PAPER GLOSSARY

A - H

A

Absorbency
The ability of paper to absorb fluids such as water or printing ink
Acidification
Decrease in the pH of soil and water due to precipitation containing dissolved ammonium compounds, sulphur and nitrogen oxides; an indirect cause of forest damage
Activated sludge treatment
A biological method of cleaning up waste waters in three stages. Stage I involves (anaerobic) equilibration. In stage II activated sludge containing micro-organisms is led into an aeration basin to speed up oxidation of organic matter and ammonia. In stage III the sludge is allowed to settle and the treated waste water is run off. Some sludge is removed and a portion is returned to the aeration basin
Aerated lagoon
A biological waste water treatment method in which air (oxygen) fed into an aeration basin reduces the effluent load
Air drying
Method of drying the paper web on the paper machine by blowing air along the direction of the web
Air mail paper
Light weight, thin and mainly woodfree writing papers for air mail. Anaerobic treatment Process employing micro-organisms to reduce organic matter in waste water in the absence of oxygen
AOX
Absorbable organic halogens. AOX is a sum parameter measuring total concentration of chlorine bound to organic compounds in waste water. AOX measures all chlorine compounds both harmful and harmless (a sum parameter)
Art paper
High quality and rather heavy two-side coated printing paper with smooth surface. The reproduction of fine screen single- and multicolour pictures ("art on paper") requires a paper that has an even, well closed surface and a uniform ink absorption
Artificial parchment
Woodfree paper that is produced by fine and extended grinding of certain chemical pulps and/or the admixture of special additives. As a result of the "smeary" grinding, the fibre structure closes homogeneously. It is used e.g. for wrapping meat and sausages or as corrugating medium for biscuit packaging
Auxiliary chemical
A chemical added to a stage of paper-making aimed at improving the efficiency of a part of the process.

B

Back-pressure power
Generation of both heat and electricity from fuel; gives greater efficiency than condensing power
Bale
Solid, compressed stack of pulp or paper sheets
Banknote paper
Highly resistant, age-resistant, suitable for 4-colour printing, with watermark and other falsification safeguards such as embedded metal strip. Often containing cotton fibres (See "Rag paper")
Basis weight
See Grammage
Bast
Fibres located in the inner bark layer of trees and in outer portions of other fibrous, woody plants.
Beatability
The ease with which pulp can be beaten to achieve the desired properties
Beating
Mechanical treatment of fibres to improve fibre bonding
Bible paper
Woodfree, sometimes rag-containing speciality printing paper with a low grammage, mostly with a high filler content
Biodegradation
Breakdown of organic matter by micro-organisms into carbon dioxide and water or into less harmful compounds
Biological waste water treatment
A method of cleaning up waste water using living micro-organisms such as bacteria. See: Activated sludge treatment, Aerated lagoon, Anaerobic process
Biosludge
Sludge formed (in the aeration basin) during biological waste water treatment or other biological treatment process
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
Bleach plant
Department of a pulp mill where pulp is bleached
Bleached lined folding boxboard
Bleached lined folding boxboard is a multi-layer paperboard that has a bleached woodfree liner on one or both sides. Between two liners there are intermediate layers and middle layers of mechanical or waste paper pulp
Bleached pulp
Pulp whose natural brightness has been improved using chemicals
Bleaching
Removal or modification of coloured components in pulp to improve brightness. Bleaching is normally carried out in several consecutive stages
Blotting paper
Bulky, highly absorbent, filler-free paper which is mostly produced from pure cotton in the form of bleached linters and from chemical pulp
Board
Generic term for stiff paper usually made in several layers with a substance normally varying from 160 to 500/g/m², for certain grades even higher; widely used for packaging (e.g. folding cartons) and graphic applications
Book paper
Woodfree or mechanical paper used for printing book
Brightening
Addition of optical brighteners to the stock to make the pulp/paper appear whiter
Brightness
A measure of the whiteness of pulp and paper
Broke
Papermakers own waste paper created during papermaking process it is usually repulped
Brush glazing
Glazing of coated paper with the aid of brushes
Bulk product
A mass-produced product sold in large volumes without individual specifications, usually in compliance with a standard. For example, newsprint

C

Cable paper
See "Electrical insulating paper"
Calcium carbonate
Used in papermaking as a filler or coating pigment
Calender
Machine in which paper is given a glazed finish by passing it between two or more rolls, either on or off the paper machine
Calendered paper
Paper that has been smoothed and compacted between the rolls of a calender and is thus more or less glossy (sharp or matt calendered). The effect produced in the calender unit is the result of friction combined with temperature and pressure
Caliper
Thickness of paper, usually measured in nanometers
Capacitor paper
See "Electrical insulating paper"
Capacity utilisation rate
Indicates the efficiency (%) at which a mill or machine is operating
Carbon dioxide (CO₂)
Produced by burning coal and other carbon containing products. Burning fossil fuels or wood based products raises atmospheric carbon dioxide levels
Carbon paper
Carbon paper is a thin paper with a waxy coating, that is used to produce carbon copies on typewriters or other office equipment. Carbon base paper is made from chemical pulp
Carbonless copy paper
Paper that permits making multiple copies without intervening layers of carbon paper. The paper translates pressure into a dye reaction which transfers the image to the copy. Carbonless copy papers are mainly used for continuous form sets, for cov-ered pay slips, for vouchers to be dispatched by post and for payment forms. In the US and some other countries, carbonless copy paper is also called NCR paper (= Non Carbon Required)
Cast-coated paper
Cast-coated papers are coated papers that have obtained their high gloss by moulding on a highly polished, chromium plated drying cylinder
Causticizing
Process by which green liquor from sulphate pulping is converted to white liquor, thus allowing the cooking chemicals to be reused
Cellulose
Structural material giving strength to wood cells
Chemical oxygen demand (COD)
The amount of oxygen consumed in complete chemical oxidation of matter present in waste water; indicates the content of slowly degradable organic matter present.
Chemical pulp
Pulp in which wood fibres have been separated by chemical, rather than mechanical, means
Chemicals recovery
In chemical pulping, the recovery, treatment and regeneration of cooking chemicals
Chemi-thermomechanical pulp (CTMP)
Chemi-mechanical pulp produced by treating wood chips with chemicals (usually sodium sulphite) and steam before mechanical defibration
China clay
Mineral (kaolin) used in papermaking as both filler and coating pigment
Chipboard/Grey board
Paperboard made from waste paper pulp, rough or machine glazed, also lined on one or two sides or unlined
Cigarette paper
This light weight, unsized paper (grammage 18 to 24g), converted to improve glowing. It normally has a filler content of approx. 30%
Clarification
Separation of a solid component from a solution
Clarifier
Basin where sludge is removed from treated effluent by settling; see Activated sludge treatment
Coated paper
The uniform application of a coating yields a more even and more closed surface of printing papers, which is suitable for the reproduction of fine screen artwork. The coating is applied in separate coaters or in the paper machine
Coating
Process by which paper or board is coated with an agent to improve its brightness and/or printing properties
Coating colour
Mixture used to coat paper and board: contains pigment, binder, special additives and water. Also coating slip
Coating colour kitchen
Department where coating colour is prepared and mixed
COD
See Chemical oxygen demand
Combined deinking
Deinking process combining flotation and washing; cf. flotation deinking, washing deinking
Condensing power
Power generation in which fuel is burned for electricity production only
Consistency
Dry solids content (%) of pulp present in a pulp slurry
Continuous cooking
A method used in chemical pulping in which raw material is fed continuously into the digester, while at the same time pulp and black liquor are removed (cf. batch cooking)
Converting
The operation of treating, modifying, or otherwise manipulating the finished paper and paperboard so that it can be made into end-user products
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
Copying paper
Copying paper is an uncoated paper in woodfree or mechanical grades, white or col-oured in A4 and A3.
Core
The tube, usually made of paperboard, on which a paper roll is wound
Corrugated board
Corrugated board is produced by guiding a paper web, the corrugating medium or fluting, through a slit between two corrugated rolls and pressing it into a waveform through a combination of pressure and heat. In the same machine, an even paper web (facing or liner) is then glued on to this corrugated paper on one or both sides. See "Kraftliner".
Corrugating medium
Papers used as fluting for the production of corrugated board.
Critical load
Highest pollutant load that, in the long term, does not damage essential characteristics in an ecosystem
CTMP
See chemi-thermomechanical pulp

D

Dandy roll
A cylinder on a paper machine used to improve formation; also wire roll
Decor paper
Woodfree, white or single-colour paper, often printed with various patterns, e.g. wood grains. The final product consists of laminated boards or directly coated particle boards used for furniture production.
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)
Paper pulp produced by deinking of recovered paper
Deinking
Removal of printing ink and impurities from recovered paper; 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
The removal of lignin, the material that binds wood fibres together, during the chemical pulping process
Deposit
Mass of airborne pollutants deposited on a unit area of land or water in a given time, e.g. grams per square metre per year (g/m²/a)
Deresination
Reducing the resin (pitch) content of wood prior to cooking either by storage or using bleaching chemicals to reduce the resin content in pulp
Digester house
That part of a chemical pulp mill where cooking takes place
Direct cooking
Cooking in which heating is achieved by blowing steam into the cooking liquor
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
Document paper
Document paper is paper with a high ageing resistance. It is woodfree but may also contain rags or be fully made from rags and is used for documents that have to be preserved for a longer period
Double coating
Coating of paper or board twice on one or both sides
Drainage
Formation of a paper or board web on the wire by removing water at the paper machine wet end
Drawing paper
The range of drawing papers includes woodfree and mechanical grades with proper-ties that are tailored for specific drawing techniques. They have a low opacity and are erasure proof and often also wash-fast
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 end
Final part of the paper machine from the drying section onwards
Dry solids
Mass of dried sample as a percentage of mass of original sample
Dry strength
Mechanical strength of a dry paper sheet (includes tensile strength, tearing resistance and folding endurance)
Duplex board
Duplex board consists of two layers, mostly made from waste paper pulp. It is used for packaging purposes

E

Elastic strength
The ability of paper or board to resist stress acting in the plane of the sample
Electrical insulating paper
Strong, pore-free paper, sometimes impregnated with synthetic resins, made from chemical pulp. Electrical insulating paper must neither contain fillers nor conductive contaminants (metals, coal, etc.) nor salts or acids. Cable papers, that are wound around line wires in a spiral-like fashion, are electrical insulating papers with a par-ticularly high strength in machine direction. Electrical insulating papers also include electrolytic papers and capacitor paper
Electrostatic precipitator
Used to clean up flue and process gases. Removes 99.5-99.8% of dust particles emitted from recovery boilers, lime kilns and bark-fired boilers
Emulsion coating
Coating of paper with an emulsion containing plastic or resin
Envelope paper
Envelope paper can be woodfree or wood-containing, machine glazed or calendered, white or in colour and is used for envelopes. It must be opaque, writable, and printable and must have a high folding strength
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
Evaporation plant
Unit used at pulp mills to concentrate spent liquor to make it suitable for burning and chemicals recovery
Extended cooking
Method of cooking pulp to low lignin content, thereby reducing the need for bleaching chemicals

F

Fibre loss
Loss of fibre material in pulp and paper processing
Fibreboard
Board made from defibrated wood chips, used as a building board
Fibrillation
A structural change occurring in the walls of chemical pulp fibres during beating
Filler
Pigment, added to papermaking stock to improve properties such as opacity and smoothness, and often to reduce cost
Filler content
Percentage of filler in a paper
Filter paper
Unsized paper made from chemical pulp, in some cases also with an admixture of rags, sometimes with a wet strength finish. Filtration rate and selectivity, which are both dependent on the number and the size of the pores, can be controlled by specific grinding of the pulps and creping
Fine paper
High-quality printing, writing or copy paper produced from chemical pulp and usually containing less than 10% mechanical pulp
Fine paper
Quality term for a large number of woodfree printing papers, based on chemical pulp with usually less than 10 % mechanical pulp. Sometimes fine paper also is made with an admixture of rags or wholly from rag pulp
Flame resistant paper
Flame resistant paper may ignite but must extinguish immediately so that it chars. This property is imparted to the paper by impregnation with certain chemicals
Flong paper
A pulp-like, coated-type paper
Flotation deinking
Deinking process in which air is blown into a dilute fibre suspension. Ink particles adhere to the air bubbles and rise to the surface, where they are removed
Flue gas scrubber
Equipment for removing impurities from flue gases by dissolving them in aqueous solution
Fodder pulp
Protein produced from pulp mill spent liquors and sometimes mixed with animal feeds
Folding boxboard
Single or multilayer paperboard made from primary and/or secondary fibres, sometimes with a coated front, used to make consumer packaging (cartons)
Fourdrinier wire
Horizontally moving metal or plastic mesh belt (wire) on which the paper web is formed
Fraction
A component of a mixture that can be separated on the basis of some property or properties
Fully bleached pulp
Pulp that has been bleached to the highest brightness attainable (> 90 ISO)

G

Glassine paper
Paper made from finely ground chemical pulp that is largely greaseproof but does not have wet strength. Its high transparency is achieved by very intense calendering (smoothing between rolls). Used as chocolate wrapping, in photo albums, wrapping for fish preservatives, protective covers for leaflets, envelope windows etc.
Glazing
First calendering, in which paper is passed through a roll nip to give it a smoother surface
Grammage
Weight in grams of one square metre of paper or board; also basis weight
Gravure paper
Mostly mechanical, highly calendered (smoothed) paper with a high ash content, which is produced as coated or uncoated grade (See "Coated paper"). It must ensure uniform ink trapping at high printing speeds. In order to accept the ink from the deep etched or engraved ink cells of the gravure cylinders, gravure paper must have a certain degree of softness and suppleness. Applications: magazines and reviews, mail-order and travel catalogues, brochures and inserts with high print runs
Greaseproof paper
Greaseproofness is either achieved by grinding of the pulp and pore-free web formation or by special additives
Grinder
A machine in which logs are defibrated against a revolving grindstone
Groundwood mill
An installation for producing mechanical pulp by grinding
Groundwood pulp
A fibrous slurry produced by mechanically abrading the fibres from barked logs through forced contact with the surface of a revolving grindstone. It is used extensively in the manufacture of newsprint and publication papers
Gumming
Paper with a coating of an adhesive which becomes sticky when wet

H

Hard pulp
A commonly used term to describe chemical pulp with a high lignin content
Hardwood chemical pulp
Chemical pulp made from hardwood
Headbox
Chamber at the beginning of a paper machine that dispenses pulp stock evenly onto a moving wire
Hood
A hood covering the paper machine drying section and designed for moist air removal
Hot screening
Pulp cleaning at elevated temperature using pressure screens
Hot-ground wood pulp
Mechanical pulp produced by grinding logs that have been pre-treated with steam
Humus
Dead organic material derived from decomposition of plant and microbial wastes