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Abrasion: A surface loss apparently caused by friction on the surface of the design or paper (other terms include scrap, rub and wear).

Accession Number: A number assigned to an object that has become a part of a permanent collection. This number allows the object to be tracked throughout its lifetime in the collection.

Accretion: An accumulation of extraneous material on the surface of an object which alters the original texture and sometimes the color (other terms - incrustation).

Acetate: An acidic plastic that causes photographs and documents to deteriorate and fade.

Acetone: A highly flammable solvent used to dissolve lacquers, adhesives, etc.

Acids: A substance that produces hydrogen ions when dissolved in water. Acids have a pH of less than 7.0. Acids are produced in paper when the paper and chemicals within the paper deteriorate, or when acids are absorbed from the environment. Over time, acids break down the paper fibers causing the paper to deteriorate and become brown and brittle.
Acid free: A non-specific term that refers to papers that do not contain acids with a pH value of 7.0 or higher. Acids can cause paper to discolor, become inflexible, and eventually turn brittle. All papers, envelopes and boxes used to store valuable documents, photographs and artwork should be acid free. See also PAT Test and buffered.

Acid-free tissue paper: Highly purified, chemically treated wood pulp paper. Unbuffer (neutral pH) and buffered products made from rag fibre are also available.

Acid migration: The transfer of acids from one acidic material to another less acidic material, either by direct contact or by absorption of acidic gases from the surrounding atmosphere. The less acidic material usually becomes stained and weakened.

Abrasions: The scratching or rubbing of a surface thereby affecting its color, texture, surface gloss etc.

Acryloid B-72 - (ethyl methacrylate/methylacrylate): (a trade name) An acrylic resin produced by the Rohm and Haas Company that is used as an adhesive by conservators.

Adhesive: A substance that causes two or more materials to bond. The action of bonding varies among adhesive types (e.g., pressure-sensitive vs. glue).

Adhesive residue: Residue left in the paper after the tape or glue has been removed. This is usually acidic in nature.

Agents of deterioration: A variety of mechanisms that cause damage to museum collections. The agents include: light, pests, incorrect temperature and humidity, fire, water, physical force, and vandals.

Alkali, alkaline, or base: A varied group of substances that when dissolved in water create a hydrogen ion concentration less than 10-7. This term has also been used with paper products to imply the inclusion of an alkaline buffer.

Alkaline chemical (or alkali): A substance that reacts with acids. Alkaline is added to paper pulp at a level sufficient enough to neutralize acids. All buffered paper also has a reserve of alkaline that can react with acids absorbed from the atmosphere or produced by future degradation of the paper. This makes the paper alkaline (or acid free) and will reduce future deterioration of the paper.

Alkaline bath: Used in context with documents that have been washed to remove dirt. An alkaline bath deposits an alkaline buffer (reserve) into the paper that wards off future acid deterioration that may come from the environment, materials stored in the same general area, etc.

American Institute For Conservation (AIC): the national membership organization in the United States of conservation professionals dedicated to preserving the art and historic artifacts of our cultural heritage for future generations.

ANSI (American National Standards Institute, Inc.): An organization that publishes industry standards that relate to the quality of goods manufactured in the United States.

Archival: A term often used to imply that a product will be stable over time and/or will not be reactive with enclosed photographs. The term currently has no standard definition or quantifiable method for verification and is therefore often used improperly on product packaging.

Artifact: An object showing human workmanship.

Backing: Material placed behind the back mat for additional protection. The term is also used as a mounting procedure by paper conservators where the object verso is lined with a sheet of Japanese paper and starch paste (see. lining).

Binder’s board: A thick paperboard used to impart rigidity to book bindings, boxes, and photo albums.

Bleaching: A cosmetic process done to works of art on paper which involves permanently changing the chemical structure of substances that are colored to yield substances that are not colored. The practice of bleaching with chlorine is no longer considered acceptable.

Bleed-proof: A term used to describe an ink that does not migrate from its original point of application over time. This applies to both wet and dry environments.
Bleed-through: The migration of a colorant from one side of a material to the other.

Bleeding: The suffusion of a color into adjacent materials, often caused by water or other solvents.

Blocking: The adhesion of glass, plastic films, or papers to the surface of photographs as a result of gelatin softening. This usually occurs under conditions of high humidity. In severe cases, the photographs cannot be removed.

Bloom: A white or bluish cloudiness that is often seen on the surface of a coating of natural resin. Sometimes seen on varnished prints that have been exposed to moisture.

Bone Folder: An extremely smooth, polished piece of real bone used to make sharp creases and folds in paper or Mylar.
Buckling: A bulge in the surface of the paper.

Buffer: A term used to describe a material to which slightly water-soluble acid or base has been added in order to stabilize the pH. In paper this is an alkaline substance, such as calcium carbonate (CaCO3), which is used to reduce the quantity of acids that may build up as a result of the degradation of paper fiber or acid absorption from the environment.

Buffered: A term used in the paper industry designating that an alkaline filler has been added during the paper-making process, which makes the paper acid free. It also increases the smoothness of the paper surface, improves brightness and opacity, and helps prevent ink from feathering.

Buffered tissue: Paper to which an alkaline substance has been added. Is generally used as a protective sheet either over or behind works on paper.

Calcium carbonate (CaCO₃): The primary filler added in the paper-making process that makes paper acid free (neutral pH or buffered pH).
CD-ROM: A compact disc that can store large amounts of digitized photographs and data files.
Cellulose: C₆H₁₀O_{5
Paper; a polysaccaride with the glucose units linked.}

Cellulose acetate: Used in the context of lamination (see below) it is the plastic film between which a document to be laminated is placed and which bonds with paper when heated.
Cleavage: Separation between or in any of the layers in a stratified construction.

Coated paper: A paper with a finishing layer on one or both sides of the core sheet. The most common form of coated paper is magazine, art book and poster stock.
Cockling: A broad wrinkle or system of wrinkles without creasing, usually referring to the conformation of paper or parchment.
Collections Care: The protection of a group of artifacts using preventive measures to avoid physical and environmental damage.
Collections Care Specialist: An individual who is trained and experienced in specific preventive care activities and who works in conjunction with or under the supervision of a conservator.

Colorfast: A pigment or dye that is resistant to environmental exposure, such as light, water, acid, heat and other atmospheric conditions. Materials such as storage enclosures, mat board and display cloths should all be colorfast when exposed to moisture to avoid bleeding of color onto valuables.
Condensation: Humidity that is trapped and forms a vapor. Condensation often results in mold growth, water stains and foxing in paper.
Conservation: The profession devoted to the preservation of cultural property for the future. Conservation activities include examination, documentation, treatment, and preventive care, supported by research and education.
Conservator: A professional whose primary occupation is the practice of conservation and who, through specialized education, knowledge, training, and experience, formulates and implements all the activities of conservation in accordance with an ethical code such as the AIC Code of Ethics and Guidelines for Practice.

Conservation Administrator: A professional with substantial knowledge of conservation who is responsible for the administrative aspects and implementation of conservation activities in accordance with an ethical code such as the AIC Code of Ethics and Guidelines for Practice.

Conservation Educator: A professional with substantial knowledge and experience in the theory and techniques of conservation whose primary occupation is to teach the principles, methodology, and/or technical aspects of the profession in accordance with an ethical code such as the AIC Code of Ethics and Guidelines for Practice.

Conservation Scientist: A professional scientist whose primary focus is the application of specialized knowledge and skills to support the activities of conservation in accordance with an ethical code such as the AIC Code of Ethics and Guidelines for Practice.
Conservation Technician: An individual who is trained and experienced in specific conservation treatment activities and who works in conjunction with or under the supervision of a conservator. A conservation technician may also be trained and experienced in specific preventive care activities.
Conservation Treatment: Techniques employed by a conservator to stabilize damage and/or deteriorated artifacts.
Copy negative: A negative made by reproducing a photograph or reproducing artwork.
Coroplast^TM: Chemically inert corrugated plastic (polyethylene polypropylene copolymer).

Cropping: Altering the boundaries of a finished photograph by trimming or masking the photograph. Cropping is NEVER carried out by a conservator during any treatment.
Cultural Property: Objects, collections, specimens, structures, or sites identified as having artistic, historic, scientific, religious, or social significance.

Deacidification: An alkaline-salt process that raises the pH level in or on paper. It impregnates the paper with a high alkaline reserve and neutralizes existing and future acids until the reserve is used up.

De-ionized water: Water from which practically all minerals have been removed.

Dent: A concavity caused by a blow.

Documentation: The recording in a permanent format of information derived from conservation activities.
Dark stability: The ability of a material to resist degradation when stored in the dark
Digital image: Any image stored as numerical values on optical or magnetic media. This term is also used for any print created from such a set of stored numerical values.
Distilled water: Water obtained from steam freed from volatile gases and condensed back to a liquid state.

Dry Cleaning: A conservation technique to remove surface dirt and grime from paper using a special eraser or draft-cleaning pad/powder without damage or staining the paper.

Dust: Loose soil tenaciously held on the surface of an object.

Dye: A soluble colorant. Dyes are typically less stable than pigment colorants, but they can produce a greater, more vivid, color gamut.

Encapsulation: A method of artifact protection in which a single paper or photograph is sandwiched between two sheets of Mylar Type D and sealed in with double-sided tape.

EthafoamTM: Inert, white, translucent expanded polyethylene foam in slabs of varying thicknesses; available in a variety of densities.

Ethanol: An alcohol type solvent used to dissolve dirt. Typically mixed with water for washing documents.
Examination: The investigation of the structure, materials, and condition of cultural property including the identification of the extent and causes of alteration and deterioration.

Fading: The gradual loss of color due to the breakdown of colorants to invisible forms.

Fiber-based print: A photographic print on a paper base that has not been laminated with polyethylene. Fiber-based paper was used until the advent of polyethylene-laminated papers in the late 60s. Fiber-based paper is currently used only for certain black-and-white photographic print products. Because of the way it is made, fiber-based paper can have a 200-year life expectancy (if taken care of and processed correctly).
Flaking, Flaked Loss: A loss of paint following cleavage or weakness in or between layers.

Flattening: Flattening is necessary following aqueous treatment. Flattening is done between blotters or felts under moderate pressure. Objects that have been lined can be flattened on a drying screen.
Foxing: The result of chemical action between the iron impurities within the paper and organic acids. Visually it looks like brown spots on or through a piece of paper. It generally indicates the presence of mold but may come from other sources.

Frass: Fecal matter and food debris from insects.

French Ivory: Synthetic ivory made from cellulose nitrate in the late 1800s to early 1900s.

Fugitive dye: A dye that is not permanent. It will fade when exposed to light, run when water is applied, and will transfer color to other items.
Fumigation: Fumigation, once a standard treatment for mold and insects, is now seldom done. This is because chemical fumigants can have adverse effects both on works of art and on personnel. Moreover, fumigation is ineffective in the long run if the objects are returned to storage conditions that were responsible for the mold in the first place.

Glassine: A translucent paper storage enclosure most often used for photographic negatives. This material can become permanently embedded in gelatin under very humid conditions. ISO has determined glassine inappropriate for use as a photographic storage enclosure.

Grime (surface): Dirt of any kind tenaciously held on the surface of an object.

Ground wood pulp: Pulp created by the action of mechanically grinding wood. This low-cost pulp is chemically unstable and should be used only for short-term paper needs such as newspapers and magazines.

Hand tinting (hand coloring): The process of applying colors with oils or dyes to the surface of a black-and-white photograph, giving it the appearance of a colored photograph.

Heat set adhesive: Synthetic adhesive which are activated by slight pressure and heat.

Humidity: The measurement of the moisture content of air.
Hydrolysis: One mechanism by which paper fiber and color dyes degrade. It is driven by moisture, pollutants (acid or alkaline), and heat.

Inert: Will not change, will not cause change; non-reactive.

Inhibitor: A substance that slows or stops a chemical reaction.

Inpainting (Retouching): Inpainting is done by judicious application of watercolor, acrylics, gouache, or pastel to filled areas or to surface losses such as scratches, small abrasions, or media losses along tears.

Interleaving: An acid-free sheet that is placed between pages in a scrapbook, album, book, box or drawer to separate items from one another to reduce the risk of scratching, acid migration, image transfer etc.

Iron gall ink: An acidic, indelible ink popular from the middle ages to the mid 20th century when it was replaced by carbon ink. Made of tannin, iron sulfate, gum Arabic and water, and with age turns brown.

Japanese paper: A long fiber paper that is made from the inner bark of the Kozo tree and because it is extremely strong and delicate, is used to mend paper tears.

Lamination: This was a standard practice in libraries and archives between 1930-50's for strengthening fragile documents but is now obsolete. The process was done by placing the document between sheets of cellulose acetate and applying high heat and pressure. The heat causes the layers of the material to bond to the original document making it irreversible.

Leaf-casting: paper repairs using matching pulp infills.

Lightfast: A term used to describe a colorant resistant to fading on exposure to light.

Light stability: The ability of a material to resist degradation when exposed to light. This applies to both photographs and scrapbook components, such as papers, plastics, inks, and adhesives.

Lignin: A chemically complex substance found in plants that bonds the cellulose fibers together. Lignin can be largely removed during pulping, but the cost of low-lignin papers is higher than than that of high-lignin or ground wood papers. Lignin is believed to contribute to the degradation of both papers and photographs causing it them to turn yellow over time.

Lignin free: To be considered lignin free, paper can contain a maximum of one percent lignin.
Lining: The process whereby a tensioned piece of Japanese paper is attached to the verso of a piece with starch paste. Usually carried out to consolidate tears and/or losses or strengthen a weak primary support.

Mending: Tears are carefully aligned and reinforced on the reverse with thin strips of Japanese paper or tissue and a starch-based adhesive. With double-sided documents, fine tissue is used to avoid obscuring writing on the reverse.

Migration: The movement of chemicals to neighboring materials. This term is often used to describe the movement of acids between adjacent materials, such as storage papers and enclosed photographs.

Mold/Mould/Mildew: A large group of small fungi, the vegetative structures of which invade many organic substances. Provided sufficient moisture is present, these structures produce enzymes which dissolve or degrade the host material. This chemical action may leave wastes which stain the hosts, as foxing marks on paper. Mold activity can be arrested by maintaining a dry environment (below 65% relative humidity).

Mount: The secondary paper or board to which the 'support' is attached.

Mylar D: Invented in the 1960s. Mylar is the proprietary name for uncoated sheet polyester plastic made by Dupont. It is chemically stable (inert) and does not release harmful gases. Mylar D is used in sheet protectors, photograph sleeves and is safe for encapsulation.

Neutral pH: The center reading of 7.0 on the pH scale of 0-14. It is neither acidic nor alkaline. For manufacturers, the acceptable pH neutral range is from 6.5-7.5.
Non-migrating: A composition in a material that will not transfer or spread to a neighboring item.

Opaque: Any substance or surface that will not allow any light to pass through.
Ortho-phenylphenol: A chemical sometimes added to starch paste as a preservative.

Oxidation: The chemical action of electron removal from one atom or molecule by another atom or molecule. This action is often cited as the cause of image fading in black-and-white photographs. Removal of an electron from an atom of metallic silver converts that silver to an ionic – and invisible – form. Oxidation is also implicated in the degradation of color images and papers.

Paste: Adhesives (starches) made from the carbohydrate reserves in plants.

PAT Test: The Photographic Activity Test, a test used to predict certain chemical interactions between scrapbooking materials and photographic images. This is one of many tests used to determine if a material is safe for use with photographs. A pass result in the PAT is not necessarily an indication that the material is completely photo-safe.

Permanence: A term referring to a material's ability to maintain its strength and color over an extended period of time (in some cases, several hundred years) without significant deterioration under normal use and storage conditions.

pH: A measurement of the degree of acidity and alkalinity. On a scale ranging from 0-14, pH 7.0 is neutral, above 7.0 is alkaline (or acid free) and below 7.0 is acidic. The scale is a logarithmic progression, meaning 6.0 is 10 times more acidic than 7.0. pH can only be measured on water-soluble materials. Note: The letters "pH" come from the French words for "hydrogen power."
pH testing pen: A pen containing a pH indicator dye that is used to assess pH. The user spreads a fine layer of the indicator dye on an object's surface and compares the resulting color to a reference.

Photographic Activity Test: See PAT Test.

Photo-safe: There is no standard definition or test method for this term. It is often used in advertising to imply a product’s non-reactivity with photographic images.

Pigment: A non-soluble substance used as a colorant that is mixed with a binder so it can be adhered to a surface. Pigments are generally more stable than dyes, but they produce a narrower color gamut.

Plasticizer: A chemical added to plastics to increase their pliability. The most notable plasticized photo storage material is flexible PVC, which has been shown to exude its plasticizer onto the surface of enclosed images. ISO storage standards recommend against the use of PVC in photograph storage enclosures.

Polyester: A clear, inert, uncoated, strong plastic generally considered safe by ISO for use as a storage enclosure for photographs. However, some of these plastics are treated with thin coatings to modify their chemical and surface properties, so polyester products should still pass the PAT. Polyester is used in making folders, book jackets and sheet protectors, and is also used for encapsulation. Common trade names are Mylar D and Melinex by Dupont.

Polyethylene: A flexible, chemically stable, naturally slippery plastic generally considered safe by ISO for use with photographs. However, some of these plastics are treated with thin coatings to modify their chemical and surface properties, so polyethylene products should still pass the PAT. Polyethylene is used primarily in the manufacturing of archival photographic sleeves and poly bags.
Polypropylene: A clear, pliable, chemically stable plastic generally considered safe by ISO for use with photographs. However, some of these plastics are treated with thin coatings to modify their chemical and surface properties, so polypropylene products should still pass the PAT.

Polyvinyl chloride (PVC): a plastic generally considered unsafe by ISO for use with photographs due to its plasticizer content and potential for emission of hydrochloric acid upon its degradation. Note that PVC comes in both flexible and rigid forms. The harmful plasticizer is used only in the flexible form. When the plasticizer degrades it emits corrosive and acidic hydrogen-chloride gas (strong plastic odor) and will exude an oily residue. Common names: vinyl and Naugahyde.

Pressure-sensitive adhesive: An adhesive that bonds on contact and whose bond strength increases with increased pressure and/or time.

Pressure-sensitive tape: A pretreated tape that adheres to a surface when pressure is applied without having first applied an adhesive or moisture or otherwise treating the surface.

Preventive care (also referred to as preventive conservation): The mitigation of deterioration and damage to cultural property through the formulation and implementation of policies and procedures for the following: appropriate environmental conditions; handling and maintenance procedures for storage, exhibition, packing, transport, and use; integrated pest management; emergency preparedness and response; and reformatting/duplication.
Preventive Care: Non-interventive actions taken to prevent damage to and minimize deterioration of a museum object. Such actions include monitoring, recording, and controlling environmental agents; inspecting and recording the condition of objects; establishing an integrated pest management program; practicing proper handling, storage, exhibit, housekeeping and packing and shipping techniques; and incorporating needed information and procedures about objects in emergency operation plans.

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

Pulp: A wet slurry of fibers and water that is the basic ingredient of paper.

Rabbet: A recess in the wood of the frame cut so as to receive the glass and the mounted object.

Rag paper/board: A paper or board with high long-fiber cotton content. Cotton fiber contains no lignin and has historically been considered the most appropriate material for use in photographic storage enclosures and framing packages. It is generally higher in cost than wood pulp papers. Recent research has shown that papers made from de-lignified, bleached wood pulps may be as safe for use with photographs as papers made from cotton pulps. It should be noted that despite the quality of pulp (wood or cotton) used in paper making, a variety of other paper additives could be reactive with photographs.

Raking light: Light shining on an object from a low angle. Flaking surfaces show up well in raking light.

Ream: A ream is 500 sheets of paper, regardless of the paper size or thickness.

Recto: In works of art on paper it refers to the front design side of the paper.

Recycled paper: Paper that meets the minimum reclaimed-content standards established by federal, state and municipal governments, and the paper industry. Fiber content usually consists of post- and pre-consumer reclaimed fiber plus virgin pulp.

Relative humidity: The amount of water vapor in a volume of air expressed as a percentage of the total water the air can hold at that same temperature.

Resin-coated paper (RC paper): A photographic paper that has been coated with polyethylene on both sides. Photographic papers that are resin-coated have a significantly lower processing time due to its water-resistant nature. All consumer color photographic prints are now printed on RC paper. Black-and-white prints can be printed on either RC or fiber-base paper.

Resizing: A process whereby a sizing material is added to paper after it has been washed or treated causing the original sizing to be removed.

Restoration: Treatment procedures intended to return cultural property to a known or assumed state, often through the addition of non-original material.

Reversible: A preservation process or treatment that can be undone without changing the object, returning it to its original state. Conservators prefer to use the term removable to describe the ability to remove materials added during a treatment rather than claiming a treatment is reversible. Certain treatments such as cleaning can not be reversed. Once removed the same dirt can not be put back on the piece.

Safety film: Film introduced in the 1950s that replaced the volatile cellulose-nitrate film. It is called safety film because it is made from an acetate base that is not flammable—it will melt but not burn unlike nitrate films.
Sections: Used in the context of book binding sections are the folded sheets of paper that make up the pages. To bind a book, one sews the pages (or sections) together thorough the folds. The sewn sections are then sewn together to form a text block.

Silking: A now obsolete but once popular way to provide additional support for fragile or torn documents by placing a document between two thin pieces of silk adhered to the document with a thin layer of paste. This process was popular between 1900-1930.
Sizing: A coating applied to the paper surface that increases water resistance, eliminates abrasiveness and fuzz, and improves bonding strength.
Solvent: A substance that dissolves another substance to form a solution. Example: Water is a solvent for sugar.

Spatter: Refers to dried droplets or splashes of foreign material on a surface.

Spine: the part of a book on which the title appears.

Stabilization: Treatment procedures intended to maintain the integrity of objects and minimize deterioration.

Stain: A discoloration caused by an agent which has penetrated a porous or absorbent surface, very common in paper.

Starch paste: an extremely pure paste used to fix Japanese tissue mends. It is soluble in water making mends applied using it reversible.

Substrate: A surface or medium on which inks may be applied, such as paper, canvas or plastic.

Support: The paper on which the art work was created.

Thymol: A general fungicide used to fumigate paper. This chemical is no longer considered acceptable for use in paper conservation.

Tipped in: The attachment of a loose leaf of paper by means of a thin line of paste that holds the item in place. A page that has fallen out of a book can frequently be 'tipped-in' eliminating the need for the book to be completely rebound.

Transmitted light: Light shining through an object from behind.

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

UV light: Electromagnetic radiation in the range of 300 to 400 nanometers. UV radiation is not visible, and therefore "UV light" is a misnomer. UV radiation has been implicated in the degradation of photographs and papers. Reducing overall image exposure to UV radiation through the use of alternate light sources (daylight and fluorescent lights emit a high degree of UV radiation, tungsten emits a low degree), low light intensity, or special UV filters will extend the life of the exposed image.

Varnish Removal: As the name implies, the removal from a work of art of the aged and/or discolored varnish of whatever kind. A variety of solvents and techniques are employed in this procedure.

Verso: In works of art on paper it refers to the reverse side of the object (usually without a design on it).

Washing: Placing the work of art in a water bath (usually de-ionized or distilled water sometimes with the addition of a buffer) to clean dirty and stained paper.

Water cutting: The technique of severing the paper fibers using a brush loaded with water. When the paper is pulled apart along the wet line it yields a feathered edge.

Waterproof: Non-water soluble. Some materials, like PVA glues, are initially water-soluble but become waterproof upon curing.
Water soluble: A term used to describe any material that dissolves in water.

Window mat: a two piece housing for works of art or documents that allows them to be safely displayed. The window piece sits on top of the document that has been mounted on the bottom or support piece. The mat is typically enclosed in a frame.

Tudhope Conservation Studio
Denver, CO (303) 831-9291