Glossary

Key terms we use 

• Absorbency
  The ability of paper to absorb fluids such as water or printing ink
• Age-resistance
  Over time, paper fibres begin to yellow and eventually disintegrate. Business papers that are designed for long-term archiving are manufactured Using pH-neutral pulp and appropriate additives to curtail this process.
• Aluminium paper
  Packaging paper made by mixing aluminium powder into the furnish or by coating or laminating the sheet with aluminium foil
• Archival paper
  Paper for permanent documents that does not discolour or become brittle with age
• Art paper
  Coated, normally woodfree, paper suitable for 4-colour printing
• Ash content
  Ratio of mass of residue after combustion to mass of sample (pulp/paper) before combustion

• Bale
  Solid, compressed stack of pulp or paper sheets
• Base board
  Board intended for coating, laminating, etc.
• Base paper
  Paper intended for further processing, e.g. by coating
• Beating
  Mechanical treatment of fibres to improve fibre bonding
• Binders
  The materials used to provide cohesive strength to coatings based on clays and calcium carbonate. The binder would be used as a polymer dispersion, for example, polyvinyl acetate
• Black liquor
  Mixture of cooking chemicals and dissolved wood material remaining after sulphate cooking; recovered during pulp washing, concentrated by evaporation and burned in the recovery boiler to regenerate the cooking chemicals and generate energy
• Blade coating
  The most widely used coating method in which excess coating colour is scraped off by a blade
• Bleached pulp
  Pulp whose natural brightness has been improved using chemicals
• Bleaching
  Removal or modification of coloured components in pulp to improve brightness. Bleaching for chemical pulp is carried out in several consecutive stages
• Blotting board or blotting paper
  Paperboard with a very high absorbency
• Board
  Thick and stiff fibre based material often consisting of several plies; widely used for packaging purposes (grammage 150-600 g/m2)
• Board types
  · Cast coated board Material that has been coated with a special blend of white pigment and plastic binder and then cast against a highly polished surface to produce a high gloss finish. European designations: GG1 (white back cast coated folding boxboard), GG2 (cream back cast coated folding boxboard), GGZ (cast coated solid bleached board). · Coated board Coated typically with a white mixture of materials such as china clay and/or calcium carbonate with binders to produce a smooth and improved surface, particularly for printing and varnishing. · Extrusion coated board Board that has been covered with a continuous layer of a thermoplastic material, typically polyethylene or polypropylene, by the extrusion coating process i.e. where a thermoplastic material is melted and forced through a narrow slot onto a moving web of board. · Folding boxboard Multi-ply construction of a coated board made predominantly from mechanical pulp but with a bleached chemical pulp liners. European designations: GC1 (white back folding boxboard), GC2 (cream back folding boxboard). · Greyboard See Unlined chipboard · Kraft board Solid pulp board produced by the sulphate process with or without bleaching. European designation: GZ (coated solid bleached board). · Lined chipboard Unlined chipboard that is modified by use of a thin layer of different pulp to provide a liner, for example, unbleached chemical pulp to give kraft lined chipboard. · Semi-chemical fluting A strong and flexible material formed as the middle layer of corrugated board, usually made from short (hardwood) fibres pulped using a combination of chemical and mechanical processes. · Solid board Made of one or more plies of bleached (solid bleached board, SBB) or unbleached chemical pulp (solid unbleached board, SUB). · Test liner A liner, used as the inner or outer layer of a corrugated construction, the material being made partly from waste paper. · Uncoated board Board not treated as in coated board, although it may have a light application of surface size. · Unlined chipboard A material made entirely from waste paper in one or more piles. The quality can vary significantly depending on the choice of waste paper and the manufacturing process. · White lined chipboard A multi-ply construction made predominantly from selected waste paper with a bleached chemical pulp liner. European designation: GD or GT (coated recycled board).
• Bond paper
  A typing paper of 70-100 g/m2 grammage
• Brightening
  Addition of optical brighteners to the stock and/or coating colour to make the pulp appear whiter
• Brightness
  A method of defining the surface whiteness. It is expressed as a percentage of the reflectance from an ideal white surface. The instrument disregards the influences of gloss and measures the reflection of blue light with a wave length of 457 nm
• Brush glazing
  Glazing of coated paper with the aid of brushes
• Bulk
  The reciprocal of paper density. Also known as specific volume
• Bulk product
  A mass-produced product sold in large volumes without individual specifications, usually in compliance with a standard. Newsprint is one example

• Cable paper
  Paper used to insulate electrical cables
• Calcium carbonate (CaCO3)
  Chalk. Used in papermaking as a filler or coating pigment
• Calendered paper
  For gloss surfaces the paper is supercalendered. To get supercalendered grades the paper web is passed between alternate hard smooth steel rolls and soft rolls made of compressed fibrous material.
• Calendering
  A process of rolling to modify surface finish or smoothness and to control the caliper.
• Caliper
  The thickness of the paper or board measured under test conditions. The units of measurement commonly used are microns
• Capacity utilization rate
  Indicates the efficiency (%) at which a mill or machine is operating
• Cartonboard
  A rigid wood fibre based packaging material. Cartonboard is normally of at least 180 g/m2 substance and 250 microns thickness.
• Chemical pulp
  Pulp in which wood fibres have been cooked with chemicals to separate out the cellulose fibres and dissolve the lignin. There are two methods: sulphate (more common) and sulphite.
• Chemicals recovery
  In chemical pulping, the recovery, treatment and regeneration of cooking chemicals
• Chemithermomechanical pulp (CTMP)
  Chemimechanical pulp produced by treating wood chips with chemicals (usually sodium sulphite) before mechanical defibration
• China clay
  Mineral used in papermaking as both filler and coating pigment
• Chipboard
  Board produced from unsorted waste paper; used for packaging purposes and as backing board for notepads, etc. Also: see particleboard
• Clay coating
  The printing properties of a board can be improved significantly by application of surface coatings to improve whiteness and smoothness and to decrease ink absorbency. The coatings are normally based on dispersions of clays and/or calcium carbonate in a plastic binder such as polyvinyl acetate
• CMC (Carboxymethylcellulose)
  A water-soluble cellulose-based polymer used as a thickening agent in foods and detergents
• Coating
  Process by which paper or board is coated with a coating color for printing, brightness and gloss
• Coating colour
  Mixture used to coat paper and board: contains pigment, binder, special additives and water. Also coating slip
• Cockling
  Paper that has been dried without restraint so that it looks like a landscape with hills and valleys. This has been caused by uneven shrinkage.
• Conditioning
  The process whereby materials are brought into equilibrium with their surroundings at a particular temperature and relative humidity
• Conductivity
  Paper's capacity to conduct electricity
• Consistency
  Dry solids content (%) of pulp present in a pulp slurry
• Cooking
  A process for producing chemical pulp by treating wood with a cooking liquor at a certain temperature and pressure
• Cooking liquor
  Liquor made up of selected chemicals and used for cooking pulp
• Core
  The tube, usually of paperboard, on which a paper roll is wound
• Corrugated board
  Consists of one or more sheets of fluted paper stuck between flat sheets of paper or board such as: i) Single face corrugated One sheet of fluted paper stuck to one flat sheet of paper or board. ii) Double face corrugated Board made up of one sheet of fluted material stuck between two sheets of paper or board.
• Crepe paper
  Paper with high elasticity produced by creping
• Creping
  Crinkling of paper during drying to produce a soft, elastic sheet
• CTMP
  Chemimechanical pulp produced by treating wood chips with chemicals (usually sodium sulphite) before mechanical defibration
• Curl
  The amount of curvature in a sheet of paper when laid on a flat surface
• Cylinder vat machine
  An old method of boardmaking where fibres are deposited on a wire mesh rotating in diluted pulp to form one ply. Each machine would have several vats.

• Defibration
  Separation of wood fibres by mechanical and/or chemical means
• Deinkability
  Suitability of recovered paper for deinking; depends on paper grade, printing process used, age of paper, and other factors
• Deinked pulp (DIP)
  Waste paper pulp produced by deinking
• Deinking
  Removal of printing ink and impurities from recovered paper; deinking is intended to produce recycled fibre pulp with maximum whiteness and purity
• Deinking loss
  Unwanted loss of solid material from pulp during deinking (usually 10-40%)
• Delignification
  In chemical pulping, the removal of lignin, the material that binds wood fibres together
• Density
  The darkness of a printed image
• Die cuttability
  Suitability of paper and board for die cutting into blanks of a given shape
• Dispersion
  The separation of a substance into the smallest possible particles using another substance (the medium). Used in papermaking to homogenize pulp properties and remove impurities
• Dissolving pulp
  A chemical pulp grade used, for example, in the production of acetate and viscose fibres and cellulose films
• Double coating
  Coating of paper or board twice on one or both sides
• Double wall corrugated board
  Corrugated board with two layers of fluting and three facings
• Drainage
  Formation of a paper or board web on the wire by removing water at the paper machine wet end
• Dry coating
  Coating method in which a binder is applied to the paper surface followed by dry coating pigment
• Dry creping
  Creping of a dry paper web
• Dry strength
  Mechanical strength of a dry paper sheet (includes tensile strength, tearing resistance and folding endurance)
• Duplex paper/board
  Paper or board consisting of two furnish layers of different composition and/or filler content; used as art board

• ECF
  Elemental chlorine free. Chemical pulp bleached using chlorine dioxide and/or other bleaching agents, without elemental chlorine
• Elastic strength
  The ability of paper or board to resist stress acting in the plane of the sample
• Electrical resistivity
  Resistivity characterises how a sheet of paper accepts and holds a charge. Since the electrostatic processes uses an electrical charge to form the print image, the electrical properties of the sheet are important to the overall imaging process.
• Emulsion coating
  Coating of paper with an emulsion containing plastic or resin
• Enzyme bleaching
  Bleaching technique in which cooked and oxygen-delignified chemical pulp is treated with enzymes prior to final bleaching. Allows pulp to be bleached without chlorine chemicals
• Extended cooking
  Method of cooking pulp to low lignin content, thereby reducing the need for bleaching chemicals
• Extrusion
  Method of coating paper or board with thermoplastic material, can also be used for lamination

• Fibre
  Wood cell whose properties vary from one tree species to another; the main raw material for papermaking
• Fibre loss
  Undesirable loss of fibre material from pulp during processing
• Fibreboard
  Board made from defibrated wood chips on a wet-lap forming machine; used as a building board
• Fibrillation
  A structural change occurring in the walls of chemical pulp fibres during beating
• Filler
  An inert inorganic material such as china clay, titanium dioxide, chalk, talc and so on, used to modify the properties of boards to improve whiteness, opacity or porosity
• Filler content
  Ratio of material originating from filler and coating chemicals to original mass of pulp
• Fine paper
  High-quality printing, writing or office paper produced mostly from chemical pulp. May be either coated or uncoated
• Flocked paper
  Paper with a velvet-like, smooth unglazed surface
• Fluff pulp
  A special pulp used in babies? nappies and sanitary towels
• Fluff pulp
  A special pulp used in babies? nappies and sanitary towels
• Flutes (A, B, C, E, F and G)
  These letters define the type of corrugated material in terms of the number of corrugations per unit length and the height of the corrugations - specifically these are: Flute Corrugations per metre Height of corrugation (mm) A 105 - 125 4.5 - 4.7 B 150 - 185 2.1 - 2.9 C 120 - 145 3.5 - 3.7 E 290 - 320 1.1 - 1.2 F 410 - 420 0.7 - 0.8 G 550 - 560 0.5 - 0.6
• Fluting
  Paperboard used to make the corrugated layer in corrugated board
• Folding boxboard
  Multilayer consumer packaging board used to make cartons, etc.
• Formation
  This refers to the even distribution of fibres throughout the sheet. Good formation is critical to the paper's performance and the quality of the printed output.
• Formers
  These are more advanced de-watering systems with pressure or suction to provide higher production speeds and improved board properties
• Fourdrinier wire machine
  A method of formation of one ply where diluted pulp is sprayed from a head box on to a continuously moving horizontal wire
• Fully bleached pulp
  Pulp that has been bleached to the highest brightness attainable
• Furnish
  A general term used to describe the type of cellulose materials (pulps) used in the construction of board

• Glazing
  Calendering for more glossy and smoother surface and for even thickness
• Grain
  The orientation of fibres in the paper
• Grain direction
  In the board manufacturing process the cellulose fibres align themselves more in the direction of making - machine direction (MD) than at right angles to it - cross direction (CD). Sheets are described as long or short grain, depending on the direction of grain relative to the longer direction.
• Grammage
  Weight in grams of one square metre (g/m2) of paper or board; also basis weight (US)
• Graphic papers
  Papers intended for printing purposes
• Greaseproof papers
  Papers resistant to the penetration of grease; made from heavily beaten chemical pulp or by treating the paper with sulphuric acid
• Groundwood pulp
  Mechanical pulp produced by grinding wood against a grindstone
• Gumming
  Coating of paper or board with an adhesive, which becomes sticky when wet

• Hard pulp
  Chemical pulp with a high lignin content
• Hardwood chemical pulp
  Chemical pulp made from hardwood
• Hardwoods
  These are typically deciduous trees, such as birch, aspen and maple, that can be used to produce hardwood pulp
• Hi-Fi paper
  (High finish paper) Machine-calendered newsprint
• Hot screening
  Pulp cleaning at elevated temperature using pressure screens
• Hygienic tissue
  Toilet tissue, facial wipes, paper towels and similar absorbent tissue products that disintegrate in water
• Hygroscopic
  Fibres are hygroscopic as they change shape as a result of picking up or releasing moisture

• Impregnation
  The absorption of an impregnating agent into paper; in pulping, wood chips are impregnated with cooking liquor; timber is impregnated with preservative
• Industrial papers
  Often plastic-coated or laminated papers used for industrial packaging and insulation purposes
• Insulation board
  A bulky, flexible paperboard used in buildings; usually coated kraft paper
• Insulation paper
  An example is the cable paper used for insulating electrical conductors
• Integration
  In an integrated pulp and paper mill, pulp is piped direct to the paper mill
• ISO brightness
  The brightness of paper and board measured at a wavelength of 457 nanometres under standard conditions

• Jumbo roll
  Large roll of paper coming off the paper machine before cutting to customer rolls

• Kappa number
  Measure of the amount of lignin remaining in pulp after cooking
• Knotter pulp
  Pulp made from the rejects from chemical pulp screening
• Kraft fluting
  Fluted paper made from strong kraft pulp
• Kraft paper
  High-strength paper made almost entirely of unbleached kraft pulp
• Kraft pulp
  Unbleached sulphate softwood pulp.
• Kraftliner
  Facing board used, for example, as an outer ply in corrugated board

• Label paper
  Paper for production of self-adhesive labels for mainly the beverage and food industry
• Lacquering
  Application of lacquer to give paper greater gloss and stiffness (brochures and some magazine covers)
• Laminant
  The bonding agent used to effect lamination, for example, water-based adhesives, solvent solution adhesives, hot melt adhesives, plastic extrusions
• Laminate
  Material used to bond together two or more layers of paper, board, etc.; also a laminated product
• Lamination
  The combination of two or more discrete materials using a bonding agent, such as paper and board or aluminium foil and board
• Laminboard
  Board constructed from glued strips not more than 7 mm in width and faced with veneer
• Lightweight coated paper (LWC)
  Coated magazine paer of low grammage (under 72 g/m2); used in magazines and sales catalogues
• Lightweight coating
  Coating applied at 7-10 g/m2 on one or both sides of the paper
• Lignin
  Natural adhesive which binds wood fibres together in the tree and imparts rigidity. In chemical pulps brightness depends on the amount of lignin removed.
• Lime sludge
  Sludge of calcium carbonate (CaCO3) formed during preparation of white liquor in the chemical pulping process
• Linen finish
  Imitation linen texture impressed onto the paper surface
• Liner
  Packaging board used as a surface layer on corrugated board or strong cartonboards
• Linting
  The dusting tendency of the paper

• Machine direction
  See Grain direction
• Machine glazed (MG) finish
  The term used to describe the finish imparted to the surface of a paper by passing it over the surface of a very large, highly polished, steam heated cylinder
• Magazine paper
  LWC, MWC or SC paper for printing magazines, advertising material, etc.
• Marbling
  Addition of strongly stained fibres to the stock to give the paper a marbled appearance
• Mat calendered paper
  The paper web is passed between soft nip(s)
• Matt finish
  A dull finish given to the surface of paper and board
• MDF
  Medium density fibreboard; used in the furniture industry in place of particleboard and other boards
• Mechanical pulp
  Pulp consisting of fibres separated entirely by mechanical means
• MF
  Machine finished. The paper is glazed in a machine stack. The paper is less smooth than supercalendered paper
• MG
  Machine glazed. Paper with a glossy finish on one side produced on the paper machine by a Yankee cylinder
• Micro-creping
  A way of improving the extensibility of paper by pressing a wet mesh against the paper web
• Micron
  One millionth of a metre or one micrometer (µm)
• Moisture
  The sheet must have the correct moisture content throughout, to prevent the paper from curling inside the machine, which can also result in jams and misfeeds.
• Multi-layer web forming
  Usually applied to a board machine on which several webs are combined into one
• Multi-stage cooking
  Chemical pulping process in which the alkalinity of the cooking liquor is varied by charging the alkali in several stages

• Newsprint
  Standardized printing paper produced from mechanical pulp; grammage 40-52 g/m2
• NSSC pulp
  Neutral sulphite semi-chemical pulp. Produced by slight cooking followed by defibration in a disc refiner.

• OCR paper
  Optical character recognition paper. A woodfree paper suitable for optical scanning or reading
• Off-machine coating
  Coating of paper on a separate coating machine
• Off-machine creping
  A method whereby paper is creped in a separate operation rather than by the paper machine's Yankee cylinder
• On-machine coating
  Coating of paper on the paper machine (also inline term is used)
• Opacity
  Opacity expresses the degree of non-tranparency. High opacity is essential when a paper is intended for duplex printing, or for intensive colour printing on one side of the sheet.
• Optical characteristics
  Characteristics of the appearance of paper or board. Most important are colour, brightness, opacity and gloss
• OTC paper
  One-time carbonizing paper. Carbon paper that produces one copy only. Used, for example, for receipts
• Oxygen bleaching
  A process in which pulp is initially treated with oxygen followed by 4-5 bleaching stages
• Ozone bleaching
  Pulp can be treated with ozone at the start of the bleaching sequence to lower its lignin content. Ozone allows bleaching to high brightness without chlorine chemicals

• Packaging board
  Board for making consumer packs (cartonboard) or transport packs (kraftliner and corrugating medium)
• Paperboard
  See Board
• Papermaking pulp
  Pulp intended for the manufacture of paper
• Parchmentization
  Method of treating a paper sheet with sulphuric acid to make it greaseproof
• Particleboard
  Board made by gluing together and compressing thin wood chippings; used for making furniture, shelves, doors, flooring and partition walls
• Passe-partout board
  Grade of board used for making frames, e.g. for photographs
• Peroxide bleaching
  Method of bleaching pulp with hydrogen peroxide (H2O2). In case of chemical pulp reduces or avoids the need for chlorine dioxide in final bleaching. In case of mechanical pulps the most common bleaching method as such.
• PGW
  See Pressurized groundwood pulp
• Picking
  Removal of particles from the paper surface during printing when ink tack is greater than surface strength
• Picking resistance
  Ability of a paper surface to resist picking by tacky printing ink
• Pigmentizing
  Light coating of paper with a chemical agent (pigment) to reduce surface porosity
• Plasticizer
  Agent mixed into coating colour to give a more flexible coating
• Ply
  Single layer of pulp from one former or wire, making up one of several layers in a board
• Porosity
  A structural property of paper reflected by the size distribution of pores
• Pressurized groundwood pulp (PGW)
  Mechanical groundwood pulp produced by grinding logs against a grindstone in a pressurized chamber.
• Printability
  Describes suitability for a given printing process
• Printing paper
  Paper specially designed for printing, e.g. newsprint and magazine paper
• Pulp
  · Bleached pulp Pulp of a high degree of whiteness produced from pulp of a natural colour (brown/buff) by a chemical bleaching process · Chemical pulp Pulp obtained by chemical treatment of de-barked wood to remove non-cellulose material, resulting in separation of fibres without mechanical aids to create longer-fibred pulps · Chemi-thermo-mechanical pulp Pulp derived from a combination of chemical and mechanical pulping processes, often partially or fully bleached (BCTMP) · Mechanical pulp Pulp obtained by a mechanical process of grinding or refining de-barked wood without the use of chemicals · Recycled pulp Collections of waste paper and board, generally from selected sources and of known quality · Sulphate/kraft pulp Cellulose fibre separated by a chemical (alkaline) process to give a brown coloured pulp of good strength · Unbleached pulp Pulp of natural colour
• Pulp and paper industry
  Covers production of pulp (both chemical and mechanical), paper and board, as well as paper and board converting
• Pulper
  Unit for defibrating (slushing) pulps and paper machine broke
• Pulpwood
  Wood suitable for making into pulp; not usually good enough for sawmilling
• Puncture resistance
  Force acting perpendicular to a paper or board surface needed to puncture the sheet

• Rag pulp
  Papermaking pulp made from textile waste, cotton, hemp or flax
• Ream
  Unit consisting of 500 identical sheets of paper (usually). In some parts of the world reams contain 480 sheets
• Recovered paper
  That portion of all waste paper that can be collected and re-used. Does not include tissue or paper recycled internally by the paper industry
• Recovery rate
  Volume of paper recovered as a percentage of volume of paper consumed
• Recycled fibre
  Fibre obtained from recovered paper; also secondary fibre (cf. virgin fibre)
• Recycled fibre pulp
  Pulp produced from recovered paper; contains only recycled fibres and is used in papermaking. Recycled fibre pulp can be used either deinked or not deinked
• Refiner
  A machine in which wood chips are broken down into fibres.
• Refiner mechanical pulp (RMP)
  Mechanical pulp produced by passing wood chips between the plates of a refiner
• Reflectivity
  Ability of paper or board to reflect light; a measure of gloss
• Reinforcement
  Method for strengthening paper with an insert or surface layer of glass or other synthetic fibre or metal
• Reinforcement pulp
  Softwood chemical pulp added to give paper greater strength and to improve runnability on the paper machine or printing press
• Reject
  Material removed and discarded during the cleaning of pulp/stock
• Relative density
  Mass of a unit volume of a particular substance
• Release paper
  Backing paper for self-adhesives
• Resolution
  A measure of the detail that can be reproduced in dpi (Dots Per Inch). The higher the figure, the better result.
• Retention
  Proportion of fibre and filler retained on the paper machine wire
• Runnability
  How smoothly paper runs through a paper machine or printing press (also how well cartons run on an automatic packaging line)

• Sack paper
  Kraft paper, usually uncalendered, used to make paper sacks; also sack kraft
• SC
  See Supercalendered
• Secondary fibre
  See Recycled fibre
• Semi-alkaline pulp (SAP)
  Sulphite pulp cooked at slightly alkaline pH (normal sulphite pulp is cooked at acid pH). SAP is superior in strength to normal sulphite pulp. Used mainly in printing papers
• Semi-bleached
  Pulp bleached to a brightness somewhere between that of unbleached and fully bleached pulp
• Semi-chemical pulp
  Pulp in which the fibres have been separated mechanically after a preliminary chemical treatment; e.g. NSSC pulp
• Settleable solids
  Suspended solids that will settle out of an effluent during mechanical treatment
• Sheeter
  Equipment for cutting paper and board from reels into sheets of desired size
• Short fibre
  Applies to paper or pulp containing a high proportion of short wood fibres
• Single-faced corrugated board
  Corrugated fibreboard consisting of two layers, one of fluted paper and one of facing; used for packaging furniture
• Sizing
  The addition of chemicals to the pulp to modify properties of the board, in order to reduce water absorption, for example. Surface sizing is carried out by application of chemicals in a water solution or dispersion to modify surface properties or provide barrier properties against, for example, grease or water.
• Smoothness
  Evenness of the paper surface. Print quality tends to improve with increasing paper smoothness.
• Softwoods
  Typically coniferous species such as spruce, fir, pine and larch, which are grown in Scandinavia and northern Europe for production of softwood pulp, commonly used for boards.
• Solid fibreboard
  Board of over 600 g/m2 intended for packaging; often has an outer ply of kraft pulp
• Special pulps
  Chemical pulps used for purposes other than ordinary papermaking (e.g. in textile production)
• Speciality papers
  Large group of papers designed and produced to meet the unique packaging, printing and labelling needs of customers with diverse and highly specialized paper needs.
• Spent liquor
  Waste liquids from pulping and washing (cf. black liquor)
• Spinning papers
  Paper with a particularly high tensile strength in the machine direction; suitable for being spun into yarn or string
• Steam finishing
  A way of treating paper before calendering to improve its density and surface smoothness
• Steaming
  Wood chips are often treated with steam prior to pulping; used in thermomechanical pulping
• Stiffness
  Describes the ability of paper or board to resist bending. Important for good runnability in printing and for end product usability
• Stock
  Suspension in water (slurry) of fibres and other components for papermaking during the period between defibration and web formation
• Strength
  Ability of paper or board to withstand mechanical stress
• Substance
  See Grammage
• Sulphate board
  An extremely strong linerboard; also kraftboard
• Sulphate pulp
  Chemical pulp produced by cooking wood in a alkaline liquor containing sodium hydroxide and sodium sulphide
• Sulphite pulp
  Chemical pulp produced by cooking wood in a liquor containing sodium, magnesium, ammonium or calcium bisulphite; not produced in Finland (SAP is an exception)
• Supercalendered (SC)
  Paper treated in a supercalender, usually separate from the paper machine; uncoated magazine paper
• Supercalendering
  Treatment of paper on an off-machine supercalender to improve smoothness and gloss
• Surface pH
  The pH value of the paper surface. Most papers are neutrally sized with a surface pH of around 7.
• Surface treatment
  Treating the surface of paper or board with size or coating colour

• Talc
  Mineral used in papermaking as a filler and coating pigment
• Tearing resistance
  Force needed to tear a sheet of paper under specified conditions
• Technical papers
  Variety of medium-grammage papers used in different industrial purposes
• Testliner
  Liner made from waste paper with an outer ply of kraft pulp; also kraft faced liner
• Thermomechanical pulp (TMP)
  Mechanical pulp produced in a refiner from wood chips pretreated with steam
• Thickness
  Thickness determines the stiffness of paper, an important quality for the texture and feel of the paper as well as its smooth running on high speed copiers and printers.
• Thin paper
  Paper made from bleached chemical pulp and having a grammage of 40 g/m2 or less
• Tissue
  General term covering a variety of high-quality, creped hygiene papers
• Totally chlorine-free (TCF)
  Pulp bleached entirely without chlorine chemicals (bleached with ozone, for example)
• Trimmings
  Paper or board left over from web or sheet cutting operations
• Twin-wire machine
  Paper or board machine in which the web is formed and partially dewatered between two wires

• Unglazed (UG)
  Uncalendered paper
• Utilization rate
  Amount of waste paper raw material used to make a certain amount of paper (usually in %)

• Veining
  Uneven colouring of pulp
• Virgin fibre
  Wood fibre never before used to make pulp, paper or board. Also primary fibre (cf. secondary fibre)
• Viscose pulp
  Dissolving pulp intended for the manufacture of viscose
• Volatile corrosion inhibitor (VCI) paper
  Paper specially designed to resist corrosive liquids

• Wallpaper baseboard
  Two-layer board, grammage 120-200 g/m2, used to make wallpaper
• Washer room
  Pulp mill department where pulp is washed free of cooking chemicals
• Waste paper
  All paper after it has been used; cf. recovered paper
• Waxing
  Coating or impregnating of paper or board with paraffin or wax
• Web
  Continuous sheet of paper formed on the paper machine wire
• Web glazing
  Imparting a gloss to the paper web; calendering
• Wet end
  First part of the paper machine up to the drying section
• Wet strength
  Mechanical strength of paper when wet
• Wet tensile strength
  Ability of wet paper to resist tension in the plane of its surface
• Whiteness
  A colour measurement which corresponds to the whiteness perception of the human eye
• Whiteness and brightness
  These are aesthetic qualities, defining the look of the paper and its likely perception in the hands of the end user, as well as impacting on print quality and visual contrast.
• Winder
  Machine for cutting the paper web longitudinally into narrower webs, which are then wound to reels; also slitter- winder
• Winding
  Operation whereby a web of paper or board is wound into one or more reels
• Wire
  Flat belt of metal or plastic mesh on which the paper or board web is dewatered
• Wood bank
  An arrangement whereby companies exchange wood raw material to minimize transport costs
• Wood fibre
  Wood cells; the main raw material for papermaking
• Woodcontaining
  Paper containing a certain proportion of mechanical pulp
• Woodfree
  Paper based mainly on chemical pulp

• Yankee machine
  Paper machine with a single large drying cylinder (Yankee cylinder) which repes the paper and produces a glazed surface on one side
• Yield
  Amount of product obtained from a process in relation to the amount of raw material used