bright, colorful patterns.
Mission statement
The basic purpose or role of an organization, expressed succinctly in abstract terms. A clearly written mission statement is the basis for formulating achievable goals and objectives in strategic planning and serves as a constant reminder of the organization's primary reason for existing. A well-written mission statement can also serve as an inspiration, especially under trying circumstances, and keep an organization from straying too far from its primary purpose(s) (Reitz, 2007).
Fungus that grows on polymer or organic materials exposed to high humidity; causes material degradation, and in most accelerated cases, irreversibly damaging.
Monochrome photograph
Includes all intermediate shades of gray-black. Most images (colloquially) referred to as black-and-white (B&W) are actually of tonal ranges fitting into one of several monochrome hue distinctions, e.g. purplish black, sepia, chocolate brown, reddish brown, etc.
Mouth Blowing
In glass blowing, blobs of molten (around 2400°F or 1316°C) viscous glass are gathered onto the end of a pre-heated blowpipe. The glass is then rolled onto a flat sheet of steel or marble called a "marver," which helps to shape the item. Next, air is blown into the glass, creating a bubble that can be increased, decreased, or to which additional glass can be added to form the piece.
A type of unfired ceramic, mudbrick is often made of a mixture of clay, sand, and silt (with fibrous materials added to prevent cracking) that is dried and then shaped
Multi-colored glass rods or canes are then cut into small, round pieces, and often used as beads in jewelry.
A cotton fabric of plain weave. Muslin is often a book cover fabric.


Visual artifact carrying the reverse image of the image (or motion picture) subject. Typically the negative is though of as an intermediate artifact produced in service of the final positive image. Dark image areas of the negative become light image areas of the positive, and vice versa. The negative is often exposed in the camera or created from a positive in the laboratory. It is printed to produce a positive for projection and viewing (NFPF, 2004).
In terms of the pH scale, "neutral" refers to materials that have a pH reading of 7.0 (and relatively close to it). Unbuffered paper is manufactured with a neutral pH level, neither acidic or alkaline. This does not ensure, however, that this paper will not become acidic over time.
It is silvery-white, hard metal that is resistant to corrosion. It is magnetic and often mixed with other metals to create special alloys, some of which are corrosion-resistant. Nickel is commonly used in coinage.
A transparent plastic base that was used for photographic film. Obtained from the treatment of cellulose with nitric acid. Highly flammable, nitrate based film was phased out by the early 1950s (NFPF, 2004).
Nitrate decay
Degradation of cellulose nitrate film base that may cause yellowing, buckling, film distortion. Can also cause gelatin binder to become soft or sticky or to disintegrate.
Nitrile gloves
Highly puncture resistant protective gloves made of a synthetic latex.
Any unwanted signal present in the total signal (Bay Area Video Coalition, 2009).
Noise reduction
A system for reducing the effect of background noise introduced in recording and transfer systems (National Film and Sound Archive, 2008). Circuits, systems, and/or a combination of the two designed to reduce subjective noise generated or added by the recording or transmission system on/in sound and/or picture quality (Miliano & IASA, 1999).
Acronym for National Television Systems Committee. The U.S. standard for color television transmission, calling for 525 lines of information, scanned at a rate of 30 frames per second. NTSC standard is used mainly in North America, Japan, and parts of South America. One of three international standards, including PAL and SECAM (Bay Area Video Coalition, 2009).


See Optical Brightening Agent.
An element that, in part, constitutes a collection. Often used interchangeably with "item."
An extrusive (forming above the surface of the earth; smaller grains), nonporous igneous rock. Obsidian is considered "volcanic glass" because it shares many of the same attributes as man-made glass. The most well-known form of obsidian is black and shiny, but it can be green or brown.
The tendency of some materials, e.g., acetate and nitrate film bases, to give off harmful vapors as they decay.
Onionskin (paper)
Thin paper support implemented primarily to receive an impression by way of carbon copy paper used in a typewriter. The paper is lightweight, often translucent and is best characterized by its white or canary-colored "onionskin" appearance. Surface is unglazed and has a cockled texture.
Ability of light to pass through a material. A low opacity film or tracing paper may be called translucent, and a material that allows no noticeable level of light to pass through it may be called opaque.
Optical Brightening Agent
OBAs are used to make paper appear more bright. Fluorescence produces a higher contrast for printed matter. Coloring/brightening agents added to papers (internally or as a coating) may not be lightfast, and can lead to faded, yellowed, or brittle paper.
Optical sound track
Photographically printed sound record carried on the film print or produced as a separate element (NFPF, 2004).
The earliest generation of an audiovisual medium; the initial manifestation of something; a thing from which copies are made, especially a prototype. NOTE: Originals are considered to be the most authentic form of a document, based on the assumption that any copy involves some loss of fidelity (Pearce-Moses, 2005).
See Off-gas.
Chemical reaction of an element with oxygen, typically. Oxidation requires an oxidant, such as oxygen in the air, ozone, or pollutants such as nitrogen oxide. UV light may also activate these oxidants.
Oxidation (paper)
Causes paper to weaken, and oxidation of lignin plays a role in the darkening of low quality wood-pulp paper. Metal particles present in paper and/or inks can also oxidize, producing acids that degrade the paper through hydrolysis.
Oxidation (silver)
Silver image particles undergo a chemical and physical change, causing silver (photo images) to fade. Throughout oxidation, image highlights gradually become lighter while dark areas of the image turn from gray-black to brown. Oxidation is caused largely by the relative humidity of the storage environment. Temperature also contributes, but humidity and moisture are the primary causes of silver-image oxidation.


Pack slip
A lateral slip of select tape windings that cause high or low spots (when viewed with the tape reel lying flat on one side) in an otherwise smooth tape pack. Pack slip can cause subsequent edge damage when the tape is played, as it will unwind unevenly and may make contact with the tape reel flange (Bay Area Video Coalition, 2009).
A thin support material comprised of cellulose fibers (e.g. cotton, linen, wood). As a collection material, paper comes in many forms (sheets, roll, book, etc.) and is commonly used as a "vehicle" of information, typically written or printed content. Paper production may be mechanical or handmade. Stability of the material will vary to extremes, and is determined by numerous aspects of manufacture, not necessarily by the source of the fibers (Erhardt & Tumosa, 2005).
General term used for animal skin (often calf, goat, or sheep skin) which has been prepared as a writing or printing surface.
Pate de Verre
A glass construction method in which frit (a mixture of granulated silica and flux materials) is mixed with gum arabic binder to form a paste, which is then pressed into a mold and fired.
It is the visible product of the chemical reaction that appears as a coating on the surface of a metal object.
Pellet print
Architectural reprographic format that appears essentially as a reverse blueprint, a positive image, blue lines on a white ground. Like a blueprint, this is a wet process that sees a sensitized paper (or cloth) support exposed to UV light. In terms of preservation, pellet prints should be stored in the same fashion as blueprints.
Perforations (film)
See Sprocket holes.
An alloy of tin with antimony and copper. It can be cast easily and is often used to make jewelry, dishes, vases, and trophies. Older pewter can sometimes contain lead.
A measure that defines the alkaline or acidic nature of a material. The pH scale ranges from 0 to 14. A pH of precisely 7.0 is neutral; below 7.0 is regarded as acidic; above 7.0 is regarded as alkaline or basic. A desirable pH for paper ranges from 6.5 to 8.5.
Photographs produced without a camera, usually by placing an object directly on sensitized paper and exposing it to light. Objects rendered in the resulting image will likely be to scale.
Photographic Activity Test
Also referred to as the PAT, this is a test intended to evaluate chemical or photographic interactions between enclosure materials and photographic images, as described in ISO 14523.
Refers to a class of printing processes for photographic images. The image is comprised of ink and is not formed by the exposure to light. Most mechanical prints will be composed of some halftone pattern. Photomechanical prints are essentially ink on paper, which generally makes them more stable than most photographic materials. Examples processes include the Letterpress Halftone, Offset Lithograph, Collotype, and Woodburytype.
Pigment is a natural colorant in many inks, toners, and media. Pigment influences the color and light stability. Pigments, as opposed to dyes, are considered stable and resistant to light fading. Black pigment (carbon black) is exceptionally strong.
Pipe (as in "to pipe light")
To shine light through the back of a film pack; if the pack seems to "glow," it is piping light. This procedure is often used to distinguish polyester film from acetate film.
Occurs to ceramics when the firing temperature is increased or decreased too quickly (so volatile materials don't have a chance to completely escape before the glaze solidifies). Pitting can also happen if the glaze is fired at temperatures that are too high (boiling the glaze).
Planographic printing
Printing method in which the inked image is transferred from a flat surface onto the print surface. Examples include Lithographs and Collotypes.
A sheet, containing oriented particles, that transmits light that vibrates in only one direction.
Polyester is a generic term used for inert polymers. A transparent plastic base for photographic film and magnetic tape that is composed of a polymer of ethylene glycol and terephthalic (or naphthalene dicarboxylic) acid. It is very strong and stable. Uncoated polyester is often recommended as an enclosure and encapsulation material.
Polyester film
The toughest and most chemically stable safety film base used today (NFPF, 2004).
A tough, light, flexible synthetic resin made by polymerizing ethylene, chiefly used for plastic bags, food containers, and other packaging. Considered a safer alternative to plastic as a material for foam, sheeting, and other storage and handling materials in museums, libraries, and archives.
Popped strand
A strand of tape or film protruding from the edge of a wound tape pack (Bay Area Video Coalition, 2009).
Porcelain is a hard, vitrified high-fired ceramic with a fine-grained, white, translucent body. It is totally non-porous and impervious to water even when left unglazed. The main ingredient of porcelain is a fine-grained clay called kaolin, which can be molded easily and formed into delicate and complex structures.
Method of storing flat items (i.e. loose papers) between two sheets of cardboard. Typically this done by tying two sheets of cardboard close.
Preservation copy (or Archive copy)
The artifact designated to be stored and maintained as the preservation master. Such a designation may be given either to the earliest generation of the artifact held in the collection, to a preservation transfer copy of such an artifact, and/or to both such items in the possession of the archive. Such a designation means that the item is used only under exceptional circumstances (e.g. to prepare a dubmaster) (Miliano & IASA, 1999). See also Access copy (Reference copy); Dubmaster.
Preservation plan
A document that specifies what an institution's preservation needs are and what steps the institution needs to take to address those needs with the resources it has.
Pressure-sensitive adhesive
Category of adhesive designed to adhere a backing (or carrier) of some kind (tape, sticker, postage stamp) to any variety of surfaces simply through the moderate pressure applied by a finger or hand, no heat or solvent necessary.
A fine-grain, high-resolution film with a characteristic curve designed for making contact copies. A negative film; film used to make prints rather than slides or transparencies (Pearce-Moses, 2005).
Printing-out paper (POP)
A photographic paper which forms a visible image directly from the reaction of light on light-sensitive materials. POP prints are warm in tone, tending towards a brown, purple, or reddish color. They are almost always made in contact with a negative.
The condition where low frequency signals on one winding of a tape imprint themselves on the tape windings immediately adjacent to it. It is most noticeable on audio recordings, where a ghost of a recording can be heard slightly before or after playback of the actual recording (Bay Area Video Coalition, 2009).
Processing (audiovisual material)
The laboratory procedures used to develop, fix, and print the latent image in exposed motion picture film (NFPF, 2004).
Something that is privately owned and controlled, usually by a person or commercial enterprise. The term implies that the specifications or authority needed to reproduce the thing are withheld from public knowledge or legally protected, usually by copyright or patent. In computing, a system, interface, program, or file available only by permission of the owner or author, as opposed to one that is open to use without restrictions (Reitz, 2007).
Record of origin, custody, or ownership of an item or collection, used as a guide to authenticity or quality. Documented source(s) and chain of ownership/custody are the focus in archives; the principle of provenance (or "respect des fonds") "dictates that records of different origins (provenance) be kept separate to preserve their context" (SAA).
Public Domain
Works not protected by copyright, or for which copyright has expired, which may be printed for distribution and sale, quoted, excerpted, reproduced, and made available online to the public without infringement (Reitz, 2007).
Pure alpha-cellulose
See Lignin-free.
PVA (Polyvinyl acetate)
A synthetic copolymer emulsion, PVA is generally viscous white or creamy yellow before use which dries clear. PVA is used in various craft, bookbinding and paper conservation applications. This adhesive class is perhaps the most common type of glue on the market as it is flexible, easy to use, and non-toxic. Bookbinders and conservators use acid-free PVA as a consolidant and as a glue in conservation treatments. PVAs offered by conservation suppliers are pH neutral, do not "off-gas" once dry, are believed to not break down over time, and are relatively light stable. This adhesive, however, is not easily reversible and is sensitive to moisture and humidity.
A nitrate cellulose plastic used in the coating or impregnation of book casing fabrics, i.e. buckram.


Book or pamphlet format comprising one or more full sheets of paper on which 8 pages of text are printed and then folded twice to produce 4 leaves. Each leaf of a quarto thus represents one fourth (a quarter) the size of the original sheet. Each group of 4 leaves could be sewn through the central fold to attach it to the other gatherings to form a book.


Rag paper
See Cotton paper.
Rainbow book standard
See CD standard specification.
Raised bands
Raised ridges in the spine covering that run across the spine of a bound volume.
Record protection tab
A piece of plastic that is either removed or slid into the "save" position in order to protect the video or audio cassette from accidental erasure or copying over while in its playback machine.
Front side of a sheet.
Redox blemishing
A symptom of silver image oxidation, redox blemishes are colloidal silver formations that appear as small yellow-orange sunbursts in the silver gelatin image. Redox blemishes are typical of all silver gelatin films (well-documented in microfilms) and are also recognized in resin-coated silver gelatin prints.
Reference copy
See Access copy.
Reformatting (or Remastering, Migration, Transferring)
The process of copying the content of an existing carrier to new media. The conversion of an item from one format to another without changing its content (Reitz, 2007).
Relative humidity (abbreviated as RH)
The amount of moisture (water vapor) held in the air, expressed as a percentage of the maximum amount that the air could hold at the given temperature.
Release print
The final version of a motion picture, intended for distribution to public audiences (NFPF, 2004).
Relief printing
Printing method in which the inked image is transferred from a raised surface. Examples include letterpress (and photomechanical halftones).
A term that encompasses copying and duplication processes. Refers to the production of a small batch of copies from an original (copying) or the reproduction of virtually limitless copies (duplicating). Since the emergence of digital printing, the distinction between the two has become less clear.
Resin-coated (RC)
A resin coating applied to the surface of photographic paper base to speed processing and drying. Absorbs almost no water during processing, speeding the washing and drying process.
Restoration (audiovisual material)
The reconstruction of a specific version of a film (NFPF, 2004).
Film that is run through the camera and processed to produce a positive image. Positive reversal film has no corresponding negative (NFPF, 2004).
Quality of an object alteration bringing no harm to the object and allowing the object to be returned to its original pretreatment state.
A hand-cranked or motorized geared device used in pairs to control the winding of film for inspection and for transfer from reels to cores (NFPF, 2004). Also, the process of winding a tape or film back to the beginning after it has been played to make it ready for the next use (Reitz, 2007).
See Relative humidity.
A lack of vertical synchronization, which causes the video picture to move upward or downward (Bay Area Video Coalition, 2009).
Rose gold
A gold and copper alloy. May also be called "red gold" or "pink gold" - depending on the intensity of the "red" coloring (which depends on the copper content in the alloy).
Rosin-alum sizing
See Alum-rosin sizing.


Safety film
The term applied to all film made with a nonflammable plastic base (NFPF, 2004).
A flaw that can occur when ceramics droop or become structural weak because firing temperature are too high.
A type of surface treatment in which designs are etched onto the surface of glass through a high-pressured stream of sand and air. The final results are similar to engraving, but bolder designs are possible through sandblasting.
A soft stone that is relatively easy to carve. In addition to often being used as a building material, it was also often used to abrade and sharpen wood and other objects. The surface of sandstone typically feels "sandy" as if it were shedding bits of sand.
One or more sheets grouped by a single together. Sections can be sewn together to form the text block of a book.
Sedimentary rock
One of the three geological classifications of stone, sedimentary rocks are formed by the layering of weathering products of other rocks or materials deposited in lakes or oceans. Sedimentary rocks like sandstone and limestone are typically soft.
Air bubbles that may be found in a layer of glass.
Semi-matte (photo)
Semi-matte photo paper is fine textured with only slight gloss. Its luminosity resembles that of a glossy print. Semi-matte is conventionally used for professional exhibition as well as amateur use.
Sewing structure
Structure of threads that assemble the sections of a book's text block.
The loss of stone in grains, pieces, or flakes due to excess pressure.
See Surface sheen.
"Matte" (no surface sheen), "semi-matte," and "glossy" (high surface reflection) are the primary distinctions among photographic prints. Intermediate terms such as "semi-gloss" and "lustre" are sometimes used. Variable surface gloss is also a common trait of early photographic prints, noticeable when viewed in angled light.
Sheet film
A single piece of flat (non-roll) film found in various formats, such as 4" × 5" or 5" × 7".
A type of ceramics deterioration that happens when the glazed surface contracts or shrinks at a rate slower than the clay body, causing the glaze to flake or peel.
The contraction of film from its original dimensions, caused by moisture and solvent loss (NFPF, 2004).
Shrinkage gauge
A device used to measure the extent to which film has contracted from its original dimensions. Compares the standardized distance between perforations with that of the shrunken film and expresses the difference as a percentage (NFPF, 2004).
Signal to noise ratio (S/N)
Expressed in decibels (dBs), this term describes a ratio or difference of wanted audible or visual information (signal) versus unwanted information experienced by distorted sounds and pictures (noise). Comparatively high decibel numbers mean better sound or visual images(Bay Area Video Coalition, 2009).
Silent film
Film made without a sound track. Also used to describe commercial motion pictures produced before the widespread adoption of sound film in 1929 (NFPF, 2004).
Silica Gel
Hydrated silica in a hard granular hygroscopic form used as a desiccant in order to reduce levels of relative humidity in an enclosed area.
It is a grey, non-magnetic metal that is highly reflective when polished. Silver salts are light-sensitive and are widely used in photography. Silver itself, both in alloy or when plated onto an object, is widely used for fine utilitarian objects and jewelry.
Silver image decay
A defect of a B&W silver image, which can be manifested as redox blemishes (microspots), silver mirroring, or overall image discoloration.
Silver mirroring
A symptom of silver image oxidation, in which the silver particles migrate to the surface, creating a bluish, metallic sheen on the surface—a mirror-like appearance. This mirroring effect is typically more acute along the edges and in darker areas of the image.
Sintering is the process of compacting and forming a solid mass of material by heat or pressure without melting it to the point of liquefaction. Only when clay is fired at temperatures higher than 1652? (900?) do the particles in the clay bond/sinter, and become stronger.
A substance added to paper or fabric during manufacture meant to act as a protecting filler or glaze. Sizing is often used to manage the absorbency or smoothness of a material, i.e. to make a paper surface more suitable for carrying clear, crisp text. Alum-rosin (acidic) and gelatin (non-acidic) are two common types of paper sizing.
It is a thin layer of a liquid clay and water mixture that is sometimes applied over the clay body of a ceramic before the first firing. It is usually matte, but can be burnished to a smooth, shiny appearance.
Slip cast
A ceramic construction method in which objects are surrounded by plaster with a slip reservoir, which is a thin cavity into which the slip is inserted.
White flashes appearing in the video image caused by random noise and/or loss of magnetic particles (Bay Area Video Coalition, 2009).
A very soft metamorphic rock, soapstone typically appears gray, blue, green, or brown, and feels slippery or "soapy." It has low porosity and permeability, is acid resistant, and has a high capacity for heating. Soapstone was often used in kitchen items, funereal items, and for decoration and ornamentation, among other purposes. As a result of its softness, particular care must be taken to appropriately pad and support soapstone objects.
Softcover (or Softback, Paperback)
Type of book or bound volume with a flexible cover/case, typically of thick paper or paper board. Pages are often joined (bound) with adhesive, staples, or other hardware (wire, comb, etc.) rather than sewn, so it is therefore assumed more vulnerable to wear and tear. If mass-produced, a paperback will very likely be composed of acidic paper. See the Bound/Book profile in the Collection ID Guide for more.
A type of glass deterioration that occurs as the result of exposure to sunlight or ultraviolet (UV) rays over a long period of time. Colorless glass, typically containing manganese dioxide, will turn purple or brown when solarized. Manganese dioxide was commonly used in glass before 1915, and so many (though not all) examples of solarization are occur with glass made before that time.
Solid cast
A ceramic construction method in which a slip is poured into plaster mold to form a solid cast inside the cavity.
To break up into smaller pieces, chips or fragments. Spalling is a sign of deterioration of ceramics, glass, stone, and metal.
Part of the book where sheets are assembled.
Spine lining
Flexible material sewn (or glued) to the spine before the spine cover is applied.
The joining of two film pieces usually by cement, tape, or ultrasonic technology (NFPF, 2004).
A piece of equipment used for joining two pieces of film. Splicers come in many designs and may use cement, adhesive tape, or ultrasonic technology (NFPF, 2004).
A shrinkage-induced effect that causes a reel of film to form regular angles rather than a circular wrap (National Film and Sound Archive, 2007).
Toothed mechanism that engages with film perforations to advance the film strip through a camera, printer, or projector (NFPF, 2004).
Sprocket holes (Perforations)
Holes, usually along the film edge, used to advance the film strip through a camera, printer, or projector (NFPF, 2004).
Undesirable audio effect that is typically caused by a buildup of debris on a guide or head. Sometimes, cleaning the offending surface will eliminate the squeal. Squeal is also caused by the tape having poor lubrication or losing its lubrication with age. Coating a tape with a lubricant solution may eliminate the squeal so a copy can be made (Bay Area Video Coalition, 2009).
A chemical that is added to a solution or mixture or suspension to maintain it in a stable or unchanging state
Staging area
A room set at a temperature and humidity level between that of the cold vault and the workroom. Film is acclimated in the staging area before it is moved to a new environment (NFPF, 2004).
An iron alloy: carbon is mixed with iron to make steel. Steel usually has less than 2% carbon. Stainless steel is a mixture of iron, carbon, chromium, and nickel. Because steel does not rust easily, it is often used for machinery and tools, cooking wares, cutlery, and other utilitarian objects.
Stencil printing
Printing method in which the ink image is forced through a stencil onto the printing surface. Examples include mimeograph (stencil copy) and screen printing.
Sterling silver
It is the most common silver alloy. An alloy of roughly 92.5% silver and 7.5% copper, it is used to make food service sets, cutlery, jewelry, and decorations.
Stick slip
The process in which 1.) the tape sticks to the recording head because of high friction; 2.) the tape tension builds because the tape is not moving at the head; 3.) the tape tension level reaches a critical level, causing the tape to release from and briefly slip past the read head at high speed; 4.) the tape slows to normal speed and once again sticks to the recording head. It is a process that is repeated indefinitely and is characterized by jittery movement of the tape in the transport and/or audible squealing of the tape (Bay Area Video Coalition, 2009).
Sticky shed syndrome (Binder hydrolysis)
A condition resulting from the deterioration of the binder in magnetic tape that results in gummy residues on tape heads during playback (Pearce-Moses, 2005). The phenomenon whereby a tape binder has deteriorated to such a degree that it lacks sufficient cohesive strength so that the magnetic coating sheds on playback. The shedding of particles by the tape is a result of binder deterioration that causes dropout on VHS tapes (Bay Area Video Coalition, 2009).
Stone varies in composition, porosity, grain structure, color, sheen, and hardness. It can be shiny or dull, have high or low porosity, and contain large or small grains, all depending on the materials in its composition. If the porosity is high (this may be visible), the stone is at higher risk from weathering agents and attack from pollution.
Stoneware is a type of high-fired ceramic that is partially vitrified, so it is that is less porous than earthenware. It is usually opaque, but can be quite thin and thus somewhat translucent.
Strain Cracking
A glass item with strain cracking has a series of intricate multi-directional cracks that will eventually appear "sugary" as deterioration continues.
Streaming (media)
A technology for transferring data so that it can be received and processed in a steady stream (, n.d.). A method of sending a sequence of compressed audio or moving images one way over a data network, at the user's request or broadcast at a fixed time, which allows listening/viewing to begin before the entire file has been transmitted. To counteract any delays caused by packet switching and to maintain the impression of continuous motion, a buffer on the client computer is used to store a few seconds of content before it is displayed on the screen. Unlike content that is downloaded for subsequent playback, streaming audio/video is stored as a temporary file and deleted when the application used to view it is closed. Videoconferencing differs from streaming video in providing two-way transmission in real time (Reitz, 2007).
A natural alloy of gold and silver. Also called "electrum."
Substrate (audiovisual)
The layer that supports the magnetic layer in a magnetic tape, most commonly made of polyethylene terephthalate (PET) (Bay Area Video Coalition, 2009). An alternate term for backing film.
Type of leather made from the underside of softer animal skins (lamb, goat, calf) or produced through splitting the hides of thicker cow or deer skins. Suede does not include the exterior skin layer, so it is therefore softer and more delicate than full-grain leather—"fuzzy" texture on both sides.
Base material that acts as a vehicle for information or media (image, text, etc.). In a 2-D collections context, it is often paper or a paper-like flexible sheet that serves as the support for a image or text material.
Support (photo)
The paper, plastic, or glass base on which the image layers of photographic film or prints are layered.
Surface sheen
"Matte" (no surface sheen), "semi-matte," and "glossy" (high surface reflection) are the primary distinctions among photographic prints. Intermediate terms such as "semi-gloss" and "lustre" are sometimes used. Variable surface gloss is also a common trait of early photographic prints, noticeable when viewed in angled light.
Surface texture
Description of the visual or tactile qualities of a material surface. For example, a calendered or finished support may be smooth; an unfinished or dense-fibered support may be rough-surfaced.


The end of a film, video, or audio tape roll (NFPF, 2004).
Tail out
Film, video, or audio tape wound on a reel or core so that its end is on the outside of the roll (NFPF, 2004). A procedure used in film repositories to encourage reinspection before viewing (Reitz, 2007).
Tape pack
The structure formed by and comprised solely of tape that is wound on a hub or spindle; a tape reel consists of a tape pack, the metal, plastic, or glass hub, and flanges (National Film and Sound Archive, 2007).
Tape shield
The movable plastic leaf found on videocassettes that protects the tape from dust, material, and being handled.
A layer of corrosion on metal that causes a loss of luster, especially as a result of exposure to air or moisture.
The term "terracotta" refers to any kind of fired clay, but more specifically it is an unglazed low-fired ceramic object made from coarse, porous clay.
Text area
Section of a document that bears the written or printed text or content. "Text area" is a phrase typically used when discussing manuscripts or pages of a book.
The total of a book's leaves, a volume. The textblock is typically bound into a case (or cover).
See Surface texture.
Thermoplastic adhesive (Heat-sensitive)
Type of adhesive activated, i.e. rendered into a pliable and sticky liquid, when heated above a specific temperature. As it cools, it "sets," returning to its original solid form, though some may remain tacky at room temperature. Heat sensitive adhesives of this type are broad and include waxes, resins (natural or synthetic), some acrylics, and proprietary heat-set mending tissue adhesives.
Thermoset adhesive
Type of adhesive that has set or hardened on exposure to heat and will remain solid regardless of subsequent reheating.
Stain from an accumulation of chemicals at the edge of a liquid spot or exposure to moisture.
A silvery-grey, non-magnetic metal that is commonly alloyed with other metals.
Tinted paper
A tinted photo will have a single overall color, or tint, throughout the photographic image though most apparent in highlights and midtones. The dyes (impregnated within the emulsion or binder by the paper manufacturer) have likely faded considerably over time. Popular colors included pale pink, blue, and mauve in albumen print papers and gelatin silver printing-out papers. Not to be confused with hand-colored.
Titanium dioxide
A base whitener added to resin-coated photographic papers. The titanium dioxide (TiO2) pigment is layered on the emulsion side of the polyethylene resin, setting an opacity and brightness, serving the same function of the baryta layer in a fiber-based print.
A monochromatic, silver-based photo image may have been colored during and/or after processing using mineral toning. A print categorized as "B&W" may contain accents such as gold, selenium, sulfur, or platinum to produce specific hues and increase image contrast. Resulting tones vary, depending on the minerals used: most have a brown overtone with purple and violet undertones, though sometimes a purple/violet hue is unmistakable. Toning has also proven to enhance the stability of images in many cases, particularly gold and selenium.
Tracing paper
Semi-translucent paper conventionally used for trace-copying technical drawings. Another drawing serves as the master original from which the copy is reproduced. Some especially thin translucent papers also functioned as intermediary for photo-reproductions of drawings. Tracing paper is defined as such because of its function rather than a specific manufacture, as any low-opacity paper will allow for tracing.
The angle and speed at which the tape passes through the video heads. Loss of tracking is evidenced by picture breakup or loss of video in segments of the picture.
Tractor feed paper
See Continuous form paper.
Tree-free paper
Fairly new designation for eco-friendly alternative to wood-pulp. Fiber sources
agricultural residue (sugarcane, bagasse, husks, straw), crops and wild plants (bamboo, kenaf, hemp, jute, flax), and textile waste.


Ultrasonic splicer
A machine that splices polyester film by fusing the two film ends using high frequency energy (NFPF, 2004).
Unbound records
Broad category of collection materials, including correspondence, documents, leaflets, booklets, minutes, and broadsides (and many more) that are not bound together in a volume. These items are typically stored in file folders and boxes (if not oversized or too thick).
Unbuffered paper is manufactured at a neutral pH level, neither acidic or alkaline. This does not ensure, however, that this paper will not become acidic over time.
Uncoated paper
A photographic paper support without any emulsion layer. The image often appears to be embedded within the paper. For non-photographic items, the term may be used to refer to plain office copy paper.
Uncompressed formats (digital)
Audio and moving image digital formats that do not use digital compression; all information is encoded without loss of content. Files sizes are generally very large.
An item so rare that no other copies are known to exist. Examples include 8mm, Super 8mm, and 16mm reversal originals, etc. (Reitz, 2007).


Parchment made from fine-quality calf skin, though it is often a term loosely used to describe parchments made from a wide variety of mammal skin. Vellum was used as a printing and writing surface, and appears in the form of a single sheet, scroll, manuscript, or book. Though known for its smoothness and durability, under poor storage conditions vellum may become brittle, fragile, and susceptible to mold growth.
Vellum paper
"Vellum" paper is a modern synthetic paper product made from plasticized wood pulp and/or cotton. This imitation vellum has an ivory or creamy quality and is semi-translucent, relative to thickness, available in low gloss and matte finishes. Also called vegetable vellum or Japanese vellum. Modern vellum (since the 19th century) is used for architectural and technical drawings, plats, plans, and posters.
Back side of a sheet.
A microfilm duplicate process intended for service copies. Unlike silver-gelatin microfilm, vesicular is not regarded as preservation quality, but permit relatively quick in-house processing. Diazonium salts in the emulsion are sandwiched between two polyester layers. During processing, expanding nitrogen forms tiny bubbles (or vesicles) in exposed areas that remain after the film is cooled. The image is formed by heating the film to form these bubbles or "vesicles" inside the film.
VHS (Video Home System)
An analog format of half inch videotape that is packaged in a cassette (NFPF, 2004).
Viewing copy
A videotape dubbed from a master and made for repeated viewing (Bay Area Video Coalition, 2009).
Vinegar syndrome
Popular term for acetate decay. The degradation of acetate base, which is characterized by the odor of vinegar (acetic acid). Once the reaction is started it cannot be stopped, since hydrolysis of the acetate is catalyzed further by the presence of acetic acid. The reaction is autocatalytic, feeding on itself and speeding up over time (National Film and Sound Archive, 2007).
1.) The abbreviation of polyvinyl chloride (PVC).
2.) Imprecisely used to refer to any of a number of plastics, many of which are not appropriate for use in preservation.
3.) A contemporary slang term for a disc record (Miliano & IASA, 1999).
In ceramics, vitrification is the progressive partial fusion of a clay, or of a body, as a result of a firing process. As vitrification proceeds the proportion of glassy bond increases and the apparent porosity of the fired product becomes progressively lower.
VOC (paint)
Paint made of organic chemicals that have a high vapor pressure. The higher the VOC level, the more chemical molecules will enter the air as it dries. VOCs are often dangerous to humans, the environment, and, of course, collection materials. Whenever possible, choose a low VOC or non-toxic paint/sealant.
Volatile Organic Compound (paint)
See VOC.
Group of bound sheets or sections, sewn together in book form. In total, volumes add up to a text block.


When an item becomes bent or twisted out of shape. Warping can happen when the clay body of a ceramic is unevenly heated or cooled.
A type of deterioration that can affect museum objects, typically involving a change in appearance or texture as the result of exposure or reaction to air or chemicals in the air.
A form of glass deterioration that appears as droplets of liquid on the glass surface, and is caused by water vapor in the air that leaches components from the glass.
White gold
An alloy of gold with a white metal, often nickel.
Interlayer slippage or magnetic tape in roll form, resulting in bucking of some strands of tape. The tape may fold over itself, causing a permanent vertical crease in the tape. Also, if not fixed, it will cause increased dropout (Bay Area Video Coalition, 2009).
Wire recording
An audio magnetic recording medium that uses metal wire as the carrier of the recorded signal (Miliano & IASA, 1999).
Wood-free paper
Paper formed from a chemical pulp process that removes enough lignin that it loses the designation of being wood. Wood-free is not as susceptible to the effects that come with mechanically-pulped wood, i.e. high acidity, and yellowing and embrittlement.
Wove paper
Form of paper with a fine, gridded texture: a uniform surface, not exhibiting a ribbed texture.
Wrought iron
A pure iron with glass inclusions. Wrought iron was rarely used after World War II, but was used for outdoor fittings, such as railings, doors, fences, and grilles.


Discoloration that affects a color image or, in earlier color processes, the white border of a print.