Paper - Glossary of Terms

• ABSORBENCY The extent to which a paper will take up and hold a liquid.

• ACID-FREE PAPER In principle, paper which does not contain any free acid. Special precautions are taken during manufacture to eliminate any active acid that might be present in the fl.irnish.

• ADDITIVE A mineral, chemical or dye added to pulp and coatings to give it special qualities such as opacity.

• AIR DRIED PAPER Paper dried by exposure to air, generally warm.

• AIR-DRY PULP Technically, pulp of which the moisture content is in equilibrium with the 5mbient atmosphere. Commercially, pulp at a theoretical moisture Content agreed between the buyer and the seller (e.g. loper Cent is common).

• AIR-KNIFE COATED PAPER Paper coated by a process where the freshly applied wet coating is smoothed and the excess removed by means ofajet of air discharged from a slit orifice placed at an angle to the web.

• AIRMAIL PAPER Paper made in the lightest substance consistent with strength and a good surface, ~ reasons of'io~ca"e ccsi~. Generally pmdieed in white, off white as a pak ldi~e far ststionery purposes, isially b~l.uw 40g/m². Manifolds and lightweight bonds are also often known as airmail papers.

• ALUM A term commonly, but incorrectly, applied in the papei industiy to various qualities of aluminium sulphate.

• ANTIQUE A characteristic low degree of surface finish which typifies certain commercial descriptions of paper such as Antique Wove, Antique Laid etc.

• ANTI-RUST PAPER Paper containing added substances which give it the property of protecting the surfaces of ferrous metals against rusting.

• ANTI SET-OFF SPRAY A device used on the delivery end of the printing machine to prevent set-off by projecting a fine spray, of liquid or powder, at the sheet.

• AOX Adsorbable Organic Halogens. AOX expresses the amount of organic chlorine compounds in effluent produced as the chlorine chemicals react with the residual lignin (q.v.) in the bleaching of pulp. A safe AOX limit is easier to achieve using chlorine dioxide than with chlorine.

• APPARENT DENSITY The quotient of the grammage of a paper and its thickness in micrometres.

• ART PAPER This is a generic term given to woodfree coated papers, which has traditionally referred to papers in the upper quality bracket and which have a high polished surface. Today the term is less used because of the introduction of more categories in the sector. However, 'Real Art' is still used for those woodfree coated papers, gloss or matt, which are considered to be of the very highest quality.

• ASH CONTENT The amount of residue when a sample of paper is burned under controlled conditions so that all ignitable matter is removed. The ash derives from the mineral loading in the p~it'er

• BACK-UP To print on the reverse side of a printed sheet.

• BACKWATER The liquid which passes through the forming surface when stock is deposited upon it. It is essentially ~vater, but generally contains dissolved matter or suspended matter such as fines, filler, etc. Backwater is normally recirculated within the paper making process, or sent to treatment plant for the recovery of materials in suspension.

• BAGASSE PULP Pulp obtained by chemical means from bagasse, the residue after extracting the juice from sugar cane.

• BAMBOO PULP Pulp obtained by chemical means from the stems of bamboo, a type of grass common to Asiatic countries.

• 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 a substance of about 6Og/m~, are often used for correspondence and letterheads, and are known as bonds, while the lighter weights called banks used largely for file copy papers have less use today with the introduction of the automated office.

• BARI~ WASTE A major source of energy for pulp mills. The raw timber is debarked before chipping, the bark being recovered and burnt at a steam power plant.

• BASE PAPER Paper intended to be converted, e.g. by a coating process or by impregnation. Term sometimes used also for paper to which a layer of other material (aluminium, plastics, etc.) is bonded. Also called Body Paper or Rawstock.

• BEATING OR REFINING The mechanical treatment of fihrous materials in a beater or refiner to modify certain of their characteristics in order to give them the properties necessary for the manufacture of a desired quality of paper.

• BIBLE PAPER Very thin printing papers. Originally made specifically for bibles and prayer books, this grade of paper is also used for other commercial purposes, such as dictionaries, where many pages are required with an overall low volume. Bible paper is also known as India paper.

• BINDER The adhesive used to stick the layers ccl coating together and to the paper or board surface. 1he most frequently used binder ~s ctareb but synthetic binders are also 'tsed to give inipro'ed perforrniitt~.c.

• BIODEGRADABLE A substance which ssill decontpose as the result of action by bacteria and other living organisms.

• BIOLOGICAL OXYGEN DEMAND (BOD) This expresses the amount of dissolved oxygen consumed by micro-organisms as they decompose organic material in polluted or natural water, The higher the amount of decomposable material, the higher the BOD value.

• BIOLOGICAL WASTE WATER TREATMENT A variety of methods are used by pulp and paper mills for purifying their waste water (such as the activated sludge method) in which natural microorganisms decompose the organic substances. The organisms constitute a nutrient cycle consisting of bacteria. protozoa and higher organisms. The method reduces the biological oxygen demand by over 95% and removes about 50% of the organic compounds from effluent, organic chlorine compounds included.

• BLACKENING Defect associated with calendered paper occurring as unintended local areas of apparently darker or greyer colour due, for example, to the paper being too damp when passed through the calender.

• BLADE COATED PAPER Paper coated by a process in which the freshly applied wet coating is smoothed and the excess removed by a thin, flexible metal blade which bears on the coated surface.

• BLANKET CYLINDER The cylinder on a printing machine covered with a rubber (or similar) blanket, which conveys the image from the plate to the sheet.

• BLANKET-TO-BLANKET MACHINE A printing machine in which the blanket cylinders act as opposing impression cylinders, so allowing both sides of the web or sheet to be printed simultaneously.

• BLEED Thepart of a printed imaged iraiage baycad the create which the finished print will be cut.

• BLISTER PACK This term describes a packaging system which is a combination of board and plastics. The product is sealed to the board by a transparent plastics film. This system is often used for small products of difficult shapes and sizes.

• BLOTTINGS Highly absorbent papers which can be watermarked, white or in colours. With the advent of the ball-point pen, the original use where hand writing ink is absorbed has greatly reduced demand.

• BOARD Heavy weight paper. The line of demarcation between paper and board is indeterminate. For many purposes it is taken as 220 or 225g/m² but many products below these levels are described, commercially, as board. BOD7 The biological oxygen demand (q.v) of a waste water sample, measured over seven days' exposure (c.f. BOD5,BODIO).

• BOND See Banks and Bonds

• BREAKING LENGTH The calculated limiting length of a strip of paper of any uniform width, beyond which, if such a strip were suspended by one end, it would break by its own mass.

• BROKE Paper and pieces of paper arising at any point in the mill which are suitable only for repulping, e.g. wet paper removed from the paper machine or dry paper arising as trimmings etc., faulty paper etc.

• BRUSH COATING A method of coating a web of paper in which the applied coating slip is distributed and smoothed by means of brushes, some stationary and some oscillating across the web.

• 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-wrapped.

• BULKY MECHANICAL A mechanical paper made to a specific caliper as opposed to a fixed grammage. Typical calipers are 102 and 127 microns. This type of paper, used mainly for mass market paperback books, also has several uses when converted, such as cash register rolls.

• BULKY PAPER Paper which appears to be thick in relation to its grammage.

• BURST FACTOR The quotient of the bursting strength of a paper and its oven-dsy grammage as defined in the standard method of test.

• BURST INDEX The quotient of the bursting strength of a paper and its grammage in the conditioned state as defined in the standard method of test.

• BURSTING STRENGTH The pressure necessary to rupture a sample of paper fixed horizontally between two ring clamps.