- NBHK Northern Bleached Hardwood Kraft. An important variety of market pulp, produced chiefly from birch trees, it is brighter than NBSK but not as strong.
- NBSK Northern Bleached Softwood Kraft. One of the chief varieties of market pulp, produced mainly from spruce trees from Scandinavia, Canada and north-eastern USA. It consists of longer (hence stronger) fibres than NBHK.
- 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expression, which was introduced by the National Cash Register company (which formerly owned the patents), has now been superseded by the term Carbonless (q.v.).
- NEWSPRINT The relatively low grade paper intended for the printing of newspapers; it is mainly produced from mechanical softwood pulp and recycled fibres.
- OCR PAPER (Optical Character Recognition Paper) Similar to MICR Paper (q.v.), a high-quality bond paper of good surface and dimensional stability for printing with characters for computer recognition.
- OFF-MACHINE COATED PAPER Base paper to which a mineral coating has been applied on a coating machine separate from the paper making machine.
- OFFSET BLANKET A covering for a cylinder on a printing machine for accepting the ink image and then transferring it to the surface to be printed.
- OFFSET LETTERPRESS See DRY-OFFSET
- OFFSET PRINTING A method of printing in which the image on the plate is transferred to the final substrate via an intermediate surface.
- OFFSIDE LAY The sidelay opposite to the operating side of a printing machine.
- ON-MACHINE COATED PAPER Paper which has been coated with mineral matter by coating equipment installed as an integral part of the paper making machine.
- ON-MACHINE COATING The process of covering the surface(s) of a paper with one or more layers of coating slip or
- other materials in fluid form, without recourse to a separate operation, the necessary equipment being an integral part of the making machine.
- OPACITY The extent to which a paper is capable of obscuring matter printed on the verso or on an underlying page or other surface.
- OPTICAL BLEACHING See FLUORESCENT WHITENING AGENT
- OUT TURN SHEET A sheet of paper, taken during manufacture, serving as a reference for the mill or client.
- OXYGEN BLEACHING A method of reducing the lignin content of pulp by introducing oxygen in an alkaline environment, thereby reducing the need for other chemicals in final bleaching.
- OZONE BLEACHING A method in which the lignin content of pulp is reduced by means of ozone, a triatomic form of the element oxygen. Used in combination with oxygen and hydrogen peioxide, it can with present-day technology produce almost white pulp without any chlorine chemicals. A toxic gas, it has to be removed from the exhaust gases.
- PACKAGING The paper and board used for wrapping or packing goods.
- PAPYRUS An ancient writing material made from the stem of the papyrus plant, an African reed. Although the word ~paper’ is derived from papyrus, papyrus is not paper.
- PARCHMENT A sheet of writing material made from animal skin, nowadays usually used to denote Vegetable Parchment (q.v), or parchmentised papeis. These have a high rcsistaikcc to the penetration of grease and atmospheric humidity. Used largely for wrapping purposes, there are also grades of imitation parchments which are less impervious. Similar to greaseproof paper (q.v.). See also Vellum Paper.
- PASTEBOARD This grade of board consists of one or more layers, usually of pulp board, pasted together. It may be lined both sides with paper of one type or another, depending on end use.
- PERFECTING Printing both sides of the substrate at the same pass through a printing machine.
- PERMANENT PAPER Paper free from mechanical woodpulp or unbleached fibre, generally neutral/alkaline sized and containing calcium carbonate filler, made to controlled pH value and alkali reserve, intended for the printing of books and similar works for posterity.
- PERNICIOUS CONTRARIES Any material present in waste paper that is difficult to see or detect and which might be detrimental to the paper being manufactured from the wastepaper or which might either damage paper making equipment or render repulping difficult.
- PHLOROGLUCINOL SOLUTION An acidic spot test reagent for paper that produces a red coloration in contact with lignified fibre.
- PHOTOSETTING The process of composing text matter directly Onto a photographic or other light sensitive material.
- pH VALUE A number on a logarithmic scale extending from 0.3 to 14.5 which indicates the active acidity or alkalinity of an aqueous liquid. Neutrality is represented by pH 7.07, figures descending below this reading indicating increasing amounts of acidity, and those above, alkalinity.
- PICKING The rupture of the surface of a paper during manufacture or during printing, which occurs when an external tensile force applied to the surface is greater than the cohesion of the paper.
- PIPING Defect in reels, consisting of ridges running around the circumference, due to moisture take-up by the surface layers.
- PLASTERBOARD A type of board with a centre layer of gypsum and Outer layers of board, used in the building industry.
- PLATE CYLINDER The cylinder in a printing unit to which printing plates are fixed.
- POSTER PAPER An MG grade with a quick drying surface used for outdoor poster work. The rough underside lends itself to rapid pasting.
- PRESSPAHN This is a German word used to describe a grade of board used for a variety of purposes, often industrial. It is of a light weight, extra hard, rolled and friction glazed.
- PRESSURE SENSITIVE COATED PAPER Paper coated with a self-adhesive material which in dry form (solvent free) is permanently tacky at room temperature. A bond with the receiving surface maybe formed by the application of pressure (e.g. by the finger or hand). A permanent adhesive is characterised by relatively high ultimate adhesion and a removable adhesive by low ultimate adhesion. Until the time of application, the adhesive surface should be covered by a suitable release coated paper.
- PROOF A pre-production print, made for the purpose of checking the accuracy of lay-out, type matter, tone and colour reproduction.
- PULP Chemical pulp is made from a cellulose raw material (usually wood) by treating it (cooking) with chemicals to separate the cellulose fibres and dissolve the lignin, etc., which binds them together; it can be bleached or unbleached. Mechanical pulp is made from wood by purely mechanical means, i.e. grinding or refining of chips; lignin and other impurities are not removed, and further processing (bleaching) is required if a white sheet is required. Fibre obtained from wood by either of the above methods is called primasy, or virgin, fibre. Some pulping processes involve both methods and also include heat treatment.
- PULP BOARD Also known as Printers’ Board, this grade is made from a single web of pulp on a paper making machine, and is produced in various substances. Used for index cards and other general products, these boards may be white or coloured.
- PULPER Any apparatus intended for slushing pulp or paper.