PULP AND PAPER DICTIONARY
This page contains definitions of the terms, words and phrase commonly used in pulp and papermaking, printing, converting and paper trading.
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
C1S Coated on one side of the paper.
C2S Coated on both sides of the paper.
CALCIUM CARBONATE CaCO3, a naturally occurring substance found in a variety of sources, including chalk, limestone, marble, oyster shells, and scale from boiled hard water. Used as a filler in the alkaline paper manufacturing process, calcium carbonate improves several important paper characteristics, like smoothness, brightness, opacity, and affinity for ink; it also reduces paper acidity. It is a key ingredient in today's paper coatings.
CALENDER A stack of highly polished metal cylinders at the end of a paper machines that smoothes and shines the paper surface as sheets pass through.
CALENDER BLACKENING Coverage of calendared paper web with glazed translucent spots due to excessive calendar roll heat, calendar pressure, poor and/or excessive and uneven moisture.
CALENDER CUT WEAK LINES OR FRACTURES IN PAPER THAT BREAK EASILY UNDER TENSION, CAUSED BY WRINKLES GOING THROUGH THE CALENDER STACK OF THE PAPER MACHINE.
CALENDER SPOTS Paper defect usually indicated as a transparent spot in the sheet; caused by foreign material adhering to a calendar roll and being impressed into the sheet with each revolution.
CALENDERING Passing paper web through a stack of calendar rolls. The main object of calendaring is to impart the desired finish to paper.
CALLIPER - Thickness and caliper usually refer to a single layer (one sheet of product or one ply of paper), whereas bulk usually refers to a stack of layers. The problem with determining the thickness or caliper of a single layer is that the surface of an absorbent tissue paper is not only highly irregular, but also porous. There are always a few fiber ends protruding high above the rest, and holes that pass all the way through the paper. Neither of these have much effect upon how we normally think of thickness in a practical sense, and should be ignored. The preferred method of measuring the thickness of paper is to place it between two parallel flat plates that are pressed together with a predefined force. The gap between the plates is reported as the thickness of the paper. The test result is very dependent upon the pressure that is applied by the plates. The effect of embossing upon thickness is more obvious when a relatively light compressive force is used.
MACHINE CALENDERING: Paper passes through one or more nips formed by a set of iron rolls.
SUPER-CALENDERING: Paper passes through one or more nips formed by steel roll and a fibre roll made of compressed fibrous material.
GLOSS CALENDERING: Paper passes through one or more nips formed by soft roll (e.g. rubber covered) and highly smooth mirror like finish steel roll at high temperature.
MATT CALENDERING: Any calendaring technique used to produce a smooth surface without a considerable increase in gloss.
FRICTION CALENDERING: The calendaring is achieved by speed differential between rolls. The paper passes through one nip (2 steel rolls) or 2 nips (2 steel rolls separated by a fibre roll) in which rolls are driven independently and speed variation may be from 10 to 30%.
BRUSH CALENDERING: The paper is pressed against a cylindrical brush by a backing roll or by web tension. The circumferential speed of the brush is several times higher than the web speed.
CALLIPER The thickness of paper usually expressed in thousandths of an inch in English system of units and in millimetres in Metric system of units.
CAMBER Larger diameter in the centre of a papermaking rolls (press & calendar etc), compared to the ends, to compensates the deflection of roll due to its own weight.
CANADIAN STANDARD FREENESS (CSF) It is a measure of pulp freeness. The unit of measurement is ml CSF.
CAPACITY UTILIZATION RATE The production rate a plant or machine is operating with respect to design capacity. Also in some cases it indicates the efficiency (%) at which a plant or machine is operating.
CARBOHYDRATE Organic compounds made up of carbon, hydrogen, and oxygen and having approximately the formula (CH2O) n; includes cellulosics, starches, and sugars.
CARBON FOOTPRINT The total set of Green House Gases (GHS) emissions caused directly and indirectly by an individual, organization, event or product by UK Carbon Trust.
CARBON PAPER A low basis weight paper (8 to 15 g/m2) with very low air permeability, free of pin holes and with a waxy coating, which is used to produce carbon copies on typewriters or other office equipment.
CARBONLESS PAPER A paper that uses a chemical reaction between two different contacting coatings to transfer image when pressure is applied.
CARDBOARD A thin, stiff paperboard made of pressed paper pulp or sheets of paper pasted together. Used for playing cards, greeting cards, etc.
CARTON A folding box made from boxboard, used for consumer quantities of product. A carton is not recognized as a shipping container
CARTRIDGE PAPER Tough, slightly rough surfaced paper used for a variety of purposes such as envelopes; the name comes from the original use for the paper which formed the tube section of a shotgun shell.
CAST COATER A device that applies a wet coating colour to a paper web before it contacts a heated drum having a highly polished surface, which cast the coating in to an image of the smooth, mirror-like drum surface.
CAUSTICIZING It is the process in which Green Liquor is converted in to White Liquor. Technically speaking it is the process of converting sodium carbonate in to sodium hydroxide.
CD - Acronym for cross direction
CDT - Acronym for Cross Direction Tensile strength. See tensile strength.
CELLULOSE It is a high molecular weight, stereoregular, and linear polymer of repeating beta-D-glucopyranose units. Simply speaking it is the chief structural element and major constituents of the cell wall of trees and plants.
CELLULOSE FIBRE An elongated, tapering, thick walled cellular unit, which is the main structural component of woody plants. Fibres in the plants are cemented together by lignin. In British English Fibre is spelled as Fibre. Thermal conductivity of cellulose fibre varies from 0.034 to 0.05W/m K, making it a good insulator.
CHALKING Improper drying of ink. Ink vehicle has been absorbed too rapidly into the paper leaving a dry, weak pigment layer which dusts easily.
CHECK OR CHEQUE PAPER A strong, durable paper made for the printing of bank checks or cheques.
CHELATING AGENT An organic compound that forms more than one coordinate bond with metals in solution; organic compound participating in chelation; e.g. EDTA and DTPA.
CHELATION A chemical complexing (forming or joining together) of metallic cations (such as iron) with certain organic compounds, such as EDTA (ethylene diamine tetracetic acid); a reaction between a metallic ion and an organic compound that removes the metallic ion from solution.
CHEMICAL GHOSTING A light duplication of a printed image on the other side of the same sheet, created by chemical reaction by the ink during the drying stages; also referred to as "gas ghosting.".
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. COD is easier to measure compared to BOD (Biological Oxygen Demand).
CHEMICAL PULP Pulp obtained from the chemical cooking or digestion of wood or other plant material.
CHEMICAL RECOVERY It is the process in which cooking chemicals are recovered.
CHEMI-THERMO-MECHANICAL PULP (CTMP) Mechanical pulp produced by treating wood chips with chemicals (usually sodium sulphite) and steam before mechanical defibration.
CHEST Vessel equipped with an agitating device for storing, collecting, mixing, blending and/or chemical treatment of pulp suspension. Chest can be horizontal and or vertical. Tower are special type of chest generally used in bleached plant to provide retention time and to provide down/upward flow out of pulp.
CHINA CLAY Natural mineral, consisting essentially of hydrated silicate of alumina, used as a filler or as a component in a coating colour. (Also see clay)
CHIP Wood chips produced by a chipper; used to produce pulp, fibreboard and particle board, and also as fuel.
CHIPBOARD A paperboard, thicker than cardboard, used for backing sheets on padded writing paper, partitions within boxes, shoeboxes, etc.
CHIPPER The machine that converts wood logs in to chips.
CHLORINE NUMBER A test method to determine the bleach requirement of a pulp. It indicates the number of grams of chlorine consumed by 100 g of pulp under specified conditions.
CHROMO A term used to describe both papers and boards used for subsequent brush coating. The various qualities are determined both by the actual grade of base material used and the quality of the coating, which may be gummed. Coating may be applied to one or both sides, depending on end use.
CIGARETTE PAPER This light weight, unsized paper (grammage 18 to 24g/m2), converted to improve glowing. It normally has approx. 30% calcium carbonate as filler to control the burning rate and match it with tobacco burning rate. Very long fibre such as jute, cotton etc is used to achieve high strength and porosity.
CLARIFIER Basin where sludge is removed from treated effluent by settling.
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. Collared coatings may also be used and the body stock for coating may be any variety of paperboard.
CLEANERS A conical or partly cylindrical device with no moving parts, designed to remove grit from thin-stock furnish by the centrifugal action of rotating liquid.
CLOSED LOOP RECYCLING When a used product is recycled in to a similar product; a recycling system in which a particular mass of material is remanufactured into same product.
CLOSED SYSTEM Papermaking system wherein white water is mainly re-circulated and not discharged as effluent.
CLOT Thick element composed of several entangled fibres. Its presence is harmful to the production process and needs to be eliminated.
COARSE PAPER (ALSO INDUSTRIAL PAPER) Various grades of papers used for industrial application (abrasive, filter etc.) rather than cultural purposes (writing, printing etc.)
COAT WEIGHT The amount of coating applied to base paper, expressed as pounds of air-dried coating on the surface of a 25X38 in ream or grams per meter square.
COATED PAPER Term that applies to paper which has a special coating applied to its surface. Material such as clay, casein, bentonite, talc, applied by means of roller or brush applicators; or plastics applied by means of roll or extrusion coaters.
COATED WHITE TOP LINER White liner that is coated to produce superior printability.
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.
COATING COLOUR KITCHEN Section of Coating Plant where coating colour is prepared and mixed
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 container board used in hazardous material transport.
COCKLE FINISH Produced by air drying paper with controlled tension. This uneven surface is available in bond papers.
COCKLING When the surface of the paper has wave like appearance.
COGENERATION It is the process to generate electricity from high pressure steam and using low and/or medium pressure steam in the mill process.
COIN-EDGE EMBOSSING A special embossing pattern normally seen around the edges of a dinner napkin or cocktail napkin. Its purpose is partly decorative and partly for ply bonding. Also see paper napkin
COLD BLOW Pressure ejection of cooked pulp from batch or continuous digesters after the pulp has been cooled to below 1000C. The cooling step reduces damage to the fibres.
COLOUR-FAST PAPERS Coloured papers that will not run when wet or fade under bright light.
COLOURED KRAFT Natural or bleached Kraft paper to which a dye or pigment has been added.
COLOURED PIGMENTS These are water insoluble coloured materials. They belong in the category of fillers and loading material but are coloured and used in small quantity. Pigments have no affinity to fibre and must be used in conjunction with alum or a cationic retention aid in order to retain them.
COMMERCIAL MARKEY - Manufacture and sale of product for use away from the home. Products are purchased by the case from a catalog, rather than from a display shelf. Storage space is often at a premium. Embossing patterns must be designed to accommodate this.
COMBINED DEINKING Deinking process combining flotation and washing.
COMPRESSION STRENGTH (CD OR MD) Can be referred to as ring crush or "STFI (stiffy)". The amount of force needed to crush paper resting on its edge. Compression testers hold and support the paper specimen so as to emulate its position and orientation in the walls of a corrugated container. Due to the corrugated board making process, paper must support compressive loads orthogonal to their grain (a CD orientation). The test is unidirectional so the paper orientation during testing must be known.
CONIFEROUS TREES Cone bearing and evergreen trees. Also known as soft wood trees. e.g. pine, spruce etc.
CONSISTENCY The percentage of bone dry solids by weight in pulp or stock.
CONSISTENCY REGULATOR A device or instrument used to regulate the consistency of the pulp on-line. Regulator works only in reducing the consistency i.e. add water, but can't remove water or thicken.
CONSTRUCTION PAPER Sheathing paper, roofing, floor covering, automotive, sound proofing, industrial, pipe covering, refrigerator, and similar felts.
CONSUMER MARKET Manufacture and sale of product for use in the home. Most of the volume is sold in grocery stores. Products and packaging must be designed for display on the store shelf, in very direct competition with other brands. Embossing plays a key part in this.
CONTAINERBOARD The paperboard components (linerboard, corrugating material and chipboard) used to manufacture corrugated and solid fibreboard. The raw materials used to make containerboard may be virgin cellulose fibre, recycled fibre or a combination of both.
CONTINUOUS PULPING Production of pulp in continuous digester as compared to a batch digester.
CONTRARIES Unsuitable material found in wastepaper which must be removed from the pulp before making it into paper, e.g. paperclips, string, plastics.
CONTRAST The degree of difference between light and dark areas in an image. Extreme lights and darks give an image high contrast. An image with a narrow tonal range has lower contrast.
CONVERTING The operation of treating, modifying, or otherwise manipulating the finished paper and paperboard provided by a paper machine so that it can be made into end-user products. The word "converting" may also mean the machinery that applies a converting process, or even the manufacturing area or department where it is done.
CROSS DIRECTION (CD) - Perpendicular to the direction of the flow of paper through a machine and in the plane of the paper. Almost all of the rollers in the machine have axes that are aligned in the CD. Also see machine direction (MD) and Z direction (ZD).
COOKING Reacting fibrous raw material with chemical under pressure and temperature to soften and or remove lignin to separate fibres.
COOKING LIQUOR Liquor made up of selected chemicals and used for cooking pulp. e.g. cooking liquor in Kraft pulping mainly consist of NaOH and Na2S.
COOLING CYLINDERS OR COOLING DRUMS Water cooled cylindrical metal vessel over which dry paper web after dryers is passed to cool the paper before calendaring..
COPIER PAPER OR LASER PAPER Lightweight grades of good quality and dimensionally stable papers used for copying correspondence and documents. For detailed characteristics of copier/Laser paper, please visit Paper Needs of Xerographic Machines (A Summary) by Chuck Green
COPPER NUMBER It is the measure of degree of fibre degradation. It is weight of copper in grams reduced to cuprous state by 100 grams of pulp.
CORD Pulpwood volume measurement indicating a pile measuring 4 ft x 4 ft x 8 ft, equalling 128 ft³ (3.62 in³). A long cord measure 4ft x 5ft x 8ft equalling 160 ft3. Also see cunit
CORE Fibrous tube used to wound paper for shipment.
CORE PLUG Metal, wood, particleboard, or other material plugs which are driven into the ends of the paper core of finished roll to prevent crushing of the core.
CORONA TREATMENT An electrostatic treatment that reduces the surface tension of a substrate (e.g., a polycoated substrate) to ensure adhesion of ink and glue.
The Corona treatment involves high voltage, high frequency electricity discharged from an electrode when it pours through the polycoated board increases the surface energy of the board to better receive inks or glue.
CORRUGATED BOARD Usually a nine-point board after if has passed through a corrugating machine. When this corrugated board is pasted to another flat sheet of board, it becomes single-faced corrugated board; if pasted on both sides, it becomes double-faced corrugated board or corrugated (shipping) containerboard.
CORRUGATED CONTAINER Containers made with corrugating medium and linerboard.
CORRUGATED MEDIUM OR MEDIA The wavy center of the wall of a corrugated container, which cushions the product from shock during shipment (see flute). Media can contain up to 100% post-consumer recycled fibre content without reducing its ability to protect the product.
CORRUGATION - See ridging
CORRUGATOR Machine that presses medium into flutes, applies glue to the medium and affixes sheets of linerboard to form corrugated board .
COTTON FIBER Cotton is a natural fibre and is one of the strongest and most durable fibres known to man. Papers manufactured of cotton fibre will last longer and hold up better under repeated handling and variant environmental conditions than paper made from wood pulp. Generally, given reasonable care, one can expect one year of usable life for every 1% of cotton contained in the sheet. Typically cotton fibre papers are made of either all cotton fibre (100% cotton) or a blend of cotton and wood pulp.
Cotton "fibres" are made from unicellular hairs that grow out from the surface of the seed immediately after fertilization. The hairs are twisted into usable thread which is tough and strong. Cotton hairs (lint) of tetraploid (4n) species may be up to 50 mm long. In the cotton gin, fine brushes pull the lint off the seed by drawing it through holes too fine for the seeds to pass. Cotton thread is spun from countless billions of microscopic hairs covering the surface of cotton seeds, each hair up to 50 mm (2 inches) in length. The total length of hairs in a single cotton boll (one seed capsule) may exceed 300 miles. Imagine how many miles of cotton hairs are in a standard 500 pound bale. Cotton is the textile produced in the largest volume worldwide. (From http://waynesword.palomar.edu/traug99.htm )
COTTON LINTER The cotton fibre’s that adhere to the cottonseed used to produce pulp for cotton fibre papers.
COTTON PAPER OR RAG PAPER Paper made with a minimum of 25% cotton fibre. Cotton paper is also called rag paper.
COUCH PIT OR HOG PIT This is the pit below the couch roll. It collects water draining from this section, wet wire trim and any wet broke generated due to the paper break at the wire part. Couch pit has agitator (s).
COUCH ROLL Couch roll serves the following functions 1) Main drive for the wire, 2) Transfer the wet sheet from wire part to press part and 3) Removes water (if suction type couch roll). Couch roll can be solid or suction type.
COVER PAPER Any wide variety of fairly heavy plain or embellished papers, which are converted into, covers for books, catalogues, brochures, pamphlets, etc. Good folding qualities, printability, and durability characterize it.
CRACK 1. A defect in coated paper, caused by the separation of the coating layer on the formation of fissures in the surface of the coating due to printing or other converting process.
2. Crack at fold: Fissures in the crease when any paper is folded along a fold line. May be due to separation of coating or separation of fibres. 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 fibre failure during a folding operation.
CREASE 1. Deformation remaining from a fold over.
2. Cross direction wrinkles( Washboard): Fold over of a web in the cross machine direction, giving a crease running in the machine direction.
3. Blade crease: A crease essentially in the machine direction devoid of coating in the creased area.
4. Calendar Crease: Usually a sharp crease caused by passage through the Calendar of a crease or of a fold generated at the Calendar; often cut through when it is preferable to call it a Calendar out.
5. Smoothed crease: A flattened-out crease running mainly in the machine direction. Can occur at the wet press section, dryer (dryer wrinkles), size press, winder or sheeter.
CREPING The operation of crinkling a sheet of paper to increase its stretch and softness.
CRESCENT FORMER Sheet forming section in a tissue machine, with the pulp suspension jet-out of the headbox flowing between a felt and a wire both moving at the same speed.
CRINKLES A defect in linerboards caused by the separation of the liner ply and/or the formation of fissures (cracks) in the surface of the liner during creasing.
CROSS-MACHINE DIRECTION A direction perpendicular to the direction of web travels through the paper machine.
CRYSTALLIZATION A condition of a dried ink film, which repels another ink printed on top of it.
CUNIT A term used in the measurement of pulpwood, i.e. 100 cubic feet of solid wood, bark excluded. One cunit corresponds to 2.83 cubic meter of wood. Also see Cord
CURL Tendency of paper by itself to bend or partly wrap around the axis of one of its directions. For more details on Curl, please read Curl Basics by Chuck Green.
CUSTOMARK A customark is a watermark made with a rubber printing plate treated with a tranparentizing solution that leaves a mark in the paper. This process produces a wire appearance in which the mark is lighter than the surrounding paper. It can be produced in smaller quantities and at a lower price than a genuine watermark, which requires a dandy roll.
CUT SHEET Paper cut in sheets (letter, legal, A, B or any other standard size) to be used in printer, photocopier, fax machines etc.
CUTTER A machine in the Finishing House of a paper mill, used for converting paper from reel to specific sheet sizes.
CUTTER DUST Small loose paper particles which chip out of the edges of a sheet of papers as it is cut by the chopping blade and/or disc knives on a sheet cutter.
CUTTING (REFINING) A refining or beating action that splits the fibres in to two or more pieces.
CYLINDER MOULD OR CYLINDER MACHINE It is a type of papermaking machine. Wire-covered cylinders are rotated through a vat of pulp, and paper is formed as the water drains from the cylinder. Cylinder machines are used primarily to manufacture paperboard. Multi-cylinder machines produce multi-layered paperboard (one layer for each cylinder