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Air Dried Paper
A term applied usually in relation to handmade or mould-made papers that are dried slowly in a current or air, or over skeleton drum dryers, and not by means of conventional drying cylinders.
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Banks and Bonds.
A range of printing and writing papers, the better qualities of which were at one time made largely from rags. The heavier substance papers, above around 60g/m2, are often used for correspondence and letterheads, and are known as bonds, while the lighter weights are called banks used largely for file copy papers have less use today with the introduction of the automated office.
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Binder.
The adhesive used to stick the layers of coating together and to the paper or board surface. The most frequently used binder is starch, but synthetic binders are also used to give improved performance.
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Bleaching.
A Chemical treatment used to whiten, brighten and improve the performance of pulp.
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Boards.
A term applied to paper above an accepted weight. The substance when paper becomes known as board varies a great deal between manufacturers and can vary from as low as 180grm2 to as high as 250grm2. The lower substance definition usually refers to boards in the graphic sector.
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Brush Coating.
A method of coating a web paper in which the applied coating slip is distributed and smoothed by means of brushes, some stationary and some oscillating across the web.
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Bulk.
A term applied to the substance, thickness and feel of a paper, for example, bulky mechanical (qv).
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Bulky Mechanical.
A mechanical paper made to a specific caliper as opposed to a fixed grammage. Typical calipers are 102 adn 127 microns. This type of paper, used mainly for mass market paperback books, also has several uses when converted, such as cash register rolls.
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Bulk packed on pallets (BPOP).
A method of packing paper in which the sheets are not wrapped in parcels but stacked on the pallet, tabbed at the required intervals to indicate quantity and over-wrappped.
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Cast coating.
A method of drying coated paper by contact of the freshly coated surface with a highly polished chromium plated heated metal surface. Cast coated papers or boards have an extremely high gloss finish for top quality printing. The finish is obtained by the coating mix solidifying while in contact with the polished surface, resulting in the surface of the paper or board possessing the mirror like quality of the surface on which it is dried.
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Cellulose.
Complex fibrous substances forming the walls of plant cells; the prime raw material in pulp.
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Chemical pulp.
Fibre pulp made by means of chemicals that dissolve the bonding agent - lignin - in the wood. The chemical pulping process produces all the energy it needs through burning the dissolved wood constituents and recovering and regenerating the pulping chemicals.
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Chemi-thermo mechanical pulp.
Thermo mechanical pulp (qv) which has undergone further chemical bleaching, resulting in a pulp not far below the quality of woodfree pulp. The highest grade of mechanical pulp.
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Cheque or Security papers.
The grade carrying this term is printed on a paper with a sensitised body as a protection against fraud. Of good quality, the paper is chemically treated in such a way as to show any sign of unauthorised change. Additionally, the paper can contain certain fibres that can only be detected under special light.
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Coated Paper or Board.
Material coated on one or both sides with a mixture of china clay, latex and other loadings to fill up the surface pits and improve the printing surface. There are a variety of coating methods including roll coating, blade coating, air-knife coating and brush coating, or combinations of these types. A very high quality form of off machine coating is cast coating.
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Coating.
The application of a layer of minerals applied to one or both sides of paper or board to improve brightness, gloss and printability; the mineral most often used is china clay (hydrated aliminium silicate), but calcium carbonate and titanium dioxide are also used; the coating is held together and stuck to the paper by a binder.
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Coat weight.
The amount of coating on a base paper expressed as dry weight on a given area in grams per square metre (g/m2).
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Continuous stationery.
A grade widely used on modern high speed accounting and similar machines. The paper is supplied in reel form and along with the printing process many finishing techniques can be used, such as perforation and special folds. A particular use is for invoices, statements and similar documents, when it is normally fan folded.
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Converter.
A company that specialises in sheeting, re-reeling or changing the format of reels and sheets of paper and board into packing or finished goods for sale to the trade or public.
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Copier paper.
Lightweight grade of good quality, used for copying correspondence and documents. May be glazed or unglazed. Most copier papers are laser compatible and special grades are made for colour copying.
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Core.
The tube on which material is wound. Usually cardboard, but may be plastic or metal.
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Cover papers and boards.
A range of different grades which may be plain, embossed, or coated and which offer a very wide range of materials for printing and design. These grades may also be made into two ply or three ply papers for special cover work. Many cover papers are characterised by strength, flexibility and durability.
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Creping.
Operation of crinkling paper from a roll or cylinder in order to increase its stretch and softness. Two types are produced: dry creping, an on machine operation carried out on a dried web, and wet creping, an on or off machine operation carried out on a wet or partially dried web, using a doctor blade.
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Cut set.
A multipart business form which is cut to a precisely required size and in an individual set (ie not continuous). (Also known as a unit set; a snap apart set is a particular type of cut set.)
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Cutting ahead.
Operation of slitting and cutting watermarked paper without regard to where the design falls in each sheet. The design(s) may fall in different places in sucessive sheets and some may be cut.
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Cutting to register.
Operation of slitting and cutting watermarked paper so that the watermark design falls in a given position in every sheet.
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Drawing papers and boards.
These grades are manufactured from top quality pulps with special treatment of the furnish. The best grades are tub-sized and air-dried, with sheet surfaces varying according to use.
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Dry Coating.
Coating method in which a binder is applied to the paper surface followed by dry coating pigment.
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Dry end.
The part of a paper machine where the drying of the paper is completed, usually by bringing the web into contact with a series of steam heated drying cylinders.
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Dummy.
An unprinted representation of the text pages of a book or magazine made by folding and collating sheets of the intended quality, size and grammage of paper so that an idea may be formed of the general appearance and thickness of the final result.
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Duplex paper and board.
Grade made from two different webs combined during the manufacturing process while still moist, without the use of adhesive. This combination may, for example be two different webs of furnish, colour or substance.
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ecf.
A common definition for pulp bleaching without using elemental chlorine. Originally any of the bleaching techniques for chemical pulp, when no molecular (elemental) chlorine is used.
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Embossed paper.
Paper on which a raised and/or depressed design has been produced by pressure, generally between an engraved or otherwise patterned steel roll or plate and a paper or cotton backing roll or 'bowl'.
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Fibre.
Wood cell whose properties vary from one tree species to another, the main raw material for papermaking.
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Fibreboard.
Board made from defibrated wood chips on a wet-lap forming machine;used as a building board.
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Filler.
A material, generally white mineral matter such as china clay or calcium carbonate, which is added to the paper furnish to increase opacity, improve flatness and allow a smoother finish to be obtained.
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Fine paper.
Fibre based paper usually containing less than 10% mechanical pulp, eg quality printing and writing paper.
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Foil paper and board.
A strong base paper is coated with an adhesive and a fine bronze powder, and subsequently burnished. Other metals such as tin, aluminium, and leaf may be used which provide a surface suitable for applications that demand decoration particularly in packaging and wrapping.
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Folding Boxboard.
Although boxboards can vary in quality from grey board to high class board made from virgin fibre, the term is usually taken to mean white lined boards. They are made on multi layer machines, and the outer layers may be of a different furnish to the centre layer.
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g/m2(gsm).
Both stand for grams per square metre, g/m2 is the correct definition by paper makers but gsm is used more frequently by printers. This is the primary measurement of the weight of paper, ie 60g/m2 is a paper of weight 60 grams per square metre, obviously lighter than an 80g/m2 paper.
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Gloss.
Gloss can refer to the reflectivity of paper itself or to the printed result on it. Gloss of paper is measured by using a Gardner gloss meter, which measures reflected light at an angle of 75 degrees, and is expressed in Gardner gloss units - the higher the number , the glossier the paper surface.
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Grammage.
Another expression of gsm or g/m2 used to express the weight of paper or board (g/m2).
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Grey board.
A board made entirely from waste paper. It can be lined or unlined and is used for a variety of packaging purposes.
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Gummed paper.
Many different papers are used for this quality. Suitable body papers are web coated with various types of adhesive which will adhere to a variety of different surfaces when dampened.
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ISO9000
An international quality standard for industry defining the structure of an organisation, its obligations and authorisations, the structure of production and its ability to manufacture products or to produce services at a continuous quality level in conformity with the standard
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ISO Brightness.
The brightness of paper and board measured at a wavelength of 457 nanometres under standard conditions.
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Integrated mill.
A mill that starts with logs or wood chips and produces wood pulp which it then processes to make paper or board without intermediate drying.
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Internal sizing.
The addition of materials such as rosin and alum to stock, generally in order to increase the resistance of the finished paper to the penetration and spreading of aqueous liquids, eg ink.
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Ivory board.
High quality board with a bright, clear appearance, particulary used for high class printed work. Original Ivory board was and still is made in Holland (Dutch Ivory Board), although the grade is now made in many countries.
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Kraft paper.
Paper made from a particular type of chemical wood pulp, ie kraft pulp. It may be bleached or unbleached and is a strong paper that is largely used for wrapping and packaging.
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Kraft pulp.
Chemical wood pulp produced by digesting wood by the sulphate process. Originally a strong, unbleached coniferous pulp for packaging papers, kraft pulp has now spread into the realms of bleached pulps from both coniferous and deciduous woods for printing papers.
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Label papers.
A large variety of body papers that are made to be qummed, or for application of a self-adhesive material.
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Laminate
A converted product made by combining together suitable paper or board either with other paper or board or with other materials such as plastics or metal foil, generally by means of an adhesive, to form a product with particular qualities.
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Lick coating.
A light form of mineral coating, achieved by supplying the surface sizing press of the papermachine with coating material instead of normal surface sizing solution.
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Lignin.
A substance in wood that binds its fibres together and reinforces its structure. Lignin is removed in the manufacture of chemical pulp.
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Listing paper.
A form of continuous stationery used for computer listings, punched with sprocket holes at the edges and traditionally printed with light green horiziontal lines set to the same pitch as the printing device.
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Machine direction.
The direction in a sheet of paper corresponding to the direction of travel of the forming surface; the majority of the fibres in the sheet position themselves with their lengths parallel to this direction.
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Machine finished.(MF)
Any finish obtained on a papermachine. It can refer to either the finish on the sheet as it leaves the last drying cylinder of the machine, or the finish given to a sheet by calendering, but on machine.
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Machine glazed (MG).
Paper that has one side made smooth and glossy by pressing and drying in contact with a very large, heated, polished metal cylinder which forms part of the drying section of the machine. The other side of the paper remains relatively rough.
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Manila.
Originally paper made from pulp produced partly or entirely of manila hemp, but now mostly composed of softwood kraft pulp. Most frequently employed in industrial uses including the printing industry, especially envelopes.
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Market pulp.
Pulp produced for sale on the open market, as opposed to that produced for consumption in an integrated mill.
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Mechanical paper.
A paper which contains a proportion of mechanically produced wood pulp. These papers enjoy good opacity and caliper, but will yellow with age and tend to be very weak. Newspapers are printed on mechanical papers.
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Mechanical pulp.
Wood defibred to form pulp by means of mechanical energy. Almost 100% of the raw timber is used in making pulp. The process has a higher electricity consumption than chemical pulp production. Mechanical pulp is usually bleached with peroxide. Paper made from mechanical pulp turns brown with age.
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Mill board.
A thick, dense, homogeneous board, made generally from waste paper on an intermittent board making machine, one sheet at a time. Used in binding case bound books or ledgers, as binders' boards.
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Mill conditioned paper.
Paper that has undergone conditioning at the mill to regulate the moisture content and prevent it warping and curling when exposed to the air.
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Mini web reels.
Paper suitable for web offset printing, sometimes coated, which is made into reels for small high speed web printing presses (maximum width about 660mm).
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Moisture content.
The amount of moisture in paper, expressed as a percentage of its weight. A moisture content of around 7 to 8% is recommended for printing papers.
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NCR.
No Carbon Required. This expression, which was introduced by the National Cash Register Company (which formerly owned the patents) has now been superseded by the term carbonless.
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Newsprint.
The relatively low grade paper intended for the printing of newspapers; it is mainly produced from mechanical softwood pulp and recycled fibres.
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Opacity.
The extent to which a paper is capable of obscuring matter printed on the other side or on an underlying page or other surface lying underneath. For example, a sheet with good opacity is one on which the printing on one side cannot be seen from the other under normal conditons. It is expressed as a percentage.
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Packaging.
The material used, or the act or technique of protecting and performing other necessary purposes, so that goods so treated reach their point of usage in perfect condition.
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Papermark.
A mark placed in the paper after it has been made and not during the papermaking process. The mark can be produced through printing, chemical application or embossing. Some marks are good imitations of a watermark but are imitations.
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Parchment.
A sheet of writing material made from animal skin, nowadays usually used to denote vegetable parchment or parchmentised papers. These have a high resistance ot the penetration of grease and atmospheric humidity.
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Permanent paper.
Paper free from mechanical woodpulp or unbleached fibre, generally neutral or alkaline sized, and containing calcium carbonate filler. It is made to controlled pH value and alkali reserve, and is used for the printing of books and sililar works for posterity.
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Plasterboard.
A type of board with a centre layer of gypsum and outer layers of board, used in the building industry.
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Poster paper.
An MG grade with a quick drying surface used for outdoor poster work. The rough underside lends itself to rapid pasting.
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Printings.
A general term used to describe a wide variety of papers and boards to which print is intended to be applied in one form or another.
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Pulp.
A generic term for the cellulose fibre material used in papermaking.
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Pulp board.
Also known as printer' board this grade is made from a single web of pulp on a papermachine, and is produced in various substances.
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Ream.
Five hundred (500) sheets of paper of the same quality, size, and grammage. In earlier times, a ream could also consist of 480 or 516 sheets.
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Reel.
A continuous length of paper wound on a core, irrespective of diameter, width or weight. Reels may thus be rewound into smaller reels or slit into coils.
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Register set.
A small, multipart business form, which as two large punched holes at the head of the form for placing on a writing pad, which has two metal pins to hold the set in position whilst in use.
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Reinforced paper.
Any paper that has been strengthened mechanically by the incorporation of other materials such as plastics, threads, cloth or strips of metal.
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Relative humidity.
Quotient of the amount of moisture in air and the amount that would saturate it at the same temperature and pressure, expressed as a percentage. Standard testing conditions for paper use 23degree c and 50% relative humidity (RH).
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Repro paper.
Sometimes known as baryta paper, this is a speciality grade (usually in substances of around 160g/m2 and 125g/m2) that has a hard sized white coating and good absorbency for quick ink drying.
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Retree paper.
Paper which has become available because of overmaking or side-runs or because it is in some way less than perfect. Although sold without a guarantee the substance and size tolerances would be expected to conform to industry standards. Often referred to as clearance paper.
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Rigidity.
The rigidity of paper or board is measured using a Taber stiffness tester. This operates by measuring the force required to bend a strip of the material to an angle of 15 degrees. Ther greater the force required, the more rigid the material and the higher the value.
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Roll coating.
A method of coating a web of paper in which the coating is applied directly to the paper by transfer from an applicator roll that carries the coating material. The roll may rotate in the same direction as the paper web or in the other direction (reverse roll coating).
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Rollup/Roll back.
The surface of a board delaminates and becomes a tight roll. Always occurs from an edge and usually affects bulky boards. Roll ups inevitably damage printing blankets.
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Security paper.
Paper that includes identification features such as metallic strips and watermarks to assist in detecting fraud and to prevent conterfeiting.
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Self-adhesive paper.
Used essentially for labelling purposes, this grade has a self-adhesive coating on one side and a surface suitable for printing on the other. The adhesive is protected by a laminate that enables the sheet to be fed through printing machines, the laminate subsequently being stripped when the label is applied.
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Semi-chemical pulp
Pulp obtained by partial removal from the raw material of those non-cellulosic components that can be removed by a direct chemical treatment, eg cooking to resolve the fibres; some subsequent mechanical treatment is necessary.
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Short grain.
The fibres in paper naturally take up an alignment roughly parallel to the direction of travel of the web on the papermachine; this becomes the grain direction. When cut, the paper's grain direction may be parallel either to the long edge of the finished sheet (when it is called long grain) or the short edge (short grain). Papers are normally stocked in long grain form, short grain being supplied to special order. The grain direction affects the stiffness in a particular dimension and must be taken into account when planning a job that needs to be folded, as paper usually folds easier with the grain.
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Slitting.
Dividing a web of paper in the length-wise direction into two or more narrower webs. An operation often carried out by converters.
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Smoothness.
The surface smoothness of paper is measured by the Bendtsen smoothness test. The test measures the amount of air escaping between an annular ring and the material surface, and results are measured in ml/min. Papers having a value higher than 50 are usually referred to as Matt, below 50 as Silk (sometimes called satin or velvet).
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Solvent coated paper.
Paper coated by any suitable coating process with resins or plastics dissolved in volatile solvents that are subsequently evaporated.
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Splice
Joint in a web of paper in or approximately in the cross direction, made by an adhesive or an adhesive strip, either in order to obtain a reel of the desired length or to permit, (for example on a converting machine) a continuous operation between the end of one reel and the beginning of the next.
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Stock.
An aqueous suspension of papermaking raw materials from the stage of disintegration of the pulp to the formation of the web or sheet.
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Substance.
The weight of paper or board, shown by scales, taken from a sample. The weight is defined by grammage per square metre of a single sheet (g/m2).
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Supercalendered (SC).
A surface finish or paper that may vary from relatively dull but smooth to highly glazed, produced by passing damp paper through a supercalender stack. This is broadly similar to a machine calender stack except that it is separate from the papermachine and some of the rolls are made of compressed fibre.
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Surface sizing.
The application to the surface of the web, by means of a size press situated in the dryer section of the papermachine, of a suitable solution intended to improve the surface strength of the paper and resist penetration by oil based inks.
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Thermal paper.
The base paper used for thermal papers is first pre-coated and then treated with a special emulsion containing heat sensitive modifiers, co-reactants, pigments and colour formers. The heat from a thermal head (eg in a fax machine) melts the modifier, which in turn dissolves the co-reactant that allows the colour formers and pigments to mix, producing a high contrast image on the paper.
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Thermo mechanical pulp.
A stronger mechanical pulp in which the wood chips are heat treated with steam before refining. In some cases a degree of chemical treatment is employed as well (chemi-thermo mechanical pulp or CTMP).
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Top side.
The side of a web of paper that is uppermost during manufacture, ie opposite to the wire side.
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Twin wire.
A two ply paper or board made on a papermachine with duplicated wire parts. In this way two sheets of the same composition are formed and combined, wire side to wire side, so that the finished sheet has two identical printing surfaces.
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Vegetable parchment.
Paper that has been modified by the action of sulphuric acid, to give it a continuous texture, an increased surface hardness and a high degree of resistance to penetration by organic liquids and particularly fats, oils and greases. The structure also confers on the paper resistance to disentegration by water, even at boiling point.
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Vellum paper.
Vellum paper is strong, tough and of high class appearance. It is made to imitate the fine smooth finish of a parchment made from animal skin.
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Virgin fibre.
Paper or board pulp fibre being used for the first time. (As opposed to recycled or secondary fibre.)
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Volume basis.
An expression used to denote the theoretical thickness in millimetres of 100 sheets of the given paper in 100g/m2. It thus gives an indication of the bulk of the paper.
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Watermark.
A deliberate design or pattern in paper that is visible when viewed by transmitted light or against a contrasting background, made by a dandy roll at the wet end of the papermachine.
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Web.
The term given to the continuous piece of paper that passes through all the processes of a papermachine before being wound onto the jumbo reel.
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Wet end.
The first stages of a papermachine, before the drying process, where much of the high percentage of water in the stock is eliminated by drainage, suction and pressure. A web of paper is left, which then passes to the drying cylinders.
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Wire side.
The face of a web or sheet of paper that was in contact with the forming wire during manufacture.
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Woodfree.
A pulp or paper that contains no mechanical wood pulp. In commercial practise, a small percentage of mechanical fibre is usually acceptable. It does not denote paper or pulp made from materials other than wood.
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