Abrasion resistance – the level at which paper can withstand continuous scuffing or rubbing.
Absorption – the properties within paper that cause it to absorb liquids (inks, water, etc.) which come in contact with it.
Accordion fold – a binding term describing a method of folding paper. When unfolded it looks like the folds of an accordion.
Acetate proof – a transparent, acetate printing proof used to reproduce anticipated print colors on a transparent acetate sheet.
Acetate pulp – a manufactured fiber in which the fiber–forming substance is called cellulose acetate. Acetate is manufactured by treating purified cellulose refined from cotton linters and/or wood pulp with acetic anhydride in the presence of a catalyst.
Acid free – paper made in a neutral pH system, usually buffered with calcium carbonate. This increases the longevity of the paper.
Acidity – degree of acid found in paper measured by the pH level. From 0 to 7 is classified acidic versus 7 to 14, which is classified as alkaline.
Adhesives – any substance that can hold materials together in a functional manner by surface attachment that resists separation. “Adhesive” as a general term includes cement, mucilage, glue, and paste—terms that are often used interchangeably for any organic material that forms an adhesive bond.
Against the grain – a right angle to which the fiber direction of a piece of paper lies. Folding with, not against, the grain is recommended.
Aging – irreversible alteration, generally deterioration, of the characteristics of paper or board produced in the course of time such as folding endurance, color etc. It is commonly associated with the diminishing of brightness of pulp and paper with age or the developing of a yellow color.
Alcohol / Alcohol substitutes – liquids added to the fountain solution of a printing press to reduce the surface tension of water.
Alkaline papermaking – alkaline papermaking refers to the formation of paper sheets from fiber slurries having a pH generally in the range of 7 to 9. Alkaline paper sheets typically contain some form of calcium carbonate filler.
Aluminum plate – a metal press plate used for moderate to long runs in offset lithography to carry an image.
Anti–offset spray – in printing, a material (usually dry starch particles) sprayed on to the wet ink film surface to prevent set–off.
Antique finish – a paper finish, usually used in book and cover papers, that has a tactile surface. Usually used in natural white or cream white colors.
Apparent density – weight (mass) per unit volume of a sheet of paper obtained by dividing the basis weight (or grammage) by caliper (thickness).
Aqueous coatings – aqueous coating is a clear, fast–drying water–based coating that is used to protect printed pieces. It provides a high–gloss or matte surface that deters dirt and fingerprints. Aqueous coating improves the durability of postcards and other printed pieces as they go through the mail and protects business cards as they are carried in peoples' wallets. It also looks beautiful on brochures, catalog covers, and presentation folders. Aqueous coatings provide more substantial scuff–resistance than varnishes. Aqueous is typically applied to the entire printed piece, usually by the last unit on a printing press. Due to its water base, aqueous coating is more environmentally friendly than varnish or UV coatings.
Archival – acid free or neutral paper that includes a minimum of 2% calcium carbonate to increase the longevity of the paper.
Artwork – original materials, including the illustrations, lettering, charts, color blocks, etc. which are to be reproduced in a printed piece.
Ascenders – the tops of lower–case letters such as: b,d,h and t.
Back cylinder pressure – additional pressure applied through the impression cylinder assisting the image transfer to the press sheet.
Backbone – the back of a bound book; also called the spine.
Backing up – printing the reverse side of a sheet already printed on one side.
Baggy roll – a roll that gives non–uniform drawing across the web. There are slack and tight sections across the width of the sheet.
Bale – solid, compressed stack of pulp or paper sheets.
Bank note paper – an age–resistant paper, suitable for 4–colour printing, with watermark and falsification safeguards such as embedded metal strip. Often containing cotton fibers.
Band – (1) a strip of paper printed or unprinted, that wraps around loose sheets (in lieu of binding with a cover) or assembled pieces. (2) the operation of putting a paper band around loose sheets or assembled pieces. (3) metal straps wrapped around skids of cartons or materials wrapped in waterproof paper, to secure the contents to the skid for shipment.
Barrier paper – paper that is specially treated, coated, or laminated to provide resistance to the passage of moisture, vapor, gases, oils, water and other liquids.
Base color – a first color used as a background on which other colors are printed.
Base stock – manufactured paper that will be further processed as laminated, Duplex Cover, Bristol Cover, or off machine embossed papers.
Baseline – in typesetting, the invisible line on which letters and numbers are set.
Basic size – a standard sheet size used to establish basis weight for a given grade of paper. The standard size varies, depending upon the grade or type of paper and is related to the traditional end usage.
Basic weight – the weight in pounds per ream of paper cut to its basic size. A standard ream is defined as 500 sheets.
Binder – materials, which cause coating pigments to bond. The most frequently used binder is starch, but synthetic binders are also used to give improved performance.
Binders board – grey colored, glazed board often used in the binding of hardcover books.
Binder migration – a coated paper defect where specks give a grainy or textured appearance to the coated surface.
Bindery – (1) attaching sheets into a single unit by adhesives, sewing, stitching, metal prongs, snaps, etc. The operations that comprise collating, perforating, and folding elements of a form into the finished product. (2) that portion or edge of a book of forms which is bound.
Binding edge – the edge where the binding will be done.
Biodegradable – organic materials such as food and paper that are broken down by microorganisms into simple compounds such as carbon dioxide, water, or minerals.
Bioenergy – energy generated from renewable biomass e.g. plants and plant components.
Biofuels – renewable fuels for example from wood and bark.
Black printer – in four-color process printing, the black plate made to give definition to neutral tones and details.
Blade coating – a widely used coating method in which excess coating color is scraped off by blade.
Blade mark – caused by a foreign piece of material caught under the coating blade, resulting in a scratch or streak that causes the paper surface to appear less opaque under a low angle light. Also known as a blade scratch or blade streak.
Blanket – in offset lithography, the rubber coated fabric clamped around the blanket cylinder, which transfers the image from plate to paper.
Blanket–to–blanket – a printing method in which a sheet of paper is passed through two blanket cylinders and is printed on both sides.
Blanket contamination – unwanted matter that becomes attached to the offset blanket and interferes with print quality.
Blanket creep – movement of the blanket surface that meets the printing plate or paper.
Blanket cylinder – the printing press cylinder on which the blanket is mounted.
Blanket pull – the tack between blanket and paper.
Blanks – types of paperboards with good stiffness and printing quality used for making posters, merchandising displays, and other types of signs.
Bleaching – chemical treatment to brighten, whiten, purify, refine, and balance pulp fiber.
Bleed – (1) an illustration that extends to one or more of the edges of a printed piece; bleed illustrations are usually printed 1/8” beyond the planned trim edge (s). (2) term applied to a lithographic ink pigment, which dissolves in the fountain solution and causes it to be tinted. (3) the discoloration of dyed pulp and paper due to the removal of color by liquid, thereby making it susceptible to staining other materials it contacts.
Blind embossing – a printing technique in which a design is pushed forward without foil or ink.
Blisters – small, bubble–like formations which appear on both sides of the web in the same area, primarily in areas of heavy ink coverage. Excessive moisture cannot escape because the ink coverage traps it.
Blocking – the sticking of piled printed sheets caused by wet ink.
Blocking out – eliminating portions of negatives by opaquing the image.
Blueprint – in printing, a type of photoprint used as a proof. It can be folded to show how the finished printed product will look.
Boldface – thicker, visually heavier type vs. thin visually light type. Darker type.
Board – generic term for stiff paper, often consisting of several plies and with a grammage normally above 150g/m2.
Bond paper – strong, durable writing paper, consisting of wood, cotton, or both, most commonly used for letterheads, stationery, business forms, etc.
Bonding strength – the strength of the paper fibers to resistance of picking or tearing during offset printing.
Bone dry – (1) descriptive term for the moisture–free conditions of pulp paper. (2) refers to air containing no water vapor.
Book paper – a general term used to define papers that are most suitable for book manufacture.
Booklet – a printed piece bound together, containing few pages.
Boxboard – paperboard used in the manufacture of boxes. May be made of wood pulp or wastepaper. May be plain, lined or clay coated.
Brightener – fluorescent dye or pigment that absorbs ultraviolet radiation and re–emits blue light, thereby effecting a white appearance to a sheet of paper when added to the furnish stock.
Brightness – the percentage of light at a certain wavelength (457 nanometers) that is reflected from the surface of the paper and is related to how light or dark the sheet appears. High brightness papers give greater contrast with black inks and a more vivid appearance of ink colors. Low brightness papers are traditionally used in book printing or limited use read and dispose.
Brightness reversion – the loss of brightness of bleached pulp, paper, and paperboard over a period of time. Also known as color reversion and yellowing.
Bristol paper – heavyweight or thick paper (usually 6 pt. or higher) commonly used for filing or mailing.
Brittleness – a property of paper that causes it to break when subjected to binding, converting, finishing, folding, and handling. Factors, which contribute to brittleness are composition, moisture, drying and aging.
Brochure – a pamphlet that is bound in booklet form.
Broke – (1) paper trimmings or damaged paper due to breaks on the paper machine and in finishing operations. (2) paper which has been discarded during any stage in its manufacture; represents loss in time, money and effort.
Bulk – the degree of thickness of paper. In book printing, the number of pages per inch for a given basis weight.
Burnout – the loss of color during drying.
Bursting strength – a measure of the strength of paper to withhold pressure without rupturing.
C1S – paper that has been “coated one side”; label paper.
C2S – paper that has been “coated two sides”; coated paper for text, publication, or commercial printing.
Caking – when printing, the spots of ink pigments on printing plates or press rollers, due to the vehicle carrying the ink not being able to hold the pigment in suspension.
Calcium Carbonate, CaCO3 – chemical used as a filler.
Calender Cuts – calender cuts have a glazed edge and are straight, sharp cuts running for a relatively short distance at an angle to the direction of the web travel.
Calendering – to impart a smooth finish on paper by passing the web of paper between polished metal rolls to increase gloss and smoothness.
Caliper – thickness of a sheet of paper or paperboard, measured under certain specifically stated conditions expressed in units of thousandths of an inch (called “mils” when referring to paper, and “points” when referring to paperboard). In regions using metric measurement, usually measured in millionths of a meter (microns or µm). Also called thickness.
Carbonless paper – collectively, a set of two or more papers that are engineered to transfer images though applied pressure from the top sheet to one or more sheets below, without the use of a carbon sheet.
Cardboard – a thin, stiff paperboard made of pressed paper pulp or sheets of paper pasted together. Used for playing cards, greeting cards, etc.
Card Stock – a heavy grammage paper also known as Cover. Used as covers of catalogs, brochures, books or business cards.
Casebound – a book bound with a hardcover.
Cast coated paper – very high gloss coated paper and paperboard with surface characteristics produced by allowing applied coating to harden while in contact with a surface of steam heated, highly polished, chrome plated drum.
Catalog paper – a lightweight paper of good printing quality suitable for use in mail–order catalogs or telephone directories.
Cellulose fiber – the fiber remaining after bleaching and pulping of wood used in paper making.
Center spread – the facing pages in the center of a bound signature.
Chain of custody – the channel through which products are distributed from their origin in the forest to their end–use.
Chalking – improper drying of ink. Ink vehicle has been absorbed too rapidly into the paper leaving a dry, weak pigment layer which dusts easily.
Character count – the number of characters in a line of text, page or group of text.
Check paper – a strong, durable paper made for the printing of bank checks or cheques.
Chemical ghosting – a light duplication of a printed image on the other side of the sheet, created by chemical reaction by the ink during drying stages; also referred to as “Gas ghosting.”
Chemical pulp – wood fiber cooked using chemicals producing a pulp used to manufacture numerous printing papers and paperboard products. Papers manufactured with chemical pulp are called “free–sheet” papers.
Chip – wood chips produced by a chipper; used to produce pulp, fiberboard and particle board, and as fuel.
Chip board – (1) inferior quality, low density, solid or lined paperboard made primarily from recycled wastepaper stock and used in low strength applications. (2) name used for cardboard made from wastepaper, normally consisting of several plies. (3) colloquial name given to particleboard wood panel material.
Chlorine – chlorine and its components are commonly used to bleach fibers. This has been mostly eliminated. Virgin fibers are generally ECF, meaning no elemental chlorine or TCF meaning the bleaching is done with hydrogen peroxide, oxygen or ozone. Recycled fibers are generally PCF, meaning they were put back into the paper without the use of any chlorine or its compounds.
Chucks – blocks inserted at the end of core to support a roll of paper on the roll stand.
CIE – Commission Internationale de l'Eclairage
CIE Whiteness – paper whiteness measured as per the CIE standards.
Clay – a natural substance used as both a filler and coating ingredient to improve a paper's smoothness, brightness, opacity and/or affinity for ink.
Clay coated boxboard – a grade of paperboard that has been clay coated on one or both sides to obtain whiteness and smoothness. It is characterized by brightness, resistance to fading, and excellence of printing surface. Colored coatings may also be used and the body stock for coating may be any variety of paperboard.
Coat weight – the grammage of a coating layer, expressed in g/m2.
Coated – papers and paperboards that contain a layer of coating material, such as clay or pigment, in combination with an adhesive.
Coating – in printing, an emulsion, varnish or lacquer applied over a printed surface to protect it. Paper coating ranges from dull to very glossy. This creates paper with greater smoothness, higher quality and better ink holdout than uncoated papers.
Coating Streak – a coating streak will show up as an area of light coat–weight or as a broad indentation in the coating surface. The length may vary from a few feet to several hundred feet in the machine direction.
Cobb test – measures paper's water absorption rate and is expressed as the amount of water pick–up per unit surface area of paper by TAPPI method T441. The test duration must be specified to properly know the absorption rate. United Nations (UN) and Code of Federal Regulations require the 30–minute pick–up must be 155 grams per square meter or less for containerboard used in hazardous material transport.
Cold color – a color on the bluish side.
Collate – in binding, gathering sections (signatures) in sequence for binding.
Color balance – the correct combination of black, cyan, magenta and yellow to (1) reproduce a photograph without color cast, (2) produce a neutral gray, or (3) reproduce the colors in the original scene or object.
Color bars – printed bars of ink colors used to monitor a printed image. These bars show the amount of ink to be applied by the press, the registration, and the densities across the press sheet.
Color down – refers to the sequence of applying printing inks to the paper, e.g. the magenta could be the 2nd “color down” in a “four–color process” job.
Color fastness – the ability of dyed paper to maintain its color in the presence of exposure to light, heat etc.
Color guide – instructions attached to artwork or disc with the location, percentage, and type of color required.
Color process printing – printing done using cyan, magenta, yellow and black inks, each requiring its own negative and plate. Also called four–color process.
Color proofs – initial printed pieces pulled off the press for final approval.
Color scanner (electronic scanner) – a scanner that makes the color separation required in full color process printing.
Color separation – the method used in breaking down primary colors needed to prepare plates for printing color work.
Commercial match – paper manufactured to within acceptable tolerances of a sample provided to the mill.
Commodity papers – a classification of low–quality bond and offset papers.
Communication papers – all types of papers used in the communication field which have been converted into convenient form for use with communications equipment, such as rolls, tapes, special cut–size, etc.
Composite image – multiple images placed together to form a single, combined picture.
Comprehensive proof – final proof presented in the format the printed piece will take.
Condensed type – a typeface that allows more print per line, as though the letters were squashed at their sides.
Conditioning – allowing paper to adjust itself to the temperature and humidity of the printing plant prior to use.
Construction paper – heavy type of paper used for watercolor and crayon artwork, made in various colors primarily from groundwood pulp.
Containerboard – single and multi–ply, solid and corrugated boards used to make boxes and other containers for shipping materials.
Continuous tone – a photographic image containing gradient tones from black to white.
Converting paper – paper that is meant to be used as a base material to be altered through a conversion process to create another paper product. Examples include envelopes, paper bags, tablets and forms.
Copy /duplicator – when used in either form as a single term, refers to a system and equipment that rely upon electrostatic reproduction principles to either generate an offset lithographic plate, or even the copies themselves, directly from the electrostatic photoreceptor.
Copying – the act of reproducing an image on paper that is a duplication of the image on another document, such as by a photographic or xerographic process, or with carbon or carbonless papers.
Core – a tube usually made of paperboard, on which a paper roll is wound.
Core plug – metal, wood, particleboard, or other material plugs which are driven into the ends of the paper core of a finished roll to prevent crushing of the core.
Corrugated board – (1) a pasted single or double faced, multi layered board having a fluted bottom or middle layer. (2) the fluted paperboard after it has gone through the corrugating operation and before it is pasted to the flat facing board sheet.
Corrugations – diagonal ridges and furrows running in the machine direction and of a relatively constant width which occur around the circumference of the roll.
Cotton content paper – papers utilizing cotton linters. Today most cotton content papers are made for letterhead applications. Papers made with cotton range from 25% to 100% cotton content.
Cover paper – also referred to as card stock; a heavyweight paper designed to be used as booklet, magazine covers or brochures.
Crack at the fold – fissures in the crease when any paper is folded along a fold line. May be due to separation of coating or separation of fibers. More prevalent when the paper has been over–dried. In boards it may occur along score–folds even though the scoring has been done to minimize cracking at the fold. The term is also applied when coatings crack without fiber failure during a folding operation.
Crease – deformation remaining from a fold over.
Creep – in offset lithography, the forward movement (stretch) of a printing blanket during printing. This can result in doubling. Can also apply to the movement of the packing under the plate or blanket during printing, causing excessive plate wear.
Cropping – resizing original photographs or illustrations to a different size.
Cross direction (CD) – side to side direction of a paper machine or the paper sheet made on it, as opposed to machine direction, which runs from head to exit end.
Cross grain fold – a fold at a right angle to the direction of the grain of paper.
Cross machine direction – a line perpendicular to the direction the paper travels through the papermaking machine.
Crushed core – crushed rolls are usually from stacking rolls on end too high with the bottom rolls failing in an axial direction.
Curl – the tendency for a sheet of paper to bend, either by design (as in the case of office papers) or undesirably (due to improper balance of moisture within the sheet).
Cut size – papers cut to 8 ½ x 11, 8 ½ x 14, or any other size 11 x 17 or smaller.
Cutter dust – paper dust resulting from cutting or trimming the paper which can transfer to printing blankets causing problems during a press run.
Cyan (process blue) – one of the four–process colors.
Damp streaks – streaks caused by uneven pressing of drying during paper manufacturing.
Dampening – water gum buffered acid, and various types of etches used to keep the non–image areas of the plate moist, and preventing them from accepting ink, in the lithographic printing process; also called fountain solution.
Day–Glo – trade name for inks and papers containing fluorescent pigments.
Debossing – the process in which the image is recessed into the paper.
Decurling – a paper decurling station on a sheeter or web press, used to remove paper curl.
Defibering – term for pulping processes i.e. separating the fibers of pulp bales, broke or wastepaper, in water by mechanical action.
De–inking – (1) removal of printing ink and impurities from recovered paper; to produce recycled fiber pulp with maximum whiteness by a floatation or washing process. (2) removal of ink and other undesirable materials from wastepaper by mechanical disintegration, chemical treatment, washing and bleaching before reusing as a source of papermaking fiber.
Delignification – the removal of lignin, the material that binds wood fibers together, during the chemical pulping process.
Die cut – paper and paperboard products cut by metallic die to specified dimensions or form.
Digital printing – printing technology (laser printing, inkjet printer, digital press, etc.) that can produce sheets directly from a computer file, without going through some intermediate medium, such as a film negative, or an intermediate machine, such as a plate–making machine.
Dimensional stability – ability to maintain size; resistance of paper or film to dimensional change with change in moisture content or relative humidity.
Direct printing – any printing where the ink is transferred directly from the plate to the paper; most lithographic printing is offset, i.e., a blanket is utilized to transfer the ink from the plate to the paper. Dilitho is the abbreviated term for direct lithography.
Dirt count – the average amount of dirt in a specific size or paper area. Both virgin and recycled sheets have “dirt” although recycled paper has significantly higher dirt counts. The dirt should always be small enough not to interfere with the quality of the finished printed piece.
Delamination – a separation of the paper’s surface.
Densitometer – reflection instrument measuring the density of colored ink to determine its consistency throughout a press run.
Density – identifies the weight of paper compared to the volume; it is directly related to the paper’s absorbency, stiffness, and opacity.
Descender – the parts of lower–case letters that extend below the baseline.
Die–cutting – male and female dies are used to cut out paper or board in desired shapes.
Directory paper – uncoated, lightweight, mechanical groundwood paper of thin caliper. It is manufactured in brightness levels ranging from 57 to 70 (GE) and basis weights of 18# to 24#. Historically used for phone books, it can be used in applications calling for a lightweight sheet.
Dirt – dirt in paper consist of any imbedded foreign matter or specks, which contrast in color to the remainder of the sheet.
Dished – concave rather than flat pile of paper. Also refers to roll ends of paper that are not flat.
Dissolving pulp – a high purity special grade pulp made for processing into cellulose derivatives including rayon and acetate.
Dog ears – a paper–finishing error caused by the corner of the sheet being bent under before trimming, resulting in an oversized corner when the trimmed sheet is unfolded.
Dog hairs – fuzzy–like fibers that stick up from the coated surface of a paper sheet.
Dot – individual element of a halftone printing plate.
Dot gain – in printing, a defect in which dots print larger than they should, causing darker tones or stronger colors.
Dots per inch (DPI) – a measure of the resolution of a screen image or printed page.
Dot slurring – smearing or elongation at the trailing edges of halftone dots.
Dot spread – when halftone dots print larger than they were supposed to print.
Double–black halftone printing – a means of extending the range of density available with printing ink by printing twice with black ink, using two specifically prepared halftone negatives. Also called double–black duotone.
Double–thick cover stock – a cover stock composed of two sheets of cover laminated together.
Doubling – (1) in printing, a press problem that generally occurs when sheets contact the blanket twice, once just before the impression point and the second time at the impression point, resulting in a double image. At times, with certain papers, the feeder will feed two sheets instead of one, and when pressures are extreme or out of balance, the blanket may slip at the pressure point, resulting in a slur or double image. (2) in stamping, a double impression in which the second impression or “hit” does not register perfectly over the first one.
Doughnut hickey – a printing defect consisting of a solid printed area surrounded by an unprinted area.
Drag – register trouble when the dot is enlarged towards the back (non–gripper edge) of the sheet.
Draw–down – in ink making, a term used to describe ink chemist’s method of roughly determining color shade. A small glob of ink placed on paper and drawn with the edge of a putty knife spatula to get a thin film of ink.
Drier – any substance used to hasten drying of ink on paper.
Dry back – the color change which occurs when ink dries.
Dry–end – on the paper machine, it is the section where the dryers, cutters, slitters and reels are located.
Dryer (drying oven) – oven on a web offset press through which the web of printed paper passes after it leaves the final printing unit. The drying process, standard when heat–set inks are used, heats the web to about 350 degrees Fahrenheit. Either gas or electricity dries the vehicles and air blasts drive off the volatile gases.
Drying time – the time it takes for an ink to become rub or tack–free.
Dull finish – any finish lacking gloss and/or luster; generally, refers to an intermediate gloss of coated papers or to printed ink films.
Duotone – two–color halftone reproduction from a black–and–white original.
Duplex – (1) papers and paperboards with each side having a different color, finish or surface texture, which is produced on the paper machine or by pasting. (2) general term referring to multi–ply paper and paperboard and to bags made of two separate sheets of paper.
Dusting – the accumulation of loose particles from the paper on the non-image areas of the blanket. Particles are of very small size.
Dye – an ink colorant that is soluble in vehicle or solvent.
ECF (Elemental Chlorine Free) – pulp bleached without the use of elemental chlorine. Generally, this is virgin fiber bleached with chlorine dioxide.
Eggshell finish – finish found on uncoated, uncalendered paper with a subtle but rough texture. It resembles the surface of an eggshell which isn't solidly smooth. It is similar to and may sometimes be referred to as an antique finish.
Elliptical dot – in halftone photography, elongate dots, which give improved gradation of tones particularly in middle tones and vignettes – also called chain dots.
Embossing – impressing an image in relief to achieve a raised surface; either over printing or on a blank paper (called blind embossing).
Enamel – a term applied to a coated paper or to coating material on paper. The term is usually used to refer to glossy paper.
English finish – medium finish applied to a sheet of paper that is smoother than the finish coming off dryers or calenders, but not as smooth as the finish coming off supercalenders.
Engraved printing/engraving – a form of recessed printing, as is gravure printing, where the image to be printed is etched or engraved below the non–image areas of the plate. The ink is applied to the plate and the non–image areas are then scraped or wiped clean. Gravure printing is another form of recessed printing, but the ink body and viscosity do differ. Engraved printing normally is accompanied by a slightly raised image area and a slightly recessed area on the reverse side of the paper corresponding to the printed image.
Envelope paper – paper made specifically for the purpose of converting into envelopes.
Eucalyptus pulp – is an excellent short–fiber hardwood pulp, and due to its relatively uniform fiber, simple cell structure of the fiber, low degree of lignification, its smoothness, bulk, opacity and softness, water absorption are all superior to softwood pulp.
Expansion of paper – the increase in dimension of a paper or paperboard sheet due to the absorption of atmospheric moisture.
Fade – the slow loss or change in color of paper. It is usually caused by exposure to light over a period of time.
Fanfold – continuous multiple ply form manufactured from a single wide web which is folded longitudinally.
Fanout – in printing, distortion of paper on the press due to waviness in the paper caused by absorption of moisture at the edges of the paper, particularly across the grain.
Feathering – tendency of an ink image to spread with a fuzzy, “feather like” edge.
Feed rollers – on a printing press, the rubber wheels that move the sheets of paper from the feed pile to the grippers.
Fiber – the small strands of wood, cotton or other cellulose product that is used to make the paper. In the premium paper market, all the fiber is lignin free. Fiber before it is made into the finished product is referred to as pulp.
Fiber cut – a short, straight cut located on the edge of the web, caused by a fiber imbedded in the web of the paper.
Fiber orientation – refers to the alignment of the fibers in the sheet. The degree of alignment can be controlled in the paper making process.
Fiber pick – a disturbance in the paper sheet surface that manifests itself in the lifting or complete removal of discrete fibers or fiber bundles.
Filler – minerals, such as clay and other white pigments, added to pulp to improve the opacity, smoothness, brightness, and printing capabilities of paper.
Fine papers – types of premium papers used for writing, printing, and cultural purposes.
Finish – the physical look and feel of the paper’s surface. These include smooth, vellum, felt, laid, linen and others.
First color down – the first color printed as the sheet passes through the press.
Flaking – the process of small particles of paper coating material breaking away from the surface of a paper sheet.
Flash exposure – in halftone photography, the supplementary exposure given to strengthen the dots in the shadow areas of the negatives.
Flat color – printing two or more colors without overlaying color dots (i.e. without color trap); individual color matching. This differs from process color, which is a blending of four colors to produce a broad range of colors.
Flatbed press – a press on which plates are positioned along a flat metal bed against which the paper is pressed by the impression cylinder, as compared to a rotary press which prints from curved plates.
Flexographic printing – rotary letterpress printing process using liquid ink. Solvent–based formulations made of aniline dyes and pigments (mixed with a binder) dried primarily by evaporation due to the solvent vehicle; water–based formulations have now become more common and are force–dried by heat or irradiation (if the ink contains monomers that can be polymerized by UV–irradiation). Sometimes called aniline printing.
Fluff pulp – fluff pulp (also called comminution pulp or fluffy pulp) is a type of chemical pulp made from long fiber softwoods. Important parameters for fluff pulp are bulk and water absorbency.
Fluorescent inks – extremely brilliant inks containing fluorescent pigments.
Flute – one of the wave shapes pressed into corrugated medium. Flutes are categorized by the size of the wave. A, B, C, E and F are common flute types, along with a variety of much larger flutes and smaller flutes.
Foil – a tissue–like material in sheet or roll form covered on one side with a metallic coloring used for stamping.
Folding endurance – a paper test which measures the number of double (back and forth) folds that can be made on a sheet of paper under tension, before it breaks.
Foldout – a page that exceeds the dimensions of a single page. It is folded to page size and included in the book, sometimes bound and sometimes tipped in (pasted).
Folio – refers to sheet size 17 x 22 or larger and page numbers.
Foot – the bottom of a page of printed information.
Formation – refers to the uniformity or lack of it in the distribution of the fibers when manufacturing paper; can be observed by looking through the sheet; a good formation is uniform or “Close”, while a poor formation is not.
Fountain solution – in lithography, a solution of water, a natural or synthetic gum and other chemicals used to dampen the plate and keep non–printing areas from accepting ink.
Four–color process – the printing of a full color picture or drawing by using four separate process printing inks: yellow, magenta, cyan and black.
Free sheet – paper made with pulp created in a kraft process that has removed the lignin. Free sheet paper has more longevity than groundwood which contains lignin. (Newspaper is made with groundwood).
French fold – a sheet printed on one side and folded first vertically and then horizontally to produce a four–page folder.
FSC® – Forest Stewardship Council – a global not-for-profit organization that sets the standards for what is a responsibly managed forest, both environmentally and socially. It trains, accredits and monitors third–party certifiers around the world and works to establish international forest management standards.
Galvanized sheet surface – a paper surface characterized by an uneven surface such that the variations in the smoothness and gloss create a metallic galvanized surface.
Gatefold – a four–page insert, having foldouts on either side of the center spread.
GATF – Graphic Arts Technical Foundation
Gear streaks – in printing, parallel streaks appearing across the printed sheet at the same interval as gear teeth on the cylinder.
Generation – each succeeding stage in reproduction from the original copy.
Ghosting – ghost images are unwanted images that reduce print value. Mechanical ghosting develops during the delivery of the printed sheet and is traceable to on–press conditions, ink starvation, form layout, and even to the blanket itself. Chemical ghosting, which occurs during the drying process of ink on paper, is especially bothersome because the condition cannot be detected until the job has been completed.
Gloss – the shine reflected from a surface; in paper measurement, it is the specular reflection of light, incident and reflected at a 15 degree angle from a surface, as compared to a polished plate of black glass; papers can range in finish from matte to satin or dull to glossy.
Glued–on cover – a cover fastened to the text with glue.
Gluing off – the process of applying glue to the spine of a book to be case bound, after sewing and smashing, and before trimming.
Grade – the classification given to paper due to its unique characteristics, which includes brightness, opacity, cotton content, etc.
Grain – refers to the alignment of fibers in the direction of their flow on the paper machine. Folding and scoring work best when done in the paper’s grain direction. Grain also affects tear strength, stiffness and dimensional stability.
Grain long – a sheet of paper in which the fibers are aligned parallel to the long edge. A longer dimension noted last indicates grain long – 11” x 17”
Grain short – a sheet of paper in which fibers are aligned parallel to the short edge. A shorter dimension noted last indicates grain short – 17” x 11”
Grammage – the basis weight of paper stated in metric terms of grams per square meter and expressed as g/m2. Thus, a sheet of paper 17 x 22 with a basis weight of 20 lbs. for 500 sheets would be expressed metrically as 75 g/m2. To convert from basis weight to grams per square meter (g/m2), multiply basis weight by 1406.5 (a constant factor) and divide by the number of square inches in base sheet.
Gravure printing – a form of recessed printing, as is engraving. The printing method where the very fluid ink is applied to the plate or plate cylinder and is carried in small microscopic cells, recessed into the plate. Used for long run printing applications, due to plate or cylinder costs, but long plate life; since run on rotary presses, called rotogravure. Engraved printing is based on the same principle, using larger recessed areas (as opposed to microscopic cells) and more viscous inks.
Gray balance – the dot values or densities of cyan, magenta, and yellow that produce neutral gray.
Gripper – a row of clips that holds a sheet of paper as it speeds through the press.
Gripper edge – leading edge of a sheet of paper as it passes through the printing press.
Groundwood paper – paper that is made from a furnish containing a large percentage of groundwood pulp.
Groundwood pulp – slurry produced by mechanically abrading fibers from debarked logs through forced contact with the surface of a revolving grindstone. Used extensively to make newsprint and publication grades.
Gross weight – the total weight of merchandise and shipping container.
GSM – grams per square meter is the metric standard for paper weight. GSM calculates the actual weight of a square meter of a paper.
Guide edge – the edge of a printed sheet at right to the gripper edge, which travels along a guide on the press or folder. This edge, like the gripper edge, should never be altered or mutilated between the printing and folding operations. It is the shorter edge of the sheet.
Guide marks – a method of using crossline marks on the offset press plate to indicate trim, centering of the sheet, centering of the plate, etc.; these are sometimes called register marks.
Guide side – the side the press uses to guide the sheet to the exact side toward the operator; also known as operator or control side.
Guillotine – device that is used to cut or trim stacks of paper to the desired size.
Gumming – in platemaking, the process of applying a thin coating of gum to the non–printing areas of a lithographic plate.
Halftone – a general reduction in the overall contrast of a halftone, to allow type to be easily readable when printed over it.
Halftone dot – pattern of different sized dots to simulate continuous tone images.
Halftone screen – an engraved glass through which continuous tone copy is photographed and reduced to a series of dots or halftone printing.
Handsheet – a single sheet of paper made by a hand process for testing purposes (as to determine qualities of paper to be made from a given batch of pulp).
Hard (dot) – a halftone dot characterized by a sharp, clean cut edge.
Hardcover (case bound, edition binding) – nonflexible book binding made of thick, glazed board.
Hardwood pulp – pulp produced from the wood of broad–leaved dicotyledonous deciduous trees.
Head–to–head imposition – an imposition which requires that pages be laid out with the top of a page (head) positioned across the top of the page (head) opposite on the form.
Head–to–tail imposition – an imposition which requires that pages be laid out with the top of a page (head) positioned across the bottom (tail) of the page opposite on the form.
Heat–set inks – inks used in high–speed web offset. They set rapidly under heat and are quickly chilled.
Heavyweight paper – paper falling into the upper range of weights manufactured for a particular grade.
Hickeys – in offset, spots or imperfections in the printing image traceable to such things as dirt on the press, dried ink skin, paper particles, dust etc.
High bulk – a paper (normally book paper) specifically manufactured to retain thickness not found in papers of the same basis weight. Frequently used to give thickness to a book with minimal amount of pages.
High finish – a term referring to paper that has a smooth, hard finish applied through calendering or other processes.
High yield – descriptive reference to processes in which the yield is higher than conventional yield.
Hinges – the flexible joint where the covers of hardbound book meet the spine, permitting the covers to open without breaking the spine of the book or breaking the signature apart.
Hit – an impression from a stamping die.
Holdout – in printing, a property of coated paper with low ink absorption which allows ink to set on the surface with high gloss. Papers with too much holdout cause problems with setoff.
Hole – a paper defect appearing as a small aperture in the sheet as a result of fiber aggregate in the stock, slime, splashing, etc.
Hue – in color, the main attribute of a color which distinguishes it from other colors.
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.
Hydrophilic – describes paper with an affinity for water.
Hydrophobic – describes paper that tends to be water repellent.
Hygroexpansivity – property of a material which causes it to expand or contract when its moisture content is changed; as in paper, when the relative humidity of the surrounding atmosphere is changed.
IGT test – test that measures the ability of coated or uncoated paper or paperboard to resist picking or blistering during offset printing.
Impact resistance – the ability of paperboard shipping containers to withstand damage due to impact stresses.
Impression cylinder – in printing, the cylinder on a printing press against which the paper picks up the impression from the inked plate in direct printing, or the blanket in offset printing.
Impression – pressure of a specific type of blanket as it comes into contact with paper.
Imprint – to print other information on a previously printed piece by running it through the press again.
Index paper – a heavyweight card stock typically used for folders and cards.
Ink absorption – the degree with which paper will absorb ink.
Ink gloss – an ink that contains varnish, which makes the ink appear glossy when printed.
Inkjet printing – refers to the printing technology where a digital image is reproduced through the spraying of microscopic liquid ink (or dye) droplets onto the surface of the paper.
Ink rub–off – a printing defect characterized by the printing of ink that is to all appearances dry, but which rubs off easily. Rub–off is commonly caused by an inadequate binder formation, or an inadequate quantity of binder present in the ink, both of which impede the adhesion of the pigment particles to the substrate.
Ink show–through – a characteristic of lightweight, absorbent–type papers in which ink is visible from the opposite side of the sheet due to penetration of the oil vehicle, thus making the paper more transparent.
Ink transfer – the property of ink that will cause it to adhere to paper or paperboard surfaces during printing by impression methods.
In–line – denotes a production line of machinery, required for the complete manufacturing of a given product.
Insert – a printed piece prepared for insertion into a publication or another printed piece.
Intensity – the extreme strength, degree or amount of ink.
Interleaves – paper inserted between sheets as they come off the printing press to prevent transfer of wet ink from one to the other. Also, used as accessory sheets between parts in a form.
Job lot – out of specification, defective or discontinued types of paper made in small quantities for special orders. Sometimes sold at lower than standard prices.
Jog – aligning sheets of paper into a compact pile.
Kiss coating – paper coating procedure in which a rotating roll picks up coating material from a pond and transfers it by lightly touching the sheet.
Kiss impression – printing performed with only slight pressure. The normal procedure for quality printing.
Knife coating – a process where an excess of coating material is applied to the substrate and removed by a metering blade to achieve the desired coating thickness.
Kraft paper – a strong paper made from sulfate pulp and typically used to make envelopes and bags.
Kraft process – a chemical pulping process that cooks down the tree to remove lignin, retaining the fibers for paper making. Free sheet papers are made in the Kraft process.
Lacquer – organic solution with volatile solvents used for coating paper and to give a high surface gloss, grease resistance, heat sealing and improved surface appearance.
Laminated – paper that is developed by fusing one or more layers of paper together to the desired thickness and quality.
Laser printers – electrostatic/xerographic printers using a laser as the light source activated by an electronic media.
Latex – a synthetic rubber–water emulsion made by polymerization of chemicals. It is used as an additive, coating material, adhesive, or impregnating medium in the manufacture of paper.
Leading edge – the front edge of a sheet being processed or used. Or the front of a suction box on the wet end of a paper machine.
Length – describes a property of printing ink that is the distance of which a finger and thumb can be pulled apart while maintaining an unbroken “thread” of ink between the two; as such, inks can be described as “short” or “long”. Length is related to both viscosity and tack, as a fluid or body property of ink.
Length (in paper) – the dimension of paper or paperboard reels, rolls or sheets that run in the machine direction.
Letterpress printing – also known as relief typographic printing, letterpress printing employs the use of type or designs cast or engraved in relief on a variety of surfaces which can include metal, rubber, and wood. Opposite of intaglio printing, in letterpress printing the ink is applied to the raised printing surface. Non–printing areas or spaces are recessed. Impressions are made in various ways. On a plated press the impressions are made by pressure against a flat area of type or plate. Flat–bed cylinder press printing uses the pressure of a cylinder rolling across a flat area of type or plate to create the impression. A rotary web press uses a plate that has been stereotyped (molded into a curved form) which presses against another cylinder carrying the paper.
Lift – maximum number of sheets handled by the operator of a guillotine cutting machine or by a paper handler loading paper for printing.
Lightfastness – the degree to which a paper or printed piece will resist a change in color when exposed to light.
Light spots – paper defects caused at the wet end of a paper machine by a dandy roll throwing water drops out onto the wire, a stock–lump created at the table roll, or improper settings of wet–end equipment such as the dandy roll, forming board, slice, etc.
Lightweight paper – lightweight papers include a variety of different types of low–thickness, high–opacity papers. Used in bibles, handbooks, dictionaries, encyclopedias, and other uses that require low bulk or low weight paper (for example, in material that will be mailed).
Lignin – the “glue” that binds the cells of the tree and creates its structure. This product is removed in the kraft process. Approximately one third of the tree is lignin.
Linen finish paper – a paper embossed to have a surface resembling linen cloth.
Linerboard – Kraft paperboard, generally unbleached, used to line or face corrugated core board (on both sides) to form shipping boxes and various containers.
Lint – small fuzzy particles in paper.
Line screen – number of lines of dots that appear per linear inch on a printed piece or negative.
Lithography – a generic term for any printing process in which the image area and the non–image area exist on the same plane (plate) and are separated by chemical repulsion.
Long ink – an ink that has good flow on ink rollers of a press. If the ink is too long, it breaks up into filaments on the press, and causes flying as on a newspaper press.
Longfold – folding a sheet lengthwise in the direction of the grain.
Loose back – a popular style of binding, in which the spine binding material is not glued to the binding edge of the sheets.
Loose coating – paper coating material which did not form a firm bond to the sheet during coating operation, making it susceptible to lifting on subsequent use.
Loose core – loose cores cause rotational displacement and cause the web to tear free from the core. This causes tension and control problems in subsequent processes.
Loose winding – a paper roll winding defect caused by insufficient sheet tension during winding.
Low bulk – refers to papers somewhat thinner than usual papers of the same weight, having a smooth surface, and which is a “thin” sheet.
M weight – is defined as the weight in pounds of 1,000 sheets of paper of a given basis weight and size (dimensions); M is the Roman numeral for 1,000.
Machine direction (MD) – direction from the wet end to the dry end of a paper machine or to a paper sheet parallel to its forward movement on a paper machine.
Magazine paper – magazine papers are paper grades generally used in printing of magazines. Magazines are printed on very thin gloss paper. Magazines with very high circulation (think tens of thousands of copy) print on the thinnest types of gloss paper.
Magenta – hue of a subtractive primary and a 4–color process ink. It reflects or transmits blue and red light and absorbs green light.
Makeready – in printing presses, all work done prior to running; adjusting the feeder, grippers, side guide, putting ink in the fountain, etc. Also, in letterpress, the building up of the press form, so that the heavy and light areas print with the correct impression.
Making order – a paper that is not available off the supplier’s shelf, but they will produce it when ordered. Making orders for special sizes, colors and weights of paper are subject to small minimums.
Margins – the unprinted area around the edges of a page. The margins as designated in book specifications refer to the remaining margins after the book has been trimmed.
Matte – paper and surface finishes with very low gloss or luster.
Mechanical paper – this paper contains mechanical pulp, thermomechanical pulp (TMP) or chemithermo–mechanical pulp (CTMP) and chemical pulp. The quantity of chemical and mechanical pulp varies depending on the application. Highly mechanical papers such as newsprint tend to yellow more rapidly if exposed to light and oxygen than woodfree papers so that they are mainly used for short–lived products. In printing papers, the mechanical pulp improves opacity.
Mechanical pulp – in papermaking, groundwood pulp produced by mechanically grinding logs or wood chips. It is used mainly for newsprint and as an ingredient of base stock for lower grade publication papers.
Metallic inks – ink containing metal substances, used to produce special printed output.
MICR Check paper – paper suitable for checks or other business documents that can be printed with magnetic ink. Documents can then be read by data processing equipment through magnetic ink character recognition.
Micrometer – a device for accurately measuring the thickness (caliper) of paper.
Mil – one thousandth of an inch.
Mill brand – paper which is brand–named by the manufacturer as opposed to the merchant house, which is known as a “private brand”.
Mixed office waste – wastepaper generated from offices, such as letters, memos, invoices etc. which are collected and sorted for paper qualities. This is the major source of post–consumer fiber used in recycled papers.
Moiré – geometric pattern caused when two screened images are superimposed at certain angles. Occurs when making a halftone from a halftone image.
Moisture content (MC) – refers to the amount of moisture found in a sheet of paper. Average amount ranges from 5 to 8%. This figure varies from sheet to sheet since paper will emit or absorb moisture according to the condition of the surrounding atmosphere. Moisture loss is realized in the form of shrinkage, which begins at the edges of the paper and moves across the grain causing the sheet to tighten and curl.
Moisture welts – a paper web defect characterized by either a raised welt, band, or wrinkle located near the outer portion of the roll and run in the machine direction, caused by cross–grain expansion of the outer layers of paper due to absorption of moisture.
Monotone – printed in one color only.
Mottle – (1) random non–uniformity in printed gloss, or the visual density of color of a printed area caused by uneven absorption of ink by paper. (2) a surface effect produced by the addition of heavily dyed fibers of a different color in the stock finish.
Mullen tester – device that measures the bursting strength of paper. Sometimes referred to as the pop test or pop tester.
Multi–ply – paper or paperboard sheet made up of two or more layers.
Neutral pH – offset papers manufactured with a pH of 6.0 to 8.0 on a scale of .0 to 14.0. Neutral pH factors are built into paper as a minimum value, to increase stability and improve permanence for use in printing of archival records.
Newsboard – type of paperboard made primarily from newsprint waste for use in the manufacture of setup boxes and containers. The board may be lined with a higher grade of pulp during manufacture.
Newsprint – grade of paper, combining high percentages of groundwood pulp, made especially for the use in the printing of newspapers.
Nominal weight – refers to the basis weight of the paper. Unless otherwise stipulated by the mill and customer, a tolerance of ± 5% is allowed when calculating nominal weight.
Non–impact printers – forms an image without impact.
Nonwood pulp – are any plant materials that do not come from trees and can be used for pulp and paper. This covers a wide variety of raw fiber, including cotton, rice, wheat, corn stalks, papyrus, grass straw, hemp, and kenaf.
Oblong – in binding, a booklet bound on the short dimension.
Off machine coating – process of applying coating or material to a web of paper or paperboard in a location that is away from the machine on which it is made.
Offset paper – coated or uncoated paper specifically for offset printing.
Offset printing – process of printing utilizing a lithographic plate on which the images or designs are ink receptive while the remainder of the plate is water receptive. Ink is transferred from the plate to a rubber blanket on the printing press.
One–up, two–up etc. – printing one (two, three etc.) impressions of a job at a time.
Opacity – the ability of paper to obstruct light transmission and the show–through of printing. It is particularly important in two–sided printing. It also affects readability and overall appearance. Opacity is improved by scattering, absorbing or reflecting light. Fillers such as titanium dioxide and calcium carbonate scatter light, while blue and violet dyes absorb it.
Opaque ink – an ink that conceals all color beneath it.
Opaque paper – paper characterized by a high level of opacity and a minimum amount of show–through.
Optical properties – the most important optical properties of paper are brightness, color, opacity, and gloss. The term brightness has come to mean the degree to which white or near–white papers and paperboard reflect the light of the blue end of the spectrum (i.e., their reflectance).
Orange peel – a granular surface on coated or printed paper that looks like orange peel.
Out–of–jog – sheets in a pile of paper that are not even with the edge. It is caused by improper jogging of the paper in the layboy during the sheeting process.
Out–of–register – (1) descriptive of pages on both sides of the sheet which do not back up accurately. (2) Two or more colors are not in the proper position when printed; the register does not “match.”
Out–of–round rolls – paper rolls that are not suitable for the web offset press because they are not perfectly round and will cause uneven feeding tension.
Out–of–square – refers to paper that has been trimmed improperly thus causing the corners to be less or more than 90 degrees. This leads to difficulty during the printing process and often results in misregister of the printed piece.
Overhang cover – a cover larger in size than the pages it encloses.
Overinked – describes printing when too much ink has been used, resulting in heavy print that tends to blur towards the back of the press sheet.
Overpacking – packing the plate or blanket to a level that is excessively above the level of the cylinder bearer.
Overpressure – too much pressure, causing ink to tend to plug letters, especially halftone dots.
Overprinting – double printing; printing over an area that already has been printed.
Oxidation – a chemical reaction which hardens the ink vehicle and makes the film of ink reasonably rub–proof. The process of combining with oxygen.
Packing – in printing presses, the paper or other material used to underlie a press blanket or plate, to bring the surface to the desired height; the method of adjusting squeeze pressure.
Padding compound – also called edge padding glue or adhesive; a liquid adhesive mixture which when brushed or sprayed onto the side of a pile of paper adheres the sheets together along one edge, thus forming a pad.
Page flex – the number of flexes a book can withstand before loosening from the binding.
Page proofs – initial impression of a page pulled for checking purposes before the entire job is run.
Pages–per–inch (ppi) – in book production, the number of pages contained in a one–inch stack of paper.
Pantone Matching System (PMS) – is a color standardization system that helps in color identification and matching. It uses the Pantone numbering system to identify colors, and through this numbering system printer and other equipment manufacturers can match colors without having to contact one another.
Papermaking – Invented in China by T'sai Lun some 2,000 years ago, papermaking still follows the same basic procedures. Today wood chips are cooked with chemicals to release cellulose fibers and dissolve lignin, then washed to remove impurities. Most printing papers are then bleached to lighten the color of the pulp. Pulp is mechanically and chemically treated to impart certain desired characteristics such as strength, smoothness and sizing. A large quantity of water is added to uniformly distributed fibers and additives. The resulting slurry, which is 99 to 99.5% water, is cascaded onto the continuously moving forming fabric of the Fourdrinier paper machine. Side–to–side shaking distributes the slurry, forming a tangled web of fiber as the water drains off. A wire mesh roll called a dandy roll, moves over the surface to modulate the turbulence and smooth the topside of the paper. A felt blanket absorbs more water from the paper and sends the sheet on through a channel of hot metal drums that dry and press the paper at the same time to give it a more even–sided finish. At this point the paper is fully dry and ready for off–machine processes such as coating, embossed finishes and supercalendering.
Papeterie – a paper used for greeting cards, stationery etc., which is distinctive from regular stock in that special watermarks and embossing may be used.
Parchment – originally a writing surface made from animal skins; today made from cellulose fiber paper by dipping unsized stock in sulfuric acid, to simulate the appearance and feel of genuine parchment; called “vegetable parchment” if made from cellulose fiber paper.
Parent roll – the original roll of paper made on a paper machine. It is put into inventory prior to being rewound and slit into smaller rolls or sheeted into sheets for an end–use.
Perforate – punching a series of holes or slits in a line in the paper, to weaken it so tearing will occur easily along that line. Also, the making of slits in paper during folding, at the fold, to prevent wrinkles and to allow air to escape.
Permeability – degree to which a fluid (gas or liquid) permeates or penetrates a porous substance such as paper or fabric.
Peroxide bleaching – method of bleaching pulp with hydrogen peroxide (H2O2) to remove lignin; reduces or avoids the need for chlorine dioxide in final bleaching.
PH – a number used for expressing the acidity or alkalinity of solutions or paper. A value of 7 is neutral.
Pick – (1) pulp fibers pulling away and sticking to paper machine parts, such as rolls, in wet and dry sections. (2) paper mill control test to determine surface adhesion properties of paper. (3) small particles of paper that loosen from the surface of paper, especially during printing.
Pigment – an insoluble mineral or organic powder used as a dye to color paper and as an additive to impart specific properties, such as bulk, porosity, and opacity to the sheet.
Pin holes – imperfections in paper which appear as minute holes upon looking through the sheet. They originate from foreign particles, which are pressed through the sheet.
Plate – depending on the printing process, the means by which the image area is separated from the non–image area; the image carrier.
Pliability – paper quality whereby it can be easily bent; flexibility. The paper pliability can be achieved through increasing the moisture content in order to enhance the effects of elasticizing the fibers.
Ply – layer that makes up a multi–layered, pasted or multi–cylinder formed paperboard.
Point – measurement of thickness of a sheet of paper or board (0.001 in.)
Porosity – (1) ability of fluids to pass into paper and paperboard, related to size, shape and distribution, orientation or the pores in a sheet and the compactness of the fibers. (2) a measure of the void volume (non–solid portion) of a sheet or web.
Precoating – (1) the application of a thin layer of coating material on a sheet of paper prior to the final coating operation. (2) applying a thin coating of material on the screen of a filter before beginning the actual filtering operation.
Pressure sensitive paper – good strength paper that is coated with a pressure sensitive tape or adhesive and converted to tapes and labels.
Primary colors – the additive primary colors are the three major wavelengths of light in the visible spectrum: red, green and blue, and are used in applications such as the cathode ray tube of a color television set. The subtractive primary colors are used when dealing with reflected light, such as from a full color printed piece, and are yellow, magenta and cyan. These are the three colors of ink used in process printing. In paper making, red, yellow and blue are the primary colors in the dying of paper, any two of which can be mixed to obtain secondary colors and hues (green, orange and violet).
Print gloss – the reflectivity of a printed surface of paper to light, as if seen through glass or in a mirror.
Printability – the extent to which a sheet performs regarding ink receptivity, uniformity, smoothness, compressibility and opacity.
Process Chlorine Free (PCF) – a bleaching process which entirely excludes the use of chlorine and chlorine dioxide. All recycled papers are produced using PCF.
Process colors – in printing, the subtractive primaries: yellow, magenta and cyan, plus black in four color process printing.
Proofs – samples of copy and/or layout made at various stages of production of a printing job.
Pulp – fibrous material produced by mechanically or chemically reducing plants into their component parts from which pulp, paper and paperboard sheets are formed after proper slushing treatment. Also used for dissolving purposes (dissolving pulp or chemical cellulose) to make rayon (or viscose) and other synthetic products.
Quick–set inks – inks that set–up faster and dry faster, usually from top to bottom. These inks are used when sheets must be sent back through the press faster than normal drying time will allow.
Rag paper – today it is usually referred to as cotton fiber paper. It is made from cotton cuttings and linters.
Ream – 500 sheets of printing paper.
Ream marker – piece of rectangular shaped paper used to mark off the reams in a stack of paper.
Ream weight – weight of a ream of paper.
Ream wrapped – paper which has been separated into reams and individually packaged or wrapped.
Recovered – scrap paper collected for remanufacturing into recycled paper. EPA’s definition for recovered is the most widely accepted and does not include scrap paper created in the initial papermaking process but does include scrap created in a mill after the paper comes off the paper machine. Printing waste and envelope trim are also recovered fiber.
Recyclable – this means the product can be recycled. This applies to most paper even if it is coated, waxed or otherwise treated.
Recycled paper – is paper that is reconstituted into paper again. The best paper to be using is 100% post–consumer recycled paper. Made from paper scrap that can, no longer be used for its intended purpose by the consumer, which is reprocessed into paper again.
Reducers – in printing inks, varnishes, solvents, oily or greasy compounds used to reduce the consistency for printing. In photography, chemicals used to reduce the density of negative or positive images or the size of halftone dots (dot etching).
Reel – a term given to a wound length of paper or board in which the diameter is approximately equal to the width.
Register – (1) of paper: a type of bond paper for multi–ply form use; i.e. register bond. (2) of printing: when a design or form is printed in parts or steps, as in multiple colors, it is essential that all parts or inks down match exactly. When they do, they are “in register”; otherwise, they are “out of register.”
Register mark – mark placed on a form to assist in proper positioning of after–printing operations. Two short lines at right angles are called an angle mark. Also, bulls–eye marks are placed on camera–ready copy to assist in registration of subsequent operations.
Relative humidity (RH) – the amount of moisture in the air expressed as a percentage of the maximum amount of moisture the air could hold at a given temperature. Ideal printing conditions call for a RH at 45%.
Repeatability – the ability to keep photo film and images thereon in proper register. Repeatability is usually measured in micrometers.
Repulping – to convert paper back into pulp, as during recycling.
Reprint – a term referring to printing again from standing negatives.
Retarders – chemicals that slow the setting time of printing inks.
Reverse – when the background is completely printed, and the design area is left unprinted.
Ridges – high or low caliper rings and bands around the circumference of a roll results in a permanent distortion of the sheet.
Right–angle fold – term used for two or more folds that are 90–degree angles to each other.
Ring crush – a test method for measuring the edgewise crush resistance by forming the paper into a cylinder and applying a crushing force to the edge.
Roll header – a circular piece of paper or paperboard on the side end of a roll of paper prepared for shipment. It is used to prevent damage to the edges.
Roughness – for coated boards, Parker Print Surf (PPS) roughness tester used where the test result is expressed as an average of the surface profiles in micrometers (mm) lower results show smooth surfaces while high results indicate poor surfaces. For coated board, Bendtsen method readings given as total leakage of air in ml/min. Smoother surfaces have lower readings.
Runnability – how smoothly paper runs through the paper machine. (1) in the paper mill, how well pulp stock furnished to the paper machine forms a sheet on the wire and passes through the drying and finishing operations. (2) used by customers in reference to how well the paper performs in their converting operations, such as on printing presses.
Saddle stitch – binding process for pamphlets or booklets, which works by stapling the middle fold sheets (saddle wire).
Saddle wire – in binding, to fasten a booklet by wiring it through the middle fold of the sheets.
Safety paper – a treated paper which when writing or printing on the paper is altered, the alteration attempt will leave noticeable smudge, discoloration, or other evidence of change. This type of paper might be used for making checks or other documents to discourage alterations.
Satin finish – a finish lacking gloss, generally intermediate to a matte finish and a dull finish.
Score/Scoring – the process and the resulting line or crease mechanically impressed in the paper to facilitate folding while guarding against cracking of paper and board. This is essential when heavyweight papers are to be folded.
Scratches – surface defects which occur during the coating process of paper in a paper mill.
Screen – the ruling used to determine the dots per unit area in developing tonal values in the printed piece. Screens from letterpress halftones of photographs are made ranging from 60 lines–per–inch for printing on newsprint to 300 lines for printing on coated paper and premium uncoated paper. Offset halftones for printing on most surfaces range from 133 lines to 200 lines.
Screen angles – in color reproduction, angles at which the halftone screens are placed with relation to one another, to avoid undesirable “moiré” patterns. A set of angles often used are black 45, magenta 75, yellow 90 and cyan 105.
Screen process printing – this printing process uses a screen of fine–mesh silk (thus the common name silk screen printing) tautly stretched across a frame. A squeegee drawn across the screen forces ink through the open image areas which are cut–out by hand using lacquered tissue prior to its adherence to the silk. Special photographic negatives are adhered to the screen when faithful reproduction of intricate designs is sought.
Screen ruling – the number of lines or dots per inch on a halftone screen.
Screentone – a halftone film having a uniform dot size over its area, and rated by its approximately printing dot size value, such as 20%, 50% etc.; also called screen tint.
Scuffing – the disrupted appearance of an ink film as a result of abrasion to either the wet or dry ink film.
Scumming – a term referring to the press plate picking up ink in nonprinting areas for a variety of reasons, basically due to spots or areas remaining desensitized.
Sealed – term often applied to cut size sheets which are packaged “ream sealed”, 500 sheets to the package.
Secondary colors – a color resulting from the mixing of two primary colors.
Secondary fiber – a term used for wastepaper, also referred to as paper stock.
Self–cover – a cover that matches the inside text pages.
Semichemical pulp – lower quality pulp made by cooking fibrous materials in a neutral sodium sulphite / sodium carbonate cooking liquor followed by a final suspension of the fiber using unpressurised mechanical means.
Setback – in platemaking, the distance from the front edge of the press plate to the image area, to allow for clamping to the cylinder and for the gripper margin.
Set–off – the undesirable transfer of ink from freshly printed sheets of paper to another.
Set of rolls – a complete complement of rolls of various widths coming off a winder at the paper mill.
Shade – the color depth and hue in comparison to papers that are the same color; also used to describe the color achieved by adding dye to pulp slurry. There is a wide shade variety in white papers, as well as in colored papers.
Shaving – trim from paper converting and bindery operations.
Sheet delamination – directly related to poor surface strength, delamination will occur in the printing process. Sheet delamination could also create a problem of a blanket smash. If the delamination is large enough and thick enough, as the press continues to run, it will create a depression in the blanket, so that when the delamination buildup is removed from the blanket the depression will remain, rendering the blanket unusable. These defects pertain to both sheet–fed and web–fed equipment.
Sheeter – in paper manufacturing, rotary unit over which the web of paper passes to be cut into sheets. In printing, rotary knife at the delivery end of the web press that slices press lengths.
Sheet–fed – any printing press requiring paper in a sheet form as opposed to printing in rolls.
Sheeting – the process of cutting a roll or web of paper into sheets.
Short–grained paper – paper in which the predominant fiber orientation is parallel to the shortest sheet dimension.
Show through – printing is visible on the reverse side of a sheet due to low opacity.
Shrinkage – decrease in the dimensions of a sheet of paper or loss incurred in weight between the amount of pulp used and paper produced.
Side guide – on sheet–fed presses, a guide on the feed board to position the sheet sideways as it feeds into the front guides before entering the impression cylinder.
Side stitch – a method of binding in which the folded signatures or cut sheets are stitched with wire along and through the side, close to the gutter margin. Pages cannot be fully opened to a flat position; also called side wire.
Signature – section of a book obtained by folding a single sheet of printed paper in 8,12,16 or 32 pages.
Silhouette – halftones from which the screen around any part of the image has been removed.
Sizing – internal sizing in the paper affects absorbency, strength and performance. External sizing improves resistance to water, ink and other fluids, seals down surface fibers and improves strength. Typical sizing agents are rosin, glue, gelatin starch resins, waxes, etc.
Skid – (1) a reusable platform support, made of wood, on which sheets of paper are delivered, and on which printed sheets or folded sections are stacked. Also used to ship materials, usually cartons which have been strapped to the skid. (2) a quantity of paper, usually about 3,000 lbs., skid packed.
Slack edges – a paper roll that is baggy at the edges.
Slime hole – slime holes are voids left in the sheet due to displacement of fibers at the wet end of the paper machine.
Slip–sheeting – placing pieces of paper between folded sections prior to trimming the four sides, to separate completed books.
Slitter – a sharp disk which cuts a paper into pre–determined widths.
Slitter dust – tiny, coated fiber fragments that break off the edge of a sheet of paper during the slitting or sheeting operations and may cause problems in printing, finishing and converting operations later.
Slug hole – a paper imperfection caused by an aggregate of fibers in the sheet which is lifted during the paper machine drying process operation, leaving a hole in the web.
Slurring – the smearing or elongation of halftone dots or type and line images at their trailing edges.
Smashed or weak blanket – an area of the blanket that is no longer firm and resilient, and that gives a light impression in the center of a well printed area. Usually caused by physical damage of the blanket at impression.
Smearing – a press condition in which the impression is slurred and unclear, because too much ink was used, or sheets were handled or rubbed before the ink was dry.
Smoothness – the evenness or lack of contour in the surface of an uncoated sheet.
Soft ink – a term that describes the consistency of lithographic inks.
Softcover – another term for paperback or paperbound books.
Softwood – wood from coniferous trees having long fibers.
Solid – an area completely covered with ink, or the use of 100% of a given color. In composition, type set without space (leading) between the lines.
Solid board – single–ply, homogenous types of paperboards, made from the same stock throughout the sheet structure.
Specialty papers or boards – paper or board manufactured, or subsequently converted, for a specific use. These grades usually cannot be used for anything other than their intended special purpose.
Spectrum – the complete range of colors in the rainbow, from short wavelengths (blue) to long wavelengths (red).
Spine – backbone of a book.
Spiral binding – wires in a spiral form inserted through specially punched holes along the binding edge.
Splice – breaks at or near a mill splice usually indicate some defect in the splice or a marked change in web tension or draw near the splice.
Split fountain – a technique for simultaneously printing two colors from the same ink fountain.
Spot varnish – press varnish applied to a portion of the sheet, as opposed to an overall application of the varnish.
Spray powder – a powder used at press to prevent setoff (offset) of wet ink; also called anti–offset spray.
Square sheet – a sheet which is equally strong and tear resistant with and against the grain.
Stacker – device attached to a delivery conveyor to collate, compress and bundle signatures.
Stamping – pressing a design onto a book cover using metal foil, colored foil, or ink, applied with metal dies.
Standard conditions – unless otherwise specified, 23°C and 50% relative humidity.
Starch – type of carbohydrate adhesive and sizing material obtained primarily from corn, wheat, rice, tapioca and potatoes. Produces a higher degree of rigidity in a sheet and improves the finish by causing the fibers to lie flat.
Static electricity – an electrical charge frequently found in paper which is too dry, or which has been affected by local atmospheric conditions.
Stickies – sticky materials in recycled papermaking pulp, often resulting from pressure–sensitive labels.
Stiff – an ink with too much body.
Stiffness – the extent to which paper resists bending or crushing forces.
Stitched book – a popular method of sewing the signatures of a book together by stitching all the sheets at one time, either through the center of the inserted sheets or side–stitched from front to back. A very strong style of binding but not flexible as compared as sewing.
Stock sizes – standard sizes of paper or board.
Stock weights – weights of papers stocked by mills and merchants.
Stocking items – papers manufactured in popular sizes, weights, colors etc. on a regular basis and maintained adequately in inventory in mill warehouses.
Stocking merchant – paper distributor that stocks in his own warehouse facilities enough paper to immediately fill anticipated orders in the market. This eliminates the delay of ordering from the paper manufacturer, taking delivery, and delivering to the customer.
Stone groundwood – pulp made by abrading wood logs against a revolving stone, usually at atmospheric pressure but sometimes done under pressurized conditions.
Strength – a quality measured by tests for burst, tear, tensile and folding strength, in which each measures the ability of the paper to withstand forces in different directions.
Stretch resistance – stretch properties are essential for paper to fold well and to resist stress in use. Stretch resistance is measured on tensile testing instruments.
Strike–through – the visibility of printing on the reverse side of a sheet of paper due to excessive ink penetration through the paper.
Subtractive primaries – yellow, magenta and cyan, the hues used for process color printing inks.
Sugarcane bagasse – is the dry pulpy fibrous residue that remains after sugarcane or sorghum stalks are crushed to extract their juice. It is used as a biofuel to produce heat, energy, and electricity, and in the manufacture of pulp and building materials.
Sulphate – alkaline process of cooking pulp also known as the kraft process. Wood chips are cooked to a high brightness without fiber degradation in a substance of sodium sulfate and sodium sulfide.
Sulphite – acid process of cooking pulp. Wood chips are cooked in a solution of bisulphite.
Supercalendering – alternating rolls of highly polished steel and compressed cotton in a stack. During the process the paper is subjected to the heated steel rolls and “ironed” by the compressed cotton rolls. It imparts a high, gloss finish to the paper. Super calender stacks are not an inherent part of the paper machine whereas the calender rolls are.
Surface coated – any paper or paperboard sheet that has a coating material applied to one or both surfaces.
Surface strength – is used to describe the strength between the paperboard's coated surface and inks, varnishes or films, or the strength perpendicular to a level just underneath the surface.
Surprint – an additional printing over the design areas of previously printed matter to produce such overprint as “Sale”, “$1.98”, “Sample,” etc.
Swatchbook – a grouping of papers, usually in bound form, that displays the weights, colors, finishes and other particulars of a collection of papers to aid in the selection of grades.
Tabbing – during binding, the cutting or adhering of tabs on the edges of pages.
Tack – the pulling power or separation force of ink causing picking or splitting of weak papers.
Tag paper – a heavy, durable card stock commonly used for tags, cards, menus and folders.
TAPPI – the Technical Association of the Pulp and Paper Industry, a well–regarded professional organization who has established recognized technical standards and testing procedures pertaining to the manufacture and use of pulp and paper.
Tare weight – sometimes called unladen weight, is the weight of an empty vehicle or container. By subtracting it from the gross weight (laden weight), the weight of the goods carried (the net weight) may be determined. This can be useful in computing the cost of the goods carried for purposes of taxation or for tolls related to barge, rail, road, or other traffic, especially where the toll will vary with the value of the goods carried.
TCF (Totally Chlorine Free) – includes both virgin and post–consumer fibers that are bleached without any chlorine containing compounds.
Tearing strength – the ability of a paper to resist tearing when subjected to rigorous production demands and manufacturing, printing, binding and its conversion from flat sheets into envelopes, packaging materials etc.
Telescoped rolls – roll edge alignment “runs out” starting at the core usually as the roll rotates.
Tensile strength – relates to the stress and strain to which paper is subjected in its many end use applications. It is defined as the maximum force required to break a paper strip of a given width under prescribed laboratory conditions. Tensile strength is usually defined as pounds–per–inch width of the testing strip, or kilograms per 15–millimeter width. Tensile strength is measured in both the grain and cross–grain directions; however, it is always greater in the grain direction.
Test linerboard – types of paperboard that meet specific tests, adopted by the packaging industry to qualify for use as the outer facing layer for corrugated board, from which shipping containers are made.
Text paper – a general term applied to various grades of printing paper designed for deluxe printed booklets, programs, announcements and advertising.
Thermography – letterpress printing in which a special ink, while still wet, is dusted with a resinous powder on the paper. Then sheets are baked fusing the powder with the ink, giving it a raised effect.
Thermomechanical pulp (TMP) – pulp made by pre–steaming chips then reducing them into their fiber components during an initial mechanical treatment in refiners under elevated temperature and pressure. Subsequent refining is done at atmospheric pressure. This process produces a higher yield and stronger pulp than regular groundwood.
Three–color process – the printing of a full color picture or drawing using only three separate colors: yellow, magenta and cyan. These are also known as process yellow, process red and process blue.
Tight edges – paper with tight edges and a center are that is full and baggy. Shrunken edges will spring upward mostly. If severe enough, wrinkles will form in the center of the sheet during printing.
Tinting – an all–over color tint on the press sheet in the nonimage area of the sheet, caused by ink pigment dissolving in the dampening solution.
Tissue paper – collective term for papers normally of a grammage less than 30gsm that differ in application and composition but have the common feature of being thin and lightweight.
Tolerance – permissible degree of variation from a pre–set standard.
Toner – the “ink” of electrostatic copying/printing, defining the image area; usually consists of a magnetic ingredient to be attracted to the charged area on the photoreceptor, a colorant material (black or other) and possibly an adhesive that can be melted (or “fused”) to hold composite “ink” on the surface of the paper being printed or receiving the copy.
Top – (1) designates the felt side of a sheet of paper. The top side of a sheet is the side not against the wire during manufacture. (2) in paperboard, the top is the side that exhibits the best quality.
Transparent ink – a printing ink which does not conceal the color beneath. Process inks are transparent so that they will blend to form other colors.
Transparency – photographic positive mounted in a clear or transparent image.
Trapping – the ability to print a wet ink film over previously printed ink. Dry trapping is printing wet ink on dry paper or over dry ink. Wet trapping is printing wet ink over previously printed wet ink.
Trim in skid or roll – a paper roll or skid defect caused by the slitter trim shavings inadvertently being wound up in a roll or piled on a skid.
Trim marks – in printing, marks placed on the copy to indicate the edge of the paper where to cut or trim.
Trimmed size – the final size of a printed piece after all bleeds and folds have been cut off.
Trimmer – machine equipped with a guillotine blade that can cut paper to the desired size.
Turnover – a defect of any tear, cut or hole in the sheet which is folded over during slitting, winding or printing. It is often at the edge of the roll.
Two–sheet detector – in printing presses, a device for stopping or tripping the press when more than one sheet attempts to feed into the grippers.
Two–sidedness – in paper, the property denoting a difference in appearance and printability between its top (felt) and bottom (wire) sides.
Two–up – printing the same page or group of pages from two sets of plates, thereby producing two impressions of the same matter at one time.
Type face – a design of letters of the alphabet intended to be used in combination.
Unbleached – paper not treated to bleaching; it has a light brown hue.
Uncoated – paper that has not been coated.
Undercolor removal – to improve trapping and reduce ink costs in the process color web printing, color separation films are reduced in color in areas where all three colors overprint and the black film is increased an equivalent amount in these areas.
Undertrimmed – trimmed to a size smaller than the specified trim size.
Uniformity – being uniform in the structure of the paper, the color and finish.
UV – ultraviolet radiation method of drying process color inks on high–speed multicolor offset presses.
UV inks – in printing, solventless inks that are cured by UV radiation. They are used extensively in screen printing, narrow web letterpress and flexographic printing.
Varnish – a thin, protective coating applied to a printed sheet for protection or appearance. Also, in inkmaking, it can be all or part of the ink vehicle.
Vehicle – the liquid part of an ink that gives it flow, enabling it to be applied to a surface.
Vellum finish – a paper finish characterized by a slightly rough or toothy surface. Vellum finish should not be confused with vellum paper, which is a translucent paper used primarily for drafting.
Vellum paper – very strong, good quality cream colored, or natural paper made to impersonate calfskin parchment. Also, the term is often applied to the finish of paper rather than a grade of paper. Stationery is often referred to as vellum. Also, translucent paper is used by architects and artists is often referred to as vellum.
Vignette – halftone whose background gradually fades away to blend with the surface of the paper.
Virgin – paper made from fibers in their first use, usually from wood pulp.
Virgin fiber – pre consumer waste, also known as white waste or primary fiber.
Viscose – a type of rayon fiber that is made from natural sources such as wood and agricultural products that are regenerated as cellulose fiber. The molecular structure of natural cellulose is preserved in the process.
Warm color – color of ink falling in the red–orange–yellow family.
Wash–up – operation between ink/color changes. Time required between ink color changes.
Wastepaper – all types of used paper that provide a source of fiber for manufacturing of some papers, paperboards and chipboards. More correctly called Paper for Recycling or Secondary Fiber.
Water fountain – the metal trough on a lithographic press which holds the dampening solution.
Water in ink – a press condition of too much water, which breaks down or dilutes the ink.
Water resistance – quality of a sheet of paper to resist penetration by water from one surface to the other.
Waterless plate – in platemaking, printing on a press using special waterless plates and no dampening system.
Watermark – a term referring to the impression of a design, pattern or symbol in a sheet while is it being formed on the paper machine wire. It appears in the finished sheet as either a lighter or darker area than the rest of the paper. Two types of watermarks are available. A shaded watermark is produced by a dandy roll located at or near the suction box on the Fourdrinier. The desired design is pressed into the wire covering the surface of the dandy roll similar to an intaglio engraving. As the wet pulp moves along the web the dandy roll presses down and creates an accumulation of fibers, thus the watermark is seen as darker than the rest of the sheet.
The second type of watermark, called wire mark, is accomplished by impressing a dandy roll with a raised surface pattern onto the moving paper web in a similar manner to the shaded mark. This creates an area of less fiber, making it lighter and more translucent.
Watermarks come in a variety of placement styles. Random, the least expensive to create, is a watermark that appears repetitively throughout the sheet in no particular order. A localized watermark is one that appears in a predetermined position on each sheet. Paraded watermarks appear in a line, either vertically or horizontally on each sheet. A staggered watermark pattern consists of several watermarks on each sheet in a predetermined fashion.
Wavy edges – when paper picks up moisture along the edges, the paper swells. But the center of the sheets does not change, causing the edges to pucker and acquire a wave.
Weave – a defect in a paper roll that produces a side–to–side oscillating motion of the sheet either during the winding operation in papermaking or during the unwinding of the roll during printing.
Web – roll of paper used in web or rotary presses and most often folded, pasted and converted in one continuous form. Also, a ribbon of paper as it unwinds from a roll and threads through the press.
Web press – an offset press that uses web paper as opposed to sheet fed paper.
Weight tolerance – acceptable degree of variation in a paper’s shipped weight, usually within 5% of the paper’s nominal weight.
Wet rolls – water or dampness on the edges of the roll can weld or bond the paper together, which will then break on the infeed, a problem easily determined by the press crew.
Wet strength – the strength retained by a sheet when completely wetted with water; generally, tensile strength.
Whiteness – the color white is defined in colorimetric terms as a color with the highest luminosity, no hue and no saturation.
White paper – (1) any paper made from pulpstock whose natural color has been corrected by the addition of blue, yellow and red dyestuff. (2) in printing, any paper sheet that is devoid of printing material.
Wire binding – a continuous double series of wire loops running through punched slots along the binding side of a booklet.
Wire mark – on the bottom or wire side of the paper, these are impressed traces of the machine wire.
With the grain – parallel to the direction in which the paper fibers lie.
Woodfree pulp – chemical pulp.
Work and turn – to print one side of a sheet of paper and turn the sheet over from left to right and print the second side. The same gripper and plate are used for both sides.
Wove – finish characterized by the impression of a felt dandy roll covered in woven wire and without laid lines.
Wrapper – the materials, consisting usually of paper or paperboard, sometimes with treatment for moisture barrier properties, which are used to protect the roll or pile form damage.
Wrinkles – (1) creases in paper occurring during printing or folding. (2) in inks, the uneven surface formed during drying.
Writing paper – a general term applied to papers used for writing.
Xerography – copying process that uses a selenium surface and electrostatic forces to form an image.
Yellow – hue off a subtractive primary and a 4–color process ink. It reflects red and green light and absorbs blue light.
Yellowing – describes a transformation inherent to all vegetable fibers which is caused by aging. Paper made of vegetable fibers will turn various degrees of yellow as its environment couples with aging to produce this phenomenon. Yellowing is very evident in groundwood papers and only a few hours in direct sunlight is enough to yellow newspaper.
Zig–zag folding – folding used with continuous forms with alternating position (head and foot). Commonly used to convert roll paper to easily managed flat–back.