pulp and paper dictionary

PULP AND PAPER DICTIONARY


This page contains the definition of term, words and/or phrase commonly used in pulp and papermaking, printing, converting and paper trading.
A
Abrasive Papers
Papers covered on one or both sides with abrasive powder, e.g. emery, sandpaper etc.
Absorbent Paper
Papers having the specific characteristic of absorbing liquids such as water and ink. These papers are soft, loosely felted, unsized and bulky.
Acetate Pulp
A highly purified (high alpha cellulose) pulp made especially to be dissolved in acetic acid, acetic anhydride and sulfuric acid to make acetate rayon and acetate fiber.
Accelerated Aging
Exposing paper at elevated temperature usually 110C in an oven or on a hot plate. The purpose of accelerated aging is to simulate the effect of aging in the laboratory.
Acid Free Paper
A type of paper which does not contain any acidic substance that may affect acid sensitive material. Acid free paper is anti rust and is used for metal wrapping.
Acid Migration
The transfer of acid from an acidic material to a less acidic or neutral-pH material. Occurs when neutral materials are exposed to atmospheric pollutants or when two paper materials come in contact. Acid can also migrate from adhesives, boards, endpapers, protective tissues, paper covers, acidic art supplies, and memorabilia.
Acid Proof Paper
A paper that is not affected by acid physically or chemically. This paper is used with substance containing acid.
Acid Sizing
Internal sizing carried out in acidic pH range (0-7). Rosin and alum sizing is acid sizing.
Activated Carbon
A highly absorbent powdered or granular carbon used for purification by adsorption.
Activated Sludge
The biomass produced by rapid oxygenation of effluent.
Active Alkali
Caustic (NaOH) and Sodium sulfide (Na2S) expressed as Na2O in alkaline pulping liquor.
Additives
Clay, fillers, dyes, sizing and other chemicals added to pulp to give the paper greater smoothness, color, fibered appearance or other desirable attributes.
Adsorbable Organic Halogen (AOX)
A measure of the amount of chlorine that is chemically bound to the soluble organic matter in the effluent.
Aerated Lagoon
A biological waste water treatment method in which air (oxygen) fed into an aeration basin reduces the effluent load.
Against the Grain
Cutting, folding or feeding paper at right angles to the grain or machine direction of the paper.
Aging
Irreversible alteration, generally deterioration, of the properties of paper in course of time. Aging also causes reduction in brightness and yellowing effect.
Agitator
An equipment used to keep content of a tank or chest in motion and well mixed.
Air Brush Coater
A coater which uses the pressurized air to atomize the coating mixture and spray it on the paper.
Air Dry (AD)
Refers to the weight of dry pulp/paper in equilibrium with the atmosphere. Though the amount of moisture in dry pulp/paper will depend on the atmospheric condition of humidity and temperature but as a convention 10% moisture is assumed in air dry pulp/paper.
Air Drying
Using hot air to dry pulp or paper sheets.
Air Filter Paper
A type of paper used for filtration of air to remove suspended particles. (car air filter, vacuum bag etc.)
Air Knife Coater
A device that applies an excess coating to the paper and then removes the surplus by impinging a flat jet of air upon the fluid coating, leaving a smooth, metered film on the paper.
Air Mail Paper
It is lightweight, high opacity, good quality writing/printing type paper used for letters, flyers and other printed matter to be transported by airlines.
Air Pollution
The contamination of air around the plant due to the emission of gases, vapors and particulate material in the atmosphere.
Albumin Paper
A coated paper used in photography; the coating is made of albumen (egg whites) and ammonium chloride.
Algae
Micro organic plant life that forms in paper mill water supplies.
Alkali Resistance
Freedom of paper from a tendency to become stained or discolored or to undergo a color change when brought in contact with alkaline products such as soap and adhesives.
Alkaline Papermaking
Paper manufactured under alkaline conditions, using additives, basic fillers like calcium carbonate and neutral size. The anti-aging properties in alkaline paper make it a logical choice for documents where permanence is essential.
Alkaline Pulping
Pulping by alkaline solutions of sodium hydroxide, with or without sodium sulfide. Without sodium sulfide, soda process with sodium sulfide, Kraft or sulfate processes.
Alpha Pulp
A specially processed, high alpha cellulose content, chemical pulp. It is also called dissolving pulp.
Alum
The paper maker alum is hydrated Aluminum Sulfate {Al2(SO4)3}. It is used to adjust the pH of the mill water or as a sizing chemical in combination with rosin size.
Anthra Quinone (AQ)
A quinoid compound added to white liquor (alkaline cooking liquor) to improve pulp yield and to increase the rate of delignification.
Antique Finish
A term describing the surface, usually on book and cover papers, that has a natural rough finish.
Approach Flow System
The stock flow system from fan pump to headbox slice.
Aqueous Coating
A water-based coating applied after printing, either while the paper is still on press ("in line"), or after it's off press. An aqueous coating usually gives a gloss, dull, or matte finish and helps prevent the underlying ink from rubbing off. Unlike a UV coating or a varnish, an aqueous coating will accept ink-jet printing, making it a natural choice for jobs that require printing addresses for mass mailings
Archival Paper
A paper that is made to last for long time and used for long lasting records.
Ash Content
The residue left after complete combustion of paper at high temperature. It is generally expressed as percent of original test sample and represents filler content in the paper.
Azure
The light blue color used in the nomenclature of "laid" and "wove" papers.
B
Back Liner
The back side layer in a multi-ply paperboard. Normally back liner is made out of inferior grade pulp compared to top liner.
Backing up
Printing the reverse or back side of a sheet that has already been printed on one side.
Back Water
See White Water.
Bag Paper
Any paper made to be used in the manufacturing of bags.
Bagasse
Sugarcane residue after extracting the juice.
Bale
A large rectangular shaped compressed package of waste paper, rag, pulp etc. Bale dimensions and weight varies widely depending on the baling material and handling capabilities.
Bamboo
A plant of grass family grown in Asian countries and used for papermaking fibers.
Barker
An equipment used to remove bark from wood.
Base Paper
Refers to paper that will be subsequently be treated, coated or laminated in other ways.
Basis Weight
In English system of units, basis weight is the weight in pounds of a ream (500 sheets) of paper cut to a basic size. (Basic size differs from category to category of the paper. Basic size for Bond and Ledger is 20"x26", book, offset and text paper have basic size of 25"x38"). In metric system of units, basis weight is the weight in grams of a single sheet of area one square meter. Basis weight is also called as substance and grammage in metric system of units.
Bast Fibers
Fibers derived from the bark of some annual plants such as flax, gampi, hemp, jute, kozo and mitsumata etc. Main characteristic of these fiber is long length.
Beater
An equipment used for beating, refining and mixing pulps.
Beating or Refining
The mechanical treatment of the fibers in water to increase surface area, flexibility and promote bonding when dried.
Binder
Chemicals which facilitate fiber bonding. .
Biodegradable
Capable of destruction by biological action.
Biochemical Oxygen Demand (BOD)
When effluent containing biodegradable organic matter is released into a receiving water, the biodegradation of the organic matter consumes dissolved oxygen from the water. The BOD of an effluent is an estimate of the amount of oxygen that will be consumed in 5 days following its release into a receiving water; assuming a temperature of 20°C.
Biological Waste Water Treatment
A method of cleaning up waste water using living micro-organisms such as bacteria
Black Liquor
The liquor that exits the digester with the cooked chips at the end of the Kraft cook is called "black" liquor.
Biomass Boiler or Hogged Fuel Boiler
Biomass boilers burn bark, saw mill dust, primary clarifier sediment and other solid waste, and other wood-related scrap not usable in product production. Also called "hogged fuel" boilers, biomass boilers make steam and heat for mill use.
Blade Coater
A device that first applies a surplus coating to paper and then remove extra color after evenly leveling by means of a flexible steel blade.
Bleaching
A chemical process used to whiten and purify the pulp. Bleaching also adds to the sheet's strength and durability.
Bleed
The feathered edge of inks caused by absorption into un-sized paper.
Bleed Through
When printing on one side of a sheet of paper shows through to the other side.
Blotting Paper
An un-sized paper used generally to absorb excess ink from freshly written manuscripts, letters and signatures.
Blow
It is the discharging of the pressure and contents of the digester in to Blow Tank.
Blow Heat Recovery System
The system used to recover heat from the flash steam generated while digester is blown in to Blow tank.
Blow Tank
The tank in which cooked chips and spent liquor is blown from digester at the end of the cooking cycle.
Board
Thick and stiff paper, often consisting of several plies, widely used for packaging or box making purposes. Its grammage normally is higher than 150 g/m2 or thickness is more than 9 point (thousandth of an inch).
Bond Paper
The name "bond" was originally given to a paper, which was used for printing bonds and stock certificates. It is now used in referring to paper used for letterheads and many printing purposes. Important characteristics are finish, strength, freedom from fuzz, and rigidity.
Bonding Strength
The internal strength of a paper; the ability of the fibers within a paper to hold to one another. Bonding strength measures the ability of the paper to hold together on the printing press or other converting processing machines. Good bonding strength prevents fibers from coming loose ("picking"). Bonding strength of fiber is improved by beating/refining and/or adding bonding agent.
Bone Dry
Moisture free or zero moisture.
Book Paper
A general term used to define a class or group of papers having in common physical characteristics that, in general, are most suitable for the graphic arts, exclusive of newsprint.
Boxboard
A paperboard used in the manufacture of light non-corrugated container.
Breaking Length
The length beyond which a strip of paper of uniform width would break under its own weight if suspended from one end. Usually expressed in meters.
Breast Roll
A medium size metal or plastic/fiberglass/granite covered roll located at the headbox side of the paper machine to support the wire.
Brightness
The reflectance or brilliance of the paper when measured under a specially calibrated blue light. Not necessarily related to color or whiteness. Brightness is expressed in %.
Bristol Board
A fine quality cardboard made by pasting several sheets together, the middle sheets usually of inferior grade.
Brittleness
Property of paper causing it to break while bending.
Broke
Paper that is unusable because of damage or non-conformity to the specifications. It is put back in to the pulping system.
Brown Stock
The unbleached chemical pulp.
Brush Coating
A Coating method in which the freshly applied coating color is regulated and smoothed by means of brushes, some stationary and some oscillating, before drying.
Buffering
The neutralizing of acids in paper by adding an alkaline substance (usually calcium carbonate or magnesium carbonate) into the paper pulp. The buffer acts as a protection from the acid in the paper or from pollution in the environment.
Bulk
Reverse of density, expressed as cubic centimeter per gram.
Bursting Strength
The resistance of paper to rapture as measured by the hydrostatic pressure required to burst it when a uniformly distributed and increasing pressure is applied to one of its side.
C
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.
Caliper
The thickness of paper usually expressed in thousandths of an inch in English system of units and in millimeter in Metric system of units.
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, that 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.
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 color 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.
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 Fiber
An elongated, tapering, thick walled cellular unit, which is the main structural component of woody plants. Fibers in the plants are cemented together by lignin. In British English Fiber is spelled as Fiber.
Check or Cheque Paper
A strong, durable paper made for the printing of bank checks or cheques.
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.
Chip
Wood chips produced by a chipper; used to produce pulp, fiberboard and particleboard, 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.
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.
Closed System
Papermaking system wherein white water is mainly re-circulated and not discharged as effluent.
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.
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.
Color-fast papers
Colored papers that will not run when wet or fade under bright light.
Colored Pigments
These are water insoluble colored materials. They belongs in the category of fillers and loading material but are colored and used in small quantity.
Pigments has no affinity to fiber and must be used in conjunction with alum or a cationic retention aid in order to retain them.
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.
Continuous Pulping
Production of pulp in continuous digester as compared to a batch digester.
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.
Cooking
Reacting fibrous raw material with chemical under pressure and temperature to soften and or remove lignin to separate fibers.
Core
Fibrous tube used to wound paper for shipment.
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 fiber content without reducing its ability to protect the product.
Cotton Fiber
Cotton is a natural fiber and is one of the strongest and most durable fibers known to man. Papers manufactured of cotton fiber 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 fiber papers are made of either all cotton fiber (100% cotton) or a blend of cotton and wood pulp
Cotton Paper or Rag Paper
Paper made with a minimum of 25% cotton fiber. Cotton paper is also called rag paper.
Couch Pit l
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.
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.
Curl
Tendency of paper by itself to bend or partly wrap around the axis of one of its directions.
Cut Sheet
Paper cut in sheets (letter, legal, A, B or any other standard size) to be used in printer, photocopier, fax machines etc.
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. Multicylinder machines produce multi-layered paperboard (one layer for each cylinder).
D
Dandy Roll
A hollow wire covered roll that rides on the paper machine wire and compacts the newly formed wet web to improve the formation and if required to impart watermark or laid finish the paper.
Debossing
Pressing letters or illustrations into a sheet of paper using a metal or plastic die to create a depressed (debossed) image.
Deciduous Trees
Broad leafed or hardwood trees which lose their leaves in fall such as birch, maple etc.
Decker
A drum type filter used for pulp thickening.
Deckle
The width of the wet sheet as it comes off the wire of a paper machine. Also defied as the wood frame resting on or hinged to the edges of the mould that defines the edges of the sheet in handmade papermaking or strap or board on the wet end of a paper machine that determines the width of the paper web.
Deckle Edge
The untrimmed, feathery edges of paper formed where the pulp flows against the deckle.
Deinking
The process of removing inks, coatings, sizing, adhesives and/ or impurities from waste paper before recycling the fibers into a new sheet.
Delamination
The separation of the layers of a multiplex paper/paperboard.
Delignification
The removal of lignin, the material that binds wood fibers together, during the chemical pulping process.
Densitometer
A sensitive photoelectric instrument that measures the density of photographic images or of colors. Used in quality control to accurately determine the consistency of color throughout the run.
Digester
The reaction vessel in which wood chips or other plant materials are cooked with chemical to separate fiber by dissolving lignin.
Dimensional Stability
The ability of paper or paperboard to maintain size. It is the resistance of paper to dimensional change with change in moisture content or relative humidity. Dimensional stability is essential for keeping forms in registration during printing and keeping sheets from jamming or wrinkling on press or in laser printers.
Direct Cooking
Batch cooking in which digester contents are heated by blowing steam directly into the digester.
Dispersion
Following the deinking process of waste papers, residual ink particles are dispersed into tiny bits that are usually invisible to the eye. Bleaching the fibers helps to remove the last of the inks and improve paper brightness.
Dissolving Pulp
A high purity special grade pulp made for processing in to cellulose derivatives including rayon and acetate.
Doctor Blade
Thin metal plate or scraper in contact with a roll along its entire length to keep it clean. Blades are also used for creping.
Double Coating
Coating of paper or paperboard twice on one or both sides.
Down Cycling
Every time cellulose fibers are recycled they deteriorate slightly and become contaminated, so the new product is of lower quality than the original product which went to form the waste; the progressive deterioration of fibers means that there is a limit to the number of times they can be recycled, thus the term downcycling is used as a more accurate description of recycling.
Draw
Difference in speed between two adjacent section of the paper machine.
Dregs
The solids which settle down in the clarifiers in the causticizing process.
Dry End
That part of the paper machine where the paper is dried, surface sized, calendered and reeled.
Drying
This is the final stage of water removal from wet web of the paper formed on wire. After pressing the moisture content of the web is apprx. 40-45%. The remaining water (up to 95% dryness) is removed by evaporation . This is done by moving the web around a series of steam heated iron drums in the dry end of the paper machine.
Durability
The ability of paper to maintain its properties with continued usage and handling.
Dust
Loose flecks of fiber, filler and/or coating on the paper that sometimes sticks to the printing blanket and prevents ink from reaching the paper surface.

E
Effective Alkali
Caustic (NaOH) and one half of Sodium sulfide (05*Na2S) expressed as Na2O in alkaline pulping liquor.
Electrical Grade Paper
Strong, pin-hole free paper, sometimes impregnated with synthetic resins and made from unbleached Kraft pulp. Electrical insulating paper must neither contain fillers nor conductive contaminants (metals, coal, etc.) nor salts or acids. Lava stone bars are used on rotor and stator to avoid any metal contamination. Cable papers, that are wound around line wires in a spiral-like fashion, are electrical insulating papers with a particularly high strength in machine direction. Electrical grade papers include cable papers, electrolytic papers and capacitor paper.
Electronic Printing
Photocopiers, ink jet, laser printers and other similar printing methods that create images using electrostatic charges rather than a printing plate.
Electro photography
A printing process that uses principles of electricity and electrically charged particles to create images - e.g., photocopiers and laser printers.
Elemental Chlorine Free (ECF)
ECF papers are made exclusively with pulp that uses chlorine dioxide rather than elemental chlorine gas as a bleaching agent. This virtually eliminates the discharge of detectable dioxins in the effluent of pulp manufacturing facilities.
Embossing
Pressing a shape into a sheet of paper with a metal or plastic die, creating a raised (embossed) image.
Enamel
A general term referring to coated paper that has a higher basis weight than coated publication (magazine) paper but a lower basis weight and caliper than coated cover paper.
English Finish
A smooth-finished, machine made and calendered book paper. It is soft, dull and pliable. Normally used for letterpress printed magazines.
Engraving
A printing process using intaglio, or recessed, plates. Made from steel or copper, engraved plates cost more than plates used in most other printing processes, such as lithography. Ink sits in the recessed wells of the plate while the printing press exerts force on the paper, pushing it into the wells and onto the ink. The pressure creates raised letters and images on the front of the page and indentations on the back. The raised lettering effect of engraving can be simulated using a less costly process called thermography.
Envelop Paper
The paper made specifically for die cutting and folding of envelopes on high-speed envelop machine.
Esparto
A grass from North Africa which makes a soft, ink receptive sheet.
Extensible Kraft
Very strong virgin Kraft papers which stretches more and tears less easily than regular Kraft paper.
External Fibrillation
A refining action that results in partial detachment of fibrils from outer layer of a fiber.
F
Feathering
The tendency of liquid ink to spread along the paper fibers so that the image produced does not have sharp, clean edges. .
Felt
A woven cloth used to carry the web of paper between press and dryer rolls on the paper machine.
Felt Side
The side of the paper which does not touch the wire on the paper machine. The "top side" or felt side is preferred for printing because it retains more fillers.
Fiber
The slender, thread-like cellulose structures that forms the main part of tree trunk and from separated and suitably treated, cohere to form a sheet of paper.
Fiber Cut
A fiber cut is a short, straight cut located on the edge of the web, caused by a fiber imbedded in the web of paper.
Fiber Axis Ratio
Ratio of fiber width to fiber thickness.
Fiber Coarseness
Weight per unit length of fiber.
Fibrils
Thread like element in the wall of the fiber.
Filler
Any inorganic substance added to the pulp during manufacturing of paper.
Filtrate
The effluent from the washing or filtering process.
Fines
Small particles fiber defined arbitrarily by classification.
Fine Papers
Uncoated writing and printing grade paper including offset, bond, duplicating and photocopying.
Finish
The surface characteristic of a sheet created by either on-machine or off-machine papermaking processes. Popular text and cover finishes include smooth, vellum, felt, laid, and linen.
Finishing
The trimming, winding, rewinding and packing of paper rolls or trimming, cutting, counting and packing of paper sheets from parent roll.
Flashing
Spontaneous boiling and cooling of a liquid caused by the reduction of pressure below the vapor pressure of the liquid. Flashing occurs in blow tank during blowing.
Flexography
A form of rotary letterpress using flexible rubber or photopolymer plates.
Flotation Deinking
Using flotation method for removing ink from paper during the de-inking process.
Fluorescent Dye
A coloring agent added to pulp to increase the brightness of the paper. It may give a slight blue or green cast to the sheet.
Fluorescent Inks
Printing inks that emit and reflect light. Generally, they are brighter and more opaque than traditional inks, but they are not color fast, so they will fade in bright light over time. Their metallic content will also affect dot gain and trapping.
Flute
One of the wave shapes pressed into corrugated medium. These are categorized by the size of the wave.
Foil
The flat strip used to support wire. Only the leading edge of the wire touches the foil. Foil helps in removing water by creating gentle suction and also doctor the water removed in previous section.
Folding
Doubling up a sheet of paper so that one part lies on top of another. Folding stresses the paper fibers. To create a smooth, straight fold, heavy papers like cover stocks and bristols need to be scored before they're folded.
Folding Strength or Folding Indurance
Folding strength is most important in currency paper. Multiple fold strength is also important for paper used in books, maps, and pamphlets. It's far less important in one-fold greeting cards or envelopes, where fold cracking is the vital consideration. Folding endurance or strength is measured and reported in numbers.
Formation
The dispersion of fibers in a sheet of paper. The more uniform and tightly bound the fibers, the better the sheet will print and look.
Four-color Printing Process
A printing method that uses dots of magenta (red), cyan (blue), yellow, and black to simulate the continuous tones and variety of colors in a color image. Reproducing a four-color image begins with separating the image into four different halftones by using color filters of the opposite (or negative) color. For instance, a red filter is used to capture the cyan halftone, a blue filter is used to capture the yellow halftone, and a green filter is used to capture the magenta halftone. Because a printing press can't change the tone intensity of ink, four-color process relies on a trick of the eye to mimic light and dark areas.
Each halftone separation is printed with its process color (cyan, magenta, yellow, and black). When we look at the final result, our eyes blend the dots to recreate the continuous tones and variety of colors we see in a color photograph, painting, or drawing.
Fourdrinier
Named after its inventor, the Fourdrinier papermaking machine is structured on a continuously moving wire belt on to which a watery slurry of pulp is spread. As the wire moves, the water is drained off and pressed out, and the paper is then dried.
Freeness
A term used to define how quickly water is drained from the pulp. The opposite of freeness is slowness. Freeness or slowness is the function of beating or refining. Freeness and slowness reported in ml CSF and degree SR respectively are also the measurement of degree of refining or beating.
Freesheet
Paper that is free of mechanical wood pulp, which is true of virtually all fine printing papers.
Furnish
A blend of fibers, pigments, dyes, fillers and other materials that are fed to the wet end of the paper machine.
Fuzz
Fibrous projections on the surface of a sheet of paper, caused by excessive suction, insufficient beating or lack of surface sizing. Lint appears in much the same manner but is not attached to the surface.
G
Gatefold
Two or more parallel folds on a sheet of paper with the end flaps folding inward.
Gloss
The property that's responsible for a paper's shiny or lustrous appearance; also the measure of a sheet's surface reflectivity. Gloss is often associated with quality: higher quality coated papers exhibit higher gloss.
Glassine Paper
A translucent paper made from highly beaten chemical pulp and subsequently supercalendered.
Grade
Papers are differentiated from each other by their grade. Different grades are distinguished from each other on the basis of their content, appearance, manufacturing history, and/or their end use.
Grain
The direction in which most fibers lie in a sheet of paper. As the pulp slurry moves forward on the papermaking machine's formation wires, the fibers tend to align themselves in the direction of movement. Binding books parallel to the grain allows for a smoother fold then working across the grain. Grain direction of sheet fed papers is usually indicated by underlining the number, e.g., 23" X -35". On a web press, the grain direction should run along the length of the paper web.
Grain Long
Grain running lengthwise along a sheet of paper.
Grain Short
Grain running widthwise along a sheet of paper.
Gravure
A printing process that uses intaglio, or recessed, image carriers. The image carrier, which is flat or cylindrical, moves through an ink pool. A blade scrapes excess ink off the plane of the plate, leaving ink in the recessed wells. A second cylinder presses the paper onto the plates, where it picks up ink from the wells. The high speed of gravure presses and the durability of the metal intaglio plates make gravure an economical printing method suitable for large print runs (more than two million copies).
Greaseproof Paper
A protective wrapping paper made from chemical wood pulps, which are highly hydrated in order that the resulting paper may be resistant to oil and grease.
Greenfield Mill
Mill or production facility built on undeveloped site.
Green Liquor
The liquor that results when the inorganic smelt from the recovery furnace is dissolved in water is called "green" liquor.
Groundwood Papers
A general term applied to a variety of papers made with substantial proportions of mechanical wood pulp together with bleached or unbleached chemical wood pulps (generally sulfite), or a combination of these, and used mainly for printing and converting purposes.
Groundwood Pulps
A mechanically prepared (by grinding wood logs against a rough surfaced roll rotating at very high speed) coarse wood pulp used in newsprint and other low cost book grades where it contributes bulk, opacity, and compressibility. Groundwood pulp is economical since all the wood is used; however, it contains impurities that can cause discoloration and weakening of the paper.
Guillotine
A machine used to trim stacks of paper, which works the same way the original French guillotine worked. A cutting blade moves between two upright guides and slices the paper uniformly as it moves downward.
H
Half Tone
Picture with gradations of tone, formed by dots of varying sizes in one color.
Handmade Paper
A sheet of paper, made individually by hand, using a mould and deckle.
Hard Cook
Undercooked pulp with respect to target conditions.
Hard Sized Paper
Paper treated with high degree of internal sizing.
Hardwood
Wood from trees of angiosperms class, usually with broad leaves. Trees grown in tropical climates are generally hardwood. Hardwood grows faster than softwood but have shorter fibers compared to softwood.
Head Box
The part of the paper machine whose primary function is to deliver a uniform dispersion of fibers in water at the proper speed through the slice opening to the paper machine wire.
Hemicellulose
A constituent of woods that is, like cellulose, a polysaccharide, but less complex and easily hydrolysable.
Hickey
An irregularity in the ink coverage of a printed page. Hickeys are caused by paper or pressroom dust, dirt, or pick out on the printing blanket, all of which prevent the ink from adhering to the paper surface.
Hydrophilic
Having strong affinity for water.
Hydrophobic
Lacking affinity for water.
Hydropulper
An equipment used to slush broke/paper in to pulp.
Hygroscopic
Having the property to absorb water vapor from the surrounding atmosphere. Most of the papers (except glassine, greaseproof or wet strength etc.) are hygroscopic in nature.
I
Imbibitions
The absorption of liquid by a fiber without a corresponding increase in volume.
Impression Cylinder
The cylinder or flat bed of a printing press that holds paper while an inked image from the blanket is pressed upon it.
Index Paper
A stiff, inexpensive paper with a smooth finish. The high bulk but low weight of this paper makes it a popular choice for business reply cards.
Industrial Papers
A very general term, which is used to indicate papers manufactured for industrial uses as opposed to cultural purposes. Thus, building papers, insulating papers, wrapping papers, packaging papers, etc. would be considered industrial papers.
Ink
Printing inks are made up of pigment, pigment carrier and additives formulated to reduce smudging, picking and other printing problems associated with ink. The choice of ink depends on the type of paper and printing process.
Ink Absorption
A paper's capacity to accept or absorb ink.
Ink Holdout
The way the ink pigment sits on the surface of the paper. Strong ink holdout results in a sharp, bright image.
Intaglio
A method of printing in which an image or letter is cut into the surface of wood or metal, creating tiny wells. Printing ink sits in these wells, and the paper is pressed onto the plate and into the wells, picking up the ink.
Integrated mill
A mill which starts with logs or wood chips and first produces wood pulp which it then processes to make paper or board.
Internal Bonding Strength
Determines how strongly the coating is fused to the body stock. Caused by long periods of hydration, paper with high internal bonding strength resists picking during the printing process
Internal Fibrillation
Loosening of internal bond within a fiber.
Internal Sizing
Occurs when sizing materials are added to the water suspension of pulp fibers in the papermaking process. Also known as Beater, or Engine sizing.
J
Jog
To shake a stack of papers, either on a machine or by hand, so that the edges line up. Finisher jog the paper to remove any improperly cut sheet. Printers jog the paper to get rid of any dust or particles and to ensure proper feeding into the press.
K
Kappa Number
A term used to define the degree of delignification.
Kenaf
An annual agricultural plant, native of India, which has along fiber in the bark that, is suitable for papermaking.
Knotter
Vibratory screens used for separating knots, uncooked chips and shives from the pulp at the blow tank.
Kozo
The most common fiber used in Japanese papermaking, it comes from the mulberrv tree. It is a long, tough fiber that produces strong absorbent sheets.
Kraft Paper
A paper of high strength made from sulfate pulp. Kraft papers vary from unbleached Kraft used for wrapping purposes to fully bleached Kraft used for strong Bond and Ledger papers.
L
Laid
A finished produced with a dandy roll having closely spaced wires.
Laminated Paper
A paper built up to a desired thickness or a given desired surface by joining together two or more webs or sheets. The papers thus joined may be alike or different; a totally different material, such as foil, may be laminated with paper.
Laminated Linerboard
Two or more plies of linerboard adhered to one another for increased structural stability.
Ledger Paper
A strong paper usually made for accounting and records. It is similar to Bond paper in its erasure and pen writing characteristics.
Lignin
A complex constituent of the wood that cement the cellulose fibers together. Lignin is brown in color.
Like-Sided
Paper that has the same appearance and characteristics on both sides.
Linerboard
The inner and outer layers of paper that form the wall of a corrugated board.
Linen Finish
A finished paper that has an overall embossed pattern on the surface resembling the look and feel of linen cloth, and one manufactured with engraved embossing rolls.
Lines Per Inch (LPI)
The number of lines in an inch, as found on the screens that create halftones and four-color process images (for example, "printed 175-line screen"). The more lines per inch, the more detailed the printed image will be. With the demand for computer-generated imagery, the term "dots per inch" (which refers to the resolution of the output), is replacing the term "lines per inch."
Lint
Loosely bonded fibers at the paper surface that attached to the plate or blanket of the printing machine.
Litho
A generic term for any printing process in which the image area and the non-image area exist on the same plate and are separated by a chemical repulsion. Usually oil based offset printing.
Loading
Addition of fillers.
M
M Weight
The weight of one thousand sheets of paper, any size; or double the ream weight.
Machine Direction
The direction of the web through the paper machine.
Manifold Paper
A light weight bond paper used for making carbon or manifold copies or for airmail correspondence.
Manila
A semi-bleached chemical sulfate paper. Not as strong as Kraft, but have better printing qualities.
Manufacturing Order
Also known as making order. A quantity of paper manufactured to custom specifications, such as a special weight, color, or size not available as a standard stocking item.
Market Pulp
Pulp which is made to be used elsewhere for the production of paper. Usually dried to reduce freight costs but may be "wet lap" ( 50% water).
Matte Finish
A dull, clay-coated paper without gloss or luster.
Mechanical Pulp
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 printing papers.
Metamerism
The tendency of color to appear different under different light sources such as fluorescent or natural sunlight.
MG Machine
A paper machine incorporating a Yankee or a MG drying cylinder in the drying section to produce MG paper.
Mill
The physical site where paper is manufactured; also refers to a company that manufactures paper.
Mill Broke
Paper generated at the paper mill prior to completion of the manufacturing process. Wet mill broke originates at the wet end of the papermaking machine, while dry mill broke comes from the dry end of the papermaking machine.
Mottle
A random non-uniformity in the visual density, color or gloss of a printed area; also known as orange peel, back-trap mottle, wet-trap mottle, pigment flocculation, striations, etc.
Multiply Paper Making Process
A paper/board making process in which different layers of fibers are deposited one over the other to form the sheet. The multiply process is used to make the optimum use of various type of fibers available. It is also used to make heavy basis weight papers.
N
Newsprint
A paper manufactured mostly from mechanical pulps specifically for the printing of newspaper.
Nip
Point where two rolls on the paper machine come in contact.
Non Wood Fibers
Papermaking fibers derived from plants other than trees such as cotton, hemp, bagasse, jute, bamboo or straws.
Nonwoven
Fabric-like material made from long fibers, bonded together by chemical, mechanical, heat or solvent treatment.
O
Off-Machine Coating
Application of coating to the paper off the paper machine, or as a separate operation to the papermaking.
Offset Paper
Also known as book paper. General description of any paper primarily suited for offset printing. Can be coated or uncoated. Characterized by strength, dimensional stability, lack of curl and freedom from foreign surface material. Finish can be vellum or smooth.
Offset Printing
Also know as web offset or lithography. Offers highest degree of precision, clarity, and quality.
On-Machine Coating
Application of coating to the paper at the paper machine, or in line as it is being made.
Old Corrugated Container (OCC)
Brown boxes that have been used for their intended purpose, then collected for recycling.
Opacity
That properties of paper which minimizes the "show-through" of printing from the backside or the next sheet.
Orange Peel
A type of sheet surface that looks like orange.
Oxygen De-lignification
A process in which oxygen gas and sodium hydroxide are used to remove lignin from brown stock.
Ozone (O3)
A highly reactive gas with molecules made up of three oxygen atoms.
Ozone Bleaching
A process that uses ozone to whiten cellulose fibers following the Kraft pulping and oxygen de-lignification processing.
P
Pallet
A platform with a slatted bottom, used to hold and ship cartons of paper stacked on top of each other.
Paper
A homogeneous sheet formed by irregularly interviewing cellulose fibers.
Paperboard
A heavy weight, thick, rigid and single or multi-layer sheet. What differentiates paperboard from paper is the weight of the sheet. If paperboard is very heavy it is called Board. Paper heavier than 150 gram per meter square are normally called Paperboard and paperboard heavier than 500 gram per meter square are called board.
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. Large quantity of water is added to uniformly distribution of 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.
Paper Cut
The excruciating, often unforeseeable, and usually invisible-to-the-naked-eye cut received when skin slides along the edge of a piece of paper at just the wrong angle.
Paper-ink Affinity
The tendency for paper and ink to attract and stay attracted to each other. This keeps the ink on the paper and off the reader's hands or the next sheet. An incompatibility between ink and paper can cause printing problems.
Papyrus
The Egyptians used this aquatic plant to create a writing sheet by peeling apart the plant's tissue-thin layers and stacking them in overlapping, crosshatched pieces to form a sheet. Despite giving us the word "paper," papyrus is not a true paper.
Parchment
To simulate the look of ancient parchment, which was made from animal skin, text and cover versions are made with a variegated surface, translucent colors and rigid feel. Parchment is often used for diplomas, certificates and contracts.
Perfecting Press
A printing press that simultaneously prints both sides of a sheet of paper as it passes through the press. On other presses, printing both sides means running the sheet through the press to print one side, allowing the ink to dry, turning the paper over, and then running the sheet through the press again to print the other side.
Permanence
The degree to which paper resists deterioration over time.
Permanganate Number (K Number)
Chemical test performed on pulp to determine the degree of delignification.
Permeability
Degree to which a fluid (gas or liquid) permeates or penetrate a porous substance such as paper or fabric.
pH (Hydrogen Ion Concentration)
A measure of the acidity (or alkalinity) of a solution. Range from 0-14 with 7 being neutral, less than 7 being acid; higher than 7 being alkaline.
Pick Out
A problem on press caused by unevenly sealed paper, or paper with low bonding strength. The ink "picks" off weak areas of the paper, lifting coating from a coated stock or lifting fibers from an uncoated stock, and transferring them to the printing blanket.
These fibers will eventually be transferred back onto the sheets being printed, causing inking and surface inconsistencies.
Pick Resistance
The ability of paper fibers to hold together during the printing process.
Picking (Papermaking)
To transfer the wet sheet from wire part to press part. If the sheet moves unsupported is called "poor man pick up". If a solid/suction roll is used to lick/pick the sheet, it is referred as closed transfer.
Picking (Printing)
The problem of ink picking off paper fibers during printing. This may be an indication of a paper with low bonding strength or the use of an ink with too much tack for the paper it is printed on.
Pigment
An ingredient added to pulp to increase the brightness and opacity of white paper or dye the pulp to create a colored 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.
Pitch
Resinous material present in wood (mainly softwood) that carry over into the pulping and papermaking system to form insoluble deposits.
Polymer
Organic chemical compounds consisting of repeating structural units. Cellulose is a polymer.
Ply
The separate webs, which make up the sheet formed on a multi-cylinder machine. Each cylinder adds one web or ply, which is pressed to the other, the plies adhering firmly upon drying.
Point
A unit of paper or paperboard thickness measuring one-thousandth of an inch.
Porosity
The property of paper that allows the permeation of air, an important factor in ink penetration.
Post-Consumer Waste Paper
Waste paper materials recovered after being used by consumers.
Precision Sheeting
Converting rolls of paper into finished sheet sizes in a single operation.
Pre-Consumer Waste Paper
Paper recovered after the papermaking process, but before used by a consumer.
Press
A combination of two or more rolls used to press out water from wet paper web. Following are some of the types of the press.
1. Plain Press or Solid Press
This is the simplest and the oldest type of press which is now a days rarely used except on very slow speed machine. The solid press consist of two solid rolls covered with rubber and or granite. The top roll is somewhat offset for the squeezed out water to flow by gravity.
2. Suction Press
In this type of press, one roll is drilled and shell of the drilled roll rotates over a suction box. The squeezed water is sucked out through the felt.
3. Grooved Press
In this type of press, one roll is grooved. The squeezed water is hold in the groves and removed by doctoring or sucking out on the return run of the roll.
Press Part or Press Section
The section of the paper machine which contains press (es). It is usually located between wire part and dryer part.
Printability
The overall performance of the paper on press.
Printing
The transfer of ink onto paper or other materials to reproduce words and images.
Pulp
A suspension of cellulose fibers in water.
R
Rag
The term “rag” is often used interchangeably with “cotton fiber content” and harkens to a period of time when paper was actually made using cotton rags which were cleaned and then broken down into fibers which were then used to manufacture paper. In a sense it could be stated that the fine paper business has been engaged in recycling materials for production since its very beginning. Today paper is no longer made from rags and the term “rag” is falling in disfavor by the industry in lieu of the phrase “cotton fiber content”.
Ream
500 Sheets of paper.
Reel
A continuous sheet of paper wound on a core.
Refiner
An equipment used to give mechanical treatment to the fibers.
Refining
Mechanical treatment of fibers to enhance bonding.
Refractiveness
A measure of how much a sheet of paper deflects the light that hits it. The more light a sheet deflects, the greater its refractiveness, allowing a printed image to be more brilliant and detailed.
Registration
Putting two or more images together so that they are exactly aligned and the resulting image is sharp.
Relief
A method for printing ink on paper, using type or images that rise above the surface of the printing plate. Ink sits on top of these raised surfaces, and as the paper is pressed onto them it picks up ink. Letterpress, flexography, and rubber stamps all use relief plates. In letterpress, intense pressure can cause images to be slightly debossed or depressed below the surface of the paper.
Residual Fibers
Fibers derived from sawmills scraps, plywood plants and other timber management activities.
Resilience
A paper's ability to return to its original form after being stretched, bent or compressed during the printing and bindery process.
Rice Paper
A common misnomer applied to lightweight Oriental papers. Rice alone cannot produce a sheet of paper. Rice or wheat straw is used occasionally mixed with other fibers in paper making. The name may be derived from the rice size (starch) once used in Japanese papermaking
Roe Number
Measure of the amount of chlorine required for bleaching pulp.
Rosin
Rosin, a natural resin from pine trees in combination with alum, is used for internal sizing of paper in acidic paper making. The chemical formula of rosin is C19H29COOH.
Rosin Size
Partially or completely saponified (neutralized) rosin. The chemical formula of rosin is C19H29CONa.
Rough
Heavily textured surfaces produced by minimal pressing after sheet formation.
Runnability
The ease with which a paper moves through a printing press or converting machine. This is primarily determined by the paper's strength, tear resistance, dimensional stability, bonding strength and water resistance .
S
Salt Cake
Or sodium sulphate added to the black liquor to compensate for the soda loss.
Save-All
Equipment used to reclaim fibers from white water.
Score
To impress or indent a mark with a string or rule in the paper to make folding easier.
Secondary Fibers
Fibers recovered from waste paper and utilized in making paper or paperboard.
Security paper
Paper which includes identification features such as metallic strips and watermarks to assist in detecting fraud and to prevent counterfeiting.
Semi-chemical Pulp
Pulp produced by chemical treatment followed by mechanical treatment.
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.
Sheffield
A test used to measure the smoothness of paper by measuring the rate of air flow over the surface of the sheet. The lower the number, the smoother the sheet.
Show-Through
The undesirable condition in which the printing on the reverse side of a sheet can be seen through the sheet under normal lighting conditions. The more opaque a sheet, the less the show-through.
Shives
Small bundles of fibers that have not been separated completely during pulping.
Sizing
The treatment of paper which gives it resistance to the penetration of liquids (particularly water) or vapors. Sizing improves ink holdout.
Slimes
Fungus or other bacteriological growth. If not controlled in papermaking system, may cause process and quality problems.
Slitter
Rotary knife used to slit or trim a paper web into specified width.
Slowness
Measure of pulp drainage. Has an inverse relationship to freeness.
Smelt
Inorganic chemicals obtained in molten form from the recovery furnace.
Smoothness
The surface uniformity of paper. Sheets that are flat and even provide better ink dot formation and sharper images.
Soft Cook
Over-cooked pulp.
Softwood
Woods obtained from coniferous trees. Generally grown in cold climates. Softwood grows slower than hardwood but have longer fibers compared to hardwood.
Specific Energy (Refining)
Energy applied per unit weight on oven dry basis (KWH/MT) during refining.
Specific Surface (Fiber)
Fiber surface area per unit weight (OD basis)
Splice
Formed by overlapping webs and joining with a strip of double-faced adhesive tape. Used for lighter-weight grades of paper.
Stampers
The wooden hammers used in a watermill to pulp rags in order to separate the fibers.
Stencil
A sheet of plastic, paper, or other material with letters or an image cut out of it. When placed on a surface and inked, it reproduces the cut-away images onto the material behind it.
Stiffness
The ability of paper or paperboard to resist an applied bending force and to support its own weight while being handled. A sheet that is too limp can cause feeding and transport problems in copiers and printers. An adequate degree of stiffness is important to avoid distortion of the paper due to the pull of ink during offset printing. Stiffness is critical to many converting operations for forms and envelope grades.
Stock
A term used to define pulp after the basic preparation in the paper making process.
Strike-through
The penetration of ink through paper.
Supercalender
A stack of alternating steel and fiber-covered rolls at the end of the paper machine which is used to increase a sheet's gloss and smoothness.
Surface-Sized
Paper that has been treated with starch or other sizing material at the size press of the paper machine. This term is used interchangeably with the term "tub-sized", although tub-size more properly refers to surface sizing applied as a separate operation where the paper is immersed in a tub of sizing (starch or glue), after which it passes between squeeze rolls and is air dried.
Swelling
An increase in volume of fiber due to the absorption of liquid.
T
Table Roll
The small diameter rolls used to support the wire.
Tack or Stickiness
Tack is a critical property of the ink used in lithography. Because the ink sits on a flat surface, it needs internal cohesion; in other words, it needs to stick to itself so that it doesn't run all over the plate. However, too much tack can cause it to pull the paper apart.
When printing two or more ink colors in line, the ink tack and sequence must be adjusted in order for the inks to adhere to each other as well as to the paper.
Tag Paper
A heavy utility grade of paper used to print tags, such as the store tags on clothing. Tag paper must be strong and durable, yet have good affinity for printing inks.
Tear Strength
A measure of how likely a paper will continue to tear once started. Tear strength will differ with and against the grain.
Tensile Strength
A measure of how likely a paper is to break when pulled at opposite ends. This is very important when running through high-speed web presses.
Text Paper
Text papers are defined as fine, high quality uncoated papers. Typically, they are made in various colors, with numerous textures and a variety of surface finishes. Text papers are made from high-grade bleached wood pulp, cotton fibers, or tree-free pulp such as bamboo. Recycled sheets include high quality recycled waste paper and post-consumer waste pulp, in addition to bleached wood pulp, tree-free pulp or cotton fibers.
Thinning
A practice in which certain trees are removed from a dense stand to allow the remaining trees adequate sunlight, nutrients and moisture to grow at an even rate.
Tint
To vary a color by adding white. Also, a very light or delicate variation of a color.
Tissue
A low weights and thin sheet. Normally a paper sheet weighing less than 40 gram per meter square is called tissue.
Titanium Dioxide
An opaque and expensive compound used as a white pigment and opacifier in papermaking. Elemental titanium is a lustrous, lightweight, white metal with exceptional strength.
Tolerance
Permissible degree of variation from a pre-set standard.
Total Alkali
NaOH + Na2S + Na2CO3 + 0.5*Na2SO3 all expressed as Na2O in alkaline pulping liquor.
Totally Chlorine Free (TCF)
Totally chlorine free applies to virgin fiber papers that are unbleached or processed with a sequence that includes no chlorine or chlorine derivatives. (Also see ECF)
Twin-wire Machine
A papermaking machine with two continuous forming wires, rather than just one. Twin-wires were designed to create a less two-sided paper than paper manufactured on a Fourdrinier paper machine.
Other techniques for reducing two-sidedness have since been developed, enabling paper manufacturers to create paper on single-wire machines with little side-to-side variation.
Two-Sidedness
The property denoting a difference in appearance and printability between its top (felt) and wire sides.
U
Union Kraft
A packaging material comprising two layers of Kraft paper bonded together by means of a laminant that is resistant to the transmission of water in liquid or vapor form. E.g. bitumen or plastic.
Urban Wood
Used pallets, wooden shipping crates and clean construction wood diverted from the waste stream and chipped for use in making particleboard and medium density board.
UV Coating
A very glossy, slick coating applied to the printed paper surface and dried on press with ultraviolet (UV) light. UV coating can cause slight variations in match colors, so consult an ink manufacturer or printer for best results.
UV Ink
An ink specially formulated to dry quickly with ultraviolet light while still on press. Fast UV drying eliminates the need to wait for the first side to dry before printing the second side.
V
Vehicle
The liquid part of the ink, giving it the flow properties that enable it to be applied to a surface.
Vellum Paper
(1) Paper finish that exhibits a toothy surface similar to eggshell or antique and is relatively absorbent for fast ink penetration.
(2) A high-grade paper made to resemble parchments originally made from calf’s skin.
(3) Social and personal stationery is often called vellum.
Virgin Fiber
Fiber that has never been used before in the manufacture of paper or other products.
Virgin forest
Forest in its natural state, untouched by man.
Virgin Kraft
First run or non-recycled Kraft paper.

W
Wall Paper
A paper used for wall covering. Also known as hanging paper.
Washing
A process of separating spent cooking or bleaching chemicals from pulp fibers.
Water-Color Paper
A medium weight, hard sized, coarse surface paper, suitable for painting with water based colors.
Water Finished Paper
A high glazed paper produced by moistening the sheet with water or steam during calendering.
Waterleaf
A paper with little or no sizing, like blotter, making it very absorbent If dampening is desired, this paper can be sprayed with an atomizer.
Watermark
The image impressed into the formation of paper by the dandy roll on the wet end of the paper machine; can be seen by holding the watermarked sheet up to the light. Can be either a wire mark or a shaded image.
Web
Term used for the full width of the paper sheet in the process of being formed, pressed, dried, finished and/or converted.
Wet Strength Paper
A chemically treated paper strong enough to withstand tear, rupture or falling apart when saturated with water.
White Liquor
White liquor is the aqueous solution of sodium hydroxide & sodium sulfide used as the cooking liquor in Kraft pulping.
White Water
The filtrate from the wet end of the paper machine.
Whiteness
Whiteness of pulp and paper is generally indicated by its brightness, which is the reflectance of a wavelength of blue light. So-called white papers have a definite hue. Most are made with a blue white tint.
Wire
The moving "screen" at the wet end of a paper machine where the sheet is formed.
Wire Guide Roll
The small diameter roll used for guiding (keeping on track) the wire. One end of the roll is adjusted to compensate any misalignment.
Wire Return Roll (s)
The small diameter rolls used at the return run (Couch roll to Breast roll) of the wire.
Wire Tension Roll
The small diameter rolls used at the return run (Couch roll to Breast roll) of the wire to adjust the tension of the wire.
Wire Side
The side of a sheet next to the wire in manufacturing; opposite from the felt or top side; usually not as smooth as the felt or topside.
Wood-Free
Pulp furnish without mechanical pulp.
Wove
The Paper having a uniform surface and no discernible marks. Soft, smooth finish, most widely used writing, printing, book and envelope paper. Relatively low opacity, brightness and bulk.
X
Xerography
The printing process used by photocopying machines. Electric charge creates the image on an eloctro-photographic surface that works as a plate. This surface is cleared after each copy is made, and used over again for the next copy.
Y
Yankee Machine
A type of Fourdrinier paper machine employing a single dryer of large circumference with highly polished surface.
Yellowing
Or brightness reversion is the discoloration of white paper primarily due to aging.
Yield
Ratio of product output and raw material input, expressed in percentage.
Z
Z-Direction Tensile Strength
The tensile strength measured perpendicularly to its surface.


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