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A.N.S.I - Abbreviation for American National Standards Institute.

accelerated ailing tests - A process using elevated temperature and humidity to simulate the natural aging process on material samples.

acetates - Material composed of cellulose combined with acetic and sulfuric acids used in making various products including photographic films and packaging sheets. Tri-acetates are archival; di- acetates are not.

acid - In chemistry, a substance capable of forming hydrogen ions when dissolved in water. Acids can weaken cellulose in paper, board, and cloth, leading to embrittlement. Acids may be introduced in the manufacture of papers and may be left in intentionally (as in certain sizings) or incidentally (insufficient bleaching). Acids may also be introduced by migration from other materials or from atmospheric pollution. See also pH and acid migration.

acid migration - The transfer of acid from an acidic material to a less acidic or pH neutral material. This may occur directly, when the two materials are in intimate contact. For instance, acid may migrate from boards, endpapers, and protective tissues, as well as the paper covers of books and pamphlets, to the less acidic paper of the text.

acid-free paper - In principle, papers which contain no free acid and have a pH value of 7.0 or greater. Such papers may be produced from cotton fibers or chemical wood pulps, or virtually any other fiber. However free of acid the paper may be after manufacture the paper must also not have aluminum sulfate (alum) sizing applied to the surface. Unless the paper has been buffered with a substance capable of neutralizing acids, (calcium carbonate) overtime pollution in the atmosphere will make the paper acidic. The term “Acid Free” does not necessarily mean the paper is safe to use in archival applications. Look for additional specification on what the paper is made of, cotton or purified wood pulp, buffering content and neutral or alkaline sizing is used.

acid-neutralizing paper - A type of paper which contains an alkaline neutralizer intended to absorb any acidity that may appear in the environment of a book or work of art on paper.

acrylic - A plastic noted for transparency, light weight, weather resistance, color fastness and rigidity. In addition to these qualities, acrylics are important in preservation because of their stability, or resistance to chemical change over time, a characteristic not common to all plastics. acrylics are available in sheets, films, and resin adhesives. Some common trade names for the sheet form are: Perspex, Lucite and Plexi-Glass.

acrylic impregnated buckram - A heavy gauge covering cloth used- in book binding and presentation cases. Acrylic fillers are added to the buckram cloth to inhibit moisture and dirt from attacking the binding, providing a cleaner and longer lasting case. Typically used on public library and text books, and on portfolio box and binders.

actinic - (as in actinic light) Light radiation in the visible and UV spectrum that causes chemical changes and reactions, especially to photographic emulsions.

adhesive - A substance capable of holding materials together by surface attachment. It includes such materials as glue, mucilage, and paste. Archival adhesives have a neutral pH and are sulfur- free.

albumen prints - An antiquarian photographic printing process most popular from the 1850s to the 1890s utilizing the whites of eggs (albumen) instead of gelatin--in current use--to form the emulsion.

alkali - A caustic substance having a pH above 7. It has the quality of neutralizing acid.

alkaline - Alkaline substances have a pH over 7.0. They may be added to a material to neutralize acids or as an alkaline reserve or buffer for the purpose of counteracting acids that may form in the future. A buffer may be added during manufacture or during the process of deacidification. While a number of chemicals may be used as buffers, the most common are magnesium carbonate and calcium carbonate.

alkaline reserve - Buffer or reserve of an alkaline substance added to paper to counteract acid. Usually 3 percent precipitated calcium or magnesium carbonate by weight of paper.

alpha cellulose - A form of cellulose derived from cotton. The presence of high percentages (87%+) of alpha cellulose in paper or board is one indication of its stability or longevity. Non-cellulosic components of wood are believed to contribute to the degradation of paper and board.

alternative process - Typically, processes not involving popular black and white/gelatin silver emulsions available commercially, but rather processes that require the artist to mix and hand coat emulsions onto a support (paper, cloth, etc.) by hand. Examples include cyanotype, kallitype, VanDyke, and gum bichromate processes.

alum - Aluminum sulfate used with rosin to size paper, giving it water-resistant properties. Alum sized paper is acidic and therefore undesirable for archival applications.

anti-Newton Ring Glass - Specially coated glass designed to eliminate the optical phenomena of Newton Rings, a rainbow. ring effect caused by air pockets trapped between two layers of transparent materials, as in glass or mylar.

anti-tarnish adhesive - Adhesive whose properties will not adversely affect the surface of a metal, especially silver.

aperture - An opening, as in that of a photographic lens, which may be adjusted in measured pre-set diameters to control the amount of light in exposing light sensitive film. Used in tandem with a shutter and its various shutter speeds to control the effect of depth of field in recording an image (latent) on film.

archival processing - Photographic processing procedures designed to result in maximum permanence and stability of negatives and prints through a series of precise fixing, washing, and toning baths. Following thorough washing, photographs are treated with a gold solution or a toner, such as selenium. Archival processing requires the use of fiber-based rather than resin-coated papers. Archival processing alone will not insure archival quality; adherence to precise storage and handling procedures (as specified by the American National Standards Institute) is also required.

archival rinse - A washing agent used to assist in the maximum removal of residual fixer (hypo), silver sulfur compounds, and other harmful chemistry that would adversely effect image permanence on emulsions and paper board fibers. Also, shortens rinsing time and water consumption for some degree of permanence

archival; archivally sound - A non-technical term that suggests that a material or product is permanent, durable, or chemically stable, and that it can therefore safely be used for preservation purposes. the phrase is not quantifiable; no standards exist that describe how long an "archival" or “archivally sound" material will last.

archives - The non-current records of an organization or institution preserved because of the continuing value (see also collection). 2) The agency responsible for selecting, preserving, and making available archival materials.

atmospheric acid contaminations - Adverse contamination of object surfaces (as in photographic prints, drawings or paintings) caused by acidic particles and elements suspended in the immediate air environment or atmosphere.

backing piece - A stiff material used to support the artwork in the frame and help to keep it close against the glass. Most backing pieces are made of corrugated cardboard, chipboard or foamcore. They should be the same size as the mat and, if it is a folder mat, be placed immediately behind it.

baked enamel finish - A heat-cured painted finish of enamel and suspended pigment that produces a smooth, hard surface that is more resistant to scratching and abrasion and protects the underlying surface (usually metal).

barrier sheets - Pieces of well-sized acid-free paper used as barriers to prevent the migration of acid or oil from one material to another. Buffered barrier sheets counteract acid migration.

basis weight - Weight, measured in pounds, of a ream (500 sheets) of paper in its basic size. The phrases basis weight and substance weight are often used interchangeably. Also note that a ream of some tissue grades and wrapping is considered to be 480 sheets.

basswood - A strong, lightweight, close-grained hardwood desirable in construction of cases, boxes and other storage containers because it is low in resin which can be corrosive to the materials enclosed.

binder's board - A heavy grade of single-ply solid paperboard used for book covers. It is made from mixed paper stock and low grade rags. Davy Board is a brand name. Kappa binder’s board a bookmaking board with no glue between layers.

bleaching - Pulp fibers are generally bleached to produce white fibers for papermaking. Other reasons are: to increase the chemical stability and permanence of wood fibers by chemical purification; and to obtain clean, sanitary fibers as required for food packaging papers.

bleed resistant - The ability of a color agent or coating (as in colored museum board) to resist transfer during contact with a paper stock or other material.

blind embossing - Design is stamped without using foil or ink. Also called debossing.

blotting paper - Specialized paper designed to absorb moisture from materials, to assist in the drying process. Uses include drying of fiber base photographic papers and various conservation procedures for other paper and fabric artifacts. Should be discarded after several uses due to cumulative contaminant build-up.

bond paper - A strong and durable paper with good absorbing and erasing qualities. It originally referred to paper used for legal documents, stock certificates and government bonds, now used for letterheads, basic forms and xerographic copiers.

bonding - A uniting or fusing, as by an adhesive. Holding together or solidifying by means of a bond or binding.

bowed cuts (e.g., mat): - The deviation, usually outward, from a straight line cut, creating an undesirable effect visually. Commonly caused by faulty technique or improper use of equipment in mat cutting.

Box - A paper or carton structure used to hold goods for storage, transport etc.

brads, wire brads - The small nails used to join small frames and to fasten the backings to frames of all sizes. They are sold by the length and the gauge of the wire from which they are cut. The larger the number the smaller the diameter of the wire. Typical sizes used for framing are 3/4 x 18, 1 x 18, 1 x 16, and 1-1/4 x 16.

bristol - A paperboard that is hard, strong and rugged and has a smooth surface suitable for writing. Index cards are an example.

buckram - A filled (coated) binding cloth with a heavy weave (poly-cotton) base. In the U.S., it is made to the specifications of the National Bureau of Standards. It is especially sturdy and can be cleaned with a damp cloth. Acrylic coatings are considered archival while peroxylin coatings break down in time to corrosive elements.

buffering - The addition of alkaline agents such as calcium or magnesium carbonate during the papermaking process in order to counteract the effect f acidic contamination; the degree of buffering (usually 2-3%) is measured by percentage of paper weight. See alkaline.

burnishing bone (or folding bone) - Smooth, flat, non-abrasive utensil used for smoothing and finishing of mat edges, especially at corners. Also used as a folding and scoring instrument in book binding and box making.

C.R.I. (CRI rating): - Abbreviation for Color Rendering Index--which represents a numerical rating (95 being the standard) for overall brightness and evenness of a viewing light field, as in that of a light table.

calcium carbonate - An alkaline chemical used as a buffer in papers and boards.

calendering - In papermaking, the process of passing the web of paper between polished metal rolls to increase gloss and smoothness.

caliper - The thickness of a sheet measured under specified conditions. It is usually expressed in thousandths of an inch. Thousandths of an inch are often called "points."

cambric-quality - A cotton fabric that resembles the fine thin white linen fabric of cambric.

card stock - A heavyweight, smooth surface paper stock, used for a variety of applications including linings, dividers, album pages and file folders.

cardboard mounts - Standardized cardboard slide mounts for film positive transparencies used for projection in slide projectors. Cardboard mounts are usually half as thick as plastic mounts (with glass), so group storage systems will hold twice as many cardboard mounts as plastic.

Cartes de Visite - Name describing small photographic calling cards (similar to a business card) of the turn of the century. Usually the card had a portrait of the "caller" on one side and relevant information about the "caller" on the back.

catalog (verb): - A complete systematic organizing of items (as in works of art) for the purpose of accessible storage. Usually items are labeled with a unique number. All pertinent information is recorded and referenced to that number.

cellulose fiber: - The primary component of paper. It is obtained by separating the non-fibrous elements from wood, woody plants, cotton and other sources by bleaching in the pulping process.

cellulose triacetate - An inert plastic film used for a film base and in making storage enclosures for photographic materials. One of the few safe plastics used for photographs.

channel - In picture frame moldings, the space, accessible from the back, provided for insertion of glass, mats, and backing material.

chipboard - A paperboard generally made from reclaimed paper stock. Used for many purposes including partitions and the filler (center ply or plies) of solid fibreboard. This low grade of paperboard generally contains a high degree of lignin and acid content.

chromogenic dyes - Dyes or color produced in a color print by a colorless dye precursor embedded in the photographic emulsion combined with a dye coupler in the developer solution. The interaction of the two after exposure to light produces a color print. Prints are produced from color negatives.

cibachrome - Name of non-chromogenic color print process in which preformed dyes (yellow, magenta, and cyan) are placed in the paper's emulsion. Once exposed, processing bleaches away the unwanted dye color, leaving the desired color. (e.g., The red of a stop sign is formed by bleaching away most of the cyan dye, leaving the yellow and magenta dyes to form red.) Prints are produced from color transparencies.

clamshell-design (portfolio): - A hinge design that opens the top and bottom of a case in complete opposite direction. In the case of portfolios, the hinge will lay down flat once opened and allow easy access to materials contained within either side of the portfolio.

color balanced - Term describing the reproduction of the color scale by photographic or print processes matching as closely as possible the color scale of nature.

color separation - The process of dividing full-color originals into the primary process printing colors: magenta, yellow, and cyan.

color temperature - Rating scale describing a light source's value on the spectrum. Important to photographers in that individual films are designed to respond to particular color temperatures to reproduce a neutral or "balanced" color value, based on the appearance of color in natural or daylight conditions.

conservation board - Purified wood pulp, acid- and lignin-free board designed to meet archival standards at an economical price. Conservation board is designed for matting and storage of works of art without, by its composition, adversely affecting the original work of art.

conservation: - The treatment of library or archive materials, works of art, or museum objects to stabilize them chemically or strengthen them physically, sustaining their survival as long as possible in their original form. See also preservation.

conservator - One responsible for care, restoration, and repair of museum articles.

contact print - A print made by exposing photographic paper to a light source while it is in direct contact against the negative. Since there is no magnification, the print is the same size as the negative.

continuouston - An image containing gradiant values of gray as well as the black and white extremes.

copy negative - A film negative made by photographing (copying) a print. It is used to make more prints.

corrugated - Fluted or shaped into parallel rows to provide strength without excessive weight, as in corrugated board. In matting, corrugated is sometimes used as backing board in a frame.

cotton board - Matboard whose pulp originates from cotton which is chemically and physically broken down to fibers and molded into paper stock or board. "Cotton" as a term is usually recognized as a board that is archival and composed of only cotton, as opposed to wood pulp which is, in general, perceived as non-archival when untreated. Also see Rag Board, Museum Board.

cotton fibers - Selected new cotton cuttings acquired from the textile industries. They are free of synthetic fibers and are a source of cotton fibers used in the manufacture of cotton content papers. Basic cotton and cotton linters are also used in the manufacture of pulp.

crop - To trim off or mask out unwanted parts of an image.

cyanotype - Alternative non-silver photo process distinctive for its brilliant blue print color (referred to as a blue-print) using chemistry coated onto paper stock and exposed by contact printing with ultraviolet light. (Non-enlarging process--contact printing only.)

darkroom - A light-tight area, either completely dark or specially illuminated, for handling light- sensitive materials.

data base - A collection of data organized especially for rapid search and retrieval, usually stored and accessed by a computer.

deacidification - A common term for a chemical treatment that neutralizes acid in a material such as paper and deposits an alkaline buffer to counteract future acid attack. While deacidification increases the chemical stability of paper, it does not restore strength or flexibility to brittle materials. See also pH.

deckle - The natural uneven edge on handmade paper or an edge torn to simulate it. Tearing wet paper against a saw or straightedge is one way to make a deckle edge.

densitometer - A machine used in the science of sensitometry to measure the densities of exposed and processed emulsions. It is the densitometer that enables a photographer to take highlight and shadow readings from processed negatives to determine the density range of the negatives.

densitometer - A device used to measure the optical density of an image or support material by measuring the amount of incident light that is reflected or transmitted.

desiccant - Any agent--particularly a silica gel--that removes gaseous water from the air and that reduces relative humidity. Desiccants can be used in sealed enclosures to protect photographs from humidity. Silica gels can be made to give up their absorbed moisture by heating, and then reused.

developer - A chemical substance in dry, liquid, or gaseous form used to make visible a latent image, after exposure.

dextrin base - Soluble carbohydrate from starch used in adhesives and as sizing in papers and textiles.

diazo - (diazotype, diazotypy white printing): A generic term for films employing light-sensitive diazonium salts for the production of the film image. The image is a dye and thus subject to fading.

die-cut - A cut made with special steel rule dies. The act of making a part or container which is cut and scored to shape by such tools. Also used to denote a board which has been die-cut.

dimensional stability - The quality in a support, such as film, of not changing its size by shrinking or stretching.

doublewall - Reference to corrugated board--using two layers of fluted corrugated board for additional strength and rigidness while minimizing excessive weight.

D-rings - Binder mechanism -using "D"-shaped reclosable rings for 3-ring binders. The straight side of the "D" ensures all pages will be aligned when the binder is closed.

dropspine - Specially designed hinge that allows the spine of a case to lie flat when opened, allowing access to both sides of the case without interference from the hinge.

dry transfer - Typically, the transfer of material caused by contact of one surface against another, usually assisted by pressure. (As in adverse transfer of pigment from one colored surface to another or as in dry transfer lettering.)

dry-mount - A non-aqueous method for mounting artwork. Two types of dry-mount methods exist--heat mount and cold mount. "Heat mount" is a technique used principally to mount photographs by attaching them to a board with dry-mount tissue and heat. The full system uses a dry-mount press. The piece is backed with dry-mount tissue held in place by "tacking" with a small tacking iron and is positioned on the board and placed in the dry-mount press. The press is closed for a timed interval to suit the type of tissue being used. The heat fuses the tissue to both the picture and the backing. "Cold mount" is a mounting technique utilizing a pressure sensitive adhesive to adhere artwork to mounting board. Long-term adhesion and archival characteristics of cold mount adhesives are unknown.

dye couplers - Property of chromogenic (color print) development. The dye coupler is an element in the developer solution which links and chemically reacts with a dye precursor located in the emulsion of the paper to create a color within the print.

electrostatic charge - Phenomena of attraction and repulsion of electric charges. Used in precharged dusting rags and a painting process for metal finishes.

emulsion - A gelatin containing a dispersed light-sensitive agent (usually some form of silver) that has been applied to a base of film, glass, paper, or similar material. Processing the emulsion causes the changes in density that constitutes the photograph.

encapsulation - polyester encapsulation: A form of protective enclosure for papers and other flat objects; involves placing the item between two sheets of transparent polyester film that are subsequently sealed around all edges. The object is thus physically supported and protected from the atmosphere, although it may continue to deteriorate in the capsule. Because the object is not adhered to the polyester, it can be removed simply by cutting one or more edges of the polyester.

enlargement - A photographic print that is larger than the negative; made by projecting an image of the negative through a lens onto a photographic paper.

enlarger - Device for projecting film images on to sensitized paper for the purpose of printing the images in various sizes or formats, as desired.

enlarging focuser - High power viewing lens system used to fine focus negative image in the enlarger during printing process. The focuser magnifies the grain of the negative for critical focusing of the enlarger.

ephemera - The transient everyday items that are manufactured specifically for use and disposal. For example, advertising materials, product labels, boxes, etc.

etching - An intaglio printing process in which the lines are scratched through a protective coating on a metal plate, which is then immersed in acid. The acid "bites" the image into the metal surface, which is then inked, wiped, and printed.

exposure - (1) The act of exposing a light-sensitive material to a light source. (2) A section of film containing an individual image. (3) The duration of time that a sensitive surface is exposed to a light source.

extruded polystyrene - Lightweight but strong plastic forced through a die (extruded) that composes the inner layer of a product such as Fome-Cor. The polystyrene is flexible in compression to allow Fome-Cor to be somewhat shock resistant.

f/stop - Fixed openings or settings for lens apertures that, when combined with shutter speeds, determine exposure.

ferrotype - (1) The appearance of shiny patches on the gelatin surface of photographs. Brought about by contact with smooth surface, particularly plastic enclosures or glass, under conditions of high relative humidity. If photographs are stored in plastic enclosures under pressure (i.e., in a stack), ferrotyping can occur at moderate levels of relative humidity. (2) A finishing process involving heat, pressure, and a polished metal sheet while drying fiber-base black and white prints, to create a highly glossy surface.

fiber content - A statement of the types and percentages of fibers used in the manufacture of a paper, board, or cloth. Important because the quality of the fiber significantly affects both the durability and chemical stability of the material.

field-cameras - Large format cameras (typically, 4 x 5", 5 x 7", or 8 x 10" sheet film format) usually made of wood elements. Designed to be compact and relatively lightweight for carrying to locations. Traditional and historic use centered around landscape photography out in the "fields" or remote locations.

film - A transparent plastic material, usually of cellulose acetate or polyester on which a light- sensitive emulsion is coated, or on which an image can be formed by various transfer processes.

film developer - Solution composed of developing agents, preservatives, accelerator or activator and a restrainer. The solution transforms the latent image on exposed film into a visible image.

film holder - Light-tight cartridge used to hold sheet film (4x5, 5x7, 8x10) for large format cameras. Film holder is inserted in the back of the camera and a dark slide is raised to allow for camera exposure. Film holders are usually two-sided.

fixer - A solution used in photographic processing that removes unexposed silver halides (light-sensitive metallic compounds) from the emulsion and makes the image stable and impervious to light. The amount of time the emulsion spends in the fixer is called the clearing time. Fixer is also known as hypo. Some fixers include hardening agents to make the emulsion more resistant to abrasion.

flat files - Primarily used for large print storage, flat file drawers are unusually large width and depth dimensions, but of shallow height. Used typically by museums, artists and institutions where access and careful storage of flat work is desired.

flat plate - Smooth, somewhat heavy metal plate used to hold prints or paper flat. Used in photography during and after the print drying process. Also used in dry mounting to ensure flatness and good bond after removal from the heat press.

floating mat - Matting technique, mounting the image or artwork on the backing mat and cutting the over mat larger than the artwork, leaving a small margin of space between the original artwork and over mat.

flute or corrugation - One of the wave shapes in the inner portion of combined corrugated fibreboard. The flutes most commonly used are: A-flute--3/16"(height); B-flute--3/32"; C-flute-- 9/64"; E-flute--3/64".

folio - (1) A sheet of paper measuring 17" x 22". (2) A leaf numbered on the recto; the numeral itself in a book or manuscript in which the leaves are numbered. (3) A volume made up of sheets of paper folded once; the largest size.

foot-candle (meter-candle) - A term for the measurement of light; the illumination produced when the light from a point source of one candle falls on a source one foot, or meter, away from the candle. See also lux.

formaldehyde - Solution or gas used as preservative or as an agent in many manufacturing processes. Residual formaldehyde may be found in such diversified materials as paper, paperboard, foam board, particle board, fabrics and adhesives. Photographs are adversely affected by formaldehyde.

formaldehyde - A polymer of styrene a rigid and sometimes transparent thermoplastic used in molded products and sheet materials.

foxing - Spots of various sizes and intensity, usually brownish in color,- that disfigure paper. They are caused by a combination of fungi, paper impurities, and dampness.

frame - (1) To enclose a picture in a border. (2) A decorative design around a picture. (3) The area of a photographic film exposed to light in a camera during one exposure, whether or not the area is filled with an image. (4) A single area in a grid pattern.

fungicide - An agent that destroys or inhibits the growth of fungi, as in the chemical thymol.

fungus - Parasitic lower plants that grow by absorbing dissolved organic matter. Includes molds, mildew, smuts, mushrooms and yeasts.

gelatin - A binder from animal parts used as a support for the light-sensitive particles in certain emulsions.

genealogical (genealogy) - An account of the descent of a person, family, or group from an ancestor involving methodical search, fact finding, and record keeping.

gesso - A sizing material made up of a mixture of whiting and animal glue or gelatin. It must be applied warm after liquefying it in a double boiler. This is the gesso traditionally used by artists, gilders, and framers.

glass mounted slides - Sandwiching transparent slide films between thin glass to protect against dust and fingerprints. The glass is held in place within the slide mount. Some glass mounts consist of only a single piece of glass.

glass plate - A photographic exposure material consisting of a light-sensitive emulsion coated on a plate of glass. After exposure in a camera, the emulsion was then processed and usually dried on the glass and contact printed on light-sensitive paper. Cumbersome and fragile, technical advances replaced glass with clear films of acetates and polymers around the turn of the century. Some applications still exist for glass plates (astronomical photography), however digital imaging is replacing this use rapidly.

glassine - Translucent, smooth paper made by extensive beating and subsequent super-calendering. Most commonly used as protective wrappers. Basis weight: 12 to 90 lbs. Usually acidic and hygroscopic. Not recommended for photographic storage due to tendency of emulsion to permanently adhere to glassine under conditions of high humidity or moisture exposure.

glazing - Glass or other transparent material used for framing (also windows).

grain - In paper, the direction in which most of the fibers lie in a finished sheet of paper. Fibers flow parallel to the direction in which the paper travels on the paper machine during manufacture.

grain - In photography, the clusters of light-sensitive silver halides in a negative that are changed into black metallic silver by development. The grain becomes more apparent in a print when the negative is enlarged. Generally, the more sensitive (i.e., faster) films have more grain than less sensitive (i.e., slower) films.

grain long - Term used to designate that the grain of the paper is parallel to the longest measurement of a sheet of paper. The fibers are aligned parallel to the length of the sheet.

grain short - Opposite of grain long. Grain of the paper runs at right angles to the longest dimension of the sheet. Fiber alignment in grain short paper parallels the sheet's shortest dimension.

gravure - The major commercial application of the intaglio principle of printing, often used for photographic books and frontispieces.

gray scale - A strip of standard gray tones ranging from black to white, used to measure tonal range and contrast.

groundwood pulp - Pulp composed of "ground wood". Typically, newsprint, gray cardboard or brown corrugated board (box board). Regarded as non-archival and acidic, as the pulp is processed quickly and economically leaving most of the harmful impurities (mostly lignin) in the pulp.

gum bichromate - One of the antiquated non-silver photographic process using suspended color pigments and ammonium dichromate, as the light sensitive chemistry. Non-enlarging process-contact printing only. Usually requires multiple printing and registration techniques to build density for satisfactory image.

halftone - Photomechanical process for reproducing continuous-tone photographs. Printed with one color of ink, the halftone process gives the appearance of blacks, whites, and grays by converting the image into a pattern of clearly defined dots of varying sizes. The halftone process creates the illusion of tone gradation. The largest dots appear darkest and are in the shadow areas of the image, while the smallest dots seem lightest and represent the highlight areas. Intermediate sized dots reproduce the various middle tones of gray in a photograph.

headband - In books, a small ornamented band of cotton or silk placed at the head or tail of a volume between the cover and the backs of the folded signatures.

high tack (adhesives) - Showing properties of strong, fast bonding, as in adhesives. Usually non-repositionable.

highlight - The brightest light accents in the subject of a photographic image. Therefore, the lightest of whitest parts in the positive and the darkest areas of a negative.

hinge - A small piece of neutral or acid free paper such as mulberry tissue that is folded in half and glued to the artwork and the backing or sometimes is not folded but laid across the top edge of the art and onto the backing. The term also applies to a strip of tape used to join the mat to a backing piece of board to create a folder mat.

hinging papers - Usually lightweight but strong Japanese papers of various weights combined with organic and reversible adhesives (as in wheat or rice starch paste). They form archival hinging system for attaching artwork to album pages or mounting board.

hololography - Recording on a photographic material the interference pattern between a direct (reference) light beam and one reflected or transmitted by the subject. The resulting hologram is usually viewed by coherent light, giving the appearance of three dimensions. Within limits, changing the viewpoint from which a hologram is observed shows the subject as seen from different angles.

humidity - Moisture condition of the air. Relative humidity is the percent of moisture relative to the actual amount which air at any given temperature can retain without precipitation.

hydration - In paper, when the chemical components in paper are combined with moisture and the paper expands.

hydrolysis - The decomposition of organic compounds, such as paper, by the interaction of water. The presence of acid or alkali ions compound or hasten the process.

hygroscopic - Absorbing moisture from the air. Most paper is mildly hygroscopic. Table salt as a example is very hygroscopic.

hypo (fixer, fixing bath) - Originally an abbreviation for sodium hyposulfate, but now used to refer to sodium thiosulfate, the chemical agent used in fixing baths to remove unexposed silver halides from silver emulsion film and paper. It is also more generally used to refer to a fixer solution which may also contain certain acids and/or hardening agents.

hypo clearing agent - A washing agent, specially designed to remove residual hypo fixer (especially sodium thiosulfate) from prints or papers, and shorten final washing times.

intaglio printing - A technique in which the areas to be printed are cut into a plate, so that when the plate is inked and then wiped, the depressed areas will retain the ink.

interleaves - Blank leaves that alternate with the printed leaves of a book, or are placed between prints to separate and reduce contamination from adjacent prints.

iron gall ink - This damage occurs when iron-gall ink, which is acidic, attacks the paper in the center of the pen-strokes where it is concentrated and destroys the paper under the ink. From the fifteenth century onward it was a popular writing and drawing ink. Iron gall ink passed out of use by the early twentieth century.

Japanese paper - A very absorbent high-quality paper made from plant fibers and used for printing works of art on paper, expensive editions of books, and also for hinging prints into mats.

kallitype printing - Contact printing process similar to palladium or platinum process. A mixture of ferric salt and silver nitrate, the process was very popular at the turn of the century and is now a popular alternative process.

kraft paper - A tough, strong paper made entirely from woodpulp. Usually not highly refined, so probably has high acid content.

laid paper - The closely "lined" appearance in the finish of writing and printing papers created during manufacture by a dandy roll.

lamination - A process of reinforcing fragile paper, usually with thin, translucent or transparent plastic such as vinyl or polyester. Laminations are considered unacceptable as conservation methods because of potential damage from high heat and adhesives during application, instability of the lamination materials, or difficulty in removing the laminated item, especially long after the treatment was performed.

lantern slide (diapositive) - A mounted transparency on glass plate, that is placed in a still projector for the projection of an enlarged image on to a screen. Sizes vary by type standard 4 x 3 ½”, magic lantern slides 7 1/8 x 2 ¼” and 5 x 2”.

large format - Term describing photographic films, cameras, and techniques in the typical formats of 4"x5", 5"x7", and 8"xlO". The equipment and larger film offers controls that small and medium formats cannot, such as manipulation of the film and lens planes to achieve precise focus and perspective distortion corrections.

latent image - An image contained on film or paper prior to development. A negative exposed to light in a camera or a print exposed under a negative contains an invisible image referred to as a latent image. The image is made visible by chemical development.

layered mat - A double or triple mat, a mat made up of several pieces of matboard one on top of the other.

light stain - Discoloration on paper caused by overexposure to any light source, particularly light energy sources with heavy ultraviolet energy.

light-fast - Fade-resistant to light and especially the ultraviolet in sunlight. Usually refers to dyes or pigments used in coloring papers, fabrics and artist's materials.

light-sensitive - Materials which undergo changes when exposed to light. The commonly used photographic light-sensitive materials used in films and papers are the silver halides, diazo dyes, biochromated gelatin and the photoconductive materials used in Xerography. With most photographic materials, the changes are not apparent until the material is developed.

lignin - An acid organic substance found in wood pulp. It is removed in the chemical pulping process, but is not removed in the manufacture of low grade papers made of ground wood pulp, such as newsprint.

lignin-free - In paper, this term indicates there are only trace amounts of lignin (usually less than 1%). This is desirable because lignin in paper tends to decompose into corrosive and acidic elements.

linen tape - Water activated, adhesive backed, tight woven fabric tape commonly used as hinging tape for mats.

lithograph - A print made by a surface printing process dependent on the rejection of oil and water or some similar attraction-and-repulsion system. The classic type is the stone lithograph, in which the image is made on a smooth piece of limestone by drawing with a lithographic crayon or painting with tusche. The stone is then soaked with water and inked with an oil-based ink, which is attracted to the oily surface of the image but repelled by the wet stone. Paper is put in place and pressure is applied by running it through a press to transfer the ink to the paper.

litmus paper - A type of paper which has been chemically treated with dye extracted from lichens rendering it sensitive to pH. Blue litmus paper turns red in the presence of acid. Red litmus paper turns blue in the presence of alkali.

low resin basswood - (See basswood.) Basswood has lower resin content than most other commercially available woods.

low sulfur content - As the name implies. All papers exhibit some sulfur content, however certain processes in refining pulp can reduce the amount of sulfur present, providing the paper with extended life before breakdown.

low tack adhesive - Implies adhesive or items used with adhesive will be re-positionable. (e.g., Post- It Notes by 3M utilizes a low tack adhesive, as does drafting tape and positionable mounting adhesive.)

lux - A unit of illumination; the illumination on the surface of a sphere of radius one meter when a point source of one international candle is at the center of the sphere. 10.76 lux = I footcandle; I lux = 0.0929 footcandles.

mat - A sandwich of two pieces of paper board hinged together. The bottom piece supports the print and the top piece contains an opening, or window, through which the print may be seen.

matboard - A type of paperboard made especially for matting pictures. It is available in a wide variety of colors. The standard size is 30" or 32" x 40", but there is 40" x 60" also in some colors, and whites are available in several other sizes.

medium format - Usually describes format using 120/220 size film, a common professional format that produces a larger than 35nun image on film. 6x7 cm and 2-1/4" square are common image formats. Camera designs vary diversely within this format ranging from SLR, twin lens reflex, and other designs.

methyl cellulose - Any of various gummy products that swell in water and are used as adhesives, emulsifiers and thickeners.

microfiche - A sheet of microfilm containing multiple micro-images in a grid pattern. The most common size produced today is the 105mm. x 148mm., and the format 60 or 90 pages of information per fiche.

microfilm - (1) A transparent flexible film used for the photographic reproduction of documents in reduced size. (2) Photographic reproductions on this film that can be viewed with a reading device or enlarged to make readable prints.

mil - Unit of thickness equalling one thousandth of an inch (.001"). See also point.

moisture content - The percent of moisture found in finished paper. The amount varies according to atmospheric conditions because paper is hygroscopic.

mounted - Printed matter, photographs or artwork, adhered to or lightly attached to paper or matboard using corners, hinges or dry mounting techniques.

mounting - The attaching of a piece of artwork to a support for the purpose of extending its life or bracing it to be framed. Methods of attaching include corners, hinges and dry mounting.

museum board - 100% cotton matboard. It has a uniform color throughout and is acid- and lignin- free. It is sometimes lumped together with conservator's matboard, which is not 100% cotton but also is acid-and lignin-free.

Mylar & Melinex - DuPont trade names for a clear, flexible polyester plastic sheets which is used to cover prints and documents. Mylar "Type D" and Melinex 516 have been extensively tested and is approved for photographic and conservation use.

negative - Developed film that contains a reversed-tone image of the original object. Light areas of the image are represented by heavy or dark deposits of silver, and the dark portions are light or transparent. When negatives are printed on paper or film, positive images are produced in which the tone values are similar to what they were on the original object.

neutral pH - Exhibiting neither acid nor base (alkaline) qualities; 7.0 on the pH scale. Paper and board stock with a neutral pH are recommended as a storage material for photographic materials.

newsprint - The white pulp paper on which newspapers are printed. It has high acid content and is quick to deteriorate, but artists love it because it is cheap and it has a natural tooth that receives the chalk and charcoal very well. It is used as a basic drawing pad in most schools and even by professionals.

nitrate based firms - Film base for emulsions popular in the 1920s and 1930s. Composed of cellulose nitrate, a somewhat dangerous compound known for its flammability and explosive properties. Requires special storage conditions including a buffered paper environment and/or cold storage.

non-aqueous - Solution that does not contain water or is not water-based. nonporous: Without absorbent qualities.

non-archival - Possessing qualities that indicate deterioration during aging. A non-archival product will break down, deteriorate, or cause adverse affects to items it is in contact with. Also refers to procedures that are non-reversible. An archival procedure must be reversible, i.e., not permanently alter the artifact.

non-bleeding - Showing no characteristics of dye or pigment transfer from one material in damp contact with another while under pressure for a specified period of time (48 hours).

non-buffered - As in non-buffered paper, pulp which is not impregnated with buffering agents such as calcium carbonate. Buffering agents have adverse affects on Cyanotype (blue prints) and Dye Transfer photographs and protein based textiles silk, wool.

non-reversible - A property which indicates a permanent condition. Non-archival characteristic, as in permanent adhesive, or a mounting technique that will not permit original artwork to be removed without damage occurring to the work.

non-woven - Fibrous materials that are produced without the use of a weaving process. Examples are paper and Tyvek.

offset - The accidental transfer of ink from a printed page or illustration to another page.

opaque - (1) A condition in which no light is allowed to pass through; (2) special markers or paints that block light; (3) to block out unwanted areas op transparencies before printing.

oval mat - A mat with an oval opening but usually a rectangular circumference. Sometimes, when an oval frame is -used, the oval mat is cut to fit.

overlay mat - The top mat cut with window or opening that exposes and presents the original artwork underneath. The overmat provides a spacing between the artwork and glazing material to prevent contact. Especially important with photographs, which may permanently adhere to the glass over time.

overmat - The mat that is applied on top of an undermat to create a multiple-layered effect such as the double mat or triple mat.

oxidation - Chemical reaction that converts an element into its oxide; to combine with oxygen. Image silver can react chemically with oxidizing agents, resulting in the discoloration of photographs.

P.V.A - See polyvinyl acetate.

paper hinges - Mounting technique using strips of paper affixed to the object being mounted and the backing mat by means of a fold (as in folded hinge) or other techniques (as in the T-hinge). Usually a reversible adhesive such as starch paste is used, and considerations are made in the hinge material and design to prevent damage to the original artwork.

passe-partout - A kind of "framing" in which no actual frame is used. The matted artwork is placed together with glass and backing in a sandwich condition and the edges are bound with tape.

perfect binding - A method of holding pages of a book together with glue using no stitching or sewing. The backbones of the gathered books are ground off, leaving a rough surface to which adhesive is applied. The books are usually finished with a wrap-around cover.

permanent adhesive - An adhesive that once used as a bond for materials is non-reversible.

pH - In chemistry, pH is a measure of the concentration of hydrogen ions in a solution, which is a measure of acidity or alkalinity. The pH scale runs from 0 to 14, and each number indicates a ten- fold increase. Seven is pH neutral; numbers below 7 indicate increasing acidity, with I being most acid. Numbers above 7 indicate increasing alkalinity, with 14 being most alkaline. Paper with a pH below 5 is considered highly acidic. Buffered storage materials typically have a pH between 7 and 9. See also acid; alkaline.

phased boxes - A four flap boxboard folder hand-scored and folded to fit specific dimensions of the object to be enclosed, usually a rare book, secured with tied ribbon or string.

photo sleeves - Enclosures for photographic prints, negatives, or transparencies. Usually made of transparent polyester, polypropylene, these are safe for photo storage. Can be made of unsafe PVC (vinyl), triacetate and other acetates.

photogram - A photo image produced without using a negative or camera by allowing an object to cast its shadow directly onto the light sensitive recording surface.

Photographic Activity Test (P.A.T): - Accelerated aging test using a specialized photo-emulsion in contact with a paper sample at elevated temperature and humidity levels to simulate the natural aging process used to check the archival quality of various papers and plastics products intended for photographic storage.

photographic emulsion - A suspension of a light-sensitive silver salt or a mixture of silver halides in a viscous medium (as in a gelatin solution) forming a coating on photographic plates, film, or paper.

photography - To write with light; the science, engineering, art and craft of producing relatively permanent images by the action of light (and similar electromagnetic radiation) on sensitive materials. In a narrow sense, the use of a camera to make images by the action of radiation on sensitive films or papers. In the case of digital imaging the action of light on CCD short for charge-coupled device, an instrument. Digital cameras, video cameras, and scanners all use CCD arrays.

photosensitive - The quality of reacting to light through chemical and electrical action.

pigment - Particles used to give color, body, or opacity to a semiliquid artists' material.

plastic mounts - Referring to 35mm formatted masks that both house and protect film transparencies, and are used for projection in slide projectors. Plastic mounts are an alternative to paper mounts, providing a more-rigid and potentially longer lasting mount.

plasticizer - A chemical added to plastic resins to improve flexibility, workability, or stretching. In plastic enclosures, plasticizers tend to volatize, or "outgas", and adversely affect photographs stored therein.

plate - (1) Illustrations prepared separately and inserted in a book when bound. (2) A master surface from which printing is done. (3) A photographic negative made on a glass plate.

plate finish - A hard, smooth finished paper.

platen - A flat plate (as of metal) that exerts or receives pressure. A component of the dry mounting presses.

platinum printing - A non-silver process using the light sensitivity of ferric oxalate to produce the precipitation of platinum, yielding a black image. Highly expensive and extremely permanent, platinum printing is known for its long and rich tonal scale. Requires considerable skill and a well-controlled lab/studio to produce quality prints. Like cyanotyping, it is an iron process.

PlexiGlas - Trade name for acrylic sheet material made by Rohm and Haas. See acrylic for other trade names.

ply - Any of several layers of solid paperboard.

point - Term used to describe the thickness or caliper of paperboard, a point being one thousandth of an inch. For example, .060" equals 60 points. See also mil.

polyester - A common name for the plastic polyethylene terephthalate. Its characteristics include transparency, colorlessness, and high tensile strength. In addition, it is useful in preservation because it is chemically stable. Commonly used in sheet or roll film form to make folders, encapsulations, and book jackets. Its thickness is often measured in mils. Common trade names are Mylar and Melinex by DuPont.

polyethylene - A chemically stable, highly flexible, transparent or translucent plastic with a low melting point. Used in preservation to make sleeves for photographic materials, when made of virgin material with no surface coatings or additives.

polymer - A chemical compound or mixture of compounds consisting essentially of repeating structural units.

polypropylene - A stiff, heat resistant, chemically stable plastic. Common uses in preservation are sleeves for photographs, slides or films; containers. Polypropylene has better clarity than polyethylene and less static charge than polyester.

polyvinyl acetate - A plastic usually abbreviated as PVA. A colorless transparent solid, it is usually used in adhesives, which are themselves also referred to as PVA or PVA adhesive. There are dozens of PVA adhesives, some are "internally “plasticized" and are suitable for use in conservation, due to greater chemical stability among other qualities.

polyvinyl chloride (PVC) - A plastic, often abbreviated as PVC. It is, not as chemically stable as some other plastics, since it can emit damaging hydrochloric acid as it deteriorates, and therefore has limited application in the preservation of books, photographs, and paper. Some plastics called vinyl may be polyvinyl chloride.

porosity - Of paper, the minute openings in the fiber through which air and light might pass.

portfolio - (1) A case for holding loose papers, consisting of two covers joined together at the back. (2) A group of prints or drawings issued by an artist.

positive - A photographic image on paper, film, or glass which exactly corresponds to the original subject in all details. See also negative.

post binder - Binder system typically with three posts in the form of rings that may be opened and closed. Pre-punched presentation sheets are made to be "bound" within the binder or album. The binding by the posts are reversible, as sheets may be added or taken out as desired.

posterization - Separate black-and-white negatives, each of which records either the highlights, the middle tones, or the shadows of the same image. In printing, usually each negative is used with a different color.

preservation - 1. The maintenance of objects in their original condition through retention, proper care and, if the object has been damaged, restoration. 2. Activities associated with maintaining library, archival, or museum materials for use, either in their original physical form or in some other format. Preservation is considered a broader term than conservation.

pressure-sensitive - As in adhesive labeling products, materials backed with permanent or reversible adhesive, placed on smooth release paper. The label or material is peeled from the backing sheet, exposing the adhesive which is then applied to a desired surface, adhering by contact and/or pressure.

printing out paper - The creation of a photographic image solely by the action of light on the emulsion without requiring chemical development. Early printing out papers (POPS) were contact printed by sunlight. When the image was judged complete, the remaining silver was removed by fixing. The cyanotype or blueprint is a POP process.

psychrometer - An instrument for determining relative humidity in which wet and dry-bulb temperature readings are compared with a chart that shows relative humidity.

pulp - Cellulose fiber material produced by chemical or mechanical means from which paper and paperboard is manufactured. Origins of this cellulose fiber are many and can include wood, cotton, straw, jute, bamboo, hemp, various leaf fibers, reeds, etc. There are many mechanical and chemical means of separating the fiber from its original sources.

purified wood pulp - Pulp that is processed from wood chips and broken down to a high content of alpha cellulose fibers by a bleaching process which removes impurities as in acidic lignin. The pulp is then processed to paper, creating an archival paper stock.

rag content - 1. Paper that is made chiefly from linen or cotton fibers rather than from wood pulp, which is highly acidic. High rag content usually indicates a neutral pH. 2. A term that indicates the presence of cotton fibers in a sheet of paper. The content can vary from 25% to 100%.

rag paper - Cotton fiber paper. It is made from cotton cuttings and linters.

ragboard - Another name for museum board.

RC paper - Initials standing for resin coated. These papers are less expensive and easier to process and wash than paper gelatin silver bromide/chloride emulsions. Contemporary photographic color prints are made of resin coated paper.

ream - A standard parcel of paper, formerly twenty quires, or 480 sheets, now usually 500 sheets.

reducible sulfur - Naturally occurring element in paper and board stocks. Archival paper and board is process to minimize sulfur content.

relative humidity - The ration of the quantity of water vapor present in the air to the quantity which would saturate that air at any given temperature. The figure is arrived at by relating the amount of water vapor a special volume of cold air could support without reaching dew point at the given temperature to the amount it currently has. It is expressed: RH X/XXX x 100 = X%.

release paper - Usually silicon-treated sheet that repels adhesive. Used in dry mounting process. Release papers are characterized by smooth waxy surface, used also in bookbinding and other applications where adhesives are used.

restoration - The procedures that improve the condition of a damaged object and attempt to return it as closely as possible to its original condition.

reversibility - Ability to undo a process or treatment with no change to the object. Reversibility is an important goal of conservation treatment.

rice paper - A misnomer for paper made from the pith of a small tree found in the Far East. It is often, erroneously, called India Paper.

rice starch - Traditional starch used for mounting paste.

rosin - Solution obtained by cooking rosin with caustic soda ash. It is an additive which is used as an internal sizing for paper. Rosin sized paper is acidic and therefore undesirable for archival applications.

rubber cement - Adhesive consisting typically of a dispersion of vulcanized rubber in an organic solvent. Non-archival.

Sabbatier Effect - If film or paper has been exposed, developed, washed but not fixed, and is given a second uniform exposure and developed again, a reversal of the original image will be produced. Discovered originally in 1850. Man Ray accidentally rediscovered the process in 1929, and used it successfully in his work.

scoring - Creasing by mechanical means to facilitate folding while guarding against cracking of paper and board. Scoring is essential when heavyweight papers are to be folded across the grain.

section frame - The aluminum frame that is offered in its sectional pieces. It is available in gold and silver as well as many colors. They are easily assembled using screwdrivers.

selenium tone - Toner used on blueprints and transparencies that affects print color. Depending on dilution and time, the toner will have the effect of richer blacks and eventually tone the print to a reddish warm brown to a rich brown purple. Selenium toner is somewhat of an archiving process as well, protecting the silver of a print or slide with a selenium coating.

sepia toned prints - Sepia brown toner for photographic prints. A two-bath toner, the image is first bleached and then redeveloped in the toner, which affects the entire image tone of the photograph--rendering the image in a continuous brown (sepia) scale, as opposed to neutral black and white.

sheet film - Photographic film generally used in large format work, typical sizes including 4x5, 5x7, and 8xlO. Roll Mm is the general name for small format (e.g., 35mm) and medium format (e.g., 120 fihn).

shelf-life - The period of time before deterioration renders material unusable.

shives - Undercooked, thus incompletely saturated, wood particles that are removed from the pulp before manufacture of paper begins. Sometimes shives will appear in finished paper.

short grain paper - Paper made with the machine direction in the shortest sheet dirnension.

signature - (1) A folded, printed sheet ready for sewing. (2) A letter or number placed at the bottom of the first page of each signature of folded sections to serve as a guide for the binder.

silk screen printing - A stencil technique of printing.

silver halide - A silver salt formed by mixing silver metal with one of the halides, i.e., iodide, chloride, or bromide. This silver halide compound is then suspended in a gelatin to form a light sensitive emulsion.

silver halide film/paper - Common halides used in photography are silver bromide, silver chloride, and silver iodide. Silver bromide is most popular. The silver halide is the chief component of the light-sensitive emulsion, it is suspended in gelatin to assure an even and random dispersion, gelatin mixture is then coated on support bases of plastic film, glass or paper.

single wall - Describing one thickness of corrugation, or fluting columns, in boxboard or corrugated board.

sizings - Chemicals added to paper that make it less absorbent, so that inks applied will not bleed. Acidic sizings (rosin and alum), can be harmful and can cause paper to deteriorate, but some are not acidic and are expected to be more chemically stable.

slip-case - A box designed to protect a book or album, covering it so that only its spine is exposed.

slurry - The suspension of fibers and water from which paper is made.

solander case (museum case) - (1) A box with a hinged top, shaped like a thick book, that can house prints, pamphlets and documents.

solarization - Sometimes used to refer to Sabattier Effect, but solarization in the contemporary sense refers to over-exposure to the extent that, upon development, the densities diminish and appear to reverse.

spine (backbone, back, backstrip) - The part of a book or binder that is visible when it stands closed on the shelf. Also the hinged area of a clamshell-type box.

spores - Reproductive body produced by plants and some invertebrates and capable of development into a new individual.

spray mount - A kind of rubberized adhesive available in aerosol cans. It is used to mount photographs and small artwork. There are many variations of this product so that the label must be read carefully. Usually not considered archival.

stain - In photographic conservation, this refers to changes especially in a color print that occur in the dark. A typical example is the overall yellowing of early Kodachrome prints caused by deterioration of the magenta coupler.

stereo views - Popular photo medium of around the turn-of-the-century that utilized a card with two very similar images mounted next to each other on a single card. Using a viewing apparatus, the viewer looked through the dual eyepiece at the cards fixed a short distance away on the apparatus, and an illusion of dimension in the image was created. The cards were collected and were a predecessor to picture magazines.

Stereo-cards - Mounted images side by side on a card used with a specially designed viewer. (See stereo views.)

stereograph - A pair of photographic prints mounted adjacent to each other on a 3-1/2 by 7 inch card, which gives a three dimensional, or stereographic, image when used with the proper equipment.

sulfate - In papermaking, (1) an acid process of cooking pulp for paper; (2) pulp cooked by this process.

support - The surface onto which an emulsion is coated.

tack - To attach in a few spots, as in dry-mounting to position the piece before placing it is the press.

tacking iron - Small iron with adjustable thermostat used to "spot tack", position, and hold a print in place during dry mounting process.

TAPPI - Technical Association of the Pulp and Paper Industry. The objectives of TAPPI are to further scientific advancement in the pulp and paper industry; promote investigation, research and interchange of ideas among its members; encourage education in the science and practice of pulp and papermaking; collect and disseminate information; and provide technical facts, data, and standards specific to the manufacture of pulp and paper and its end uses.

tested fade - Standard testing and rating, evaluating a color dye or pigment within a board (as in museum board in colors) to retain its overall brightness, hue, and saturation without fading or changing.

text paper - A general term applied to various grades of printing papers which are made for the specific use of bookwork. Often the papers are watermarked with the word "text".

text weight - Relative classification of thickness of paper. Text weight is usually attributed to the thickness typical in published hardbound books. Literally, paper designed to hold text on the printed page. The stock is firm, but not rigid like cover weight.

thermal material - In reference to temperature indicator strips, being or involving a state of matter dependent upon temperatures.

thymol - A crystalline phenol of aromatic odor and antiseptic properties used chiefly as a fungicide and preservative.

tin type - Popular photographic process around the 1860s using a block enamelled template instead of glass. The process is a direct collodion positive one, yielding an image directly on the plate.

tipping in - To lightly attach with paste a leaf onto a sheet or printed book. colored prints are often "tipped in" expensive art books.

tissue paper - Category of papers characterized by extreme lightness and transparency. These papers suitable for napkins and bathroom tissues, can be made on any type of paper machine. Basic size: 24 x 36. Basic weights are less than 18 lbs. A ream of tissue contains 480 sheets.

toned image - Usually a black and white print submerged in a toner bath. The toner may affect image color, print tone, or both. Some toners render the print more stable and are used for preservation, as the toning solutions coat the silver components of the print or film.

toner - (1) The material employed to develop a latent xerographic image. (2) In photography, a compound used to impart a color to a developed black-and-white silver image.

toning - Treating a black and white print with a chemical to change the color and to protect the stability of the silver. Toners commonly used for photographic conservation include gold, selenium, and brown.

tooth - Characteristic of paper. A slightly rough paper which permits acceptance of ink readily.

translucency - Ability to transmit light without being transparent.

transparency - A positive film image with the same arrangement of values as the original scene. A 35mm slide is a transparency, but the term is more usually applied to images made in larger formats such as 2-1/4 square or 4 x 5. Most often refers to a color image.

Triacetate - See acetate.

Tyvek - Synthetic material composed of dense polyethylene threads woven and then compressed to form a paper like sheet. Well-known for its characteristics of strength and archival storage capabilities.

Ultraviolet light - Radiation having a wave-length beyond the visible portion of violet in the spectrum. Sunlight is a common source of ultraviolet light.

uncoated polyethylene - Polyethylene with no added coatings or surface treatments.

undermat - The bottom mat in instances where there are two or more layers, as in double or triple matting.

UV filter - A material used to filter the ultraviolet (UV) rays out of visible light. Ultraviolet radiation is potentially damaging to library, archival, and museum objects and more is present in sunlight and fluorescent light than in incandescent light. Removing UV radiation from storage, use, and exhibition spaces can reduce the rate of deterioration of library materials stored there. Usually a UV filtering material is placed over windows or fluorescent light tubes, or over glass used in framing, or in exhibition cases. Certain acrylic sheet materials have UV filtering properties built in.

Van Dyke Process - Alternative process similar to Kallitype process also known as brown prints. An iron salt process that requires contact printing, the emulsion is composed of relatively simple chemistry. The print requires processing and toning to permanently fix the image and is best known for its distinctive rich brown color.

vapor seal envelopes - A laminated moisture proof, multilayered material designed for cold storage of films, papers and transparencies.

variable contrast papers - Photographic printing paper whose emulsions respond to general contrast filters placed in the path of the enlarger light source. The filters provide various grades of contrast in various steps from low to high contrast, to allow the printer control in printing a well- crafted print.

vellum - Originally the skin of calf, usually not over six weeks old, cleaned of adhering flesh hair, fat and muscle, and preserved by soaking in a lime solution, then carefully dried, stretched, scraped, and polished; used for writing or printing upon, or as binding material. Now used to describe a smooth paper finish.

vinyl - The word vinyl is imprecisely used to refer to any of a number of plastics, many of which are not appropriate for use in preservation. For specific safe plastics, see polyester, polypropylene, polyvinyl acetate, acrylic.

washing agent - Also known as an archival rinse, the solution aids the removal of residual fixer and silver-sulfur compounds from emulsions and paper based fibers.

water stain - Discoloration of paper caused by direct contact with fluids or excessive humidity.

watermark - The mark made within a sheet of paper by a raised design on the screen of a paper mold, which serves as the mark of the papermaker. It may be seen by holding the paper up to the light.

wet-mount - The technique of gluing artwork to a support with water-based adhesives.

wheat starch - Traditional starch used as mounting paste.

white light - The visible spectrum of light, whether artificial or natural.

window mats - An overmat cut with an opening to allow artwork mounted on backing mat to be displayed.

wood pulp - Prepared for papermaking from trees of various kinds. The process of manufacture includes two distinct classes: (1) mechanical wood pulp or ground wood from which newsprint is made; (2) chemical pulp, produced by various methods, which is a higher grade since more lignin and other impurities are removed.

xerography - A generic term for the formation of a latent electrostatic image by action of light on a photoconducting insulating surface. The latent image may be made visible by a number of methods.